Faculty Profiles - YAMAZATO Takaya

Image sensor communication and its transmitting devices Reviewed

Zhengqiang Tang, Takaya Yamazato

Optics Communications 2023.8

Achieving Successful VLC Signal Reception Using A Rolling Shutter Image Sensor While Driving at 40 km/h Reviewed

Shunki Kamiya, Zhengqiang Tang, Takaya Yamazato, Masayuki Kinoshita, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

IEEE Photonics Journal Vol. 15 ( 4 ) 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper presents the successful reception of visible light communication (VLC) signals, transmitted from an LED array, by an image sensor that utilizes a rolling shutter while driving at 40 km/h. The rolling shutter image sensors used in commercial cameras, such as those found in smartphones and dashcams, capture images line by line at a fast rate, allowing for VLC signal reception in vehicular environments. By analyzing the relationship between the signal reception rate for each line and the frame rate, we demonstrate that parallel VLC signals transmitted from the LED array can be received even while in motion. Notably, to our knowledge, this is the first time that an automobile moving at 40 km/h has successfully received a VLC signal.

DOI： 10.1109/JPHOT.2023.3287211

Simultaneous Visible Light Communication and Ranging Using High-Speed Stereo Cameras Based on Bicubic Interpolation Considering Multi-Level Pulse-Width Modulation Reviewed

Ruiyi Huang, Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E106A ( 7 ) page： 990 - 997 2023.7

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATION ENGINEERS

Visible light communication (VLC) and visible light rang-ing are applicable techniques for intelligent transportation systems (ITS). They use every unique light-emitting diode (LED) on roads for data trans-mission and range estimation. The simultaneous VLC and ranging can be applied to improve the performance of both. It is necessary to achieve rapid data rate and high-accuracy ranging when transmitting VLC data and esti-mating the range simultaneously. We use the signal modulation method of pulse-width modulation (PWM) to increase the data rate. However, when using PWM for VLC data transmission, images of the LED transmitters are captured at different luminance levels and are easily saturated, and LED saturation leads to inaccurate range estimation. In this paper, we establish a novel simultaneous visible light communication and ranging system for ITS using PWM. Here, we analyze the LED saturation problems and ap-ply bicubic interpolation to solve the LED saturation problem and thus, im-prove the communication and ranging performance. Simultaneous commu-nication and ranging are enabled using a stereo camera. Communication is realized using maximal-ratio combining (MRC) while ranging is achieved using phase-only correlation (POC) and sinc function approximation. Fur-thermore, we measured the performance of our proposed system using a field trial experiment. The results show that error-free performance can be achieved up to a communication distance of 55 m and the range estimation errors are below 0.5 m within 60 m.

DOI： 10.1587/transfun.2022EAP1078

Exposure Synchronization in Optical Camera Communications for Time Division Multiplexing Reviewed

Hiroaki Matsunaga, Tomohiro Yendo, Shintaro Arai, Takaya Yamazato

IEEE Photonics Journal Vol. 15 ( 2 ) 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Optical camera communication (OCC) is a type of visible light communication that employs a camera as the receiver. Various flicker-free OCC methods using a general-purpose low-frame rate camera have been proposed. In particular, the undersampling method uses a short exposure camera and a light-emitting diode that blinks faster than the camera's frame rate. Despite the short exposure time, the transmitter has to send a symbol for a frame period or longer because the relationship between the symbol timing of the transmitter and exposure timing of the receiver is indeterminate. We propose resolving this indeterminacy by synchronizing the exposure timing to the transmitter. In the proposed method, the transmitter sends multiple data channels in a frame period by time division multiplexing, and the receiver selects a channel. Then, a single symbol of multilevel phase shift keying is extracted from a single pixel value in a frame. Experiments confirmed that the exposure timing could be synchronized even with a degraded signal-noise ratio and that the receiver could select the desired channel. The proposed method achieved a bit error rate of 10(-6)at a signal-noise ratio of 46.2 dB under various modulation schemes.

DOI： 10.1109/JPHOT.2023.3247908

$M$-Point Combinatory for Parallel Transmission Image Sensor-Based Visible Light Communications Reviewed

Takumi Sato, Koji Kamakura, Masayuki Kinoshita, Takaya Yamazato

Journal of Lightwave Technology 2023.1

High-Speed Image Sensor Com-munication Using High Dy-namic Range Combining Reviewed

Ruiyi Huang, Takaya Yamazato, Masayuki Kinoshita, Hiraku Okada, Shintaro Arai, Koji Kamakura, Tomohiro Yendo, Toshiaki Fujii

IEICE COMMUNICATIONS EXPRESS Vol. 12 ( 9 ) page： 493 - 498 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATION ENGINEERS

An essential issue in image sensor communication (ISC) is reliable and high-speed data transmission. In order to increase the data rate, this study uses pulse-width modulation (PWM). However, the symbol decision for PWM will become challenging with increasing numbers of luminance levels because of pixel saturation. In this study, we mitigate the pixel saturation problem by achieving high dynamic range (HDR) using two high-speed image sensors with varied exposure settings. Furthermore, we proposed HDR combining for signal demodulation. The field trial experiment results show that a throughput of higher than 87.5 kbps within the communication distance of 50 m can be achieved.

DOI： 10.1587/comex.2023XBL0075

Experimental Demonstration of Optical OFDM With Polarity-Separated Transmission in Rolling Shutter Based Visible Light Communication Reviewed

Hiroshi Shimizu, Kota Kanata, Masayuki Kinoshita, Koji Kamakura, Shintaro Arai, Takaya Yamazato

2023 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS, ISCAS 2023

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Using a rolling shutter camera as a receiver, visible light communication (VLC) can achieve a significantly higher sampling rate than the frame rate because of its sequential exposure mechanism. This study focuses on optical orthogonal frequency division multiplexing (OFDM) in a rolling shutter based VLC for further high-speed data rates. Because an image sensor is employed, conventional optical OFDM, such as DC-biased optical OFDM (DCO-OFDM), must fit in the grayscale range of 0-255 levels. Therefore, DCO-OFDM suffers from poor error performance owing to its high PAPR. To address this problem, we propose a polarity-separated transmission, in which the bipolar OFDM signal is separated into positive and negative parts and then transmitted by two LEDs simultaneously. Polarity-separated transmission is expected to double the grayscale range, i.e. 0-511, and improve error performance because it reconstructs the original bipolar signal by combining the received signals from two LEDs. We experimentally demonstrate and compare the symbol error rate (SER) performance of DCO-OFDM and polarity-separated transmissions. Consequently, polarity-separated transmission improved the SER performance by 10(-2) in the fundamental frequency range of 300-700Hz when 16-PSK was adopted for subcarrier modulation.

DOI： 10.1109/ISCAS46773.2023.10181518

An Experimental Study on A Noise-aided 1-bit ADC Receiver for 4-PAM Reviewed

Zheng Jinxing, Yamazato Takaya, Saito Masato

IEICE Communications Express Vol. advpub ( 0 ) 2022.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

1-bit analog-to-digital converters (ADCs) have low power consumption and can easily speed up the analog-to-digital conversion and sampling. However, due to their resolution of only 1 bit, the nonlinearity between the input with multiple amplitude levels and output is large. With the method of utilizing noise proposed in previous studies, 1-bit ADCs can be linearized to demodulate signals with multi-level amplitude modulation like pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM). In this letter, we construct a receiver circuit using a 1-bit ADC, evaluate its performance, and show its availability through demodulation experiments on 4-PAM signals.

DOI： 10.1587/comex.2022COL0032

Noise-assisted nonlinear estimation of a one-bit ADC output and its application to a multi-antenna receiver Reviewed

Masato Saito, Yasuo Nakashima, Takaya Yamazato, Shintaro Arai, Hiroyuki Hatano, Hiroya Tanaka, Yukihiro Tadokoro

2022.4

Simplified Alamouti-Type Space-Time Coding for Image Sensor Communication Using Rotary LED Transmitter Reviewed

Zhengqiang Tang, Shintaro Arai, Takaya Yamazato

IEEE Photonics Journal Vol. 14 ( 1 ) 2022.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This study proposes a simplified Alamouti-type space-time coding (STC), improving the performance of image sensor communication (ISC) using a rotary LED transmitter. The rotary LED transmitter was developed to increase the data rate of ISC using afterimages of LED lights. The transmitter simultaneously causes the LEDs to blink and rotates them around a vertical axis. Owing to the movement of the blinking LEDs that occurs within the exposure time of the camera, multiple blinking states are captured as afterimages, thus increasing the amount of information that can be received per image. However, with increasing communication distance, the size of the LED light captured on the image sensor decreases. In this case, it is difficult to distinguish each LED blinking state, leading to a degradation of the demodulation performance. To overcome this problem, the proposed STC encodes adjacent angular afterimages as symbol pairs and transmits these symbol pairs using two symbol times. In addition, we simplified the data decoding process by using normalized LED luminance values. We evaluate the demodulation performance of the proposed method through experiments. Compared with conventional coding methods, the proposed STC requires no channel estimation and significantly improves the demodulation performance.

DOI： 10.1109/JPHOT.2021.3137601

A Preliminary Investigation For Event Camera-Based Visible Light Communication Using The Propeller-type Rotary LED Transmitter Reviewed

Zhengqiang Tang, Takaya Yamazato, Shintaro Arai

2022 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS) page： 646 - 650 2022

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This study investigates a new communication scheme for the event camera-based visible light communication (VLC) using a propeller-type rotary LED transmitter. Conventional camera-based VLC suffers from low data rates and high latency due to the limited camera frame rates. To solve this problem, the event camera has been used as the receiver in VLC. Event cameras detect changes in brightness and asynchronously output these changes as events in microsecond order. The high temporal resolution gives the event camera-based VLC good potential in terms of high speed and low latency. However, when an event camera is used as the VLC receiver, the light of the transmitter needs to be changed constantly. If the transmitter LED is continuously in the same blinking state, the event camera may not output any events and the data could not be recovered until the blinking state changes. To transmit the optical signal for event cameras, we use a propeller-type rotary LED transmitter, which is under development, for the event camera-based VLC. The transmitter rotates the blinking LED in circles and uses the afterimage of LED light to transmit signals. The event camera detects the afterimages and constantly outputs them as a stream of events. We filter the noise events and recover data using signal events. This study verifies the operation for the proposed system through an implementation experiment. As a result, we achieved the communication in the proposed system and provided a basic evaluation of communication quality.

DOI： 10.1109/ICCWORKSHOPS53468.2022.9814467

Roadside LED array acquisition for road-to-vehicle visible light communication using spatial-temporal gradient values Reviewed

Kento Nakamura, Ruiyi Huang, Takaya Yamazato, Masayuki Kinoshita, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

IEICE COMMUNICATIONS EXPRESS Vol. 11 ( 8 ) page： 462 - 467 2022

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATION ENGINEERS

Most of the previous research on the acquisition of the LED Array transmitter assumes that the onboard receiver approaches the LED transmitter from the car's front. In this study, we considered a case where the vehicle's receiver crosses the LED transmitter. This letter modifies the algorithm using spatial-temporal gradient values to detect LED arrays. As a result, we achieved error-free acquisition and successfully communicated up to 9728 [bits] at a vehicle speed of 25 [km/h].

DOI： 10.1587/comex.2022TCL0008

Luminance Inversion for Parallel Transmission Visible Light Communication Between LCD and Image Sensor Camera Reviewed

Kotomi Takahashi, Koji Kamakura, Masayuki Kinoshita, Takaya Yamazato

Journal of Lightwave Technology 2021.11

Vehicle distance measurement based on visible light communication using stereo cameras Reviewed

Ruiyi Huang, Takaya Yamazato, Masayuki Kinoshita, Hiraku Okada, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

IEEE Intelligent Vehicles Symposium, Proceedings Vol. 2021-July page： 853 - 858 2021.7

Publishing type：Research paper (international conference proceedings)

Visible light communication based intelligent transportation systems (ITS-VLC) show great potential for future urban mobility. This study presents a performance evaluation of range estimation between vehicles and infrastructures in an ITS-VLC system. In the proposed ITS-VLC system, it is easy to simultaneously conduct communication and ranging using stereo cameras. However, the stereo camera calibration becomes a problem during simultaneous communication and ranging due to vehicle vibration. Using the data from LED transmitters and stereo cameras, it can obtain multiple measurements of distance. The monocular-stereo fusion algorithm is applied to visible light ranging in the proposed scheme using particle swarm optimization. We employed real data from the field trial experiment and achieved a ranging accuracy of 60 ± 1.0 m.

DOI： 10.1109/IV48863.2021.9575534

Special section on intelligent transport systems Reviewed

Saho K.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E104A ( 2 ) 2021.2

Optical Wireless Communication: A Candidate 6G Technology? Reviewed

Shintaro Arai, Masayuki Kinoshita, Takaya Yamazato

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E104A ( 1 ) page： 227 - 234 2021.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We discuss herein whether an optical wireless communication (OWC) system can be a candidate for post 5G or 6G cellular communication. Almost once per decade, cellular mobile communication is transformed by a significant evolution, with each generation developing a distinctive concept or technology. Interestingly, similar trends have occurred in OWC systems based on visible light and light fidelity (Li-Fi). Unfortunately, OWC is currently relegated to a limited role in any 5G scenario, but the debate whether this is unavoidable has yet to be settled. Whether OWC is adopted post 5G or 6G is not the vital issue; rather, the aim should be that OWC coexists with 5G and 6G communication technologies. In working toward this goal, research and development in OWC will continue to extend its benefits and standardize its systems so that it can be widely deployed in the market. For example, given that a standard already exists for a visible-light beacon identifier and Li-Fi, a service using this standard should be developed to satisfy user demand. Toward this end, we propose herein a method for visible-light beacon identification that involves using a rolling shutter to receive visible-light communications with a smartphone camera. In addition, we introduce a rotary LED transmitter for image-sensor communication.

DOI： 10.1587/transfun.2020WBI0001

Circuit Experiment of Photodiode-type Visible Light Communication Using the Stochastic Resonance Generated by Interfering Light Noise Reviewed

Shintaro Arai, Wataru Tamura, Takaya Yamazato, Hiroyuki Hatano, Masato Saito, Hiroya Tanaka, Yukihiro Tadokoro

2021 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS (ISCAS) Vol. 2021-May 2021

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This study focuses on visible light communication (VLC) using a photodiode as a receiver. Accurate data transmission by this type of VLC is a challenge because the photodiode cannot detect weak light of subthreshold intensity owing to its insufficient light sensitivity. To overcome this problem, we employ a stochastic resonance, which is a nonlinear phenomenon in which the response characteristics of a system improve as its noise intensity increases, for the receiver of this VLC system. We also employ additive light-emitting diode light, which interferes in the photodiode as intentional noise. As an experimental result, the stochastic resonance was achieved by setting the parameters of the noise source appropriately, and we recovered the weak transmitting signal at the receiver.

DOI： 10.1109/ISCAS51556.2021.9401452

Comparison of distance performances of modulation schemes in intelligent transport system image sensor communication Reviewed

Takuya Yamamoto, Takaya Yamazato, Hiraku Okada, Masayuki Kinoshita, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

IEICE COMMUNICATIONS EXPRESS Vol. 10 ( 8 ) page： 498 - 504 2021

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This study describes intelligent transport image sensor communication (ITS-ISC) systems that use LED arrays as transmitters that imitate traffic lights. Three signal-transmission schemes -luminance modulation, spatial modulation, and combined luminance and spatial modulation- use LED array. However, their suitability for ITS-ISC has not been explored yet. Therefore, we compare the communication performance of these three systems under strong saturation and present the results.

DOI： 10.1587/comex.2021ETL0032

Deep Learning Detection for superimposed control signal in LEO-MIMO Reviewed

Okema R.

2020 IEEE Global Communications Conference, GLOBECOM 2020 - Proceedings Vol. 2020-January 2020.12

Performance Evaluation of Range Estimation for Image Sensor Communication Using Phase-only Correlation Reviewed

Ruiyi Huang, Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

2020 IEEE Globecom Workshops, GC Wkshps 2020 - Proceedings 2020.12

Publishing type：Research paper (international conference proceedings)

Stereo cameras, serving as the 'eyes' of automotive vehicles, can determine the distance between objects and the vehicles. In this paper, stereo cameras are introduced into image-sensor-based visible light communication (IS-VLC) systems, in which the combination of VLC and stereo ranging shows promising prospects for intelligent transport systems. However, one of the problems of IS-VLC stereo ranging is that the luminance level of LEDs in the captured images would greatly affect disparity estimation, which would result in inaccurate range estimation. This paper gives the performance evaluation of this problem using phase-only correlation algorithm with luminance selection. The proposed scheme using stereo cameras exhibited a ranging accuracy of 60± 0.15m in static conditions.

DOI： 10.1109/GCWkshps50303.2020.9367540

Estimation for direction of signal arrival based on area density of estimated lines for ultrasonic sensor array Reviewed

Morita E.

2020 IEEE 9th Global Conference on Consumer Electronics, GCCE 2020 page： 333 - 335 2020.10

Sequential maximum likelihood decoding incorporating reliability determination for image sensor communication Reviewed

Zhengqiang Tang, Shintaro Arai, Tomohiro Yendo, Di He, Takaya Yamazato

IEICE Communications Express Vol. 9 ( 8 ) page： 365 - 370 2020.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this study, the sequential maximum likelihood decoding (S-MLD) for image sensor based visible light communication, referred to as image sensor communication, is proposed. The conventional system cannot correctly decode degraded captured images. To overcome this problem, S-MLD partitions the LED area on the image into two segments and sequentially creates pseudo-captured images, which imitate all possible LED blinking patterns. This approach is based on MLD for each segment. Moreover, reliability determination is incorporated to improve communication quality. We performed computer simulations and confirmed that S-MLD exhibits superior decoding performance and approximately 90% computational cost reduction compared to the previous MLD.

DOI： 10.1587/comex.2020XBL0058

Nonlinear Transform for Parallel Transmission for Image-Sensor-based Visible Light Communication Reviewed

Takahashi K.

IEEE International Conference on Communications Vol. 2020-June 2020.6

Visible Light Communications for Automotive Intelligence Reviewed

Yamazato T.

2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings 2020.3

BER Measurement for Transmission Pattern Design of ITS Image Sensor Communication Using DMD Projector Reviewed

Arisue T.

2020 IEEE 17th Annual Consumer Communications and Networking Conference, CCNC 2020 2020.1

Nonlinear Transform for Parallel Transmission for Image-Sensor-based Visible Light Communication Reviewed

Takahashi Kotomi, Kamakura Koji, Kinoshita Masayuki, Yamazato Takaya

ICC 2020 - 2020 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) 2020

Visible light communications for automotive intelligence Reviewed

Yamazato T.

Optics InfoBase Conference Papers Vol. Part F174-OFC 2020 2020

Stereo ranging method using led transmitter for visible light communication Reviewed

Masayuki Kinoshita, Koji Kamakura, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shitaro Arai, Tomohiro Yendo

2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings 2019.12

Publishing type：Research paper (international conference proceedings)

This paper focuses on high-speed stereo cameraã receivers for visible light communication (VLC) in intelligent transport systems (ITSs), contrary to conventional studies where a single (high-speed) camera is used. An advantage of high-speed stereo cameras as VLC receivers is that both front-facing ranging and wireless communication can be achieved in one device. In this paper, utilizing features of VLC, we consider stereo ranging with high accuracy. Moreover, it is known that an LED transmitter for VLC has specific features, high-luminance and high- speed blinking. This paper proposes stereo ranging by applying LED transmitter detection (utilizing these features) to disparity estimation. Additionally, we introduce subpixel estimation using equiangular line fitting to obtain more accurate disparity. Finally, we experimentally demonstrate that the proposed stereo ranging achieves an accuracy of 60 m Â± 0.1 m.

DOI： 10.1109/GLOBECOM38437.2019.9013641

Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time Reviewed

Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time Reviewed

Takuya Mitani, Takaya Yamazato, Katsuhiro Naito, Yuki Mori

IEEE International Conference on Connected Vehicles and Expo:ICCVE 2019 2019.11

Mitani T., Yamazato T., Naito K., Mori Y.

2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings 2019.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings

Emergency services around the world face the problem of increasing patient transportation times. The operation of emergency vehicles is fundamentally different from that of general vehicles; hence, algorithms recommending optimal routes in a conventional way are not always applicable to emergency vehicles. In this study, we analyzed data of inter-vehicle and road-vehicle communication collected at 700 MHz band intelligent transport systems and demonstrated that the overall travel time of emergency vehicles can be reduced by decreasing their travel time at intersections.

DOI： 10.1109/ICCVE45908.2019.8965232

Direct wireless link to out-of-range node with assistance of surrounding nodes Reviewed

Hiroya Tanaka, Shintaro Hiraoka, Shintaro Arai, Takaya Yamazato, Yukihiro Tadokoro

IEEE Transactions on Vehicular Technology Vol. 68 ( 11 ) page： 10703 - 10712 2019.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We propose a method that establishes a direct wireless link from a transmission source to an out-of-range destination with the assistance of the surrounding communication nodes. In this method, a weak (subthreshold) signal is amplified by utilizing the interference signals transmitted from the surrounding communication nodes. To evaluate the amplification gain, we study the mutual information in a multipath fading channel. As a result, we reveal that the mutual information is enhanced owing to the interference signals, and the proposed method enlarges the radio coverage area of the source node. To understand the enhancement mechanism, we introduce a toy model of the propagation channel and discuss the role of the interference signals. We find that the interference signals allow the subthreshold signals into the detectable region in the signal space. Moreover, the mutual information is maximized at the optimal power of the interference signals. In addition, a detailed discussion of the channel capacity shows that there exists an optimal a priori probability of symbol transmission.

DOI： 10.1109/TVT.2019.2934502

Proposal for identification scheme of driver and impostor based on acceleration data Reviewed

Proposal for Identification Scheme of Driver and Impostor based on Acceleration Data Reviewed

Yuki Mori, Ryota Ono, Takuya Mitani, Katsuhiro Naito, Takaya Yamazato

IEEE International Conference on Connected Vehicles and Expo:ICCVE 2019 2019.11

Mori Y.

2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings 2019.11

Noise-aided demodulation of direct spread-code division multiple access signals with a 1bit analog-to-digital converter Reviewed

Yasuo NAKASHIMA, Takaya YAMAZATO, Shintaro ARAI, Hiroya TANAKA, Yukihiro TADOKORO

IEICE TRANSACTIONS on Communications Vol. J102-B ( 8 ) 2019.8

High performance demodulation method with less complexity for image-sensor communication Reviewed

Ohira Yuki, Yendo Tomohiro, Arai Shintaro, Yamazato Takaya

OPTICS EXPRESS Vol. 27 ( 15 ) page： 21565 - 21578 2019.7

MD2.3-visible light communication and ranging system using high-speed stereo cameras (Invited) Reviewed

Kinoshita M.

IEEE Photonics Society Summer Topical Meeting Series 2019, SUM 2019 2019.7

{For the applications of Stochastic resonance in the telecommunications Reviewed

IEICE TRANSACTIONS on Communications Vol. J102-B ( 6 ) page： 445 - 458 2019.6

Maximum Likelihood Decoding Based on Pseudo-Captured Image Templates for Image Sensor Communication Reviewed

Shintaro ARAI, Haruna MATSUSHITA, Yuki OHIRA, Tomohiro YENDO, Di HE, Takaya YAMAZATO

Nonlinear Theory and Its Applications, IEICE Vol. 10 ( 2 ) page： 173 - 189 2019.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper focuses on an image sensor communication system that uses an LED as the transmitter and a high-speed image sensor (camera) as the receiver. Communication in this scheme depends on the quality of images transmitted from the LED to the sensor. If the image becomes unfocused on the way to the receiver, the LED luminance that make up the signal cannot be detected, so the receiver cannot demodulate the signal data. To overcome this problem, this study proposes a novel demodulation scheme to recover data from a degraded image, based on a maximum likelihood decoding (MLD) algorithm. The proposed method creates template images that imitate all possible blinking patterns produced by the LED transmitter, and then calculates the Euclidean distances between pixels in the captured image and the pseudo images for all possible blinking patterns. Finally, the algorithm chooses the image template with the smallest Euclidian distance from the received signal as the recovered data. Though an exhaustive set of image templates must be prepared for the proposed MLD, the number of templates depends on the number of LEDs on the transmitter. Thus, the computational complexity of this method increases as the number of transmitter LEDs increases. To reduce the computational complexity of the proposed MLD algorithm, the binary differential evolution (BDE) algorithm is used, which is a swarm intelligence technique. Computer simulations are used to evaluate the BDE algorithm's usefulness for reducing computational complexity and improving the BER of the communication system.

DOI： 10.1587/nolta.10.173

Parallel Transmission Using M-Point DFT for Image-Sensor-Based Visible Light Communication Reviewed

Kibe S.

2018 IEEE Globecom Workshops, GC Wkshps 2018 - Proceedings 2019.2

Performance Evaluation of Precoded Pulse Width Modulation for Image Sensor Communication Reviewed

Satoshi Kamegawa, Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Koji Kamakura, Tomohiro Yendo, Shintaro Arai

2018 IEEE Globecom Workshops, GC Wkshps 2018 - Proceedings 2019.2

Publishing type：Research paper (international conference proceedings)

Light-emitting diodes (LEDs) can add visible light communication (VLC) by high-speed blinking to their original lighting function. VLC using image sensors as receivers is referred to as image sensor communication (ISC). ISC eliminates noise and interference and enables multiple and simultaneous communication; hence it is suitable for outdoor mobile environments such as intelligent transport systems (ITSs). On the other hand, since the communication rate depends on the frame rate, it is difficult to increase. Therefore, the purpose of this study is to increase the communication rate by multilevel pulse width modulation (PWM). When the modulation level is increased, demodulation becomes difficult due to the bit per pixel (bpp) limitation of the image sensor. First, in order to perform efficient luminance extraction in limited bpp, we compare the maximum luminance extraction and the average luminance extraction. Then, we propose improving the nonlinearity between the transmitter and receiver, which is a problem in average luminance extraction suitable for a mobile environment, by applying precoded PWM. Finally, we evaluate effectiveness of precoded PWM experimentally.

DOI： 10.1109/GLOCOMW.2018.8644347

Enhancing a BPSK receiver with Stochastic resonance by employing practical parallel arrayed network Reviewed

Yukihiro Tadokoro, Hiroya Tanaka, Yasuo Nakashima, Takaya Yamazato, Shintaro Arai

Nonlinear Theory and Its Applications, IEICE Vol. 10 ( 1 ) page： 106 - 114 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Stochastic resonance (SR) is a noise-enhancement phenomenon that enables the detection of sub-threshold signals by adding noise and using nonlinear systems. This paper explores the applicability of SR in a BPSK receiver with sub-threshold signals. Although received signals are amplified as a result of the nonlinear behavior of the receiver, they are somewhat distorted. This results in the lower performance of SR receivers in comparison with linear receivers. Employing a parallel network of SR systems is expected to solve this problem. The present theoretical analysis demonstrates that in a certain noise intensity range, the output of the network can fully describe an input sub-threshold signal, and hence, the performance close to that of the linear receivers can be obtained. The effectiveness of the SR receiver was also demonstrated through a numerical example of the bit error rate (BER). However, achieving good BER performance requires an infinite number of arrayed SR systems, which is not realistic in practical systems. A design framework for an SR network with a finite number of elements and an appropriate noise intensity that can realize BER performance close to that in linear systems is also provided.

DOI： 10.1587/nolta.10.106

Noise-aided demodulation with one-bit comparator for multilevel pulse-amplitude-modulated signals Reviewed

Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time Reviewed

Mitani Takuya, Yamazato Takaya, Naito Katsuhiro, Mori Yuki

2019 8TH IEEE INTERNATIONAL CONFERENCE ON CONNECTED VEHICLES AND EXPO (IIEEE CCVE) 2019

Proposal for Identification Scheme of Driver and Impostor based on Acceleration Data Reviewed

Mori Yuki, Ono Ryota, Mitani Takuya, Naito Katsuhiro, Yamazato Takaya

2019 8TH IEEE INTERNATIONAL CONFERENCE ON CONNECTED VEHICLES AND EXPO (IIEEE CCVE) 2019

Yasuo Nakashima, Takaya Yamazato, Shintaro Arai, Hiroya Tanaka, Yukihiro Tadokoro

IEEE Wireless Communication Letters Vol. 7 ( 5 ) page： 848 - 851 2018.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This letter proposes a demodulation method using a one-bit comparator for signals processed by multilevel pulse amplitude modulation (PAM). The proposed method is simple and provides an alternative to using an analog-to-digital converter to describe multilevel input signals. Because of the noise present in the transmitted multilevel PAM signal, the two level output of the one-bit comparator shows different statistical behavior for each level of the signal. Thus, it is possible to detect the signal level, or perform symbol decision, based on the maximum likelihood criterion. The present theoretical analysis reveals that reliable demodulation is possible even with a one-bit comparator if the probability mass function of the two-level outputs of each received symbol plus intentionally added noise is known.

DOI： 10.1109/LWC.2018.2831683

Technical Issues on IEEE 802.15.7m Image Sensor Communication Standardization Reviewed

Trang Nguyen, Amirul Islam, Takaya Yamazato, Yeong Min Jang

IEEE Communications Magazine Vol. 56 ( 2 ) page： 213 - 218 2018.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers Inc.

This tutorial article presents an outline of image sensor communication (ISC) technologies realized by light sources and cameras. It discusses the revision of the IEEE 802.15.7-2011 standard, namely, the IEEE 802.15.7m Optical Wireless Communications Task Group, which has significantly influenced the development of the ISC technology. It also reviews the ISC technical proposals of the task group and compares them with related works. The essential technical considerations of the ISC specifications are presented, and the future directions of research and development are discussed.

DOI： 10.1109/MCOM.2018.1700134

N-Stream Superimposed System with m-Point DFT for Image-Sensor-Based Visible Light Communication Reviewed

Syuto Kibe, Koji Kamakura, Takaya Yamazato

2017 IEEE Global Communications Conference, GLOBECOM 2017 - Proceedings Vol. 2018- page： 1 - 6 2018.1

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

This paper proposes an N-stream superimposed system for image-sensor-based visible light communications (ISbased VLC). Based on the principle of m-point discrete Fourier transform (DFT), a phase shift keying (PSK) signal is transmitted over m consecutive time slots mT, where T is a slot duration. In practice, the symbol rate of this paper is R/(m + 1) because a guard slot is inserted every m slots. In the superimposed system, N data streams where the symbol rate of the nth data stream, n = {1, 2,.., N}, is 1/(m+ 1)n-1 times the symbol rate of the first data stream are combined to form a pulse-width modulated (PWM) wave with a period time T. An IS receiver with a camera operating at a frame rate of R/(m+ 1)n-1 fps demodulates data streams whose symbol rate is R/m+ 1)n symbol/s or lower. Our experimental results validate that from a superimposed PWM wave of 500-symbol/s and 125-symbol/s data streams, a 2000-fps camera receiver demodulates both of the two data streams and the 500-fps camera receiver does the 125-symbol/s data stream successfully, without shortening individual error-free transmission ranges, compared with non-superimposed systems in which 500-symbol/s and 125-symbol/s data streams are independently transmitted by different light emitting diode (LED) transmitters and received by 2000-fps and 500-fps camera receivers, respectively.

DOI： 10.1109/GLOCOM.2017.8254784

Research data storage URL： http://ieeexplore.ieee.org/document/8254784/

Interference-Aided Detection of Subthreshold Signal Using Beam Control in Polarization Diversity Reception. Reviewed

Practical Applications of Visible Light Communications Invited

T. Yamazato, H. Okada

Journal of IEICE Vol. 101 ( 1 ) page： 59-65 2018.1

Simplified Vehicle Vibration Modeling for Image Sensor Communication Reviewed

KINOSHITA Masayuki, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro, YENDO Tomohiro, KAMAKURA Koji

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. 101 ( 1 ) page： 176-184 2018

Shintaro Hiraoka, Yasuo Nakashima, Takaya Yamazato, Shintaro Arai, Yukihiro Tadokoro, Hiroya Tanaka

IEEE Communications Letters Vol. 22 ( 9 ) page： 1926 - 1929 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The present letter discusses a detectability enhancement induced by co-channel interference signals in the polarization diversity reception. The challenge is the detection of weak (subthreshold) signals, the level of which is less than the detection limit of radio receivers. To understand the theory underlying the mechanism in the presented diversity scheme, we introduce an analytic model of a dual polarized antenna array in the fading channel. In addition, the channel capacity in a binary data transmission is derived. As a result, we reveal that the interference-aided diversity reception enables us to detect signals even below the detection limit of the receiver. Moreover, the appropriate source code is needed to achieve the channel capacity because the transmission channel is asymmetric in the present reception scheme.

DOI： 10.1109/LCOMM.2018.2851583

A Comparison of Reception Methods for Visible Light Communication Using High-Speed Stereo Cameras Reviewed

A Comparison of Reception Methods for Visible Light Communication Using High-speed Stereo Cameras Reviewed

Kinoshita Masayuki, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Arai Shintaro, Yendo Tomohiro, Kamakura Koji

2018 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) page： . 2018

Performance Evaluation of Precoded Pulse Width Modulation for Image Sensor Communication Reviewed

Kamegawa Satoshi, Kinoshita Masayuki, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Kamakura Koji, Yendo Tomohiro, Arai Shintaro

2018 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) page： . 2018

Parallel Transmission Using M-point DFT for Image-Sensor-Based Visible Light Communication Reviewed

Kibe Syuto, Kamakura Koji, Yamazato Takaya

2018 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) page： . 2018

Noise-aided demodulation with one-bit ADC for quadrature amplitude modulated signals Reviewed

Nakashima Yasuo, Yamazato Takaya, Arai Shintaro, Tanaka Hiroya, Tadokoro Yukihiro

2018 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) page： . 2018

LEO-MIMO Satellite Systems for High Capacity Transmission Reviewed

Goto Daisuke, Shibayama Hiroki, Yamashita Fumihiro, Yamazato Takaya

2018 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) page： . 2018

Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings 2018

Language：Japanese Publishing type：Research paper (international conference proceedings)

In-vehicle cameras can be used as receivers for visible light communication in addition to their primary functions: for viewing assistance and object recognition. Most studies with this design perform tests via a single high-speed camera that is used as the receiver, but this study employs a receiver that uses a high-speed stereo camera. The reception method developed in this paper effectively utilizes left and right stereo images to improve communication performance. Although the selective diversity reception method proposed in previous work improved communication performance, it cannot deal with cases wherein both the left and right cameras introduce errors. To further improve the communication performance of this system, maximal ratio combining (MRC) diversity is applied to the high-speed stereo camera in this study. Communication performance is then evaluated comparing to the selective diversity reception and conventional single-camera reception by experimental tests conducted under static and driving conditions.

DOI： 10.1109/GLOCOM.2018.8647953

Noise-Aided Demodulation with One-Bit ADC for Quadrature Amplitude Modulated Signals. Reviewed

Image sensor communications for future ITS Reviewed

Yamazato T.

Optics InfoBase Conference Papers Vol. Part F112-SPPCom 2018 2018

LEO-MIMO Satellite Systems for High Capacity Transmission Reviewed

Goto D.

2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings 2018

Yasuo Nakashima, Takaya Yamazato, Shintaro Arai, Hiroya Tanaka, Yukihiro Tadokoro

IEEE Global Communications Conference, GLOBECOM 2018, Abu Dhabi, United Arab Emirates, December 9-13, 2018 page： 1 - 6 2018

小特集編集にあたって Reviewed

Takaya Yamazato

電子情報通信学会誌 Vol.101 No.1 2018

Modulation and coding for image sensor communication Reviewed

Koji Kamakura, Takaya Yamazato

30th Annual Conference of the IEEE Photonics Society, IPC 2017 Vol. 2017- page： 235 - 236 2017.11

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

Most practical visible light communication (VLC) systems being currently deployed with image sensor receivers use intensity modulation and direct detection scheme for outdoor and indoor applications. A number of modulation and coding techniques that are used for image sensor-based VLC systems are presented.

DOI： 10.1109/IPCon.2017.8116086

The Uplink Visible Light Communication Beacon System for Universal Traffic Management Reviewed

Takaya Yamazato ; Naoaki Kawagita ; Hiraku Okada ; Toshiaki Fujii ; Tomohiro Yendo ; Shintaro Arai ; Koji Kamakura

IEEE Access ( 5 ) page： 22282 - 22290 2017.10

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

This paper presents a feasibility study of the uplink visible light communication (VLC) beacon system for the universal traffic management system (UTMS). The UTMS is a traffic management system beneath the National Police Agency of Japan. Currently, 55 000 UTMS infrared beacon systems have been installed, and they provide expressway and ordinary road information to cars. However, the data rate is 1 Mbps, and a faster data rate is necessary to support automotive and smart mobility devices. In this paper, we propose an uplink V2I system for the UTMS. The system is designed to match the current beacon system as closely as possible, so that the system can easily be replaced and still provide sufficient bandwidth for future automotive and smart mobility devices. We adopt a photo diode (PD) as the VLC receiver and a commercially available off-the-shelf LED headlight as a transmitter. Unfortunately, the bandwidth of such an LED is usually small, so we consider applying a bit-loading algorithm to direct-current-biased optical orthogonal frequency division multiplexing. To reduce strong background noise, such as from the sun, we narrow down the field-of-view by applying a lens to the PD, which forms a tiny communication area, smaller than the current infrared beacon system. We then consider multiple PDs with the lens to create a similar communication area as the infrared beacon system. As a result, we achieve 3.1-Mbps throughput.

DOI： 10.1109/ACCESS.2017.2759179

Modeling and parameter estimation of vehicle vibration inducing transmitter displacement in ITS image sensor communication Reviewed

Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017 page： 144 - 149 2017.6

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

Image sensor communication (ISC), which is derived from visible light communication (VLC), is a novel form of wireless communication that uses an image sensor as a receiver. ISC is an attractive solution for outdoor mobile environments and is particularly well-suited to intelligent transport systems (ITS). The purpose of this paper is to derive the dominant components of vehicle vibrations and road surface irregularities that induce transmitter displacement in ITS-ICS in paved road scenarios. Such displacements make it difficult for a ISC receiver to select the correct pixels. We measured vehicle vibrations during an actual driving scenario using a six-axis acceleration sensor installed in a smartphone. Using the results obtained, we performed a frequency analysis of the vehicle vibrations and determined the parameters of vehicle vibrations based on the frequency characteristics. This paper explains that the vehicle vibrations that affect the communication performance can be modeled by solely using Gaussian random processes when a high frame rate (e.g. 1000 fps) image sensor is used as the ISC receiver.

DOI： 10.1109/ICCW.2017.7962648

Global Communications Newsletter. Reviewed

Stefano Bregni, Takaya Yamazato, Vasile Bota,Liangping Ma

IEEE Communications Magazine Vol. 55 ( 2 ) page： 13 - 16 2017

Language：English Publishing type：Research paper (scientific journal)

Asia/Pacific Region
Interview with Takaya Yamazato, Director of the AP Region
This is the fourth article in the series of eight, started in November 2016 and published monthly in the IEEE ComSoc Global Communications Newsletter, which covers all areas of IEEE ComSoc Member and Global Activities. In this series of articles, I am introducing the six MGA Directors (Sister and Related Societies; Membership Services; AP, NA, LA, EMEA Regions) and the two Chairs of the Women in Communications Engineering (WICE) and Young Professionals (YP) Standing Committees. In each article, one by one they present their sector activities and plans.

In this issue, I interview Takaya Yamazato, Director of the Asia/Pacific Region (AP). Takaya is a professor at the Institute of Liberal Arts and Sciences, Nagoya University, Japan. He received the Ph.D. degree from Keio University, Yokohama, Japan, in 1993. From 1993 to 1998 he was an assistant professor in the Department of Information Electronics, Nagoya University, Japan. From 1997 to 1998 he was a visiting researcher in the Research Group for RF Communications, Department of Electrical Engineering and Information Technology, University of Kaiserslautern, Germany. In 2006 he received the IEEE Communication Society Best Tutorial Paper Award. He served as symposium co-chair of ICC 2009 and ICC 2011. From 2008 to 2010 he was the chair of the IEEE ComSoc Satellite and Space Communications Technical Committee and the editor-in-chief of the Japanese Section of IEICE Transactions on Communications. His research interests include visible light communication, intelligent transport systems, stochastic resonance, and open educational resources.

DOI： 10.1109/MCOM.2017.7841463

Effect of a root-raised-cosine filter on a BPSK stochastic resonance receiver

Effect of a root-raised-cosine filter on a BPSK stochastic resonance receiver Reviewed

Nakashima Yasuo, Tanaka Hiroya, Yamazato Takaya, Tadokoro Yukihiro, Arai Shintaro

IEICE NONLINEAR THEORY AND ITS APPLICATIONS Vol. 8 ( 3 ) page： 204-214 2017

Overview of Visible Light Communications - With Emphasis on Image Sensor Communications -

Yamazato Takaya

2017 23RD ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): BRIDGING THE METROPOLITAN AND THE REMOTE page： 564-569 2017

N-Stream Superimposed System with m-point DFT for Image-Sensor-Based Visible Light Communication

Kibe Syuto, Kamakura Koji, Yamazato Takaya

GLOBECOM 2017 - 2017 IEEE GLOBAL COMMUNICATIONS CONFERENCE page： . 2017

Modulation and Coding For Image Sensor Communication

Kamakura Koji, Yamazato Takaya

30TH ANNUAL CONFERENCE OF THE IEEE PHOTONICS SOCIETY (IPC) page： 235-236 2017

Nakashima Yasuo, Tanaka Hiroya, Yamazato Takaya, Tadokoro Yukihiro, Arai Shintaro

IEICE NONLINEAR THEORY AND ITS APPLICATIONS Vol. 8 ( 3 ) page： 204-214 2017

Overview of visible light communications with emphasis on image sensor communications. Reviewed

Takaya Yamazato

23rd Asia-Pacific Conference on Communications, APCC 2017, Perth, Australia, December 11-13, 2017 Vol. 2018-January page： 1 - 6 2017

V2X communications with an image sensor. Reviewed

Takaya Yamazato

J. Comm. Inform. Networks Vol. 2 ( 4 ) page： 65 - 74 2017

Performance comparison of stochastic resonance receiver with Schmitt trigger, comparator, and three-level device for subthreshold signal reception Reviewed

Hiroya Tanaka, Takaya Yamazato, Yukihiro Tadokoro, Shintaro Arai

Nonlinear Theory and Its Applications, IEICE Vol. 7 ( 3 ) page： 407 - 418 2016.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper discusses the stochastic resonance (SR) effect in a binary communication system for subthreshold signal reception. We focus on the problem of no communication when received signal strength is below receiver sensitivity. Subthreshold signal reception requires a device that exhibits SR, such as a Schmitt trigger or a comparator. Previously, we proposed an alternative three-level device and demonstrated its high performance for subthreshold signal reception in an SR receiver. In the present study, we show that our proposed three-level device outperforms the three devices and discuss reasons for this superior performance. Contributions of our present paper are twofold: first, we analytically derive bit error rate (BER) performances of SR receivers installed with a Schmitt trigger and a comparator;second, we compare performances of the Schmitt trigger, comparator, and three-level device.

DOI： 10.1587/nolta.7.407

A New Automotive VLC System Using Optical Communication Image Sensor Reviewed

Yuki Goto, Isamu Takai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shoji Kawahito, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

IEEE PHOTONICS JOURNAL Vol. 8 ( 3 ) 2016.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

As a new technology for next-generation vehicle-to-everything (V2X) communication, visible-light communication (VLC) using light-emitting diode (LED) transmitters and camera receivers has been energetically studied. Toward the future in which vehicles are connected anytime and anywhere by optical signals, the cutting-edge camera receiver employing a special CMOS image sensor, i.e., the optical communication image sensor (OCI), has been prototyped, and an optical V2V communication system applying this OCI-based camera receiver has already demonstrated 10-Mb/s optical signal transmission between real vehicles during outside driving. In this paper, to reach a transmission performance of 54 Mb/s, which is standardized as the maximum data rate in IEEE 802.11p for V2X communication, a more advanced OCI-based automotive VLC system is described. By introducing optical orthogonal frequency-division multiplexing (optical-OFDM), the new system achieves a more than fivefold higher data rate. Additionally, the frequency response characteristics and circuit noise of the OCI are closely analyzed and taken into account in the signal design. Furthermore, the forward-current limitation of an actual LED is also considered for long operational reliability, i.e., the LED is not operated in overdrive. Bit-error-rate experiments verify a system performance of 45 Mb/s without bit errors and 55 Mb/s with BER < 10(-5).

DOI： 10.1109/JPHOT.2016.2555582

A-14-8 Preliminary Study of Platoon Management using 700MHz Band Vehicle-to-Infrastructure Cooperative System Reviewed

OHNO Ryota, YAMAZATO Takaya

Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference Vol. 2016 page： 194 2016.3

A-9-17 BER Performance of NLOS Vehicle to Vehicle Visible Light Communication Using Optical OFDM Reviewed

KAWAGITA Naoaki, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro, YENDO Tomohiro, KAMAKURA Koji

Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference Vol. 2016 page： 153 2016.3

AS-3-10 High Speed Image Sensor Based I2V-VLC Channel Modeling in Outdoor Mobile Environment Reviewed

KINOSHTTA Masayuki, YAMAZATO Takaya, OKADA Hiraku, FUJII Yoshiaki, ARAI Shintaro, Yendo Tomohiro, KAMAKURA Koji

Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference Vol. 2016 page： "S - 53"-"S-54" 2016.3

BI-4-3 ITS Visible Light Communications using High-Speed Image Sensor Reviewed

Yamazato Takaya

Proceedings of the IEICE General Conference Vol. 2016 ( 1 ) page： "SS - 71"-"SS-72" 2016.3

BI-4-3 ITS Visible Light Communications using High-Speed Image Sensor Reviewed

Yamazato Takaya

Proceedings of the IEICE General Conference Vol. 2016 ( 2 ) page： "SS - 83"-"SS-84" 2016.3

N-2-2 Performance Evaluation of Stochastic Resonance Receiver in Bandlimited BPSK Modulations Reviewed

Nakashima Yasuo, TANAKA Hiroya, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference Vol. 2016 2016.3

NBS-1-1 Performance Improvement of Stochastic Resonance Receiver by Uniform Noise and Binary Noise Reviewed

TANAKA Hiroya, NAKASHIMA Yasuo, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference Vol. 2016 page： "S - 113"-"S-114" 2016.3

NBS-1-1 Performance Improvement of Stochastic Resonance Receiver by Uniform Noise and Binary Noise Reviewed

TANAKA Hiroya, NAKASHIMA Yasuo, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2016 ( 2 ) page： "S - 133"-"S-134" 2016.3

Range Estimation Scheme for Integrated I2V-VLC using a High-Speed Image Sensor Reviewed

T. Yamazato, A. Ohmura, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura

2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC) page： 326 - 330 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

High-speed image sensors, designed for machine vision and control, provide the "eyes" for autonomous and connected vehicle. A noteworthy feature of high-speed image sensors is their ability to be used as a reception device for visible light communication (VLC) signals. Due to the massive number of pixels available and the ability to spatially separate sources, a signal-receiving pixel in the image sensor plane represents the actual position of the transmitter. The VLC signal can be represented not only by a VLC time domain signal but also by the position of the transmitter. In this paper, we propose a robust range estimation scheme that integrates with a VLC function for infrastructure-to-vehicle visible light communication (I2V-VLC). The scheme is composed of an LED array transmitter and a high-speed image sensor receiver. It measures a range by taking phase-only correlation (POC) and avoids vehicle vibration from road irregularity. Field trials confirm an accuracy range of 0.3 m, even on rough road conditions, with the measurement time of 2 ms, which is much faster than that of light detection and ranging (LIDAR).

DOI： 10.1109/ICCW.2016.7503808

Visible Light Communication Systems Using Blue Color Difference Modulation for Digital Signage Reviewed

Sho Sato, Hiraku Okada, Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 1219 - 1224 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Digital signage, which is advertising media using a liquid crystal display (LCD), is increasing in popularity. One possible application is wireless communications between digital signage and viewers. We focus on image-sensor-based visible light communication (VLC). Image-sensor-based VLC requires only an image sensor (IS), which is common equipment in smart phones. In the proposed method, an information signal is displayed on LCD. However, embedding the information signal into an advertisement may decrease the quality. We propose blue color difference modulation to make such signals imperceptible. We implemented a VLC system between digital signage and IS to demonstrate, the effectiveness of the proposed modulation in a real environment.

DOI： 10.1109/PIMRC.2016.7794761

Position Estimation of LED Matrix in Image Sensor Communication Reviewed

Takazumi Asai, Tomohiro Yendo, Shintaro Arai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Koji Kamakura

2016 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA) page： 1 - 5 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

We focus on the road-to-vehicle visible light communication (VLC) that system is composed of a LED matrix as a transmitter and a high-speed camera as a receiver. In this VLC system, intensity of each LED cannot be determined from received image directly in case that the receiver is distant from the transmitter. In previous research, a method to estimate intensity of the LED from received image is proposed. In this method, intensity of LED is estimated by using Moore-Penrose pseudo-inverse matrix of coefficient matrix, which expresses relation between intensity of LEDs and pixel values. However, the coefficient matrix changes every moment because it is determined by positional relation between the receiver and the LED traffic light in VLC system. In this paper, we propose a method to estimate position of the LED matrix using simulated images. We measure sensitivity distribution of image sensor to generate simulated images. We evaluated degree of similarity between simulated images and real images.

DOI： 10.1109/APSIPA.2016.7820809

Spatial Modulation in Layered Space-Time Coding for Image-Sensor-Based Visible Light Communication Reviewed

Keisuke Masuda, Koji Kamakura, Takaya Yamazato

2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 1231 - 1236 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Spatial modulation (SM) is introduced into layered space-time coding (L-STC) used in image sensor (IS)-based visible light communication (VLC) systems. STC was basically investigated for extending the communication range of the IS-based VLC link [1], although it is out of the range when IS receivers are at the long distance from the LED array of the transmitter where the number of pixels capturing the transmitter on the image plane is less than the number of LEDs of the array. Furthermore, L-STC was done in [2] for increasing the reception rate with improving the pixel resolution while the receiver was approaching the transmitter. In this paper, SM is combined into L-STC by mapping additional information bits on the location of the pair of STC bit matrices of each layer. Experimental results show that additional SM bits are extracted with no error, without deteriorating the reception quality of and shrinking the transmission range of the original L-STC.

DOI： 10.1109/PIMRC.2016.7794763

Position Estimation of LED Matrix in Image Sensor Communication Reviewed

Asai Takazumi, Yendo Tomohiro, Arai Shintaro, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Kamakura Koji

2016 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA) 2016

Spatial Modulation in Layered Space-Time Coding for Image-Sensor-Based Visible Light Communication Reviewed

Masuda Keisuke, Kamakura Koji, Yamazato Takaya

2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 1231 - 1236 2016

Transmit Diversity with Single RF Front-end using CIOD Reviewed

Yamaoka Tomoya, Hara Teruyuki, Okazaki Akihiro, Yamazato Takaya

IEICE ComEX Vol. 5 ( 2 ) page： 44 - 48 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Complex interleaved orthogonal design (CIOD) can offers diversity gain to the part of the source in spatial modulation which has single radio frequency (RF) front-end at the transmitter despite multiple-input multiple-output, but emits the undesired component out-of-band. For the reducing out-of-band emission, we give up indicating the information source by the antenna switching and increase both the interleaver size and the antenna switching interval. The increase reduces the discontinuities in the waveform and out-of-band emission. We propose such a scheme as transmit diversity with single RF front-end using CIOD. The diversity gain of the proposed scheme is equivalent to the case for CIOD. Moreover, we evaluate the increase of out-of-band emission and confirm that of the proposed scheme compared to the ideal case is only 3dB.

DOI： 10.1587/comex.2015XBL0170

Visible Light Communication Systems Using Blue Color Difference Modulation for Digital Signage Reviewed

Sato Sho, Okada Hiraku, Kobayashi Kentaro, Yamazato Takaya, Katayama Masaaki

2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 1219 - 1224 2016

LED acquisition methods for image-sensor-based visible light communication Reviewed

Shintaro Arai; Takaya Yamazato; Hiraku Okada; Toshiaki Fujii; Tomohiro Yendo

2015 Opto-Electronics and Communications Conference (OECC) page： 1 - 3 2015.11

Language：English Publishing type：Research paper (scientific journal)

This invited paper focuses on a high-speed image sensor as a visible light communication (VLC) reception device to develop the intelligent transport systems (ITS) application using VLC technique. We refer to the VLC using a high-speed image sensor as image-sensor-based VLC. A major advantage of the image sensor is the ability to spatially separate multiple sources. Based on this ability, we proposed several methods for the image-sensor-based VLC in our previous researches. Especially, we focused on unique characteristics of the image sensor and proposed the hierarchical coding and the overlay coding to improve the data reception performance. However, to perform the image-sensor-based VLC in an actual environment, the receiver has to acquire the VLC transmitter from captured images before recovering data. Namely, the VLC transmitter acquisition and tracking are critical problem. the image-sensor-based VLC technique. This invited paper introduces two proposed methods to acquire the VLC transmitter from images captured by the image sensor.

DOI： 10.1109/OECC.2015.7340210

Layered Transmission of Space-Time Coded Signals for Image-Sensor-Based Visible Light Communications Reviewed

Katsunori Ebihara, Koji Kamakura, Takaya Yamazato

JOURNAL OF LIGHTWAVE TECHNOLOGY Vol. 33 ( 20 ) page： 4193 - 4206 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper demonstrates the feasibility of layered space-time coding (STC) in an outdoor image-sensor-based (IS-based) visible light communication (VLC) system. We examined that for low-resolution IS-based VLC channel where intensity-modulated signals from two different light emitting diodes (LEDs) are detected by one pixel of an IS, STC allows us to decouple them; thus, succeeding to receive them with no errors. Consequently, STC offers extended transmission distance to pixel-resolution-limited IS-based VLC links. In the layered STC presented in this paper, additional bit streams are laid on the 2(n) x 2(n) LED array for increasing the transmission rate per symbol duration for the case where the pixel resolution is improved. A prototype of a three-layered STC is built with an 8 x 8 LED array, where each of the LEDs is modulated at 1 kb/s and a high-speed camera with IS operating at 1000 fps. Our experimental results validate that the two additional bit streams (layer-2 and -3), aligned in the layer-1 STC matrix pair, are extracted with no errors when the receiver comes within 155 and 55 m, respectively, from the LED array, without decreasing 210 m of the transmission distance of layer-1 bit stream.

DOI： 10.1109/JLT.2015.2470091

IEICE technical committees' contribution to I-scover keyword metadata improvements and selecting effective article keywords Reviewed

Image sensor based visible light communication for V2X Reviewed

Takaya Yamazato

2015 IEEE Summer Topicals Meeting Series (SUM) page： 165 - 166 2015.9

Signal Demodulation Method from Degraded Image for Visible Light Communication Using LED and High-Speed Camera Reviewed

Y. Ohira, S. Arai, T. Yendo, T. Yamazato, H. Okada, T. Fujii, K. Kamakura

IEICE Transactions on Communications Vol. J98-B ( 7 ) page： 696-706 2015.7

Yamazato T.

Journal of the Institute of Electronics, Information and Communication Engineers Vol. 98 ( 6 ) page： 494 - 499 2015.6

Vehicle Motion and Pixel Illumination Modeling for Image Sensor Based Visible Light Communication Reviewed

Takaya Yamazato; Masayuki Kinoshita; Shintaro Arai; Eisho Souke; Tomohiro Yendo; Toshiaki Fujii; Koji Kamakura; Hiraku Okada

IEEE Journal on Selected Areas in Communications Vol. 33 ( 9 ) page： 1793 - 1805 2015.5

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Channel modeling is critical for the design and performance evaluation of visible light communication (VLC). Although a considerable amount of research has focused on indoor VLC systems using single-element photodiodes, there remains a need for channel modeling of VLC systems for outdoor mobile environments. In this paper, we describe and provide results for modeling image sensor based VLC for automotive applications. In particular, we examine the channel model for mobile movements in the image plane as well as channel decay according to the distance between the transmitter and the receiver. Optical flow measurements were conducted for three VLC situations for automotive use: infrastructure to vehicle VLC (I2V-VLC); vehicle to infrastructure VLC (V2I-VLC); and vehicle to vehicle VLC (V2V-VLC). We describe vehicle motion by optical flow with subpixel accuracy using phase-only correlation (POC) analysis and show that a single-pinhole camera model successfully describes these three VLC cases. In addition, the luminance of the central pixel from the projected LED area versus the distance between the LED and the camera was measured. Our key findings are twofold. First, a single-pinhole camera model can be applied to vehicle motion modeling of a I2V-VLC, V2I-VLC, and V2V-VLC. Second, the DC gain at a pixel remains constant as long as the projected image of the transmitter LED occupies several pixels. In other words, if we choose a pixel with highest luminance among the projected image of transmitter LED, the value remains constant, and the signal-to-noise ratio does not change according to the distance.

DOI： 10.1109/JSAC.2015.2432511

Noise-Enhanced subthreshold signal reception by a stochastic resonance receiver using a non-dynamical device Reviewed

Hiroya Tanaka, Keita Chiga, Takaya Yamazato, Yukihiro Tadokoro, Shintaro Arai

Nonlinear Theory and Its Applications, IEICE Vol. 6 ( 2 ) page： 303 - 312 2015.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Stochastic resonance (SR) is an interesting phenomenon in that noise enhances system response. Despite attractive phenomenon of SR that noise enhances system response, enhancement of the weak signal below device sensitivity, and few researchers have addressed the SR effect in communication systems. This paper discusses the SR effect in communication systems. We focus on the problem in which communication cannot be established when the received signal strength is below receiver sensitivity. The purpose of this study is to evaluate the bit error rate (BER) performance of the SR receiver and reveal the SR effect in communication systems. We propose an analysis method for the SR receiver using a non-dynamical device that exhibits SR effect. The numerical results show that the SR effect can improve the BER compared to a system without SR. The contribution of the paper is two folds: The first contribution of our present study is that the BER of the SR receiver using a non-dynamical device can analytically be derived. The second contribution of our study is that the number of samples per symbol, the received signal amplitude, and the receiver sensitivity are three important parameters. We further derive the maximum performance gain by the SR system. Although our focus is on primary communication systems; however, our findings can be applied to other systems.

DOI： 10.1587/nolta.6.303

Detection method of the LED headlight and LED headlight identification method considering occlusion for V2I-VLC Reviewed

KAWAI Yuta, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro, KAMAKURA Koji

Vol. 114 ( 508 ) page： 23 - 28 2015.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we focus on the image sensor based vehicle-to-infrastructure visible light communication (V2I-VLC) for Intelligent Transport System (ITS). In this communication system, individual detection and tracking of multiple transmitters is critical. In other words, it is identification of the LED headlight between the frames. However, when occlusion occurs due to vehicle's movement, it becomes NLOS. I have the problem that it comes to have difficulty in identification of LED headlight then. Therefore, in this paper, we propose LED identification method that predict the position of the LED headlight on the image sensor when occlusion occurs. I install a high-speed camera in the roadside and test it and evaluate proposal technique. As a result, false negative rate is 1.38%,false positive rate is 3.26%. I confirmed that I could perform LED identification even if occlusion occurred.

Alamouti-Type Space Time Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

Y. Amano, K. Kamakura, T. Yamazato

IEICE Transactions on Communications Vol. J98-B ( 3 ) page： 307-318 2015.3

Language：Japanese Publishing type：Research paper (scientific journal)

This paper proposes Alamouti-type space time (ST) coding to visible light communication (VLC) using light emitting diodes (LEDs) and image sensor-based direct detection with a high-speed camera. Although multiple LEDs of an array are used as transmitters to communicate to individual pixel elements of an image sensor which act as multiple receive elements, the received signal is essentially the image of the transmitting element, whose size in pixel reduces with distance. When the receiver captures the LED array at a distance where images of two neighboring LEDs in the array are not separated at the image plane, such distortion depreciates the symbol decision quality. Our proposed scheme aims at expanding the communication range limited by the pixel resolution of image sensor. Our implemented prototype demonstrates that ST coding is feasible to achieve 48-meter error-free transmission range while the repetition transmission achieves 26-meter error-free range.

Preliminary Study on NLOS V2V Visible Light Communication Using Retroreflective Traffic Control Devices

T. Takada, T. Yamazato, H. Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura

IEICE General Conference Vol. A-17-16 page： 249 2015.3

Detection method of the LED headlight and LED headlight identification method considering occlusion for V2I-VLC

Y. Kawai,T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura

IEICE Technical Report Vol. ITS2014-62 page： 23-28 2015.3

Language：Japanese

A-17-16 Preliminary Study on NLOS V2V Visible Light Communication Using Retroreflective Traffic Control Devices Reviewed

TAKADA Takuma, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro, YENDO Tomohiro, KAMAKURA Koji

Proceedings of the IEICE General Conference Vol. 2015 page： 249 2015.2

A-2-18 Performance Evaluation of Stochastic Resonance Receiver in BPSK and OOK Modulations Reviewed

TANAKA Hiroya, CHIGA Keita, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2015 page： 49 2015.2

Investigation on Relationship Between Communication Distance and Receiving Characteristics in Image-Sensor-Based Visible Light Communication Reviewed

Y. Ohira, E. Souke, S. Arai, T. Yamazato, T. Yendo, H. Okada, T. Fujii and K. Kamakura

Proceedings of 2015 RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP'15) page： 274-277 2015.2

Language：English

The present paper considers receiving characteristics of an image-sensor-based visible light communication (VLC) using an LED and a high-speed-image sensor. In general, a size of LED on an image decreases with increasing a communication distance. In this case, the receiver is difficult to recover data because the intensity of brightness of LED (i.e., luminance) cannot be enough recognized from the image. However, the previous studies about the image-sensor-based VLC have not enough discussed the communication distance and the recognition of LED on the image, i.e., the receiving characteristics. We focus on the communication distance and investigates the relationship between the distance and the receiving characteristics in the image-sensor-based VLC.

Outdoor Road-to-Vehicle Visible Light Communication Using On-Vehicle High-Speed Camera Reviewed

C. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

International Journal of Intelligent Transportation Systems Research Vol. 13 ( 1 ) page： 28-36 2015.1

Language：English Publishing type：Research paper (scientific journal)

We propose a road-to-vehicle Visible Light Communication (VLC) system for ITS. Here, the communication between road and a vehicle is approached using an LED array as a transmitter and an on-vehicle high-speed camera as a receiver. Modulation is conducted at the transmitter by blinking LEDs in high frequency and demodulation is conducted at the receiver by capturing the blinking patterns of the transmitter, by processing the high-speed camera images captured in high frame rate. This paper proposes an effective image processing method for capturing those blinking patterns. Out door communication experiments of the proposed VLC system are also present.

Image sensor based visible light communication Reviewed

Shinichiro Haruyama, Takaya Yamazato

Visible Light Communication page： 181 - 205 2015.1

Language：English Publishing type：Part of collection (book) Publisher：Cambridge University Press

Overview Image sensors are used in digital cameras and a large number of imaging devices for industrial, media, medical, and consumer electronics applications. An image sensor consists of a number of pixels
each pixel contains a photodiode (PD), which is generally used as a receiver in visible light communications (VLC). Thus, an image sensor consisting of a number of pixels can also be used as a VLC receiver. A particular advantage of using image sensors, due to the massive number of available pixels, is the ability to spatially separate sources. Owing to the spatial separation of multiple sources, the VLC receiver uses only the pixels that sense LED transmission sources, discarding other pixels, including those sensing ambient noise. The ability to spatially separate sources also provides an additional feature to VLC, i.e., the ability to receive and process multiple transmitting sources. In this chapter, we introduce VLC using an image sensor [1]. After presenting an overview of image sensors in Section 9.2, we introduce the use of an image sensor as a VLC receiver in Section 9.3. We provide a design of an image sensor based VLC system in Section 9.4. In Sections 9.5 and 9.6, we respectively introduce the following two unique applications of VLC systems using an image sensor: (1) massively parallel visible light transmission that can theoretically achieve a maximum data rate of 1.28 Gigabits per second
and (2) accurate sensor pose estimation that cannot be realized by a VLC system using a single-element PD. Applications of image sensor based communication are also presented in Section 9.7 for traffic signal communication, position measurements in civil engineering, and bridge position monitoring. Finally, in Section 9.8, we summarize our conclusions.

DOI： 10.1017/CBO9781107447981.009

Intensity Estimation of LEDs from Spatially and Temporally Mixed Images in Image Sensor Communication Reviewed

Takazumi Asai, Daigo Iwase, Ryoko Ieki, Tomohiro Yendo, Shintaro Arai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Koji Kamakura

2015 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA) page： 877 - 883 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

We focus on the road-to-vehicle visible light communication that system is composed of LED matrix as transmitter and high-speed camera as receiver. In proposed method, there are two problems. First problem is in case of long distance. It is difficult to receive data correctly because neighboring LEDs on the received image are merged due to less number of pixels and/or blurring by defocus. In this paper, we propose estimation method of LED intensity from merged image. We evaluated the method by measuring Bit Error Rate and confirmed effectiveness of the method. We also performed real time communication and succeeded to extend communication distance from the previous work by applying the method. Second problem is that, the transmitting rate has been reduced to half of the frame rate of the camera, to avoid intersymbol interference because of exposure time of camera frame. We propose a method to improve the communication rate. The transmitting rate is set same to receiver's frame rate, and the sent data is estimated from pattern mixed image. Using 8b/10b encoding instead of conventional reversal pattern to reduce the flickering of transmitter's lighting is also proposed.

DOI： 10.1109/APSIPA.2015.7415396

Novel Demodulation Scheme Based on Blurred Images for Image-Sensor-Based Visible Light Communication Reviewed

Yuki Ohira, Shintaro Arai, Tomohiro Yendo, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Koji Kamakura

2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) page： 1 - 6 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper proposes a novel data detection scheme based on the occurrence of blurred output images in image-sensor-based visible light communication systems. This system's receiver suffers from an inability to detect correct LED luminance values and demodulation of data because the captured image blurs owing to defocusing. The proposed method assumes that the light emitted by all LEDs that is diffused by the blur can be approximated by applying a Gaussian filter and expresses all LED luminance values as convolution equations based on this diffusion of the LED light. We estimate each LED light's condition by simultaneously solving these convolution equations and recover data according to the estimated result. To confirm the accuracy of the proposed method, we conduct computer simulations and an implementation experiment to evaluate the bit error rate performance of the proposed method.

DOI： 10.1109/GLOCOMW.2015.7414144

Layered Space-Time Coding Using LED Array for Image-Sensor-Based Visible Light Communications Reviewed

Katsunori Ebihara, Koji Kamakura, Takaya Yamazato

2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) Vol. 2015-September page： 5048 - 5053 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper demonstrates the feasibility of layered space-time coding (STC) in an outdoor image-sensor-based (IS-based) visible light communication (VLC) system. We examined that for low-resolution IS-based VLC channel where intensity modulated signals from two different light emitting diodes (LEDs) are detected at one pixel on the image plane, STC allows to decouple them, thus receiving data with no errors. Consequently, STC offers extending the transmission distance. In the layered STC presented here, additional bit streams are aligned in the 2(n) x 2(n) LED array for increasing the transmission rate per symbol duration for the case where the spatial resolution is improved. A prototype of three layered STC is built with an 8 x 8 LED array, where each of the LEDs is modulated at 1 kbps and a high-speed camera with IS operating at 1000 fps. Our experimental results validate that additional bit streams (layer-2 and -3), aligned in the layer-1 STC matrix pair, are extracted with no errors when the receiver comes within 155m and 55 m, respectively, from the LED array, without decreasing 210m of the transmission distance of layer-1 bit stream.

DOI： 10.1109/ICC.2015.7249124

Development of add-on stochastic resonance device for the detection of subthreshold RF signals Reviewed

Keita Chiga, Hiroya Tanaka, Takaya Yamazato, Yukihiro Tadokoro, Shintaro Arai

Nonlinear Theory and Its Applications, IEICE Vol. 6 ( 4 ) page： 520 - 533 2015

Intensity Estimation of LEDs from Spatially and Temporally Mixed Images in Image Sensor Communication Reviewed

Asai Takazumi, Iwase Daigo, Ieki Ryoko, Yendo Tomohiro, Arai Shintaro, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Kamakura Koji

2015 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA) page： 877 - 883 2015

LED Acquisition Methods for Image-Sensor-Based Visible Light Communication Reviewed

Shintaro Arai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Tomohiro Yendo

2015 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC) 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Outdoor road-to-vehicle visible light communication using on-vehicle high-speed camera Reviewed

LED Acquisition Methods for Image-Sensor-Based Visible Light Communication Reviewed

Arai Shintaro, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Yendo Tomohiro

2015 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC) 2015

Layered Space-Time Coding Using LED Array for Image-Sensor-Based Visible Light Communications Reviewed

Ebihara Katsunori, Kamakura Koji, Yamazato Takaya

2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) page： 5048 - 5053 2015

Novel Demodulation Scheme Based on Blurred Images for Image-Sensor-Based Visible Light Communication Reviewed

Ohira Yuki, Arai Shintaro, Yendo Tomohiro, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Kamakura Koji

2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) 2015

Chinthaka Premachandra, Tomohiro Yendo, Mehrdad Panahpour Tehrani, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Masayuki Tanimoto

International Journal of Intelligent Transportation Systems Research Vol. 13 ( 1 ) page： 28 - 36 2015

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer New York LLC

DOI： 10.1007/s13177-014-0079-y

Optical Camera Communications Using Digital Signage Reviewed

OKADA Hiraku, SATO Sho, WADA Tadahiro, YAMAZATO Takaya, KATAYAMA Masaaki

ITE Technical Report Vol. 39 ( 0 ) page： 21 - 24 2015

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

In this paper, we discuss optical cammera communication systems using digital signage, which is composed of a liquid crystal display (LCD). The digital signage, which is used as a transmitter, displays advertisement contents as visual information. The optical camera communication system using digital signage has to transmit data information not to obstruct the visual information. In this paper, we propose blue color difference modulation for the optical camera communication system using digital signage. We clarify the performance of the proposed system by data transmission experiments.

DOI： 10.11485/itetr.39.38.0_21

Layered Space-Time Coding Using LED Array for Image-Sensor-Based Visible Light Communications Reviewed

Cooperative Diversity via Simple Relaying with Quasi-Orthogonal Space-Time Block Code Reviewed

T. Yamaoka, Y. Hara, K. Ishioka, T. Hara, T. Yamazato

IEICE Transaction on Communication page： - 2014.12

Language：Japanese Publishing type：Research paper (scientific journal)

We have been proposed cooperative diversity receiving ABBA code as cooperative diversity via simple relaying with QOSTBC(Quasi-Orthogonal Space-Time Block Code). This scheme offers codinggain by permutation of space-time coded signal sequences in the relay nodes. So the relay nodes don't need carrier recovery and complete the signal process in the intermediate frequency band. In this paper we discuss two improved scheme with various channel model. These schemes improve the previous scheme without loss of the merit in its relay process. Moreover we sum up cooperative diversity via simple relaying with QOSTBC to discuss these schemes with various channel model. We evaluate effect of these scheme in terms of signal matrixes and simulate bit error rate of the prposed and improved scheme with with various channel model, respectively.

Alamouti-Type Space Time Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

Y. Amano, K. Kamakura, T. Yamazato

IEICE Transactions on Communications (to be published) page： - 2014.12

Language：Japanese Publishing type：Research paper (scientific journal)

Motion Modeling of Mobile Transmitter for Image Sensor Based I2V-VLC, V2I-VLC, and V2V-VLC Reviewed

M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura

IEEE Workshop on Optical Wireless Communications page： - 2014.12

Language：English Publishing type：Research paper (scientific journal)

Visible light communication (VLC) using light-emitting diodes (LEDs) is drawing much attention. There are two types of VLC reception devices, a photodiode and an image sensor. VLC using image sensor is called image sensor based VLC. As the receiver only uses the image sensor pixels that sense LED transmission sources and discards other pixels, including those sensing noise sources, image sensor based VLC is an attractive solution for outdoor mobile applications. However, little evidence is available for channel modeling of image sensor based VLC in mobile outdoor environments, especially for motion modeling of VLC transmitter. In this paper, we propose a motion model of VLC transmitter. In particular, we consider three cases; infrastructure-to-vehicle VLC (I2V-VLC), vehicle-to-infrastructure VLC (V2I-VLC), and vehicle-to-vehicle VLC (V2V-VLC). As a result, we show that the motion model of the VLC transmitter on the captured image for the three aforementioned situations (i.e., I2V-VLC, V2I-VLC, and V2V-VLC) can be expressed in the identical pinhole camera model.

Cooperative Diversity via Simple Relaying with Quasi-Orthogonal Space-Time Block Code Reviewed

Tomoya YAMAOKA, Yoshitaka HARA, Kazuaki ISHIOKA Teruyuki HARA, Takaya Yamazato

IEICE Transactions on Communications Vol. J97-B ( 12 ) page： 1213-1223 2014.12

Language：Japanese Publishing type：Research paper (scientific journal)

We have been proposed cooperative diversity receiving ABBA code as cooperative diversity via simple relaying with QOSTBC(Quasi-Orthogonal Space-Time Block Code). This scheme offers coding gain by permutation of space-time coded signal sequences in the relay nodes. So the relay nodes don't need carrier recovery and complete the signal process in the intermediate frequency band. In this paper, we discuss two improved scheme with various channel model. These schemes improve the previous scheme without loss of the merit in its relay process. Moreover, we sum up cooperative diversity via simple relaying with QOSTBC to discuss these schemes with various channel model. We evaluate effect of these scheme in terms of signal matrixes and simulate bit error rate of the prposed and improved scheme with with various channel model, respectively.

Investigation on Relationship between Communication Distance and Receiving Characteristic in Visible Light Communication Using LED and High-Speed Camera Reviewed

E. Souke, Y. Ohira, S. Arai, T. Yamazato, T. Yendo, H. Okada, T. Fujii and K. Kamakura

Proceedings of 2014 IEEE Workshop on Nonlinear Circuit Networks (NCN'14) page： 93-94 2014.12

Language：English

The present paper considers an optical spatial channel in visible light communication (VLC) using LED and a high-speed camera. In general, the optical spatial channel affects the communication performance. However, the previous studies have not enough discussed the channel for VLC. This study focuses on the communication distance, which is one of channel parameters, and investigates the relationship between the distance and a receiving characteristic in the VLC.

EBIHARA Katsunori, KAMAKURA Koji, YAMAZATO Takaya

IEICE technical report. Communication systems Vol. 114 ( 289 ) page： 81 - 86 2014.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper demonstrates the feasibility of layered space-time coding (STC) in an outdoor image-sensor-based (IS-based) visible light communication (VLC) system. We examined that for low-resolution IS-based VLC channel where intensity modulated signals from two different light emitting diodes (LEDs) are detected at one pixel on the image plane, STC allows to decouple them, thus receiving data with no errors. Consequently, STC offers extending the transmission distance. In the layered STC presented here, additional bit streams are aligned in the 2^n × 2^n LED array for increasing the transmission rate per symbol duration for the case where the spatial resolution is improved. A prototype of three layered STC is built with an 8 × 8 LED array. Our experimental results validate that additional bit streams (layer-2 and -3), aligned in the layer-1 STC matrix pair, are extracted with no errors when the receiver comes within 155m and 55m, respectively, from the LED array, without decreasing 210m of the transmission distance of layer-1 bit stream.

Channel Fluctuation Measurement for Image Sensor Based I2V-VLC, V2I-VLC, and V2V-VLC Reviewed

M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura

2014 IEEE Asia Pacific Conferece on Circuits and Systems page： - 2014.11

Language：English

In image sensor based VLC, transmitter acquisition and tracking are critical issue. However, the fluctuation of the VLC transmitter in the image plane caused by vehicle movement, complicates correct data reception. Therefore, in this paper, we present results of channel fluctuation measurements for infrastructure-to-vehicle VLC (I2V-VLC), vehicleto- infrastructure VLC (V2I-VLC), and vehicle-to-vehicle VLC (V2V-VLC). We analyze channel fluctuation in terms of optical flow from measured data.

データを伴う照明 Invited Reviewed

山里敬也

電波技術協会報 page： - 2014.11

Authorship：Lead author Language：Japanese

可視光通信とは，LEDを人の目に分からないほど高速に点滅（変調）させることで情報伝送を行う通信のことである．可視光通信では発光ダイオード（light emitting diode: LED）を送信デバイスに用いるのだが，LEDはものすごい勢いで普及が進みつつあり，それこそ至る所にある．つまりLEDにデータ伝送機能を追加する可視光通信はユビキタスのインフラ基盤になりうるのである．

BER Characteristic of Optical-OFDM using OCI Reviewed

Y. Goto, I. Takai, T. Yamazato, H. Okada, T. Fujii, S. Kawahito, S. Arai, T. Yendo, K. Kamakura

2014 IEEE Asia Pacific Conferece on Circuits and Systems page： - 2014.11

Language：English

Light-emitting diode (LED) transmitters based optical wireless communication (OWC) systems offer the potential for new generation communication systems. Particularly, an image sensor based OWC systems consist of the LED transmitters and camera receivers are expected to contribute to intelligent transport system (ITS) for driving supports. For high achievable data rates, orthogonal frequency division multiplexing (OFDM) based OWC systems have attracted a great deal of attention. Despite attractive features of optical OFDM, only few attempts have so far been made to adopt it as a modulation scheme of an image sensor based OWC system. There remains a need for an evaluation of adopting an optical OFDM to the image sensor based OWC systems. Another important issue needs to be addressed is the performance degradation due to a frequency response of an actual image sensor device, especially a signal attenuation loss in higher frequency. In addition to such loss, a narrow band noise generated by its circuits also degrades the performance. The purpose of this paper is to investigate BER performances of the optical-OFDM using an actual image sensor device, the optical communication image sensor (OCI). From simulation results, it is found that the frequency response and the narrowband noise at 12MHz of the OCI lead to the significant reduction of BER performances. Additionally, the results shows that ACO-OFDM shows a little better performance compared to DCO-OFDM with the same bandwidth efficiency.

A Novel Study on Coded Modulation with Triangular Costellation Reviewed

YAMAOKA Tomoya, HARA Teruyuki, OKAZAKI Akihiro, YAMAZATO Takaya

Technical report of IEICE. RCS Vol. 114 ( 254 ) page： 111 - 116 2014.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

For improvement of the coded modulation, we propose the signal sets with triangular constellation and label shaping. The proposed signal set can gain the merits of them despite of a few signal points and a simple modification. We indicate the channel capacity, PAPR (Peak to Average Power Ratio), BER (Bit Error Rate) in case of BICM-ID (Bit Interleaved Coded Modulation with Iterative Decoding) and PAPR with band limited of the 7APSK (Amplitude and Phase-Shift Keying) and modified 14APSK. Especially, the results shows modified 14APSK we proposed can improve 16QAM (Quadrature Amplitude Modulation) in terms of BER and PAPR, simultaneously.

A Transmit Diversity with a Simple Transmitter Reviewed

YAMAOKA Tomoya, HARA Teruyuki, OKAZAKI Akihiro, YAMAZATO Takaya

Technical report of IEICE. RCS Vol. 114 ( 254 ) page： 117 - 122 2014.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we proposed a transmit diversity with a simple transmitter. Specifically, we connect simplex RF (Radio Frequency) circuits with two antennas and transmit the signals whose phases are rotated and IQ component are interleaved alternately via two antennas. In the receiver, the signals with the signal space diversity are received in spite of the simple transmitter. So we can achieve space diversity and reliable wireless communications. In the performance evaluation, we confirm the 4dB gain at BER=10^<-2> in bit error rate performance.

ITS Visible Light Communication using High-Speed Image Sensor Invited

Takaya Yamazato

The 133 Microoptics Meeting, Optical Society of Japan/The Japan Society of Applied Physics page： - 2014.10

Authorship：Lead author Language：Japanese

This paper presents the visible light communication using image sensor and its application to intelligent transport systems (ITS). As an example, mage-sensor based VLC for automotive application that is currently carried out by the author is also introduced. The paper is a continuation of the paper by Prof. Matsumoto, "Evaluation of optical wireless communication," and by Prof. Haruyama, "Recent trends of visible light communication," appeared on 2014 March issue of Microoptics News.

Channel Fluctuation Measurement for I2V-VLC, V2I-VLC, and V2V-VLC Using Image Sensor Reviewed

KINOSHITA Masayuki, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro, YENDO Tomohiro, KAMAKURA Koji

Vol. 114 ( 225 ) page： 77 - 81 2014.9

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In image sensor based VLC for automotive applications, transmitter acquisition and tracking are critical. However, the fluctuation of the VLC transmitter in the image plane caused by vehicle movement, complicates correct data reception. Therefore, in this paper, we present results of channel fluctuation measurements for automotive applications. Especially, we examined the channel fluctuation based on mobile movements in the image plane detected by phase only correlation (POC) in the subpixel accuracy.

Channel Fluctuation Measurement for I2V-VLC, V2I-VLC, and V2V-VLC Using Image Sensor Reviewed

Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

Vol. 2014 ( 13 ) page： 1 - 5 2014.9

Publishing type：Research paper (scientific journal) Publisher：Information Processing Society of Japan (IPSJ)

A-2-7 An influence of Noise Bandwidth on an application of Stochastic Resonance to Radio Communication Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2014 page： 28 2014.9

A-5-2 A Study on Influence of Communication Distance in Visible Light Communication Using LED and High-Speed Camera Reviewed

SOUKE Eisho, OHIRA Yuki, ARAI Shintaro, YAMAZATO Takaya, YENDO Tomohiro, OKADA Hiraku, FUJII Toshiaki, KAMAKURA Koji

Proceedings of the Society Conference of IEICE Vol. 2014 page： 84 2014.9

A-5-1 A Study on Signal Demodulation Method Based on Blurred Camera Image in Visible Light Communication Using LED Array and High-Speed Camera Reviewed

OHIRA Yuki, ARAI Shintaro, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, KAMAKURA Koji

Proceedings of the Society Conference of IEICE Vol. 2014 page： 83 2014.9

LEDアレーと高速度カメラを用いた可視光通信における画像のボケの影響を考慮した信号復調手法の一検討

大平祐生，荒井伸太郎，圓道知博，山里敬也，岡田啓，藤井俊彰，鎌倉浩嗣

電子情報通信学会基礎・境界ソサイエティ大会 page： - 2014.9

Channel Fluctuation Measurement for I2V-VLC, V2I-VLC, and V2V-VLC Using Image Sensor

M. Kinoshita, T. Yamazato, H, Okada, T. Fujii, S. Arai, T. Yendo, K. Kamakura

IEICE Technical Report Vol. ITS2014-18 page： 77-81 2014.9

Language：Japanese

In image sensor based VLC for automotive applications, transmitter acquisition and tracking are criti- cal. However, the uctuation of the VLC transmitter in the image plane caused by vehicle movement, complicates correct data reception. Therefore, in this paper, we present results of channel uctuation measurements for automo- tive applications. Especially, we examined the channel uctuation based on mobile movements in the image plane detected by phase only correlation (POC) in the subpixel accuracy.

LEDと高速度カメラを用いた可視光通信における通信距離の影響に関する一検討

曹家永翔，大平祐生，荒井伸太郎，山里敬也，圓道知博，岡田啓，藤井俊彰，鎌倉浩嗣

電子情報通信学会基礎・境界ソサイエティ大会 page： - 2014.9

An Analysis Method of a Stochastic Resonance Receiver using a Schmitt Trigger

H. Tanaka, K. Chiga, T. Yamazato, Y. Tadokoro, and S. Arai

International Symposium on Nonlinear Theory and its Application page： 193-196 2014.9

Language：English

Stochastic resonance (SR) enhances system responses by increasing noise. By applying SR to a receiver, a subthreshold signal not receivable by a conventional linear receiver could be received. Previously, we proposed an analysis method of the SR receiver using a comparator, and evaluated its bit error rate performance. The comparator is known as a simple non-dynamical system exhibiting SR. However, a dynamical system can have better performance since it has a memory effect. In this sense, we propose an analysis method of the SR receiver using a Schmitt trigger known as a simple dynamical system, and evaluate its bit error rate performance. A performance comparison of the comparator and the Schmitt trigger is also shown.

Image Sensor Based Visible Light Communication and Its Application to Pose, Position, and Range Estimations

T. Yamazato, S. Haruyama

IEICE Transactions on Communications Vol. E97-B ( 9 ) page： 1759-1765 2014.9

Language：English

This study introduces an image sensor based visible light communication (VLC) and its application to pose, position, and range estimations. There are two types of visible-light receiver: a photodiode and an image sensor. A photodiode is usually used as a reception device of VLC, and an image sensor consisting of a large number of pixels can also be used as a VLC reception device. A photodiode detects the signal intensity of incoming light, while an image sensor not only detects the incoming signal intensity but also an accurate angle of arrival of light emitted from a visible light transmitter such as a white LED light. After angles of arrival of light are detected by an image sensor, positioning and data reception can be performed. The ability of an image sensor to detect an accurate angle of arrival will provide attractive applications of VLC such as pose, position calculation, and range estimation. Furthermore, because the image sensor has the ability to spatially separate sources, outdoor positioning even with strong sunlight is possible by discarding the associated pixels of noise sources.

SNR Improvement by Stochastic Resonance Receiver for Subthreshold Signal in Radio Frequency

K. Chiga, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai

International Symposium on Nonlinear Theory and its Application page： - 2014.9

Language：English

Stochastic Resonance (SR) is well known as a phenomenon in which the weak signal in a nonlinear system can be detected by added noise. We consider the application of SR phenomenon to a wireless communication system. The receiver using SR phenomenon can detect the subthreshold signal which is not detectable by the conventional receiver. The effect of SR receiver has been verified, but it has never been verified in radio frequency which is used by a wireless system. In this paper, we consider the implementation of SR System for Radio Frequency and evaluate its performance of Signal to Noise Ratio (SNR).

An influence of Noise Bandwidth on an application of Stochastic Resonance to Radio Communication

K. Chiga, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai

Enginnering Sciences Society Conference of IEICE page： - 2014.9

Image Sensor Based Visible Light Communication and Its Application to Pose, Position, and Range Estimations Reviewed

Takaya Yamazato, Shinichiro Haruyama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E97B ( 9 ) page： 1759 - 1765 2014.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1587/transcom.E97.B.1759

Performance evaluation of stochastic resonance receiver using Schmitt trigger

Hiroya Tanaka, Keita Chiga, Takaya Yamazato, Yukihiro Tadokoro, Shintaro Arai

IEICE Complex Communication Sciences page： - 2014.8

Distance Estimation Scheme for Integrated V2I-VLC for driving vehicle Reviewed

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura

IEICE Transaction on Communications Vol. J97-B ( 8 ) page： 695-696 2014.8

Language：Japanese Publishing type：Research paper (scientific journal)

A distance estimation scheme for vehicle to infrastructure using visible light communication is discussed. As vehicle vibration severely affect the distance estimation performance, we introduce a new LED lighting patterns for the distance estimation. As the result, we acheive nearly the same distance estimation performance for the case of non-driving.

Optical Signal Detection by Stochastic Resonance Receiver Using Schmitt Trigger for LED Visible Light Communications

S. Arai, T. Yamazato, Y. Tadokoro

The 27th Workshop on Circuits and Systems page： 116-120 2014.8

Distance Estimation Scheme for Integrated V2I-VLC for driving vehicle Reviewed

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura

IEICE Transaction on Communications Vol. J97-B ( 8 ) page： 695-696 2014.8

A New LED Array Acquisition Method Focusing on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Reviewed

S.Usui, T.Yamazato, H.Okada, T.Fujii, K.Takahashi, T.Yendo, S.Arai

IEICE Transactions on Communications Vol. J97-B ( 7 ) page： 536-545 2014.7

Language：Japanese Publishing type：Research paper (scientific journal)

This paper proposes a new LED acquisition method for visible light communication systems using an LED array as a transmitter and a high-speed camera as a receiver for road-to-vehicle communications. The first process of the receiver is to search the target LED array from the captured image (LED array acquisition). This paper focuses on the time-gradient and the space-gradient values in the captured images, and draws both gradient value as a scatter diagram. This scatter diagram enables us to regard the LED acquisition as discriminant analysis. From the above, this paper proposes a new acquisition method and confirms its effectiveness by the experiment in a driving situation.

A New LED Array Acquisition Method Focusing on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Reviewed

S.Usui, T.Yamazato, H.Okada, T.Fujii, K.Takahashi, T.Yendo, S.Arai

IEICE Transactions on Communications Vol. J97-B ( 7 ) page： 536-545 2014.7

Image-Sensor-Based Visible Light Communication for Automotive Applications Reviewed

Takaya Yamazato, Isamu Takai, Hiraku Okada, Toshiaki Fujii, Tomohiro Yendo, Shintaro Arai, Michinori Andoh, Tomohisa Harada, Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito

IEEE COMMUNICATIONS MAGAZINE Vol. 52 ( 7 ) page： 88 - 97 2014.7

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The present article introduces VLC for automotive applications using an image sensor. In particular, V2I-VLC and V2V-VLC are presented. While previous studies have documented the effectiveness of V2I and V2V communication using radio technology in terms of improving automotive safety, in the present article, we identify characteristics unique to image-sensor-based VLC as compared to radio wave technology. The two primary advantages of a VLC system are its line-of-sight feature and an image sensor that not only provides VLC functions, but also the potential vehicle safety applications made possible by image and video processing. Herein, we present two ongoing image-sensor-based V2I-VLC and V2V-VLC projects. In the first, a transmitter using an LED array (which is assumed to be an LED traffic light) and a receiver using a high-frame-rate CMOS image sensor camera is introduced as a potential V2I-VLC system. For this system, real-time transmission of the audio signal has been confirmed through a field trial. In the second project, we introduce a newly developed CMOS image sensor capable of receiving highspeed optical signals and demonstrate its effectiveness through a V2V communication field trial. In experiments, due to the high-speed signal reception capability of the camera receiver using the developed image sensor, a data transmission rate of 10 Mb/s has been achieved, and image (320 x 240, color) reception has been confirmed together with simultaneous reception of various internal vehicle data, such as vehicle ID and speed.

DOI： 10.1109/MCOM.2014.6852088

A-2-15 Derivation of the Max of Sensitivity Improvement Rate of Stochastic Resonance Receiver for Subthreshold Bi-Polar Pulse Reviewed

Derivation of the Max of Sensitivity Improvement Rate of Stochastic Resonance Receiver for Subthreshold Bi-Polar Pulse

H. Tanaka, K. Chiga, T. Yamazato, Y. Tadokoro, S. Arai

IEICE General Conference ( A-2-15 ) page： p.40 2014.3

A Study on Adaptation of Optical OFDM to Visible Light Communication using Optical Communication Imaging Sensor

Y.Goto,T.Yamazato,H.Okada,T.Fujii,I.Takai,S.Kawahito,T.Yendo,S.Arai,K.Kamakura

IEICE General Conference ( B-10-20 ) page： p.388 2014.3

TANAKA Hiroya, CHIGA Keita, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2014 page： 40 2014.3

B-10-20 A Study on Adaptation of Optical OFDM to Visible Light Communication using Optical Communication Imaging Sensor Reviewed

GOTO Yuki, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, TAKAI Isamu, KAWAHITO Shoji, ARAI Shintaro, YENDO Tomohiro, KAMAKURA Koji

Proceedings of the IEICE General Conference Vol. 2014 ( 2 ) page： 388 2014.3

IEICE Knowledge Discovery(I-Scover) Reviewed

Takaya Yamazato, Yasubumi Chimura, Fumihito Nishino, Satoshi Ikada, Toyokazu Akiyama, Miyuki Nakano, Yuji Inoue

The Journal of IEICE Vol. 97 ( 3 ) page： 240-246 2014.3

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

I-Scover, officially known as IEICE Knowledge Discovery, is a new reference search engine developed by the Institute of Electronics, Information and Communication Engineers (IEICE). It is not just a system for cross-searching articles published by IEICE. It also aims to maximize significance of the IEICE articles by organically linking related information with the articles, making them accessible on the Internet for many users. With I-Scover, berry-picking exploratory search, which has been difficult with conventional reference search engines, is possible. In this article, we will describe I-Scover in terms of its developmental background and aim, introduce its various features and characteristics, and discuss the promotional activity plan to spread I-Scover, as well as its future development plans.

IEICE knowledge discovery (I-Scover) Reviewed

Yamazato T.

Journal of the Institute of Electronics, Information and Communication Engineers Vol. 97 ( 3 ) page： 240 - 246 2014.3

IEICE Knowledge Discovery (I-Scover) Reviewed

YAMAZATO Takaya, CHIMURA Yasubumi, NISHINO Fumihito, IKADA Satoshi, AKIYAMA Toyokazu, NAKANO Miyuki, INOUE Yuji

The Journal of the Institute of Electronics, Information, and Communication Engineers Vol. 97 ( 3 ) page： 240 - 246 2014.3

Preliminary Study on LED VLC with Simple SR Receiver Using Schmitt Trigger Reviewed

H. Yokota, S. Arai, T. Yamazato and Y. Tadokoro

Proceedings of 2014 RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP'14) page： pp. 61-64. 2014.2

Language：English

The present paper focuses on an application of Stochastic Resonance (SR) for an LED visible light communication (LED-VLC) receiver. SR is well-known as a phenomenon, which enhances the response by additive noise. We consider that a weak optical signal, which is distorted due to an influence of ambient light noise, can be detected by using SR system. This study makes a simple SR circuit for LED VLC and performs its circuit experiment for exploring the possibility and availability of the LED-VLC receiver using SR system.

Alamouti-Type Coding for Visible Light Communication Based on Direct Detection Using Image Sensor

Y. Amano, K. Kamakura, T. Yamazato

IEICE Technical Report ( ITS2013-37 ) page： pp.43-48 2014.2

Language：Japanese

This paper proposes Alamouti-type space time (ST) coding to visible light communication (VLC) using light emitting diodes (LEDs) and image sensor with a high-speed camera. Although multiple LEDs of an array are used as transmitters, the received signal is essentially the image of the transmitting element, whose size in pixel reduces with distance. When the receiver captures the LED array at a distance where images of two neighboring LEDs in the array are not separated at the image plane, such distortion depreciates the symbol decision quality. Our proposed scheme aims at expanding the communication range limited by the pixel resolution of image sensor. Our implemented prototype demonstrates that ST coding is feasible to achieve 48,m error-free transmission range while the repetition transmission achieves 26,m error-free range.

LED Array Acquisition Method Based on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Using High-Speed Camera

S.Usui, T.Yamazato, H.Okada, T.Fujii, K.Takahashi, T.Yendo, S.Arai

IEICE Technical Report ( ITS2013-39 ) page： pp.55-60 2014.2

Language：Japanese

This paper focuses on road-to-vehicle visible light communication using an LED array as a transmitter and a high-speed camera as a receiver. In this communication, LED array acquisition has a significant role. The spatio-temporal images are essential for a robust LED array acquisition because the time-gradient and space-gradient values can be an important feature value of an LED array. In this paper, we focus on the time-gradient and the space-gradient values in the captured images and draws both gradient value as a scatter diagram. This scatter diagram enables us to regard the LED acquisition as discriminant analysis. From the above, this paper proposes a new acquisition method and confirms its effectiveness by the experiment in a driving situation.

Distance Estimation Scheme for Integrated V2I-VLC in Driving Vehicle

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai, K. Kamakura

IEICE Technical Report ( ITS2013-38 ) page： pp.49-54 2014.2

Language：Japanese

This paper discusses an issue of estimating the distance between an on-vehicle transmitter and a roadside equipment for vehicular-to-infrastructure visible light communication (V2I-VLC). The system integrates the VLC as well as distance estimation functions. In this paper, we discuss a technique overcoming a vehicle vibration by using a particular transmitting LED pattern and the sub-pixel estimation using the phase-only correlation. As the results, we achieve less than 0.5m errors for the distance up to 60 m by the proposed system.

Alamouti-Type Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

AMANO Yuta, KAMAKURA Koji, YAMAZATO Takaya

Vol. 113 ( 433 ) page： 43 - 48 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper proposes Alamouti-type space time (ST) coding to visible light communication (VLC) using light emitting diodes (LEDs) and image sensor with a high-speed camera. Although multiple LEDs of an array are used as transmitters, the received signal is essentially the image of the transmitting element, whose size in pixel reduces with distance. When the receiver captures the LED array at a distance where images of two neighboring LEDs in the array are not separated at the image plane, such distortion depreciates the symbol decision quality. Our proposed scheme aims at expanding the communication range limited by the pixel resolution of image sensor. Our implemented prototype demonstrates that ST coding is feasible to achieve 48m error-free transmission range while the repetition transmission achieves 26 m error-free range.

Alamouti-Type Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

AMANO Yuta, KAMAKURA Koji, YAMAZATO Takaya

IEICE technical report. Image engineering Vol. 113 ( 434 ) page： 43 - 48 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper proposes Alamouti-type space time (ST) coding to visible light communication (VLC) using light emitting diodes (LEDs) and image sensor with a high-speed camera. Although multiple LEDs of an array are used as transmitters, the received signal is essentially the image of the transmitting element, whose size in pixel reduces with distance. When the receiver captures the LED array at a distance where images of two neighboring LEDs in the array are not separated at the image plane, such distortion depreciates the symbol decision quality. Our proposed scheme aims at expanding the communication range limited by the pixel resolution of image sensor. Our implemented prototype demonstrates that ST coding is feasible to achieve 48m error-free transmission range while the repetition transmission achieves 26 m error-free range.

Distance Estimation Scheme for Integrated V2I-VLC in Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro, KAMAKURA Koji

Vol. 113 ( 433 ) page： 49 - 54 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper discusses an issue of estimating the distance between an on-vehicle transmitter and a road-side equipment for vehicular-to-infrastructure visible light communication (V2I-VLC). The system integrates the VLC as well as distance estimation functions. In this paper, we discuss a technique overcoming a vehicle vibration by using a particular transmitting LED pattern and the sub-pixel estimation using the phase-only correlation. As the results, we achieve less than 0.5m errors for the distance up to 60 m by the proposed system.

LED Array Acquisition Method Based on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Using High-Speed Camera Reviewed

USUI Syunsuke, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, TAKAHASHI Keita, ARAI Shintaro, YENDO Tomohiro

IEICE technical report. Image engineering Vol. 113 ( 434 ) page： 55 - 60 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper focuses on road-to-vehicle visible light communication using an LED array as a transmitter and a high-speed camera as a receiver. In this communication, LED array acquisition has a significant role. The spatio-temporal images are essential for a robust LED array acquisition because the time-gradient and space-gradient values can be an important feature value of an LED array. In this paper, we focus on the time-gradient and the space-gradient values in the captured images and draws both gradient value as a scatter diagram. This scatter diagram enables us to regard the LED acquisition as discriminant analysis. Prom the above, this paper proposes a new acquisition method and confirms its effectiveness by the experiment in a driving situation.

LED Array Acquisition Method Based on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Using High-Speed Camera Reviewed

USUI Syunsuke, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, TAKAHASHI Keita, ARAI Shintaro, YENDO Tomohiro

Vol. 113 ( 433 ) page： 55 - 60 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper focuses on road-to-vehicle visible light communication using an LED array as a transmitter and a high-speed camera as a receiver. In this communication, LED array acquisition has a significant role. The spatio-temporal images are essential for a robust LED array acquisition because the time-gradient and space-gradient values can be an important feature value of an LED array. In this paper, we focus on the time-gradient and the space-gradient values in the captured images and draws both gradient value as a scatter diagram. This scatter diagram enables us to regard the LED acquisition as discriminant analysis. Prom the above, this paper proposes a new acquisition method and confirms its effectiveness by the experiment in a driving situation.

Distance Estimation Scheme for Integrated V2I-VLC in Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro, KAMAKURA Koji

IEICE technical report. Image engineering Vol. 113 ( 434 ) page： 49 - 54 2014.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Preliminary Study on LED VLC with Simple SR Receiver Using Schmitt Trigger

H. Yokota, S. Arai, T. Yamazato and Y. Tadokoro

Proceedings of 2014 RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP'14) page： 61-64 2014.2

Language：English

LED Array Acquisition Method Based on Time-gradient and Space-gradient Values for Road to Vehicle Visible Light Communication Using High-Speed Camera

S.Usui, T.Yamazato, H.Okada, T.Fujii, K.Takahashi, T.Yendo, S.Arai

IEICE Technical Report Vol. ITS2013-39 page： 55-60 2014.2

Language：Japanese

Driver Assistant System using Visible Light Communications : Road-to-Vehicle Visible Light Communications using LED Array and On-Vehicle High-Speed Camera Reviewed

YAMAZATO Takaya

Technical report of IEICE. OCS Vol. 113 ( 391 ) page： 17 - 23 2014.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We are conducting a study on viheicle-infrastractuctre cooperateive systems using visible light communications for driving safty applications. This paper introduces our studies on such VLC supported ITS systems using a high-speed image sensor as a VLC receiver equiped on a vehicle. The image sensors are now adopted for a lane keeping, an obstables recognition, a range estimation and many other applications. If we could add a VLC function to those safety applications, then a driver can recognize his environment visually and also he recognize his environment by signals transmitted through an LED traffic lights, LED tail lights, LED signage board, etc in a form of VLC signals. Together, it can contribute to more extensive safety driving.

Driver Assistant System using Visible Light Communications : Road-to-Vehicle Visible Light Communications using LED Array and On-Vehicle High-Speed Camera Reviewed

YAMAZATO Takaya

IEICE technical report. Communication systems Vol. 113 ( 390 ) page： 57 - 63 2014.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Application of visible light communication to LED traffic light Reviewed

T. Yamazato

Journal of Light & Visual Environment (JLVE) Vol. 98 ( no.1 ) page： pp.17-20 2014.1

Language：Japanese

Driver Assistant System using Visible Light Communications Invited

Takaya Yamazato

IEICE Technical Report Vol. CS2013-94 page： 57-63 2014.1

Authorship：Lead author Language：Japanese

We are conducting a study on viheicle-infrastractuctre cooperateive systems using visible light commu- nications for driving safty applications. This paper introduces our studies on such VLC supported ITS systems using a high-speed image sensor as a VLC receiver equiped on a vehicle. The image sensors are now adopted for a lane keeping, an obstables recognition, a range estimation and many other applications. If we could add a VLC function to those safety applications, then a driver can recognize his environment visually and also he recognize his environment by signals transmitted through an LED traffic lights, LED tail lights, LED signage board, etc in a form of VLC signals. Together, it can contribute to more extensive safety driving.

Multiple LED Arrays Acquisition for Image-Sensor-Based I2V-VLC Using Block Matching

S. Arai, Y. Shiraki, T. Yamazato, H. Okada, T. Fujii, T. Yendo

IEEE Consumer Communications and Networking Conference page： 605-610 2014.1

Language：English

The present paper proposes a novel multiple-LED-arrays acquisition for an infrastructure-to-vehicle visible light communication (I2V-VLC) using LED arrays (transmitter) and an in-vehicle high-speed image sensor (receiver). In order to achieve a robust detection of LED arrays, we employ the block matching algorithm, which is a way of finding a corresponding position between two successive frames. The proposed method divides a captured image into a number of small domains (blocks) and determines if the LED array is present or absent using the block matching. We perform I2V-VLC experiments with multiple-LED arrays and evaluate the acquisition capability of the proposed method.

M-ary modulation scheme based on separation of deterministic chaotic dynamics for noncoherent chaos-based communications

Arai Shintaro, Nishio Yoshifumi, Yamazato Takaya

Nonlinear Theory and Its Applications, IEICE Vol. 5 ( 2 ) page： 210 - 221 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

The present paper proposes a novel M-ary modulation scheme based on separation and reconstruction of deterministic chaotic dynamics for noncoherent chaos-based communications. The M-ary modulation scheme can transmit b-bit data at a time by using M=2b distinct sequences. In order to generate M distinct sequences and recover b-bit data, the proposed system separates the chaotic dynamics having the chaotic sequence by using M interleavers, and reconstructs the original sequence based on the chaotic dynamics from the separated one by using M deinterleavers. In advance, each data symbol among M symbols is allocated to each interleaver-deinterleaver pair. The transmitter selects an interleaver corresponding to a data symbol and separates the order of samples of the chaotic sequence using the selected interleaver. The receiver feeds the received sequence into all M deinterleavers and outputs M reconstructed sequences. The proposed system can reconstruct the original chaotic sequence only when the correct deinterleaver, which becomes paired with the interleaver, is selected. Therefore, the receiver can recover b-bit data by analyzing the chaotic dynamics of each reconstructed sequence. We carry out computer simulations and evaluate performances of the proposed M-ary modulation scheme.

DOI： 10.1587/nolta.5.210

BER Characteristic of Optical-OFDM using OCI Reviewed

Yuki Goto, Isamu Takai, Takaya Yamazato, Hiraku Okada, Akitoshi Fujii, Shoji Kawahito, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) Vol. 2015-February ( February ) page： 328 - 331 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/APCCAS.2014.7032786

Channel Fluctuation Measurement for Image Sensor Based I2V-VLC, V2I-VLC, and V2V-VLC Reviewed

Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) Vol. 2015-February ( February ) page： 332 - 335 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In image sensor based VLC, transmitter acquisition and tracking are critical issue. However, the fluctuation of the VLC transmitter in the image plane caused by vehicle movement, complicates correct data reception. Therefore, in this paper, we present results of channel fluctuation measurements for infrastructure-to-vehicle VLC (I2V-VLC), vehicle-to-infrastructure VLC (V2I-VLC), and vehicle-to-vehicle VLC (V2V-VLC). We analyze channel fluctuation in terms of optical flow from measured data.

DOI： 10.1109/APCCAS.2014.7032787

Improving communication rate of visible light communication system using high-speed camera Reviewed

Improving communication rate of visible light communication system using high-speed camera Reviewed

Iwase Daigo, Kasai Makoto, Yendo Tomohiro, Arai Shintaro, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) page： 336 - 339 2014

Daigo Iwase, Makoto Kasai, Tomohiro Yendo, Shintaro Arai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) Vol. 2015-February ( February ) page： 336 - 339 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

We focus on the road-to-vehicle visible light communication that system is composed of LED matrix as transmitter and high-speed camera as receiver. Conventionally, the transmitting rate has been reduced to half of the frame rate of the camera, to avoid intersymbol interference because of exposure time of camera frame. We propose a method to improve the communication rate. The transmitting rate is set same to receiver's frame rate, and the sent data is estimated from pattern mixed image. Using 8b/10b encoding instead of conventional reversal pattern to reduce the flickering of transmitter's lighting is also proposed.

DOI： 10.1109/APCCAS.2014.7032788

Multiple LED Arrays Acquisition for Image-Sensor-Based I2V-VLC Using Block Matching Reviewed

Motion Modeling of Mobile Transmitter for Image Sensor Based I2V-VLC, V2I-VLC, and V2V-VLC Reviewed

Kinoshita Masayuki, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Arai Shintaro, Yendo Tomohiro, Kamakura Koji

2014 GLOBECOM WORKSHOPS (GC WKSHPS) page： 450 - 455 2014

Shintaro Arai, Yasutaka Shiraki, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Tomohiro Yendo

2014 IEEE 11TH CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE (CCNC) page： 605 - 610 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/CCNC.2014.6866634

Motion Modeling of Mobile Transmitter for Image Sensor Based I2V-VLC, V2I-VLC, and V2V-VLC Reviewed

Multiple LED Arrays Acquisition for Image-Sensor-Based I2V-VLC Using Block Matching Reviewed

Arai Shintaro, Shiraki Yasutaka, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Yendo Tomohiro

2014 IEEE 11TH CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE (CCNC) 2014

Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shintaro Arai, Tomohiro Yendo, Koji Kamakura

2014 GLOBECOM WORKSHOPS (GC WKSHPS) page： 450 - 455 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/GLOCOMW.2014.7063473

Spatially-Modulated Space-Time Coding in Visible Light Communications Using 2 x 2 LED Array Reviewed

Spatially-Modulated Space-Time Coding in Visible Light Communications Using 2 x 2 LED Array Reviewed

Ebihara Katsunori, Kamakura Koji, Yamazato Takaya

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) page： 320 - 323 2014

Katsunori Ebihara, Koji Kamakura, Takaya Yamazato

2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS) Vol. 2015-February ( February ) page： 320 - 323 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper demonstrates the feasibility of binary spatially-modulated space-time (SM-ST) coding in an outdoor image-sensor-based visible light communication (VLC) system. We showed that at the transmission distance where intensity modulated symbols from two different light emitting diodes (LEDs) are detected at one pixel of the image plane of the image sensor, space time (ST) coding enables to decouple the two symbols and to extend error-free transmission distance. We furthermore aim at increasing transmission rate per symbol duration when the spatial resolution is improved when the receiver approaches the LED array of the transmitter, by superimposing space shift keying (SSK) signal with the diagonal and anti-diagonal set of the 2 x 2 matrix onto the LED patterns. We built an experimental testbed with LEDs modulated at 1 kbps and a high-speed camera operating at 1,000 fps. Our experimental results validate that SM-ST coding achieves 30m of the error-free transmission distance for the additional bit based on SSK, without deteriorating the reception quality and range of the space-time coded bits.

DOI： 10.1109/APCCAS.2014.7032784

Application of Visible Light Communication to LED Traffic Light(<Special Issue>For the Further Spread of SSL and the Expansion of the Application Field) Reviewed

Yamazato Takaya

JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN Vol. 98 ( 1 ) page： 17 - 20 2014

Publishing type：Research paper (scientific journal) Publisher：The Illuminating Engineering Institute of Japan

Visible light communications (VLC) is the latest optical wireless communications technology that uses low-power light emitting diodes, or LEDs, not only to provide light but also to broadcast data. LEDs are extremely energy-efficient and predicted to become widespread in general lighting application. Because LED is a solid-state lighting device, it can be modulated at high-speed compared with other lighting sources. VLC uses LEDs, which send data by flashing light at speeds undetectable to the human eye. Widespread use of LEDs in traffic applications and growing interest in Intelligent Transport System (ITS) presents an opportunity for VLC. Data transmission using LED traffic lights, LED road illumination, and LED brake lights are typical application. In this paper, an on-going research, road-to-vehicle visible light communication, will be introduced. The LED array, assumed to be an LED traffic light, is used as a transmitter and it sends data to a moving vehicle. By providing data together with a traffic signal that is visible to a driver, a safety driving support can be realized. Finally, the author suggests readers a glimpse of wealth on "dual use of LEDs" and concludes the paper.

DOI： 10.2150/jieij.98.17

[招待論文]可視光通信の交通信号への適用 Reviewed

山里敬也

照明学会誌 Vol. vol.98, no.1 page： 17 - 20 2014

A Study on Simple LED-VLC Flashlight Transmitter for Disaster Situation Reviewed

K. Miyazaki, Y. Ohira, S. Arai, T. Yendo, T. Yamazato, H. Okada, T. Fujii

Proceedings of 2013 IEEE Workshop on Nonlinear Circuit Networks (NCN'13) page： - 2013.12

Language：Japanese

This study focuses on the visible light communication(VLC) system using LED and a high-speed camera inorder to develop robust and adaptable communication systemsin the disaster situation, such as an earthquake. Especially, we consider utilization of a flashlight, which is often used in disaster situations, as a transmitter. We develop a simple LED-VLC transmitter using a flashlight and perform a communication experiment using it.

Accuracy Improvement by Phase Only Correlation for Distance Estimation Scheme for Visible Light Communications Using an LED Array and a High-speed Camera Reviewed

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

IEICE Transaction on Communications Vol. J96-B ( no.12 ) page： pp.1365-1368 2013.12

Accuracy Improvement by Phase Only Correlation for Distance Estimation Scheme for Visible Light Communications Using an LED Array and a High-speed Camera Reviewed

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

IEICE Transaction on Communications Vol. J96-B ( 12 ) page： 1365-1368 2013.12

Accuracy Improvement by POC for Distance Estimation Scheme for VLC Using an LED Array and a High-Speed Camera Reviewed

OHMURA Akihiro, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 96 ( 12 ) page： 1365 - 1368 2013.12

[Invited Talk] SN, USN, and then ASN Invited

T. Yamazato

IEICE Technical Report ( ASN2013-112 ) page： pp.121-124 2013.11

Invited Talk : SN, USN, and then ASN Reviewed

YAMAZATO Takaya

IEICE technical report. ASN, Ambient intelligence and sensor networks Vol. 113 ( 328 ) page： 121 - 124 2013.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Technical Committees (TCs) on Ad Hoc Networks (AN) and Ubiquitous and Sensor Networks (USN) have been consolidated in new TC, Ambient Intelligence and Sensor Networks (ASN). USN was the result of integrating two TCs in different societies, Ubiquitous and Real-World Oriented Networking (URON) in Communication Society and Sensor Networks (SN) in Engineering Science Society. The author has been engaged in SN, USN, and ASN. The present article looks back the aims and backgrounds of those TCs. In expectation of the further advancement of ASN, a few concluding remarks are presented.

Image Sensor based Visible Light Communication for Automotive Applications Reviewed

T. Yamazato, I. Takai, H. Okada, T. Fujii, T. Yendo, S. Arai, M. Andoh, K. Yasutomi, K. Kagawa, S. Kawahito

Proc. of International Symposium on Optical Wireless Communications page： - 2013.11

Language：English

This talk introduces visible light communication (VLC) for automotive applications using an image sensor. In particular, vehicle-to-infrastructure visible light communication (V2I-VLC) and vehicle-to-vehicle visible light communication (V2V-VLC) are presented. Previous studies have documented the effectiveness of V2I and V2V communication using radio technology for improving automotive safety. In this talk, I identify characteristics unique to the introduced image sensor based VLC as compared to radio wave technology. The advantages of VCL are twofold: the line-of-sight feature of visible light links and an image sensor that provides not only the VLC function but also vehicle safety applications using image and video processing. We present two on-going image sensors based V2I-VLC and V2V-VLC projects.

Performance Evaluation of Error-Correcting Scheme Using Separation of Chaotic Dynamics for Number of Transmitting Data

S. Arai, Y. Nishio and T. Yamazato

IEICE Technical Report ( NLP2013-108 ) page： pp. 205-209 2013.10

Language：Japanese

Noncoherent chaos communications, which do not need to use basis signals (unmodulated carriers) for demodulation, are unique communication systems using characteristics of chaos. However, the communication performance of the noncoherent system is lower as compared with the standard communication systems. Thus, it is important to advance noncoherent system in order to improve its performance. In our previous research, we have proposed a novel error-correcting method using a separation and reconstruction of the chaotic dynamics, which is one of characteristics of chaos. As simulation results, we have confirmed that the advantage gained in BER performance of our error-correcting method is about 2--2.5 dB compared to the conventional one (w/o coding). This paper focuses on a number of transmitting data and a combination of symbols, and analyzes an error-correcting capability for evaluating advantages of the separation and reconstruction of the chaotic dynamics in detail.

Performance evaluation of the weak signal detection of the Stochastic Resonance Receiver using Schmitt Trigger

K.Chiga, H.Tanaka, T.Yamazato, Y.tadokoro, S.Arai

IEICE Technical Report ( NLP2013-73 ) page： pp.19-23 2013.10

Language：Japanese

Stochastic Resonance(SR) is a nonlinear phenomena in which the Signal-to-Noise Ratio(SNR) is enhanced by an increase of the noise. By using SR, we can detect the weak signal which cannot detect by the conventional receiver. In this paper, we consider the application of SR to the communication systems. we implement the Stochastic Resonance Receiver using Schmitt Trigger as the Stochastic Resonance system. We evaluate the performance of the weak signal responce and we discuss about the weak signal detection.

Performance evaluation of the weak signal detection of the Stochastic Resonance Receiver using Schmitt Trigger Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

IEICE technical report. Nonlinear problems Vol. 113 ( 271 ) page： 19 - 23 2013.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Performance Evaluation of Error-Correcting Scheme Using Separation of Chaotic Dynamics for Number of Transmitting Data Reviewed

ARAI Shintaro, NISHIO Yoshifumi, YAMAZATO Takaya

IEICE technical report. Nonlinear problems Vol. 113 ( 271 ) page： 205 - 209 2013.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Utilization of Spatio-temporal image for LED array acquisition in Road to Vehicle Visible Light Communication Reviewed

S.Usui, T.Yamazato, S.Arai, T.Yendo, T.Fujii, H.Okada

20th World Congress on Intelligent Transport Systems page： - 2013.10

Language：English

In this paper, we focus attention on visible light communication systems using an LED array as a transmitter and a high-speed camera as a receiver for road-to-vehicle communications (R2V-VLC) in intelligent transport systems. To implement R2V-VLC, it is necessary for the receiver to search the target LED array from the captured images (LED array acquisition) before data demodulation. We propose a new approach for LED array acquisition. We focus on spatio-temporal image and spatio-temporal cross-section image and show LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. Using such characteristic gradient values, we propose new LED array acquisition method. As the results of the experiment in driving situation, we can achieve acquisition miss rate = 0%.

Accuracy Improvement by Phase Only Correlation for Distance Estimation Scheme for Visible Light Communications Using an LED Array and a High-speed Camera Reviewed

A. Ohmura, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

20th World Congress on Intelligent Transport Systems page： - 2013.10

Language：English

In this paper, we focus on a distance estimation scheme using camera. Our distance estimation scheme is based on triangulation. The accuracy of camera based scheme is governed by resolution of a camera, or equivalently the size of pixel. Therefore we introduce phase only correlation (POC) to estimate with subpixel accuracy. As a result of experiment, we will show that our scheme achieves less than 0.3m estimation error at the distance of 60m. By using POC, the resolution of estimation reaches nearly 0.02 pixel, much less than one pixel.

A Study on Implementation of Stochastic Resonance Receiver using Schmitt Trigger

K. Chiga, H. Tanaka, T. Yamazato, Y. Tadokoro, S. Arai

IEICE Society Conference ( A-2-13 ) page： p.32 2013.9

The outline of I-Scover (IEICE Knowledge Discovery)

T. Yamazato

IEICE Society Conference page： - 2013.9

A Study on the Signal Sensitivity of Stochastic Resonance Receiver for the Subthreshold Bi-Polar Pulse Detection

H. Tanaka, K. Chiga, T. Yamazato, Y. Tadokoro, S. Arai

Enginnering Sciences Society Conference of IEICE ( A-2-14 ) page： p. 33 2013.9

Implementation of Bi-Polar Pulse SR Receiver Using Schmitt Trigger and Evaluation of its Performance Reviewed

K.Chiga, H.Tanaka, T.Yamazato, Y.Tadokoro, S.Arai

2013 International Symposium on Nonlinear Theory and its Application(NOLTA 2013) page： - 2013.9

Language：English

We consider an application of Stochastic Resonance to wireless communication system. Stochastic Resonance (SR) is well known as a phenomenon in which weak signal in nonlinear system can be detected by added noise. A receiver using Stochastic Resonance (SR Receiver) can detect a weak signal which is not detectable in the conventional receiver. In this paper, we consider the implementation of bi-polar pulse SR Receiver using Schmitt Trigger and evaluate the performance in Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER).

[Invited Talk] Application of visible light communication to LED traffic light

T. Yamazato

Proceeding of 2013 Annual Conference of IEIJ page： - 2013.9

A Study on Implementation of Stochastic Resonance Receiver using Schmitt Trigger Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2013 page： 32 2013.9

A Study on the Signal Sensitivity of Stochastic Resonance Receiver for the Subthreshold Bi-Polar Pulse Detection Reviewed

TANAKA Hiroya, CHIGA Keita, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2013 page： 33 2013.9

Let's Search IEICE Contents through New Meta-Data System I-Scover!

T. Yamazato

IEICE Global Plaza Vol. No.55 page： - 2013.8

Language：English

IEICE launched the new metadata search system called "I-Scover" on April 3, 2013. For the time being, I-Scover provides the metadata search service of all papers published in IEICE transactions covering from the first edition published in 1968 up to the present edition, Technical Reports (from 2006) and international conference papers of ISPA and EMC. The total number of searchable contents reaches 150,000. This article briefly introduces I-Scover. Before going to the details, let me start with a quiz. What phrase do you guess if you say "I-Scover" for three times?

Lectures in Nagoya University OCW that providing play and learning experiences Reviewed

T. Yamazato

2013 JSEE Annual Conference page： - 2013.8

M-ary Modulation Method Using Separation of Chaotic Dynamics for Noncoherent Chaos Communications

S. Arai, Y. Nishio and T. Yamazato

The 26th Workshop on Circuits and Systems page： - 2013.7

Distance Estimation Scheme for Integrated V2I-VLC Simulating the Vibration of Driving Vehicle

A.OHMURA, T.YAMAZATO, H.OKADA, T. FUJII, T. YENDO, S. ARAI

Technical Report of IEICE ( ASN2013-55 ) page： pp.41-46 2013.7

Language：Japanese

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from theLED array installed on roads. Robust data reception and fast communication are possible by using a high-speedcamera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we proposean integrated system of communication and distance estimation by sending a known data pattern from the LEDarray. On issues which is distance estimation performance deterioration by the vibration of the running vehicle, tryto resolve them using the technique using the phase-only correlation method.

LED array acquisition method based on Spatio-temporal image in Road to Vehicle Visible Light Communication

S.Usui, T.Yamazato, S.Arai, T.Yendo, T.Fujii, H.Okada

Technical Report of IEICE ( ASN2013-55 ) page： pp.47-52 2013.7

Language：Japanese

In this paper, we focus attention on road-to-vehicle visible light communication(R2V-VLC) in intelligent transport systems. This system uses an LED array as a transmitter and a high-speed camera as a receiver. To implement R2V-VLC, it is necessary to acquire the target LED array from the captured images at receiver before data demodulation. To achieve accurate aquisition, we analyze LED array by use of Spatio-temporal image. As the result of the analysis, we show the LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. After that we propose a new LED array acquisition method using such characteristic gradient values.

LED array acquisition method based on Spatio-temporal image in Road to Vehicle Visible Light Communication Reviewed

USUI Syunsuke, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 113 ( 129 ) page： 19 - 24 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we focus attention on road-to-vehicle visible light communication(R2V-VLC) in intelligent transport systems. This system uses an LED array as a transmitter and a high-speed camera as a receiver. To implement R2V-VLC, it is necessary to acquire the target LED array from the captured images at receiver before data demodulation. To achieve accurate acquisition, we analyze LED array by use of Spatio-temporal image. As the result of the analysis, we show the LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. After that we propose a new LED array acquisition method using such characteristic gradient values.

Distance Estimation Scheme for Integrated V2I-VLC Simulating the Vibration of Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 113 ( 129 ) page： 13 - 17 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array. On issues which is distance estimation performance deterioration by the vibration of the running vehicle, try to resolve them using the technique using the phase-only correlation method.

LED array acquisition method based on Spatio-temporal image in Road to Vehicle Visible Light Communication Reviewed

USUI Syunsuke, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 113 ( 131 ) page： 27 - 32 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we focus attention on road-to-vehicle visible light communication(R2V-VLC) in intelligent transport systems. This system uses an LED array as a transmitter and a high-speed camera as a receiver. To implement R2V-VLC, it is necessary to acquire the target LED array from the captured images at receiver before data demodulation. To achieve accurate acquisition, we analyze LED array by use of Spatio-temporal image. As the result of the analysis, we show the LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. After that we propose a new LED array acquisition method using such characteristic gradient values.

Distance Estimation Scheme for Integrated V2I-VLC Simulating the Vibration of Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report. ASN, Ambient intelligence and sensor networks Vol. 113 ( 132 ) page： 41 - 45 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array. On issues which is distance estimation performance deterioration by the vibration of the running vehicle, try to resolve them using the technique using the phase-only correlation method.

Distance Estimation Scheme for Integrated V2I-VLC Simulating the Vibration of Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Technical report of IEICE. RCS Vol. 113 ( 130 ) page： 55 - 59 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array. On issues which is distance estimation performance deterioration by the vibration of the running vehicle, try to resolve them using the technique using the phase-only correlation method.

Distance Estimation Scheme for Integrated V2I-VLC Simulating the Vibration of Driving Vehicle Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 113 ( 131 ) page： 21 - 25 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array. On issues which is distance estimation performance deterioration by the vibration of the running vehicle, try to resolve them using the technique using the phase-only correlation method.

LED array acquisition method based on Spatio-temporal image in Road to Vehicle Visible Light Communication Reviewed

USUI Syunsuke, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report. ASN, Ambient intelligence and sensor networks Vol. 113 ( 132 ) page： 47 - 52 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we focus attention on road-to-vehicle visible light communication(R2V-VLC) in intelligent transport systems. This system uses an LED array as a transmitter and a high-speed camera as a receiver. To implement R2V-VLC, it is necessary to acquire the target LED array from the captured images at receiver before data demodulation. To achieve accurate acquisition, we analyze LED array by use of Spatio-temporal image. As the result of the analysis, we show the LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. After that we propose a new LED array acquisition method using such characteristic gradient values.

LED array acquisition method based on Spatio-temporal image in Road to Vehicle Visible Light Communication Reviewed

USUI Syunsuke, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

Technical report of IEICE. RCS Vol. 113 ( 130 ) page： 61 - 66 2013.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we focus attention on road-to-vehicle visible light communication(R2V-VLC) in intelligent transport systems. This system uses an LED array as a transmitter and a high-speed camera as a receiver. To implement R2V-VLC, it is necessary to acquire the target LED array from the captured images at receiver before data demodulation. To achieve accurate acquisition, we analyze LED array by use of Spatio-temporal image. As the result of the analysis, we show the LED array in the spatio-temporal image has high time-gradient value and low space-gradient value. After that we propose a new LED array acquisition method using such characteristic gradient values.

Performance Evaluation of Stochastic Resonance Receiver for the Multi Carrier Detection Reviewed

H. Tanaka, K. chiga, T. Yamazato, Y, Tadokoro, S. Arai

NANOENERGY2013 ( pp.58-59 ) page： - 2013.7

Language：English

Stochastic Resonance (SR), known as a noise-enhanced phenomenon, can improve the performance of communication systems. By applying SR in the receiver, it is possible to detect a weak signal that is not detectable in the traditional linear receiver. In the SR systems, the input of multi-carrier has not ever been discussed. So this paper proposes the SR receiver for multi-carrier detection and evaluates its Bit-Error-Rate (BER) performance.

Discover IEICE Contents Using I-Scover

T. Yamazato

Vol. 37 page： - 2013.6

Language：English

The IEICE launched new metadata search system called I-Scover (http://i-scover.ieice.org) from April 3rd, 2013. I-Scover provides metadata search of the IEICE transactions papers (from its first edition published in 1968), Technical Reports (from 2006) and international conference papers of ISPA and EMC. The total of the contents that can be searched is more than 150,000.This article briefly introduces I-Scover. Before going to detail, let me start with a quiz. What phrase do you guess if you say I-Scover for three times?

The outline of I-Scover

T. Yamazato

IEICE General Conference page： - 2013.3

Input-output phase difference performance of Stochastic Resonance Schmitt Trigger receiver

K. Chiga, H. Tanaka, T. Yamazato, Y.Tadokoro, S. Arai

IEICE General Conference ( A-2-11 ) page： p.38 2013.3

Intensity Estimation Method of LED Array for Visible Light Communication Reviewed

T. Ito, T. Yendo, S. Arai, T. Yamazato, H. Okada, T. Fujii

Proc. SPIE 8663, Video Surveillance and Transportation Imaging Applications 2013.3

Language：English

This paper focuses on a road-to-vehicle visible light communication (VLC) system using LED traffic light as the transmitter and camera as the receiver. The traffic light is composed of a hundred of LEDs on two dimensional plain. In this system, data is sent as two dimensional brightness patterns by controlling each LED of the traffic light individually, and they are received as images by the camera. Here, there are problems that neighboring LEDs on the received image are merged due to less number of pixels in case that the receiver is distant from the transmitter, and/or due to blurring by defocus of the camera. Because of that, bit error rate (BER) increases due to recognition error of intensity of LEDs To solve the problem, we propose a method that estimates the intensity of LEDs by solving the inverse problem of communication channel characteristic from the transmitter to the receiver. The proposed method is evaluated by BER characteristics which are obtained by computer simulation and experiments. In the result, the proposed method can estimate with better accuracy than the conventional methods, especially in case that the received image is blurred a lot, and the number of pixels is small. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

DOI： doi:10.1117/12.2005738

A performance analysis of the stochastic resonance receiver for the subthreshold bi-polar pulse detection

H. Tanaka, K. Chiga, T. Yamazato, Y. Tadokoro, S. Arai

IEICE General Conference ( A-2-13 ) page： p.40 2013.3

A-2-11 Input-output phase difference performance of Stochastic Resonance Schmitt Trigger receiver Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2013 page： 38 2013.3

A-2-13 A performance analysis of the stochastic resonance receiver for the subthreshold bi-polar pulse detection Reviewed

TANAKA Hiroya, CHIGA Keita, YAMAZATO Takaya, TADOKORO Yukihiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2013 page： 40 2013.3

Performance Analysis of Error-Correcting Method Using Separation of Chaos for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio and T. Yamazato

Proceedings of RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP'13) page： pp. 225-228 2013.3

Language：English

This paper analyzes the performance of the error-correcting method, which was proposed in the previous research, using the separation and the reconstruction of chaos for noncoherent chaos communications. Especially, we focus on a number of transmitting data and a combination of symbols (i.e., data pattern). We consider that the capability of the error correction depends on the number of data and the data pattern because the proposed method performs the error correction using successive data symbols. This study performs simulations for the number of data and the data pattern, and evaluates BER performance of the proposed method.

Development of Simple Simulator for Visible Light Communication Using LED and Camera Reviewed

T. Fukumoto, S. Arai, T. Yendo, T. Yamazato, H. Okada and T. Fujii

Proceedings of RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP'13) page： pp. 33-36 2013.3

Performance Evaluation of Stochastic Resonance Bi-Polar Pulse receiver Using Schmitt Trigger

Keita CHIGA, Hiroya TANAKA, Takaya YAMAZATO, Yukihiro TADOKORO, Shintaro ARAI

IEICE Complex Communication Sciences ( CCS-2012-038 ) page： - 2013.3

Language：Japanese

We consider an application of Stochastic Resonance to wireless communication system. Stochastic Resonance(SR) is well known as a phenomenon in which weak signal in nonlinear system can be detected by added noise. A receiver using Stochastic Resonance(SR Receiver) can detect a weak signal which is not detectable in the conventional receiver. In this paper, we consider the implementation of Bi-Polar Pulse SR Receiver using Schmitt Trigger and the evaluation of the performance in Signal-to-Noise Ratio(SNR) and Bit Error Rate(BER).

A bit-error-rate analysis on the stochastic resonance receiver for the weak bi-polar pulse

Hiroya TANAKA, Keita CHIGA, Takaya YAMAZATO, Yukihiro TADOKORO, Shintaro ARAI

IEICE Complex Communication Sciences ( CCS-2012-039 ) page： - 2013.3

Language：Japanese

Stochastic resonance has an effect of improving the detection by increasing noise in the system. By applying this stochastic resonance in the receiver, it is possible to detect the subthreshold signal which is not detectable in the traditional linear receiver. This paper proposes an analysis method of the stochastic resonance receiver for the detection of the bi-polar pulse, which has good compatibility to stochastic resonance, and evaluates its bit-error-rate performance. And, the optimal noise power which maximizes the effect of stochastic resonance is discussed.

Overlay Coding of Long Range Data and Short Range Data for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

S. Nishimoto, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

IEICE Transactions on Communications Vol. J96-B ( no.2 ) page： pp.191-201 2013.2

Overlay Coding of Long Range Data and Short Range Data for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 96 ( 2 ) page： 191 - 201 2013.2

Interpixel Interference Cancellation Method for Road-to-Vehicle Visible Light Communication Reviewed

Tatsuya Kasashima, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Tomohiro Yendo, Shintaro Arai

2013 IEEE 5TH INTERNATIONAL SYMPOSIUM ON WIRELESS VEHICULAR COMMUNICATIONS (WIVEC) page： 1 - 5 2013

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper aims to improve the transmission distance for the road-to-vehicle visible light communication system (R2V-VLC) using LED array and high-speed camera by reducing interference caused at the receiver. As we can transmit multiple data using LED array and high-speed camera, parallel data transmission can be possible. However, due to the diffusion of LED and the finiteness of the pixel size of image sensor, the focused LED will affect not only the actual corresponding pixel but also its surrounding pixels. We call this phenomenon as "interpixel interference (IPI)" and it causes degradation in error rate performance. To mitigate the IPI, we propose IPI cancellation scheme for the R2V-VLC system. As the results of the experiment, we can extend the error-free distance from 40m to 60m by the IPI cancellation.

DOI： 10.1109/wivec.2013.6698237

Channel information estimation for error correcting code in road-to-vehicle visible light communication systems Reviewed

Hiraku Okada, Shinnosuke Misawa, Takaya Yamazato, Toshiaki Fujii, Tomohiro Yendo

2013 IEEE 5th International Symposium on Wireless Vehicular Communications, WiVeC 2013 - Proceedings page： 1 - 5 2013

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE Computer Society

This paper focuses on a road-to-vehicle visible light communication (VLC) system using LED traffic lights and high-speed cameras on cars. So as to improve the transmission reliability, an error correcting code like a low-density parity-check (LDPC) is applied to the road-to-vehicle VLC system. The decoder of the LDPC code needs channel information in order to maximize decoding performance. Usually, it is calculated from a signal-to-noise ratio (SNR) or bit error rate (BER) of a channel, where noise is a dominant factor of the channel characteristic. In the road-to-vehicle VLC system, not noise but interference among LEDs decides the channel characteristic. In this paper, we propose a channel information estimation method for the road-to-vehicle VLC system. The proposed method estimates a signal-to-interference ratio (SIR) from the receiving image, and calculates the channel information using the SIR. The proposed method is evaluated by experiment. As a result, the proposed method can achieve almost the same performance with the optimum case, and then maximize the decoding performance. © 2013 IEEE.

DOI： 10.1109/wivec.2013.6698229

3-215 Lectures in Nagoya University OCW that providing play and learning experiences Reviewed

Yamazato Takaya

Proceedings of Annual Conference of Japanese Society for Engineering Education Vol. 2013 ( 0 ) page： 268 - 269 2013

Accuracy improvement by phase only correlation for distance estimation scheme for visible light communications using an LED array and a high-speed camera Reviewed

Ohmura A., Yamazato T., Arai S., Yendo T., Fujii T., Okada H.

20th ITS World Congress Tokyo 2013 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：20th ITS World Congress Tokyo 2013

Alamouti-Type Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

Yuta Amano, Koji Kamakura, Takaya Yamazato

2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) page： 2430 - 2435 2013

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/GLOCOM.2013.6831438

Channel Information Estimation for Error Correcting Code in Road-to-Vehicle Visible Light Communication Systems Reviewed

Okada Hiraku, Misawa Shinnosuke, Yamazato Takaya, Fujii Toshiaki, Yendo Tomohiro

2013 IEEE 5TH INTERNATIONAL SYMPOSIUM ON WIRELESS VEHICULAR COMMUNICATIONS (WIVEC) 2013

Alamouti-Type Coding for Visible Light Communication Based on Direct Detection Using Image Sensor Reviewed

Amano Yuta, Kamakura Koji, Yamazato Takaya

2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) page： 2430 - 2435 2013

Intensity estimation method of LED array for visible light communication Reviewed

Takanori Ito, Tomohiro Yendo, Shintaro Arai, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii

Proceedings of SPIE - The International Society for Optical Engineering Vol. 8663 2013

Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1117/12.2005738

Utilization of spatio-temporal image for LED array acquisition in Road to Vehicle Visible Light Communication Reviewed

Interpixel Interference Cancellation Method for Road-to-Vehicle Visible Light Communication Reviewed

Kasashima Tatsuya, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Yendo Tomohiro, Arai Shintaro

2013 IEEE 5TH INTERNATIONAL SYMPOSIUM ON WIRELESS VEHICULAR COMMUNICATIONS (WIVEC) 2013

Usui S.

20th ITS World Congress Tokyo 2013 2013

査読の虎の巻 Reviewed

山里敬也, 佐波孝彦, 塩田茂雄, 太田能

電子情報通信学会　通信ソサイエティマガジン Vol. 6 ( 3 ) page： 222 - 230 2013

A Study on the Simulator Development for Visible Light Communication Using LED and Camera Reviewed

T. Fukumoto, S. Arai, T. Yendo, T. Yamazato, H. Okada and T. Fujii

Proceedings of IEEE Workshop on Nonlinear Circuit Networks (NCN'12) ( pp. 124-127 ) page： - 2012.12

Language：English

This paper develops a simple simulation program for visible light communication (VLC) systems using LED (Transmitter) and a camera (Receiver). In the simulation, we generate an image of LED array transmitter which consists of LEDs arranged in a square matrix. In addition, effects of optical spatial channel, which is a unique channel in VLC, are constructed by using image processing techniques. We describe a system model of the VLC simulator and carry out the simulation with various parameters of the image processing.

Intensity estimation of LED array for parallel visible light communication

T. Ito, S. Arai, T. Yendo T. Yamazato, H. Okada and T. Fujii

Technical Report of IEICE ( CS2012-90 ) page： pp.113-118 2012.12

Visible light communication system using real-time software processing of high-speed camera image

M. Kasai, T. Yendo T. Yamazato, H. Okada, T. Fujii and S. Arai

Technical Report of IEICE ( CS2012-83 ) page： pp.71-75 2012.12

Intensity estimate of LED array for parallel Visible Light Communication Reviewed

ITO Takanori, YENDO Tomohiro, ARAI Shintaro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki

IEICE technical report. Image engineering Vol. 112 ( 335 ) page： 113 - 118 2012.12

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper focuses on a road-to-vehicle visible light communication (VLC) system using LED traffic light as the transmitter and camera as the receiver. The traffic light is composed of a hundred of LEDs on two dimensional plain. In this system, data is sent as two dimensional brightness patterns by controlling each LED of the traffic light individually, and they are received as images by the camera. Here, there are problems that neighboring LEDs on the received image are merged due to less number of pixels in case that the receiver is distant from the transmitter, and/or due to blurring by defocus of the camera. Because of that, bit error rate (BER) increases due to recognition error of intensity of LEDs. To solve the problem, we propose a method that estimates the intensity of LEDs by solving the inverse problem of communication channel characteristic from the transmitter to the receiver. The proposed method is evaluated by BER characteristics which are obtained by computer simulation and experiments. In the result, the proposed method can estimate with better accuracy than the conventional methods, especially in case that the received image is blurred a lot, and the number of pixels is small.

Intensity estimate of LED array for parallel Visible Light Communication Reviewed

ITO Takanori, YENDO Tomohiro, ARAI Shintaro, YAMAZATO Takaya, Okada Hiraku, Fuji Toshiaki

IEICE technical report. Communication systems Vol. 112 ( 334 ) page： 113 - 118 2012.12

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper focuses on a road-to-vehicle visible light communication (VLC) system using LED traffic light as the transmitter and camera as the receiver. The traffic light is composed of a hundred of LEDs on two dimensional plain. In this system, data is sent as two dimensional brightness patterns by controlling each LED of the traffic light individually, and they are received as images by the camera. Here, there are problems that neighboring LEDs on the received image are merged due to less number of pixels in case that the receiver is distant from the transmitter, and/or due to blurring by defocus of the camera. Because of that, bit error rate (BER) increases due to recognition error of intensity of LEDs. To solve the problem, we propose a method that estimates the intensity of LEDs by solving the inverse problem of communication channel characteristic from the transmitter to the receiver. The proposed method is evaluated by BER characteristics which are obtained by computer simulation and experiments. In the result, the proposed method can estimate with better accuracy than the conventional methods, especially in case that the received image is blurred a lot, and the number of pixels is small.

Visible light communication system using real-time software processing of high-speed camera image Reviewed

KASAI Makoto, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro

IEICE technical report. Image engineering Vol. 112 ( 335 ) page： 71 - 75 2012.12

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We focus on a road-to-vehicle Visible Light Communication (VLC) system using LED traffic light as the transmitter and high-speed camera as the receiver. Data is sent as two dimensional brightness patterns by controlling each LED of the traffic light individually. At the receiver side, the pattern is captured in the high-speed camera image. It is necessary to find the position of transmitter in the image and to extract the intensity of each LED at high-frame rate in real-time. In this paper, we achieve tracking of the transmitter and intensity extraction in real-time by only software processing on PC.

Visible light communication system using real-time software processing of high-speed camera image Reviewed

KASAI Makoto, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, ARAI Shintaro

IEICE technical report. Communication systems Vol. 112 ( 334 ) page： 71 - 75 2012.12

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

The key to peer-review an IEICE article Reviewed

T. Yamazato, T. Saba, S. Shiota, C. Ohta

IEICE Communication Society Magazine Vol. No.23 [冬号] page： pp.222-230 2012.12

Multiple Information Sources Recognition Method for Ubiquitous Visible Light Communication Using on-Vehicle High-Speed Camera Reviewed

Y. Shiraki, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

IEICE Transactions on Communications Vol. J95-B ( 11 ) page： 1517-1528 2012.12

A Study on Error-Correcting Method for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio, T. Yamazato

Japan-Korea Joint Workshop on Complex Communication Sciences page： - 2012.11

Multiple Information Sources Recognition Method for Ubiquitous Visible Light Communication Using on-Vehicle High-Speed Camera Reviewed

Y. Shiraki, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

IEICE Transactions on Communications Vol. J95-B ( no.11 ) page： pp.1517-1528 2012.11

Multiple Information Sources Recognition Method for Ubiquitous Visible Light Communication Using on-Vehicle High-Speed Camera Reviewed

SHIRAKI Yasutake, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 11 ) page： 1517 - 1528 2012.11

Improvement of Error-Correcting Method Based on Chaotic Dynamics for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio, T. Yamazato

International Symposium on Nonlinear Theory and its Applications (NOLTA'12) page： pp.801-804 2012.10

Language：English

This paper focuses on characteristics of the chaotic dynamics and improves our previous errorcorrecting method using them for noncoherent chaos communications. Our previous method is performed by using a chaotic sequence generated according to the chaotic dynamics. In this case, it is very difficult to recover data without a successive sequence based on the chaotic dynamics. We focus on this feature and consider that an improved method separates and reconstructs the chaotic dynamics of the sequence according to a specific rule. Namely, the separation and reconstruction of the chaotic dynamics can be applied for our improved method as additional information. As results of simulations, we have confirmed that the advantage gained in BER performance of our improved method is about 2–2.5 dB compared to a conventional method (without coding).

Introduction of Nagoya University OCW

T. Yamazato

ICTSFC Workshop page： - 2012.9

Stochastic Resonance BFSK Receiver using Schmitt Trigger

K. Chiga, H. Tanaka, T. Yamazato, S. Arai

Enginnering Sciences Society Conference of IEICE ( A-2-1 ) page： p.24 2012.9

Performance Evaluation of 2 users BFSK Receiver Stochastic Resonance

H. Tanaka, T. Yamazato, S. Arai

Enginnering Sciences Society Conference of IEICE ( A-2-2 ) page： p.25 2012.9

Phase Only Correlation Based Distance Estimation Scheme for Integrated R2V-VLC

A.Ohmura,T.Yamazato,H.Okada,T.Fujii,T.Yendo,S.Arai

page： - 2012.9

A Study on Cluster Lifetime in Multi-Hop Wireless Sensor Networks with Cooperative MISO Scheme Reviewed

Z. Huang, H. Okada, K. Kobayashi, M. Katayama

Journal of Communications and Networks Vol. 14 ( no.4 ) page： pp.443-450 2012.8

Language：English

As for cluster-based wireless sensor networks (WSNs), cluster lifetime is one of the most important subjects in recent researches. Besides reducing the energy consumptions of the clusters, it is necessary to make the clusters achieve equal lifetimes so that the whole network can survive longer. In this paper, we focus on the cluster lifetimes in multi-hop WSNs with cooperative multi-input single-output scheme. With a simplified model of multi-hop WSNs, we change the transmission schemes, the sizes and transmission distances ofclusters to investigate their effects on the cluster lifetimes. Furthermore, linear and uniform data aggregations are considered in our model. As a result, we analyze the cluster lifetimes in different situations and discuss the requirements on the sizes and transmission distances of clusters for equal lifetimes.

DOI： 10.1109/JCN.2012.6292251

A-2-1 Stochastic Resonance BFSK Receiver using Schmitt Trigger Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2012 page： 24 2012.8

A-2-2 Performance Evaluation of 2 users BFSK Receiver using Stochastic Resonance Reviewed

TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2012 page： 25 2012.8

Demand of Teaching Material Development and OCW

T. Yamazato

60th JSEE Anual Conference Proceedings ( 8-331 ) page： - 2012.8

Interference Comparison of BFDM and Wavelet Based OFDM in Frequency Dispersive Channels Reviewed

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 8 ) page： 971 - 975 2012.8

Evbaluation of Error-Correcting Method Using Separation of Chaotic Dynamics for Noncoherent Chaos Communications

S. Arai, Y. Nishio and T. Yamazato

page： pp. 261-266 2012.7

Improvement Method of Data Rate for Overlay Hierarchical Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera

S. Nishimoto, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

Technical Report of IEICE Vol. no.148 ( ITS2012-9 ) page： pp.19-24 2012.7

Language：Japanese

This paper aims to improve the data rate for the visible light communication system using LED array and high-speed camera. Previously, we have proposed the decoding algorithm using inverted signals for driving situation. However, using this method the data rate become a half, because we transmit original signals and inverted signals alternately for LED array tracking. In this paper, we propose the data rate improving method for overlay coding which is coding method that overlay two data. We confirm that we can improve data rate as compared with the previous method.

Improvement Method of Data Rate for Overlay Hierarchical Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 112 ( 148 ) page： 19 - 24 2012.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Driver Assistant System using Visible Light Communications : Road-to-Vehicle Visible Light Communications usign LED Array and On-Vehicle High-Speed Camera Reviewed

YAMAZATO Takaya

IEICE technical report. WBS, Wideband System Vol. 112 ( 147 ) page： 25 - 30 2012.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We are conducting a study on visible light communications (VLC) using an LED traffic light and a high-speed camera equipped in a vehicle. Since we use the camera, we can capture and record surround images of the vehicle while receiving the data transmitted from the LED traffic light. This paper introduces the VLC system we are working on. Especially, this paper describes the advantages of road-to-vehicle VLC when the reception device is composed of high-speed camera.

[Poster Presentation] Road-to-Vehicle Communication and Distance Estimation System using Visible Light Communication

A.Ohmura,T.Yamazato,H.Okada,T.Fujii,T.Yendo,S.Arai

Technical Report of IEICE ( USN2012-9 ) page： pp.63-68 2012.5

Road-to-Vehicle Communication and Distance Estimation System using Visible Light Communication Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 112 ( 31 ) page： 63 - 68 2012.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array.

A Study on Cluster Partitioning with Cooperative MISO Scheme in Wireless Sensor Networks Reviewed

Z. Huang, H. Okada, M. Katayama, T. Yamazato

International Journal of Distributed Sensor Networks page： - 2012.4

Language：English Publishing type：Research paper (scientific journal)

This paper addresses the cluster partitioning problem in wireless sensor networks deployed in a continuous area. We present the model of the network and describe its operational details firstly. Both single-hop and multi-hop transmissions with cooperative Multi-Input Single-Output (MISO) scheme are considered for the inter-cluster communications. Besides, uniform and linear data fusions are discussed. Then the calculations of energy consumptions are derived. Different from other researches, the energy consumptions of intra-cluster communication in each cluster are included and modeled as functions of the cluster size. Finally, we simulate all possible cluster partitions by changing the numbers of clusters and cooperative transmitting nodes, and find the maximal network lifetimes. As a result, the relationships between cluster partitions and network lifetimes are clarified in different situations.

A Distance Estimation Scheme between the LED Array and On-Vihicle High-Speed Camera Using Visible Light

A.Ohmura,T.Yamazato,H.Okada,T.Fujii,T.Yendo,S.Arai

IEICE General Conference Vol. B-10B page： CD-ROM 2012.3

Preliminary Study on Bi-Polar Pulse Receiver using Stochastic Resonance

H. Tanaka, T. Yamazato, S. Arai

IEICE General Conference Vol. A-2 page： CD-ROM 2012.3

A-2-34 Preliminary Study on Bi-Polar Pulse Receiver using Stochastic Resonance Reviewed

TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2012 page： 79 2012.3

A-2-35 State Analysis of Stochastic Resonance in Quadruple-Well Potential Reviewed

Ozaki Shota, Arai Shintaro, Yamazato Takaya, Nishio Yoshifumi

Proceedings of the IEICE General Conference Vol. 2012 page： 80 2012.3

Relay Selection Scheme with Harvested Solar Energy Prediction for Solar-Powered Wireless Sensor Networks Reviewed

OTA KENTARO, KOBAYASHI KENTARO, YAMAZATO TAKAYA, KATAYAMA MASAAKI

IEICE technical report Vol. 111 ( 476 ) page： 85 - 92 2012.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Our goal is to make efficient use of the energy and therefore achieve network operation with a high packet delivery ratio, regardless of day, night and weather variations, in solar powered wireless sensor networks. One method to optimize the consumption energy in the entire network is to employ a cooperative transmission scheme in which a node uses another node as a relay, when sending its data. If we do not consider the changes in the harvested energy in the network, the packet delivery ratio declines during nights and cloudy days. In this paper, however, we propose a new relay selection scheme with harvested solar energy prediction to maintain the required high packet delivery ratio by reducing the effect of the weather variations.

Preliminary Study on BPSK Receiver using Stochastic Resonance Reviewed

H.Tanaka, T.Yamazato, S.Arai

2012 RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing page： CD-ROM 2012.3

Language：Japanese

Stochastic Resonance (SR), known as a noise-enhanced phenomenon, can improve the performance of commutation systems. In this paper, we present a preliminary study on SR and its application to BPSK receiver. We discuss a basic question arises from a receiver using SR that shall we perform SR process in a radio-frequency (RF) band or in a baseband (BB)? As results, we found that SR process in RF band shows better Bit Error Rate (BER) performance. This comes from the fact that a down conversion process that reduces the signal amplitude causes weak noise suppression by SR. While a double frequency term obtained also by the down conversion process do not affect much to the noise reduction performance.

Cancellation Method for Intersymbol Interference on Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 111 ( 441 ) page： 129 - 134 2012.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on visible light communications using an LED array as the transmitter and a highspeed camera as the receiver. LED array , composed of many LEDs, transmits information by flashing LEDs, unfortunately an LED light diffuses around and affects neighboring LEDs. This problem causes degradation in error rate performance. We treat this ploblem as intersymbol interference (ISI) and try to cancel. In this paper, we first propose an area average quantization for the reduction of ISI. Next, we propose a new ISI cancellation method for overlay decoding and evaluate this method.

Cancellation Method for Intersymbol Interference on Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 111 ( 441 ) page： 129 - 134 2012.2

Cancellation Method for Intersymbol Interference on Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report. Image engineering Vol. 111 ( 442 ) page： 129 - 134 2012.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

LED Array Tracking Method for Road-to-Vehicle Visible Light Communications in the Driving Situation Reviewed

T. Nagura, T. Yamazato, S. Arai, H. Okada, T. Yendo, T. Fujii

IEICE Transactions on Communications Vol. J95-B ( 2 ) page： 326-336 2012.2

Gaussian Pulse Shape Optimization of BFDM in Highly Mobile Environments Reviewed

D. Goto, T. Yayazato, B. Mongol

IEICE Transactions on Communications Vol. J95-B ( 2 ) page： 317-325 2012.2

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we focus on reducing intersymbol interference (ISI) and intercarrier interference (ICI) in a highly mobile environment by optimizing the Gaussian pulse shape of Biorthogonal Frequency Division Multiplexing (BFDM). In time-frequency dispersive channels, reducing the signal interference depends on the shaping of signal pulse. BFDM was invented to reduce the interference through a flexible design of signal pulse shaping. However, the shape of Gaussian pulses used in BFDM is not always optimized in every situation and as a result the interference is not always minimized. This research is to optimize the shape of Gaussian pulse. In particular, we optimize the Gaussian pulse in BFDM by maximizing the ratio of the ambiguity function of the transmitter (Gaussian) and its receiver pulses. Numerical results obtained show that the proposed method is effective for the optimization of BFDM. Furthermore, we show that the BFDM outperforms the conventional OFDM in time-frequency dispersive channels.

Cooperative Transmission Scheme with the Reactivation Condition of Inactive Nodes in Solar-Powered Wireless Sensor Networks Reviewed

K. Ota, K. Kobayashi, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J95-B ( 2 ) page： 246-256 2012.2

Language：Japanese Publishing type：Research paper (scientific journal)

Our goal is the improvement of the data arrival rate in solar-powered wireless sensor networks. We consider the application of a cooperative transmission scheme that uses a relay node when a node sends data to reduce the consumption of energy of the entire network. In this paper, we propose the selection method of a relay node based on node battery and consumption energy. The overall data arrival rate is improved through the method. However, if we do not consider the variations in energy harvesting, the data arrival rate declines during nighttime. Then, we smooth out the day-and-night data arrival rate variations by introducing the new inactive node reactivation condition to the cooperative transmission scheme and achieve the required high data arrival rate.

Cooperative Transmission Scheme with the Reactivation Condition of Inactive Nodes in Solar-Powered Wireless Sensor Networks Reviewed

OTA Kentaro, KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 2 ) page： 246 - 256 2012.2

LED Array Tracking Method for Road-to-Vehicle Visible Light Communications in the Driving Situation Reviewed

T. Nagura, T. Yamazato, S. Arai, H. Okada, T. Yendo, T. Fujii

IEICE Transactions on Communications Vol. J95-B ( 2 ) page： 326-336 2012.2

Gaussian Pulse Shape Optimization of BFDM in Highly Mobile Environments Reviewed

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 2 ) page： 317 - 325 2012.2

LED Array Tracking Method for Road-to-Vehicle Visible Light Communications in the Driving Situation Reviewed

NAGURA Toru, YAMAZATO Takaya, ARAI Shintaro, OKADA Hiraku, YENDO Tomohiro, FUJII Toshiaki

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 2 ) page： 326 - 336 2012.2

A Simple Cooperative Relaying with Alamouti Coded Transmission Reviewed

Tomoya Yamaoka, Yoshitaka Hara, Noriyuki Fukui, Hiroshi Kubo, Takaya Yamazato

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E95B ( 2 ) page： 643 - 646 2012.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Cooperative diversity using space-time codes offers effective space diversity with low complexity, but the scheme needs the space-time coding process in the relay nodes. We propose a simple cooperative relay scheme that uses space-time coding. In the scheme, the source node transmits the Alamouti coded signal sequences and the sink node receives the signal sequence via the two coordinated relay nodes. At the relay nodes, the operation procedure is just permutation and forwarding of the signal sequence. In the proposed scheme, none of the relay nodes need quadrature detection and space-time coding and the simple relay process offers effective space diversity. Moreover, simulations show the effectiveness Of the proposed relay process by some simulations.

DOI： 10.1587/transcom.E95.B.643

[Technology Exhibition] Real-Time Data Transmission of Road-to-Vehicle Visible Light Communication System Using LED array and High-Speed Camera

T.Kasashima, Y.Shiraki, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

Technical Report of IEICE Vol. USN2011-89 page： 173-175 2012.1

Language：Japanese

In this paper, we discuss road-to-vehicle visible light communications using an LED array as the transmitter and a high-speed camera as the receiver. The visible light communication (VLC) is a wireless communication that a transmitter consists of LED array and it transmit data by Turing LEDs on and off at high speed. We consider applying this VLC technique to the road (infrastructure) -to-vehicle communication for a purpose to support safety driving. So far, we have confirmed effectiveness of the VLC system through static and driving experiments. However, all those experimental results were obtained by off-line processing.

Decline in Probability of False Recognition of Non-Information Sources in Visible Light Communication for Intelligent Transport System

Y. Shiraki, T. Yamazato, S. Arai, T. Yendo, H. Okada, T. Fujii

Technical Report of IEICE Vol. USN2011-59 page： 13-18 2012.1

Technology Exhibition : Real-Time Data Transmission of Road-to-Vehicle Visible Light Communication System Using LED array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, SHIRAKI Yasutake, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 111 ( 386 ) page： 173 - 175 2012.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Real-Time Data Transmission of Road-to-Vehicle Visible Light Communication System Using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, SHIRAKI Yasutake, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 111 ( 386 ) page： 173 - 175 2012.1

Real-Time Data Transmission of Road-to-Vehicle Visible Light Communication System Using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, SHIRAKI Yasutake, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 111 ( 384 ) page： 87 - 89 2012.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Decline in Probability of False Recognition of Non-Information Sources in Visible Light Communication for Intelligent Trasport System Reviewed

SHIRAKI Yasutake, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, OKADA Hiraku, FUJII Toshiaki

IEICE technical report Vol. 111 ( 386 ) page： 13 - 18 2012.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Visible light communication systems which enable data transmission by blinking LEDs at fast rate attract attention for their applications to Intelligent Transport Systems (ITS). In this paper, we assume that there are multiple information sources and we recognize them with on-vehicle high-speed camera in such systems. To lower probability of false recognition which represents how often non-information sources are recognized as information sources, we propose an improved multiple sources recognition method. We evaluate the proposed method by performing experiments.

High-Speed LED Traffic Light Tracking Method Using Image/High-Speed Communication Hybrid Sensor Reviewed

K. Maeno, M. Tehrani, T. Fujii, H. Okada, T. Yamazato, M. Tanimoto, T. Yendo

International Workshop on Advanced Image Technology (IWAIT2012) page： CD-ROM 2012.1

Language：English

Visible Light Communication (VLC) is a wireless communication method using LEDs. In this paper, we use a hybrid sensor designed for VLC which has advantages of photodiode and high-speed camera, that is, high transmission rate and easy detecting of the transmitter. The light receiving section of the sensor consists of communication pixels and video pixels. This sensor can communicate in static environment in previous research. However in dynamic environment, high- speed tracking of the transmitter is essential. We realize the high-speed tracking of the transmitter using the information of the communication pixels. Experimental results show the possibility of communication in dynamic environment.

High-speed Transmission of Overlay Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

Sayaka Nishimoto, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Tomohiro Yendo, Shintaro Arai

2012 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) ( pp.1234-1238 ) page： 1234 - 1238 2012

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper aims to the improve the data rate for the visible light communication system using LED array and high-speed camera. Previously, we have proposed the decoding algorithm using inverted signals for driving situation. However, using this method the data rate become a half, because we transmit original signals and inverted signals alternately for LED array tracking. In this paper, we propose the data rate improving method for overlay coding which is coding method that overlay two data which are called as the long range data and the short range data. In the proposed method, for the long range data, we transmit original signals and inverted signals alternately. On the other hand, for the short range data, we transmit only original signals while we transmit inverted signals of long range data. We confirm that we can improve data rate as compared with the previous method.

DOI： 10.1109/GLOCOMW.2012.6477757

A Study on Cluster Partitioning with Cooperative MISO Scheme in Wireless Sensor Networks Reviewed

8-331 Demand of Teaching Material Development and OCW Reviewed

YAMAZATO Takaya

Proceedings of Annual Conference of Japanese Society for Engineering Education Vol. 2012 ( 0 ) page： 718 - 719 2012

Zheng Huang, Hiraku Okada, Masaaki Katayama, Takaya Yamazato

INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS Vol. 8 2012

Language：English Publishing type：Research paper (scientific journal) Publisher：HINDAWI PUBLISHING CORPORATION

This paper addresses the cluster partitioning problem in wireless sensor networks deployed in a continuous area. We present the model of the network and describe its operational details firstly. Both single-hop and multihop transmissions with cooperative Multi-Input Single-Output (MISO) scheme are considered for the intercluster communications. Besides, uniform and linear data fusions are discussed. Then, the calculations of energy consumptions are derived. Different from other researches, the energy consumptions of intracluster communication in each cluster are included and modeled as functions of the cluster size. Finally, we simulate all possible cluster partitions by changing the numbers of clusters and cooperative transmitting nodes and find the maximal network lifetimes. As a result, the relationships between cluster partitions and network lifetimes are clarified in different situations.

DOI： 10.1155/2012/490823

B-10-103 A Distance Estimation Scheme between the LED Array and On-Vihicle High-Speed Camera Using Visible Light Communication Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2012 ( 2 ) page： 426 2012

Gaussian Pulse Shape Optimization of BFDM in Time-Frequency Dispersive Channels Reviewed

Goto Daisuke, Yamazato Takaya, Mongol Bayarpurev

2012 IEEE 75TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING) 2012

High-speed Transmission of Overlay Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

Nishimoto Sayaka, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Yendo Tomohiro, Arai Shintaro

2012 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) page： 1234 - 1238 2012

Gaussian Pulse Shape Optimization of BFDM in Time-Frequency Dispersive Channels Reviewed

Daisuke Goto, Takaya Yamazato, Bayarpurev Mongol

2012 IEEE 75TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING) page： 1 - 5 2012

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

The objective of this research is to reduce inter-symbol interference (ISI) and intercarrier interference (ICI) in a highly mobile environment by optimizing the performance of Biorthogonal Frequency Division Multiplexing (BFDM). In time-frequency dispersive channels, reducing the signal interference depends on the shaping of the signal pulse. BFDM was invented to reduce the interference through a flexible design of the signal pulse shaping. However, the shape of the Gaussian pulses used in BFDM is not always optimized in every situation and as a result the interference is not always minimized. This research seeks to optimize the shape of the Gaussian pulse. In particular, we optimize the Gaussian pulse in BFDM by maximizing the ratio of the ambiguity function of the transmitter (Gaussian) and its receiver pulses. Numerical results obtained show that the proposed method is effective for the optimization of BFDM. Furthermore, we show that the optimized BFDM outperforms the conventional OFDM in time-frequency dispersive channels.

DOI： 10.1109/VETECS.2012.6240287

Visible light communication in dynamic environment using image/high-speed communication hybrid sensor Reviewed

Keita Maeno, Mehrdad Panahpour Tehrani, Toshiaki Fujii, Hiraku Okada, Takaya Yamazato, Masayuki Tanimoto, Yendo Tomohiro

BROADBAND ACCESS COMMUNICATION TECHNOLOGIES VI Vol. 8282 2012

Publishing type：Research paper (international conference proceedings) Publisher：SPIE-INT SOC OPTICAL ENGINEERING

Visible Light Communication (VLC) is a wireless communication method using LEDs. LEDs can respond in high-speed and VLC uses this characteristics. In VLC researches, there are two types of receivers mainly, one is photodiode receiver and the other is high-speed camera. A photodiode receiver can communicate in high-speed and has high transmission rate because of its high-speed response. A high-speed camera can detect and track the transmitter easily because it is not necessary to move the camera. In this paper, we use a hybrid sensor designed for VLC which has advantages of both photodiode and high-speed camera, that is, high transmission rate and easy detecting of the transmitter. The light receiving section of the hybrid sensor consists of communication pixels and video pixels, which realizes the advantages. This hybrid sensor can communicate in static environment in previous research. However in dynamic environment, highspeed tracking of the transmitter is essential for communication. So, we realize the high-speed tracking of the transmitter by using the information of the communication pixels. Experimental results show the possibility of communication in dynamic environment.

DOI： 10.1117/12.907697

Interference Comparison of BFDM with Optimum Gaussian Pulse and Wavelet Based OFDM in Highly Mobile Environments Reviewed

Relay Selection Scheme Using Prediction of Harvested Energy for Solar-Powered Wireless Sensor Networks Reviewed

K. Ota, K. Kobayashi, T. Yamazato, M. Katayama

International Symposium on EcoTopia Science 2011 page： 106 2011.12

Language：English

Solar-powered wireless sensor networks are attracting attention for outdoor long time operation such as environmental monitoring. Even if sensor nodes are charged by solar energy, nodes far from the BS (Base-Station) are stopped due to the lack of energy during nighttime. To prevent this problem, we consider the use of cooperative transmission. In cooperative transmission, energy consumption is balanced among the nodes because of the use of another node as a relay for data transmission of distant nodes. The conventional scheme to select a relay node is based on available battery energy and the expectation of energy consumption of each node. In this paper, we propose a relay selection scheme which is based on the prediction of harvested energy in addition to the available battery energy and the expected value of energy consumption. We evaluate the proposed scheme through packet delivery ratio and show its effectiveness.

Interference Comparison of BFDM with Optimum Gaussian Pulse and Wavelet Based OFDM in Highly Mobile Environments

D. Goto, T. Yayazato, B. Mongol

Technical Report of IEICE Vol. RCS2011-11 page： 91-95 2011.11

Language：Japanese

In this paper, we conduct a comparison between the Biorthogonal Frequency Division Multiplexing (BFDM) and the Wavelet Based Orthogonal Frequency Division Multiplexing (OFDM) in terms of intersymbol interference (ISI) and intercarrier interference (ICI) reduction in highly mobile environments with assumed time-frequency dispersive channels. ISI and ICI depend largely on the pulse shaping of the signal. BFDM can reduce the signal interference by applying a Gaussian pulse known as a properly localized time-frequency pulse with adaptable characteristics. On the other hand, Wavelet Based OFDM is known to lower interference due to its wavelet basis. In this paper, we propose an optimization method for the Gaussian pulse in BFDM to minimize ISI/ICI by maximizing the ratio of the ambiguity function. In addition, we compare its performance with BFDM and Wavelet Based OFDM.

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

Technical report of IEICE. RCS Vol. 111 ( 289 ) page： 91 - 95 2011.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Overlay Coding for Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

S. Nishimoto, T. Nagura, T. Yamazato, T. Yendo, T. Fujii, H. Okada, S. Arai

International IEEE Conference on Intelligent Transportation Systems page： 1704-1709 2011.10

Language：English

This paper aims to improve the visible light communication system using LED array and high-speed camera by proposing what we call "overlay coding." "Overlay coding" is a new coding method to realize a hierarchical coding, through which a high-priority data can be received even if the receiver is far from a transmitter. Conventionally, the hierarchical coding has been realized through the wavelet transform that has a limitation of number and disposition of LEDs, and as a result it does not always match with the design of the transmitters (e.g. traffic lights, etc.) used in real life. To solve the limitation problem, we propose a more flexible way of designing the application of LEDs depending on the transmitters. In particular, overlay coding is realized through the procedures of coding and decoding. In coding, we replace one LED with a flexible number of LEDs, and the number depends on whether the data is high-priority or low-priority, then high-priority data and low-priority data are overlaid. In decoding, we first obtain the high-priority data, and then the low-priority data using retrieved high-priority data. The experimental result shows that the distance for receiving error-free data is extended from 30m to 70m in the overlay coding.

A Study on Cluster Lifetime of Single-hop Wireless Sensor Networks with Cooperative MISO Scheme Reviewed

Z. Huang, K. Kobayashi, M. Katayama, T. Yamazato

IEICE Transactions on Communications Vol. E94-B ( 10 ) page： 2881-2885 2011.10

Language：English Publishing type：Research paper (scientific journal)

This letter investigates the cluster lifetime of single-hop wireless sensor networks with cooperative Multi-Input Single-Output (MISO) scheme. The energy consumptions of both intra-cluster and out-cluster communications are considered. Moreover, uniform and linear data aggregations are discussed. It is found the optimal transmission scheme varies with the distance from the cluster to the base station. More interestingly and novelly, the effect of cluster size on the cluster lifetime has been clarified.

A Study on Cluster Lifetime of Single-Hop Wireless Sensor Networks with Cooperative MISO Scheme Reviewed

Zheng Huang, Kentaro Kobayashi, Masaaki Katayama, Takaya Yamazato

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E94B ( 10 ) page： 2881 - 2885 2011.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1587/transcom.E94.B.2881

Estimation of Channel Information for Error Correcting Code in Visible Light Communication Using LED Array and High-Speed Camera

S. Misawa, H. Okada, T. Yamazato, T. Yendo, T. Fujii

Enginnering Sciences Society Conference of IEICE Vol. A-17-6 page： 210 2011.9

Cooperative Transmission Scheme with Inactive Node Reactivation Condition for Solar-Powered Wireless Sensor Networks Reviewed

K. Ota, K. Kobayashi, T. Yamazato, M. Katayama

IEEE International Workshop on Wireless Distributed Networks (WDN2011) page： 2394-2398 2011.9

Language：English

Our goal is the improvement of the node activity rate in solar-powered wireless sensor networks. We consider the application of a cooperative transmission scheme that uses a relay node when a node sends data to reduce the consumption of energy of the entire network. However, if we do not consider the variations in energy harvesting, the node activity rate declines during nighttime. In this paper, we smooth out the day-and-night node activity rate variations by introducing the new inactive node reactivation condition and achieve the required high node activity rate.

Instructor's message that can be read from Nagoya Univeristy OCW teaching materials

T. Yamazato

Journal of Japanese Society for Engineering Education (JSEE) page： 9-217 2011.9

I-074 Road-to-vehicle Visible Light Communication Using High-speed Camera in Driving Situation Reviewed

Premachandra Halpage Chinthaka Nuwandika, Yendo Tomohiro, Tehrani Mehrdad Panahpour, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Tanimoto Masayuki

情報科学技術フォーラム講演論文集 Vol. 10 ( 3 ) page： 459 - 464 2011.9

Publishing type：Research paper (scientific journal) Publisher：FIT(電子情報通信学会・情報処理学会)運営委員会

Intelligent Transport System(ITS) has been proposed to give solutions for traffic problems such as traffic accidents and traffic jams. On the other hand, high frame rate image techniques are getting popular in last several years. In this paper, we propose a Visible Light Communication(VLC) system using high frame rate techniques for Intelligent Transport System. Here, the communication between infrastructure and the vehicle is approached using an LED array as a transmitter and on-vehicle high speed camera as a receiver. The LEDs in the transmitter emit light in 500Hz and the emission patterns are used to achieve communication, capturing them in high frame rate(1000fps) utilizing a high-speed camera. The images captured by high-speed camera are processed to find the transmitter, track the found transmitter, and capture the LED lighting pattern of transmitter in consecutive frames. In our previous work, we proposed algorithms to finding and tracking. In this paper, we introduce method to capture the lighting pattern of the transmitter. Then, out door communication experiments were conducted to confirm the effectiveness of the proposed V LC system.

A-17-6 Estimation of Channel Information for Error Correcting Code in Visible Light Communication Using LED Array and High-Speed Camera Reviewed

MISAWA Shinnosuke, OKADA Hiraku, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki

Proceedings of the Society Conference of IEICE Vol. 2011 page： 210 2011.8

Unique teaching practices presented at Nagoya University OCW Reviewed

T. Yamazato

Journal of Japanese Society for Engineering Education (JSEE) Vol. 59 ( 4 ) page： 4_105-4_107 2011.8

Unique Teaching Practices Presented at Nagoya University OCW Reviewed

YAMAZATO Takaya

Journal of Jsee Vol. 59 ( 4 ) page： 105 - 107 2011.7

Multiple LED Arrays Recognition Using Block Matching for Road-to-Vehicle Visible Light Communication

Y. Shiraki, T. Yamazato, S. Arai, T. Yendo, H. Okada, T. Fujii

Technical Report of IEICE Vol. USN2011-18 page： 73-78 2011.7

Language：Japanese

Visible light communication systems which enable data transmission by blinking LEDs at fast rate attract attention for their applications to Intelligent Transport Systems (ITS). In this paper, we assume that there are multiple information sources and we recognize them with on-vehicle high-speed camera in such systems. To distinguish multiple sources, we propose multiple sources recognition method based block matching. We evaluate the proposed method by performing experiments.

Multiple LED Arrays Recognition Using Block Matching for Road-to-Vehicle Visible Light Communication Reviewed

SHIRAKI Yasutake, YAMAZATO Takaya, ARAI Shintaro, YENDO Tomohiro, OKADA Hiraku, FUJII Toshiaki

IEICE technical report Vol. 111 ( 134 ) page： 73 - 78 2011.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Visible light communication systems which enable data transmission by blinking LEDs at fast rate attract attention for their applications to Intelligent Transport Systems (ITS). In this paper, we assume that there are multiple information sources and we recognize them with on-vehicle high-speed camera in such systems. To distinguish multiple sources, we propose multiple sources recognition method based block matching. We evaluate the proposed method by performing experiments.

Visible Light Communication and Its Application to ITS

T. Yamazato

International Symposium on Emerging Short Range Communications page： - 2011.6

Gaussian Pulse Shape Optimization of BFDM in Highly Mobile Environments

D. Goto, T. Yamazato, B. Mongol

Technical Report of IEICE Vol. RCS2011-06 page： 221-226 2011.6

Language：Japanese

[Requested Talk] What Visible Light Communication (VLC) can do, what VLC cannot do. What I found from the research on VLC using LED array and High-Speed Invited

T. Yamazato

Technical Report of IEICE Vol. RCS2011-49 page： 85-90 2011.6

What Visible Light Communication (VLC)can do, what VLC cannot do. What I found from the research on VLC using LED array and High-Speed Camera Reviewed

YAMAZATO Takaya

IEICE technical report Vol. 111 ( 94 ) page： 85 - 90 2011.6

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Optimizing Gaussian Pulse Shape of BFDM to Reduce ISI/ICI in Highly Mobile Environments Reviewed

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

IEICE technical report Vol. 111 ( 94 ) page： 221 - 226 2011.6

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In highly mobile environments assumed time-frequency dispersive channels, reducing intersymbol interference(ISI) and intercarrier interference (ICI) depends on the signal pulse shape. Biorthogonal Frequency Division Multiplexing (BFDM) is an efficient modulation in terms of designing pulses flexibly. So BFDM can use Gaussian pulse which is a time-frequency well localized. However, the Gaussian pulse shape is not optimized in every channel. In this paper, we optimize the Gaussian pulse shape against the channels by maximizing the ratio of the ambiguity function of the pulses. Numerical result show that the proposed method is effective for the optimization of the Gaussian pulse shape.

Erasure coding for road-to-vehicle visible light communication systems Reviewed

Okada H.

2011 IEEE Consumer Communications and Networking Conference, CCNC'2011 page： 75 - 79 2011.6

[Tutorial] Visible Light Communications Invited Reviewed

T. Yamazato, S. Haruyama

IEEE International Conference on Communications page： CD-ROM 2011.6

Authorship：Lead author Language：English

Visible light communications (VLC) is the latest optical wireless communications technologies that uses low-power light emitting diodes, or LEDs, not only to provide light but also to broadcast data. LEDs are extremely energy-efficient and predicted to become widespread in general lighting application. It is expected that LED market will reach $29 billion in 2017 that is comparable to today's NAND and DRAM markets [1]. Because LED is a solid-state lighting device, it can be modulated at high-speed compared with other lighting sources. VLC uses LEDs, which send data by flashing light at speeds undetectable to the human eye.

The pioneer of VLC using LEDs is Professor Masao Nakagawa of Keio University. His first paper on this subject appeared in the early 2000, together with his successor Prof. Shinichiro Haruyama, the instructor of this tutorial. Later in 2003, he formed Visible Light Communication Consortium (VLCC). Now VLCC is lead by Prof. Haruyama. Please see the following video, an interview of Prof. Haruyama about VLC, which has been broadcast by NHK World in June 4, 2009. http://www.naka-lab.jp/movie/nhk_world.wmv

So far various experimental VLC systems and prototypes are demonstrated. Such includes 4.8kbps visible light ID as an infrastructure to mobile-terminal application, independent sound transmission through RGB visible lights and 100Mbps VLC wireless LAN system. Using LED array, the data rate of 1 Gbps achieved by Keio University (Prof. Haruyama) that is the fastest at the moment [1]. In terms of longer range, there has been a demonstration by VLCC that achieved 1kbps transmission of the distance 2km, that is the world's longest distance for VLC. Samsung and ETRI are also active in developing VLC applications. They have demonstrated 120Mbps full duplex mobile-to-mobile transmission and 100Mbps signboard transmission. Please see the following video of Nakagawa lab. http://www.youtube.com/watch?v=QEh5f49LsB4

Widespread use of LEDs in traffic applications and growing interest in Intelligent Transport System (ITS) presents an opportunity for VLC. Data transmission using LED traffic lights, LED road illumination, and LED brake lights are typical application. Dr. Yamazato, the instructor of this tutorial, is a leader in VLC application to ITS and he recently achieved 16kbps data transmission and distance up to 70m in a driving situation with a vehicle moving with 30km/h. Today VLC using LED is a hot topic and VLC projects have been initiated in Europe and US. In 2006 Siemens launched VLC project. Later in 2008, European Commission established OMEGA project with a consortium of 20 European partners from industry and the scientific community [3]. Meanwhile, in 2008, the US National Science Foundation has approved a grant of $18.5 million to help establish and the Engineering Research Center focuses on VLC. The members of the Center include the Rensselaer Polytechnic Institute in New York, Boston University and the University of New Mexico. The University of California also have launched five-year research project called the Ubiquitous Communication by Light (UC-Light) that is founded with $3.5 million from the University. The project is anticipated to begin in 2009 and run for five years.

VLC is in the process of standardization by the IEEE 802.15 TG7 and VLCC as well as other standard organizations. The first VLC specification standard was released from JEITA in conjunction with VLCC in 2007. Later in 2008, VLCC released their first specification standard adopting and expanding the IrDA physical layer. IrDA transceiver transmission wavelength (IrDA physical layer) is expanded to accommodate the visible light wavelength. By adapting this specification, the existing IrDA optical modules can be used for VLCC data transmission with slight modification. In January 2009, IEEE 802.15 (Wireless Personal Area Networks) Task Group 7 (Visible Light Communication) has been launched. At the 6th meeting held in November 2009 they adopted the baseline draft text for the development of the 802.15.7 standard.

The goal of this tutorial is to introduce current VLC technology and its trends. Starting with an overview of VLC, participants will learn basics of VLC, on-going standardization activities and VLC. We will provide some experimental results and furthermore detail to enhance VLC application.

Visible Light Communication and its application to ITS Invited

T. Yamazato

OBN page： - 2011.6

Road-to-Vehicle Visible Light Communication using LED array and on-vehicle high-speed camera Invited

T. Yamazato

Technical Report of IEICE Vol. AN2011-5 page： 21-26 2011.5

Dynamic Resource Allocation for Improvement of Spectrum Efficiency of Satellite Terrestrial Integrated Mobile Communication System Reviewed

T. Aman, T. Yamazato

IEICE Transactions on Communications Vol. J94-B ( 3 ) page： 373-382 2011.3

TDOA UWB Positioning with Three Receivers Using Known Indoor Features Reviewed

J. Kietlinski-Zaleski, T. Yamazato

IEICE Transactions on Fundamentals Vol. E94-A ( 3 ) page： 964-971 2011.3

Language：English Publishing type：Research paper (scientific journal)

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal 3D Time Difference of Arrival (TDOA) positioning, at least four receivers with an unblocked direct path to the transmitter are required. A requirement that is not always met. In this work, a novel method for TDOA positioning using only three receivers is presented. TDOA positioning with three receivers is possible by exploiting the knowledge of some of the indoor features, namely positions of big flat reflective surfaces, for example ceiling and walls. The proposed method was verified using data from a measurement campaign.

LED Traffic Light Detection Using High-speed-camera Image Processing for Visible Light Communication System Reviewed

H. C. N, Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

The Journal of the Institute of Television Engineers of Japan Vol. 65 ( 3 ) page： 354 - 360 2011.3

Dynamic Resource Allocation for Improvement of Spectrum Efficiency of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

AMAN Tomohiro, YAMAZATO Takaya

The IEICE transactions on communications B Vol. 94 ( 3 ) page： 373 - 382 2011.3

TDOA UWB Positioning with Three Receivers Using Known Indoor Features Reviewed

Jan Kietlinski-Zaleski, Takaya Yamazato

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E94A ( 3 ) page： 964 - 971 2011.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1587/transfun.E94.A.964

B-20-15 A note on turbo compression and joint error correction of temporally and spatially correlated sources Reviewed

Optimization of gaussian pulse using ambiguity function in Biorthogonal Frequency Division Multiplexing (BFDM)

D. Goto, T. Yamazato, B. Mongol

IEICE General Conference Vol. B-5-28 page： 414 2011.2

A note on turbo compression and joint error correction of temporally and spatially correlated sources

K. Kobayashi, T. Yamazato, M. Katayama

IEICE General Conference Vol. B-20-15 page： 610 2011.2

Channel model for Road to Vehicle Visible Light Communication System using LED Array and High-Speed Camera

T. Ozawa, T. Nagura, T. Yamazato, T. Yendo, T.Fujii, H. Okada

IEICE General Conference Vol. A-17-6 page： 252 2011.2

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2011 ( 2 ) 2011.2

B-5-28 Optimization of gaussian pulse using ambiguity function in Biorthogonal Frequency Division Multiplexing (BFDM) Reviewed

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

Proceedings of the IEICE General Conference Vol. 2011 ( 1 ) 2011.2

A-17-6 Channel model for Road to Vehicle Visible Light Communication System Reviewed

OZAWA Toshiyuki, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

Proceedings of the IEICE General Conference Vol. 2011 page： 252 2011.2

High-Speed LED Traffic Sign Tracking Method Using Image Sensor with High-Speed Capturing Ability of Partial Area

K. Maeno, T. Yendo, M. P. Tehrani, T. Fujii, T. Yamazato, H. Okada, M. Tanimoto

Technical Report of IEICE Vol. ITS2010-41 page： 101-106 2011.2

Overlay Coding for Visible Light Communication using LED Array and High-Speed Camera

S. Nishimoto, T. Nagura, T. Yamazato, T. Yendo, T. Fujii, H. Okada, S. Arai

Technical Report of IEICE Vol. ITS2010-39 page： 89-94 2011.2

Performance Improvement with the Inverted Signal to Track an LED Array Transmitter on Road-to-Vehicle Visible Light Communications

T. Nagura, T. Yamazato, T. Yendo, T. Fujii, H. Okada

Technical Report of IEICE Vol. ITS2010-40 page： 95-99 2011.2

Overlay Coding for Visible Light Communication using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku, ARAI Shintaro

IEICE technical report Vol. 110 ( 420 ) page： 89 - 94 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on visible light communications using an LED array as the transmitter and a highspeed camera as the receiver. A challenge is that the longer the distance between the transmitter and the receiver, the more reduction in the resolution of the receive image occurs. To solve the problem, we allocate high priority data to low frequency components of spatial frequency. Then, we can receive high priority data even if the receiver is far from the transmitter. For that, we have used the Wavelet transform in our previous researches. However, the conventional scheme limits the number and the disposition of LEDs which can be allocated data. In other words, the hierarchical coding using the Wavelet transform has a low degree of freedom of design. In this paper, to improve a degree of freedom of design, we propose the overlay coding which does not limit the number and the disposition of LEDs.

Overlay Coding for Visible Light Communication using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku, ARAI Shintaro

IEICE technical report Vol. 110 ( 421 ) page： 89 - 94 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Performance Improvement with the Inverted Signal to Track an LED Array Transmitter on Road-to-Vehicle Visible Light Communications Reviewed

NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 110 ( 421 ) page： 95 - 99 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we consider road-to-vehicle visible light communication systems on driving situation using a LED array transmitter and a high-speed camera receiver. In our previous research, we have proposed inverted signal to track an LED array transmitter. We propose decoding method with inverted signal to improve BER performance. Furthermore, we confirm that we can suppress the flicker of LED in PDF.

Performance Improvement with the Inverted Signal to Track an LED Array Transmitter on Road-to-Vehicle Visible Light Communications Reviewed

NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 110 ( 420 ) page： 95 - 99 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

High-Speed LED Traffic Sign Tracking Method Using Image Sensor with High-Speed Capturing Ability of Partial Area Reviewed

MAENO Keita, YENDO Tomohiro, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, YAMAZATO Takaya, OKADA Hiraku, TANIMOTO Masayuki

IEICE technical report Vol. 110 ( 420 ) page： 101 - 106 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Visible Light Communication(VLC) using LEDs has been proposed as a wireless communication method. As an application of VLC in ITS, we propose a road-to-vehicle visible light communication system using an LED traffic sign as a transmitter and an image sensor as a receiver. For conducting the communication, it is necessary to have high-speed tracking of the LED traffic sign by the image sensor. In this paper, we propose new high-speed tracking method for this system.

High-Speed LED Traffic Sign Tracking Method Using Image Sensor with High-Speed Capturing Ability of Partial Area Reviewed

MAENO Keita, YENDO Tomohiro, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, YAMAZATO Takaya, OKADA Hiraku, TANIMOTO Masayuki

IEICE technical report Vol. 110 ( 421 ) page： 101 - 106 2011.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Channel Estimator by Sum of Kalman-Based Estimation and Interpolation Estimation for MC-CDMA based Inter-Vehicle Communication Reviewed

H. Hiraiwa, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J94-B ( 2 ) page： 304-307 2011.2

Language：Japanese Publishing type：Research paper (scientific journal)

LED Traffic Light Detection Using High-speed-camera Image Processing for Visible Light Communication System, Reviewed

H. C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

The Journal of the Institute of Television Engineers of Japan Vol. 65 ( 3 ) page： 354-360 2011.2

Language：English Publishing type：Research paper (scientific journal)

We propose a visible light road-to-vehicle communication system at intersection as an ITS (Intelligent Transport System) technique. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light at high frequency, and those emitted light is captured by the high-speed camera for communications. Here, the luminance value of the LEDs in the transmitter should be found, and then it should be tracked in consecutive frames while the vehicle is moving by processing the images from the high-speed camera. In this paper, we propose new algorithms for finding and tracking the transmitter, which result in increased communication speed and data rate compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

Channel Estimator by Sum of Kalman-Based Estimation and Interpolation Estimation for MC-CDMA Based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

The IEICE transactions on communications B Vol. 94 ( 2 ) page： 304 - 307 2011.2

Improvement of the Node Activity Rate by Introduction of New Inactive Node Reactivation Condition in Solar-Powered Wireless Sensor Networks Reviewed

K. Ota, K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. USN2010-63 page： 137-142 2011.1

Improvement of the Node Activity Rate by Introduction of New Inactive Node Reactivation Condition in Solar-Powered Wireless Sensor Networks Reviewed

OTA Kentaro, KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 378 ) page： 137 - 142 2011.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Our goal is improvement of the node activity rate in solar-powered wireless sensor networks. One method to reduce the consumption energy of the entire network is a cooperative transmission that uses a relay node when a node sends data. But if we don't consider the change in harvesting energy, the node activity rate is declined during nighttime. In this paper, we smooth the day-and-night node activity rate by introducing the new inactive node reactivation condition and achieve the required high node activity rate.

Erasure Coding for Road-to-Vehicle Visible Light Communication Systems Reviewed

H. Okada, T. Ishizaki, T. Yamazato, T. Yendo, T. Fujii

IEEE Intelligent Vehicular Communications System Workshop page： 970-974 2011.1

Language：English

In this paper, we focus on a road-to-vehicle visible light communication (VLC) system using LED traffic lights. In this system, an LED traffic light consists of a 2-dimensional LED array (2D LED array), and cars are equipped with high-speed 2-dimensional cameras (2D image sensors). An important issue of this system is frame loss. Sometimes, 2D image sensor in a car fails to get a frame. So as to mitigate the influence of frame loss, we propose to apply erasure coding to the road-to-vehicle VLC system. In the proposed system, a data sequence is encoded by LDPC code whose length is much longer than the size of 2D LED array. In addition, code synchronization is required for the proposed system. We also propose a code synchronization scheme, which makes use of error detection capability of LDPC code. We evaluate the performance of our proposed system, and show that it can recover frame loss for high SNR when less than 8 frames among total 18 frames are lost. In addition, we show that our proposed code synchronization scheme can ignore its errors.

Hierarchical Encoding System of Road-to-Vehicle Communication Reviewed

T. Masuda, T. Yendo, T. Yamazato, H. Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

International Workshop on Advanced Image Technology (IWAIT2011) page： CD-ROM 2011.1

Language：English

In this paper, we propose the new visible light road-to-vehicle communication system. We use the LED traffic light as the transmitter and the high-speed camera on the vehicle as the receiver. In this system, the data is encoded hierarchically and assign with the each frequency components of the image. We use the DFT for hierarchical encoding considering channel characteristic and quantization of the luminance. The communication experiments were conducted to confirm the effectiveness of the proposed method.

Parallel Communication Using Visually Non-Lighting LEDs Reviewed

K. Maeno, T. Yendo, M. P. Tehrani, T. Fujii, H. Okada, T. Yamazato, M. Tanimoto

International Workshop on Advanced Image Technology (IWAIT2011) page： CD-ROM 2011.1

Language：English

Previous studies on visible light communication uses visually lighting LEDs. However, LEDs are not always lighting. In this paper, we propose visible light communication method using visually non-lighting LEDs. This method enables us to communicate in different situations, e.g. using visually non-lighting tail lamps of cars or visually non-lighting traffic lights. We realize visually non-lighting LEDs by reducing luminescence energy of LEDs according to the brightness in the environment. To reduce luminescence energy of LEDs, we reduce the number of emitting LEDs, increase the interval of emitting, and decrease the luminance of emitting LEDs. In our research we consider the case that the transmitter is tail lamps of cars and the receiver is high-speed camera. We conduct two types of experiments to demonstrate the performance of the proposed system. One is to confirm that LEDs are visually non-lighting. The other is measurement of Bit Error Rate of communication using visually non-lighting LEDs. Experimental results demonstrate that it is possible to make communication using visually non-lighting LEDs. In our future work, we plan to use different sensor devices such as photo diode or CCD in order to decrease the error rate in communication.

Image Processing Based Road-to-vehicle Visible Light Communication Reviewed

H. C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamasato, H. Okada, T. Fujii, M. Tanimoto

International Workshop on Advanced Image Technology (IWAIT2011) page： CD-ROM 2011.1

Language：English

Visible Light Communication(VLC) has been introduced as a new wireless communication method. In this paper, we propose a VLC system for Intelligent Transport System (ITS) to communicate between infrastructure and the vehicle. In this system, we use a LED array as a transmitter and on-vehicle high speed camera as a receiver. Here, LEDs in the transmitter emit light in 500Hz and the emission patterns are used to achieve communication, by capturing them using the high speed camera in high frame rate. The images captured by high speed camera are processed to find the transmitter, track the found transmitter, and capture the emission pattern of transmitter in consecutive frames. In our previous work, we proposed algorithms to finding and tracking. In this paper, we introduce method to capture the emission pattern of the transmitter. Then out door communication experiments were conducted to confirm the effectiveness of the proposed VLC system.

9-217 Messages provided by a teacher that can be read from the Nagoya Univeristy OCW Reviewed

Yamazato Takaya

Proceedings of Annual Conference of Japanese Society for Engineering Education Vol. 2011 ( 0 ) page： 440 - 441 2011

Cooperative Transmission Scheme with Inactive Node Reactivation Condition for Solar-Powered Wireless Sensor Networks Reviewed

Ota Kentaro, Kobayashi Kentaro, Yamazato Takaya, Katayama Masaaki

2011 IEEE 22ND INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 2384 - 2388 2011

Cooperative Transmission Scheme with Inactive Node Reactivation Condition for Solar-Powered Wireless Sensor Networks Reviewed

Kentaro Ota, Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

2011 IEEE 22ND INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC) page： 2384 - 2388 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/PIMRC.2011.6139948

LED Traffic Light Detection Using High-speed-camera Image Processing for Visible Light Communication Reviewed

Premachandra H. Chinthaka N., Yendo Tomohiro, Tehrani Mehrdad Panahpour, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Tanimoto Masayuki

Information and Media Technologies Vol. 6 ( 3 ) page： 785 - 791 2011

Publishing type：Research paper (scientific journal) Publisher：Information and Media Technologies 編集運営会議

We propose a visible light road-to-vehicle communication system at intersections as an ITS(Intelligent Transport System) technique. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light at high frequency, and those emitted light is captured by the high-speed camera for communication. Here, the luminance value of the LEDs in the transmitter should be captured in consecutive frames to achieve communication. For this purpose, first the transmitter should be found, and then it should be tracked in consecutive frames while the vehicle is moving by processing the images from the high-speed camera. In this paper, we propose new algorithms for finding and tracking the transmitter, which result in increased communication speed and data rate compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

DOI： 10.11185/imt.6.785

Overlay Coding for Visible Light Communication using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku, ARAI Shintaro

ITE Technical Report Vol. 35 ( 0 ) page： 89 - 94 2011

Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

DOI： 10.11485/itetr.35.9.0_89

Performance Improvement with the Inverted Signal to Track an LED Array Transmitter on Road-to-Vehicle Visible Light Communications Reviewed

NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

ITE Technical Report Vol. 35 ( 0 ) page： 95 - 99 2011

Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

DOI： 10.11485/itetr.35.9.0_95

Overlay Coding for Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

Nishimoto Sayaka, Nagura Toru, Yamazato Takaya, Yendo Tomohiro, Fujii Toshiaki, Okada Hiraku, Arai Shintaro

2011 14TH INTERNATIONAL IEEE CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC) page： 1704 - 1709 2011

Overlay Coding for Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

Sayaka Nishimoto, Toru Nagura, Takaya Yamazato, Tomohiro Yendo, Toshiaki Fujii, Hiraku Okada, Shintaro Arai

2011 14TH INTERNATIONAL IEEE CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC) page： 1704 - 1709 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper aims to improve the visible light communication system using LED array and high-speed camera by proposing what we call "overlay coding". "Overlay coding" is a new coding method to realize a hierarchical coding, through which a high-priority data can be received even if the receiver is far from a transmitter. Conventionally, the hierarchical coding has been realized through the wavelet transform that has a limitation of number and disposition of LEDs, and as a result it does not always match with the design of the transmitters (e.g. traffic lights, etc.) used in real life. To solve the limitation problem, we propose a more flexible way of designing the application of LEDs depending on the transmitters. In particular, overlay coding is realized through the procedures of coding and decoding. In coding, we replace one LED with a flexible number of LEDs, and the number depends on whether the data is high-priority or low-priority, then high-priority data and low-priority data are overlaid (section III-B1). In decoding, we first obtain the high-priority data, and then the low-priority data using retrieved high-priority data (section III-B2). The experimental result shows that the distance for receiving error-free data is extended from 30m to 70m in the overlay coding (section IV-B).

DOI： 10.1109/ITSC.2011.6082943

High-Speed LED Traffic Sign Tracking Method Using Image Sensor with High-Speed Capturing Ability of Partial Area Reviewed

MAENO Keita, YENDO Tomohiro, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, YAMAZATO Takaya, OKADA Hiraku, TANIMOTO Masayuki

ITE Technical Report Vol. 35 ( 0 ) page： 101 - 106 2011

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

Visible Light Communication (VLC) using LEDs has been proposed as a wireless communication method. As an application of VLC in ITS, we propose a road-to-vehicle visible light communication system using an LED traffic sign as a transmitter and an image sensor as a receiver. For conducting the communication, it is necessary to have high-speed tracking of the LED traffic sign by the image sensor. In this paper, we propose new high-speed tracking method for this system.

DOI： 10.11485/itetr.35.9.0_101

EXIT Analysis for MAP-Based Joint Iterative Decoding of Separately Encoded Correlated Sources Reviewed

TDOA UWB positioning with three receivers using known indoor features Reviewed

Kietlinski-Zaleski J.

2010 IEEE International Conference on Ultra-Wideband, ICUWB2010 - Proceedings Vol. 2 2010.12

Dynamic Bandwidth Allocation of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

T. Yamazato, T. Aman, M. Katayama

IEEE Global Communications Conference page： CD-ROM 2010.12

Language：English

In this paper, we propose two dynamic bandwidth allocation (DBA) schemes, a game theory based DBA and a successive DBA, for satellite/terrestrial integrated mobile communication system (STICS). The game theory based DBA allocate the bandwidth according to a utility function based on a weighted demand bandwidth of both satellite and terrestrial system. The successive DBA recursively allocates an unit of bandwidth according to a weighted number of bandwidth unfilled cells of both satellite and terrestrial systems, until the total bandwidth is fulfilled. As results, both DBA outperform the conventional fixed bandwidth allocation scheme. Between two proposed DBA, the successive DBA shows better spectral improvement ratio than the game theory based DBA.

LED Traffic Light Detection Using High-speed-camera Image Processing for Visible Light Communication System, Reviewed

H. C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

Workshop on Picture Coding and Image Processing, PCSJ2010/IMPS2010 page： CD-ROM 2010.12

Language：English

Intelligent transport system has been introduced to reduce traffic problems such traffic accidents and traffic congestions. In this paper, we introduce a receiver for a road to vehicle Visible Light Communication (VLC) system which is proposed as an Intelligent Transport System (ITS) technique. In this system, an on-vehicle high-speed camera is used as a receiver and an LED array is used as a transmitter. VLC is a wireless communication using luminance. Here, transmitter send information by emitting light and receiver receive them by capturing the luminance of emitting LEDs in the array(Luminance: whether each LED is on or off). For capturing the Luminance, it is necessary to find the transmitter and track it in consecutive frames. In our previous works we introduced methods for finding and tracking. In this paper, we shortly explain the proposed transmitter finding and tracking methods and then a new method is proposed for capturing the luminance of LEDs to achieve communication.

Parallel Visible Light Communication Using Visually Non-Lighting LEDs Reviewed

K. Maeno, T. Yendo, M. P. Tehrani, T. Fujii, T. Yamazato, H. Okada, M. Tanimoto

Workshop on Picture Coding and Image Processing, PCSJ2010/IMPS2010 page： CD-ROM 2010.12

Language：English

Our goal is improvement of the node activity rate in solar-powered wireless sensor networks. One method to reduce the consumption energy of the entire network is a cooperative transmission that uses a relay node when a node sends data. But if we do not consider the change in harvesting energy, the node activity rate is declined during nighttime. In this paper, we smooth the day-and-night node activity rate by introducing the new inactive node reactivation condition and achieve the required high node activity rate.

Hierarchical Encoding System for Road-to-Vehicle Communication Using LED Traffic Light Reviewed

T. Masuda, T. Yendo, T. Yamazato, H. Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

Workshop on Picture Coding and Image Processing, PCSJ2010/IMPS2010 page： CD-ROM 2010.12

Language：English

This paper discusses the visible light road-to-vehicle communication system at intersection as one of ITS (Intelligent Transport System) technique. The communication between a vehicle and an LED traffic light is approached using an LED traffic light as a transmitter, and on-vehicle high-speed camera as a receiver. In this system, it is able to send data by blinking the LEDs of the traffic light in two dimensional patterns, and able to receive them by high-speed camera with image processing [1]. Here, we aim to conduct long-distance high-speed visible light communication. When the distance between transmitter and receiver is far, the image of the LED traffic light captured by on-vehicle high-speed camera is very small. So, if the data are put on two dimension patterns without modification, data would be mistaken, because the two dimension patterns can't be realized correctly. To solve this problem, data are encoded hierarchically before they are lighted by the LED traffic light. This is called as hierarchical encoding that the data are assigned with each spatial frequency.

[Encouragement Talk] Distributed Error Correcting Coding and Joint Decoding Scheme Using Spatial Correlation of Sensor ADC Output in Wireless Sensor networks Invited

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. WBS2010-39 page： 23-28 2010.12

EXIT Analysis for MAP-based Joint Iterative Decoding of Separately Encoded Correlated Sources Reviewed

K. Kobayashi, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. E93-B ( 12 ) page： 3509-3513 2010.12

Language：English Publishing type：Research paper (scientific journal)

We develop a mathematical framework for the extrinsic information transfer (EXIT) analysis to assess the convergence behavior of maximum a posteriori (MAP)-based joint iterative decoding of correlated sources, which are separately encoded and transmitted over noisy channels. Unlike the previous work, side information about the correlation is not perfectly given at the joint decoder but is extracted from decoder output and updated in an iterative manner. The presented framework provides a convenient way to compare between schemes. We show that it allows us to easily and accurately predict joint decoding gain and turbo cliff position.

TOA UWB Positioning with Two Receivers Using Known Indoor Features Reviewed

J. Kietlinski-Zaleski, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. E93-B ( 12 ) page： 3624-3631 2010.12

Language：English Publishing type：Research paper (scientific journal)

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal Time of Arrival (ToA) positioning, at least three receivers with unblocked direct path to the transmitter are required. A requirement that is not always met. In this work, a novel algorithm for ToA positioning using only two receivers is presented. This is possible by exploiting the knowledge of some of the indoor features, namely positions of big flat reflective surfaces, for example ceiling and walls. The proposed algorithm was tested using data from a measurement campaign.

Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E93B ( 12 ) page： 3509 - 3513 2010.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We develop a mathematical framework for the extrinsic information transfer (EXIT) analysis to assess the convergence behavior of maximum a posteriori (MAP) based joint iterative decoding of correlated sources which are separately encoded and transmitted over noisy channels Unlike the previous work our approach focuses on the case side information about the correlation is not perfectly given at the joint decoder but is extracted from decoder output and updated in an iterative manner The presented framework provides a convenient way to compare between schemes We show that it allows us to easily and accurately predict Joint decoding gain and turbo cliff position

DOI： 10.1587/transcom.E93.B.3509

Recent Advances in Satellite and Space Communications Reviewed

Bisio Igor, De Gaudenzi Riccardo, Nguyen Hung, Pavlidou Fotini-Niovi, Yamazato Takaya

JOURNAL OF COMMUNICATIONS AND NETWORKS Vol. 12 ( 6 ) page： 523 - 528 2010.12

Recent Advances in Satellite and Space Communications Reviewed

Igor Bisio, Riccardo De Gaudenzi, Hung Nguyen, Fotini-Niovi Pavlidou, Takaya Yamazato

JOURNAL OF COMMUNICATIONS AND NETWORKS Vol. 12 ( 6 ) page： 523 - 528 2010.12

TOA UWB Positioning with Two Receivers Using Known Indoor Features Reviewed

Jan Kietlinski-Zaleski, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E93B ( 12 ) page： 3624 - 3631 2010.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Ultra Wideband is an attractive technology for short range positioning especially Indoors However for normal Time of Arrival (ToA) positioning at least three receivers with unblocked direct path to the trans miner are required A requirement that is not always met In this work a novel algorithm for ToA positioning using only two receivers is presented This is possible by exploiting the knowledge of some of the indoor features namely positions of big flat reflective surfaces for example ceiling and walls The proposed algorithm was tested using data from a measurement campaign

DOI： 10.1587/transcom.E93.B.3624

Distributed Error Correcting Coding and Joint Decoding Scheme Using Spatial Correlation of Sensor ADC Output in Wireless Sensor networks Reviewed

UWB positioning using known indoor features- Environment comparison Reviewed

Kietlinski-Zaleski J.

2010 International Conference on Indoor Positioning and Indoor Navigation, IPIN 2010 - Conference Proceedings 2010.12

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 326 ) page： 23 - 28 2010.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In wireless sensor networks, sensor nodes are densely deployed for reliable sensing of physical phenomenon. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on joint channel decoding utilizing the spatial correlation of multiple sensor observations. Our proposed scheme makes use of an estimation of the correlation according to ADC bit levels. In addition, the proposed scheme makes use of Gray code for avoiding multiple bit-flipping between adjacent ADC output values. The performance of our approach is examined by simulations using sensor data from experiments in a real indoor environment.

Experimental Results on Simple Distributed Cooperative Transmission Scheme with Visible Light Communication Reviewed

T. Yamazato, K. Nakao, H. Okada, M. Katayama

IEICE Transactions on Communications Vol. E93-B ( 11 ) page： 2959-2962 2010.11

Language：English Publishing type：Research paper (scientific journal)

We consider a distributed transmission of data packet to a sink where the distance of a sensor node to a sink is much longer than the maximum communication range of each sensor node. We give a simple modification to the transmitter, i.e., multiplication of random phase before the transmission. Thanks to Turbo Code, it is possible to extend the trans- mission range as the received amplitude varies symbol by symbol for our scheme while whole data packet may be lost for the conventional scheme. In this letter, we report the experimental results of our scheme equivalently developed using visible light communication.

Experimental Results on Simple Distributed Cooperative Transmission Scheme with Visible Light Communication Reviewed

Takaya Yamazato, Koji Nakao, Hiraku Okada, Masaaki Katayama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E93B ( 11 ) page： 2959 - 2962 2010.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We consider a distributed transmission of data packet to a sink where the distance of a sensor node to a sink is much longer than the maximum communication range of each sensor node We give a simple modification to the transmitter i e multiplication of random phase before the transmission Thanks to Turbo Code it is possible to extend the trans mission range as the received amplitude vanes symbol by symbol for our scheme while whole data packet may be lost for the conventional scheme In this letter we report the experimental results of our scheme equivalently developed using visible light communication

DOI： 10.1587/transcom.E93.B.2959

Kalman Channel Estimator for BFDM/OQAM System in Time-Frequency Dispersive Channels Reviewed

Performance evaluation of the cognitive piggyback overlay systems with dirty paper coding Reviewed

J. Naganawa, K. Kobayashi, M. Katayama, T. Yamazato

10th International Symposium on Communications and Information Technologies (ISCIT2010) Vol. FA1-1-4 page： 974-979 2010.10

Language：English

This manuscript considers a secondary system sharing the spectrum with the primary system at the same time and on the same frequency. We propose a cognitive overlay system in which the secondary system relays the primary signal and piggybacks its own data on it. Furthermore, the secondary system uses the channel coding based on the dirty paper coding (DPC). The result of the analysis shows that the proposed scheme allows the secondary system to communicate at the same speed as the primary system without any harm to it.

Improvement of Sequential-Test-Based Cooperative Spectrum Sensing Systems in Band Limited Control Channels Reviewed

S. Mitsuya, K. Kobayashi, T. Yamazato, M. Katayama

10th International Symposium on Communications and Information Technologies (ISCIT2010) Vol. FA1-1-3 page： 968-973 2010.10

Language：English

In a cooperative spectrum sensing system, many nodes perform spectrum sensing and report their decisions to one fusion center via control channels. This paper considers efficient use of the frequency band for the control channels. For this purpose, sequential-test is introduced for the local decision at each node. With this scheme, the transmission timing of the reports from the nodes becomes at random and necessary maximum bandwidth for the control channels decreases. Numerical results show that this sequential-test-base-scheme not only decreases the number of simultaneous reports but also improves sensing reliability. For further improvement, this paper also introduces a decision scheme at the fusion center based on probabilistic features of the reports from the nodes.

Inband and Outband Spectrum Analysis of the BFDM and BFDM/OQAM Signals with Truncated Gaussian Pulses Reviewed

B. Mongol, T. Yamazato, M. Katayama

International Symposium on Information Theory and Its Applications page： CD-ROM 2010.10

Language：English

Pulse-shaping OFDM, or more generally BFDM and BFDM/OQAM, systems are originally proposed to combat inter- carrier interference (ICI) caused by time-variance of the channel. The main property that makes these signals robust against ICI is that they allow to employ time-frequency well localized pulses, particularly Gaussian pulse which has the best time-frequency localization. However, this property also suppresses the outband or inband spectral leakage of the BFDM and BFDM/OQAM signal, making them attractive physical layer modulation scheme for cognitive radio. In this paper we analyze the power density spectra of the BFDM and BFDM/OQAM signals and numerically evaluate the inband and outband spectra for truncated Gaussian pulses.

Error-correcting scheme based on chaotic dynamics and its performance for noncoherent chaos communications Reviewed

S. Arai, Y. Nishio and T. Yamazato

NOLTA, IEICE Vol. 1 ( 1 ) page： 196-206 2010.10

Language：English Publishing type：Research paper (scientific journal)

This paper proposes a novel error-correcting scheme using chaotic dynamics for noncoherent chaos communications. In our proposed system, two successive chaotic sequences are generated from the same chaotic map; the second sequence is generated with an initial value which is the last value of the first sequence. In this case, successive chaotic sequences having the same chaotic dynamics are created. This feature gives the receiver additional information to correctly recover the information data and thus improves the bit error performance of the receiver. As results of the computer simulation, we confirm that the advantage gained in BER performance of the proposed error-correcting method is about 1-1.5 dB compared to conventional method. In addition, we achieve that the proposed error-correcting scheme is performed without the new additional redundancy code by using the chaotic dynamics.

Kalman Channel Estimator for BFDM/OQAM system in Time-Frequency Dispersive Channels Reviewed

B. Mongol, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J93-B ( 10 ) page： 1466-1480 2010.10

Language：Japanese Publishing type：Research paper (scientific journal)

Biorthogonal Frequency Division Multiplexing / Offset QAM (BFDM/OQAM) allows to employ a Gaus- sian transmitter pulse. Thus, it performs well in the time-frequency dispersive channels as it can suppress ISI and ICI without having guard interval. However, in the highly mobile environment the performance deteriorates and channel estimation schemes became essential for further improvement of BFDM/OQAM systems. This paper proposes a novel adaptive channel estimator based on Kalman filter. Especially, we derive the essential equations to design Kalman filter, namely, the process equation and the measurement equation.

MONGOL Bayarpurev, YAMAZATO Takaya, KATAYAMA Masaaki

The IEICE transactions on communications B Vol. 93 ( 10 ) page： 1466 - 1480 2010.10

A Study on Joint Channel Decoding Using Spatial Correlation of Sensor Observations According to ADC Bit levels Reviewed

K. Kobayashi, T. Yamazato, M. Katayama

IEEE International Workshop on Wireless Distributed Networks (WDN2010) page： 484-489 2010.9

Language：English

In densely deployed wireless sensor networks, observations of the sensor nodes are spatially correlated. In this paper, we study a joint channel decoding scheme utilizing bit correlation of the sensor observations according to bit levels of analog-digital converter (ADC). If sensor ADC output is interpreted as natural binary numeral, carry propagation may occur between adjacent ADC output values. Such carry propagation leads to the degradation of joint decoding gain. We focus on the use of Gray code for avoiding the carry propagation. The performance of our approach is demonstrated by simulations using sensor data from experiments in a real indoor environment.

TDOA UWB Positioning with Three Receivers Using Known Indoor Features Reviewed

J. Kietlinski-Zaleski, T. Yamazato, M. Katayama

2010 IEEE International Conference on Ultra-Wideband page： CD-ROM 2010.9

Language：English

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal 3D Time Difference of Arrival (TDoA) positioning, at least four receivers with unblocked direct path to the transmitter are required. A requirement that is not always met. In this work, a novel method for TDoA positioning using only three receivers is presented and tested using real-world measurements. Positioning with three receivers is possible by exploiting the knowledge of some of the indoor features, namely positions of big flat reflective surfaces, reflectors, for example ceiling and walls.

Tracking an LED Array Transmitter for Visible Light Communications in the Driving Situation Reviewed

T. Nagura, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

IEEE International Symposium on Wireless Communication Systems (ISWCS2010) page： 765-769 2010.9

Language：English

In this paper, we discuss on a decoding algorithm for visible light communication systems in the driving situation using an LED array transmitter and a high-speed camera receiver. We propose an LED array detection method using M-sequence and an LED array tracking method using inverted signals. We confirm that we can distinguish LED array candidates correctly with M-sequence. We also confirm that we can suppress the flicker of the LED and improve the data rate as compared with the previous method.

UWB Positioning Using Known Indoor Features - Environment Comparison Reviewed

J. Kietlinski-Zaleski, T. Yamazato

2010 International Conference on Indoor Positioning and Indoor Navigation (IPIN) page： CD-ROM 2010.9

Language：English

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal Time of Arrival (TOA) positioning, at least three receivers with unblocked direct path to the transmitter are required. A requirement that is not always met. In our previous work, we presented a novel 3D TOA UWB indoor positioning method that uses only two receivers. This is possible by exploiting the knowledge of some of the indoor features, namely ceiling and walls. In this work, we verify the usability of the method using measurement results in three environments: a lecture room, a cluttered laboratory and a corridor. By comparing the results of the method for three environments, we draw conclusions about its strengths and weaknesses.

Fast Recognition of LED Array by High-Speed Camera Invited

T. Yamazato

Enginnering Sciences Society Conference of IEICE Vol. AP-2 page： CD-ROM 2010.9

Implovement Method of transmission speed for Visible Light Communication System using LED Array and High-Speed Camera

T. Ozawa, T. Nagura, T. Yamazato, T. Yendo, T. Fujii, H. Okada

Enginnering Sciences Society Conference of IEICE Vol. A-17-8 page： 154 2010.9

Channel Characteristics of Road-to-Vehicle Paralell Optical Communications Systems and Its Reciever

K. Maeno, T. Yendo, T. Yamazato, H. Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

Forum on Informatio Technology Vol. RM-003 page： CD-ROM 2010.9

LED Traffic Light Detection Using a High-speed-camera for a Road-to-vehicle Visible Light Communication System

H. C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

Forum on Informatio Technology Vol. RM-002 page： CD-ROM 2010.9

Study on parallel visible light communication using visually non-lighting LED

K. Maeno, T. Yendo, M. P. Tehrani, T. Fujii, T. Yamazato, H. Okada, M. Tanimoto

IEEJ General Conference, page： CD-ROM 2010.8

A-17-8 Implovement Method of transmission speed for Visible Light Communication System using LED Array and High-Speed Camera Reviewed

OZAWA Toshiyuki, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

Proceedings of the Society Conference of IEICE Vol. 2010 page： 154 2010.8

AP-2-6 Fast Recognition of LED Array by High-Speed Camera Reviewed

Yamazato Takaya

Proceedings of the Society Conference of IEICE Vol. 2010 page： "SS - 24"-"SS-25" 2010.8

Influence of quantization of brightness in road-vehicle communication

K. Masuda, T. Yendo, T. Yamazato, H. Okada, P. Tehrani, T. Fujii, M. Tanimoto

Toukai Shibu Rengou Taikai page： - 2010.8

Inter-vehicle visible light communication using visually non-lighting LED

K. Maeno, T. Yendo, M. P. Tehrani, T. Fujii, T. Yamazato, M. Tanimoto

2010 IEE of Japan, Tokai Section, Wakate Seminar. page： - 2010.8

Unique teaching practices presented at Nagoya Univeristy OCW

T. Yamazato

Japanese Society for Engineering Education 58th Annual Conference & Exposition Vol. 10-107 page： - 2010.8

RM-002 LED Traffic Light Detection Using a High-speed-camera for a Road-to-vehicle Visible Light Communication System Reviewed

Premachandra Halpage Chinthaka Nuwandika, Yendo Tomohiro, Tehrani Mehrdad Panahpour, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Tanimoto Masayuki

情報科学技術フォーラム講演論文集 Vol. 9 ( 4 ) page： 45 - 50 2010.8

Publishing type：Research paper (scientific journal) Publisher：FIT(電子情報通信学会・情報処理学会)運営委員会

A new visible light road-to-vehicle communication system at intersections is proposed for the area of ITS. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter, and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light in high frequency and those emitting LEDs are captured by the high-speed camera for making communication. Here, the luminance value of LEDs in the transmitter should be captured in consecutive frames to achieve communication. For this purpose, finding the transmitter and tracking it in consecutive frames by processing the images from the high-speed camera is important. We propose new effective algorithms for finding and tracking the transmitter, which result in a increased communication speed, compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

RM-003 Channel Characteristics and Receiving System of Road-vehicle Communication Reviewed

MASUDA Takato, Yendo Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

Vol. 9 ( 4 ) page： 51 - 55 2010.8

10-107 Unique teaching practices presented at Nagoya Univeristy OCW Reviewed

Yamazato Takaya

Proceedings of Annual Conference of Japanese Society for Engineering Education Vol. 2010 ( 0 ) page： 210 - 211 2010.8

Experimental validation of TOA UWB positioning with two receivers using known indoor features Reviewed

Kietlinski-Zaleski J.

Record - IEEE PLANS, Position Location and Navigation Symposium page： 505 - 509 2010.8

Performance evaluation of the cognitive piggyback overlay systems using QAM modulation

J. Naganawa, K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. SR2010-31 page： 89-94 2010.7

Improvement of the Sequential-Test-Based Cooperative Spectrum Sensing Systems in Band Limited Control Channels

S. Mitsuya, K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. SR2010-19 page： 19-24 2010.7

Language：Japanese

In a cooperative spectrum sensing system, many nodes perform spectrum sensing and report their decisions to one fusion center via control channels. This paper considers efficient use of the frequency band for the control channels. For this purpose, sequential-test is introduced for the local decision at each node. With this scheme, the transmission timing of the reports from nodes becomes at random and necessary maximum bandwidth for the control channels decreases. Numerical results show that this sequential-test-base-scheme not only decreases the number of simultaneous reports but also improves sensing reliability. For further improvement, this paper introduces a decision scheme at the fusion center based on probabilistic features of the reports from nodes.

Visible Light Communication Between LED Array and On-vehicle High Speed Camera Reviewed

H. C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

Technical Report of IEICE Vol. ITS2010-10 page： 25-30 2010.7

Performance evaluation of the cognitive piggyback overlay systems using QAM modulation Reviewed

NAGANAWA Jun, KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 153 ) page： 89 - 94 2010.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This manuscript considers a secondary system sharing the spectrum with the primary system at the same time and frequency. The proposed cognitive overlay system relays the primary signal and piggybacks its own data on it. As the modulation scheme, phase shift keying and quadrature amplitude modulation are considered and performance with them are compared. The result of the analysis for Rayleigh fading environment shows that the proposed scheme with regenerative relay allows the secondary signal to communicate at the same speed of the primary signal without any harm to it.

Improvement of the Sequential-Test-Based Cooperative Spectrum Sensing Systems in Band Limited Control Channels Reviewed

MITSUYA Shohei, KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 153 ) page： 19 - 24 2010.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In a cooperative spectrum sensing system, many nodes perform spectrum sensing and report their decisions to one fusion center via control channels. This paper considers efficient use of the frequency band for the control channels. For this purpose, sequential-test is introduced for the local decision at each node. With this scheme, the transmission timing of the reports from nodes becomes at random and necessary maximum bandwidth for the control channels decreases. Numerical results show that this sequential-test-base-scheme not only decreases the number of simultaneous reports but also improves sensing reliability. For further improvement, this paper introduces a decision scheme at the fusion center based on probabilistic features of the reports from nodes.

Visible Light Communication Between LED Array and On-vehicle High-speed Camera Reviewed

Premachandra H. Chinthaka N., Yendo Tomohiro, Panahpour Tehrani Mehrdad, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, TANIMOTO Masayuki, Tanimoto Masayuki

電子情報通信学会技術研究報告. ITS Vol. 110 ( 150 ) page： 25 - 30 2010.7

Publishing type：Research paper (scientific journal) Publisher：一般社団法人電子情報通信学会

We propose visible light road-to-vehicle communication system at intersections for ITS. In this system, the communication between a vehicle and an LED array is conducted using an LED array as a transmitter, and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light in high frequency and those emitting LEDs are captured by the high-speed camera for making communication. Here, the data is sent by emitting LEDs in the transmitter and those data is received by capturing luminance value of LEDs by high-speed camera. To achieve this, finding the transmitter and tracking it in consecutive frames is important. We propose new effective algorithms for finding and tracking the transmitter, which result in a increased communication speed, compared to the previous methods.

Effect of Slanted LED Traffic Light on Road-to-Vehicle Visible Light Communication Reviewed

SHIRAKI Yasutake, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku, ARAI Shintaro

IEICE technical report Vol. 110 ( 150 ) page： 31 - 36 2010.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on road-to-vehicle visible light communications using an LED traffic light and a high-speed camera fixed to a vehicle. We assume that the camera is facing forwards and that it is parallel to the surface of the road. In our study, the LED traffic light in the image is slanted to represent the case in which the camera and the LED traffic light are not directly facing each other in an intersection. In order to demodulate data, we consider the slanting of the LED traffic light on the image. In this paper, we evaluate the effect the slanting of the LED traffic light on communication.

Study on parallel visible light communication using visually non-lighting LED Reviewed

MAENO Keita, YENDO Tomohiro, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, YAMAZATO Takaya, OKADA Hiraku, TANIMOTO Masayuki

IEICE technical report Vol. 110 ( 150 ) page： 19 - 24 2010.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Previous studies on visible light communication uses visually lighting LED. However, LEDs isn't always lighting. In this paper, we propose visible light communication method using visually non-lighting LED. This method enables us to communicate using visually non-lighting tail lamps of cars and visually non-lighting traffic lights and so on. We conduct two types of experiments to demonstrate the performance of the proposed system. The result shows possibility of communication using visually non-lighting LED.

Spectrum Efficiency Improvement by Dynamic Resource Allocation for Satellite Terrestrial Integrated Mobile Communication System Reviewed

AMAN Tomohiro, YAMAZATO Takaya

IEICE technical report Vol. 110 ( 136 ) page： 97 - 102 2010.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In Satellite Terrestrial Integrated Mobile Communication System, a single mobile terminal can communicate to both satellite and terrestrial communication systems depend upon his location, QoS and availability of resources among satellite and terrestrial communication systems. But it is hard to achieve high spectrum efficiency of Satellite Terrestrial Integrated Mobile Communication System using fixed resource allocation schemes because variation of satellite traffic and terrestrial traffic is different. In this paper, we propose dynamic resource allocation schemes according to traffic of satellite communication systems and terrestrial communication systems. Finally we show spectrum efficiency is improved by proposed scheme.

Spectrum Efficiency Improvement by Dynamic Resource Allocation for Satellite Terrestrial Integrated Mobile Communication System

T. Aman, T. Yamazato

Technical Report of IEICE Vol. SAT2010-27 page： 97-102 2010.7

Language：Japanese

In Satellite Terrestrial Integrated Mobile Communication System, a single mobile terminal can com- municate to both satellite and terrestrial communication systems depend upon his location, QoS and availability of resources among satellite and terrestrial communication systems. But it is hard to achieve high spectrum efficiency of Satellite Terrestrial Integrated Mobile Communication System using fixed resource allocation schemes because variation of satellite traffic and terrestrial traffic is different. In this paper, we propose dynamic resource allocation schemes according to traffic of satellite communication systems and terrestrial communication systems. Finally we show spectrum efficiency is improved by proposed scheme.

Effect of Slanted LED Traffic Light on Road-to-Vehicle Visible Light Communication

Y. Shiraki, T. Yamazato, T. Yendo, T. Fujii, H. Okada, S. Arai

Technical Report of IEICE Vol. ITS2010-12 page： 31-36 2010.7

Language：Japanese

"In this paper, we discuss on road-to-vehicle visible light communications using an LED traffic light and a high-speed camera fixed to a vehicle. We assume that the camera is facing forwards and that it is parallel to the surface of the road.
In our study, the LED traffic light in the image is slanted to represent the case in which the camera and the LED traffic light are not directly facing each other in an intersection. In order to demodulate data, we consider the slanting of the LED traffic light on the image. In this paper, we evaluate the effect the slanting of the LED traffic light on communication."

Effects and Mitigation of Channel Errors in a Wireless Control System for Cooperative Motion of Machines Reviewed

KONDO Tsugunori, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 72 ) page： 57 - 62 2010.6

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This manuscript discusses a wireless control system for cooperative motion of machines, and clarifies the influence of channel errors to a cooperative motion system. In addition, a new wireless control method is proposed to improve performance of cooperative motion when the channel errors occur. As an example of the controlled objects, rotary inverted pendulums with wireless connections in feedback loops are considered. In this study, we select a simple setting for cooperative motion, two rotary inverted pendulums are operated symmetrically. In order to improve the synchronization of their cooperative motion, we propose a system in which each pendulum receives control signals of it and also of the other pendulum. In addition, the main controller generates control signals for them based on the state information of both objects. The proposed system provides a better performance of cooperative motion than a conventional system with two independent feedback loops does.

Performance Evaluation of a Power Supply Overlaid Communication for Cooperative Motion of Multiple Machines Reviewed

MINAMIYAMA Fumikazu, KOGA Hidetsugu, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 72 ) page： 63 - 68 2010.6

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In order to reduce wiring in industrial machinery, we consider a cooperative-action system in which various devices (slaves) are multidrop-connected through a bus topology to a controlling master. Additionally, power is supplied together with communication signals over the same wiring. To accurately deliver timing information to the slaves, we propose the use of a spread spectrum (SS) signal. Together with the this signal, the control information signal is transmitted by applying an OFDM scheme. This manuscript provide an example of a set of system parameter to be used for an actual application. To assess the proposed method, the reception characteristics and mutual influence of the two overlaid signals is also explained.

High-speed-camera Image Processing Based LED Traffic Light Detection for Road-to-vehicle Visible Light Communication Reviewed

H.C.N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

IEEE Intelligent Vehicles Symposium page： 793-798 2010.6

Language：English

As one of ITS technique, a new visible light road to- vehicle communication system at intersections is proposed. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter, and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light in high frequency and those emitting LEDs are captured by the high-speed camera for making communication. Here, the luminance value of LEDs in the transmitter should be captured in consecutive frames to achieve effective communication. For this purpose, first the transmitter should be found, then it should be tracked in consecutive frames by processing the images from the high-speed camera. In this paper, we propose new effective algorithms for finding and tracking the transmitter, which result in a increased communication speed, compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

Effects and Mitigation of Channel Errors in a Wireless Control System for Cooperative Motion of Machines

T. Kondo T. Yamazato M. Katayama

Technical Report of IEICE Vol. WBS2010-11 page： 57-62 2010.6

Language：Japanese Publishing type：Research paper (scientific journal)

Performance evaluation of a power supply overlaid communication for cooperative motion of multiple machines.

F.Minamiyama, H.Koga, T.Yamazato, M.Katayama

Technical Report of IEICE Vol. WBS2010-12 page： 63-68 2010.6

Language：Japanese

In order to reduce wiring in industrial machinery, we consider a cooperative-action system in which various devices (slaves) are multidrop-connected through a bus topology to a controlling master. Additionally, power is supplied together with communication signals over the same wiring. To accurately deliver timing information to the slaves, we propose the use of a spread spectrum(SS) signal. Together with the this signal, the control information signal is transmitted by applying an OFDM scheme. This manuscript provide an example of a set of system parameter to be used for an actual application. To assess the proposed method, the reception characteristics and mutual influence of the two overlaid signals is also explained.

Extension of Network Lifetime Using Cooperative ARQ Protocol for Solar Energy Harvesting Wireless Sensor Networks Reviewed

OTA Kentaro, KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 50 ) page： 1 - 4 2010.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Wireless sensor networks require long-term operation of sensor nodes and reliable data transmission. Attention is being focused on the use of environmental energy for battery charging as a long-term operation method for sensor nodes. Besides this, one of the reliable data transmission methods is cooperative ARQ (Automatic Repeat reQuest) protocol. In this paper, we apply a cooperative ARQ protocol to solar energy harvesting wireless sensor networks. By evaluating the cooperative ARQ protocol with network lifetime, we show that it is effective for extension of network lifetime.

Joint Decoding Scheme Using Correlation of Observed Data According to ADC Bit Levels : Evaluation of Performance Improvement by Avoiding Carry Propagation of ADC Output Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 110 ( 40 ) page： 69 - 74 2010.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In wireless sensor networks, sensor nodes are densely deployed for reliable sensing of physical phenomenon. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on a joint channel decoding scheme utilizing correlation of the sensor observations according to ADC bit levels. Our proposed scheme makes use of Gray code mapping to avoid carry propagation of sensor ADC outputs. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

Correlation Estimation for Joint Decoding of Correlated Observations According to ADC Bit Levels Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

The IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences (Japanese edition) A Vol. 93 ( 5 ) page： 353 - 364 2010.5

Correlation Estimation for Joint Decoding of Correlated Observations According to ADC Bit Levels Reviewed

K. Kobayashi, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals, vol.J93-A, no.5, pp.-, May 2010. Vol. Vol.J93-A ( No.5 ) page： - 2010.5

Language：Japanese Publishing type：Research paper (scientific journal)

In wireless sensor networks, a large number of sensor nodes are densely deployed for reliable environmental sensing. Due to the high density in the sensing field, sensor observations are spatially correlated. We focus on a property that such correlated observations are available in the form of ADC\\\'s binary output. In this paper, we study a joint decoding of transmitted data with correlation estimation according to ADC bit levels. Based on analysis of correlation estimation error, we propose a simple but effective estimation method. Our proposal achieves even when correlation of some bit levels have different amplitude and sign.

Improved Decoding Methods of Visible Light Communication System for ITS using LED Array and High-Speed Camera Reviewed

T. Nagura, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

IEEE Vehicular Technology Conference page： - 2010.5

Language：English

In this paper, we consider visible light communication systems using LED array as a transmitter and high-speed camera as a receiver for Intelligent Transport System (ITS). Previously, we have proposed the hierarchical coding scheme which allocates data to spatial frequency components of the image depending on the priority. This scheme is possible to receive information of the high-priority even if communication distance is long. However, we need to distinguish multi-valued data from the received image by using a hierarchical coding. In this paper, we propose two improved decoding methods, and demonstrate to distinguish multi-valued data more correctly in the experiment.

Performance Evaluation of Error-Correcting Scheme Without Redundancy Code for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio, T. Yamazato, S. Ozawa

Proceedings of 2010 IEEE International Symposium on Circuits and Systems page： - 2010.5

Language：English

This paper considers a novel error-correcting scheme exploiting chaotic dynamics for noncoherent chaos communication. In our proposed system, two successive chaotic sequences are generated from the same chaotic map; the second sequence is generated with an initial value which is the last value of the first sequence. In this case, successive chaotic sequences having the same chaotic dynamics are created. This feature gives the receiver additional information to correctly recover the information data and thus improves the bit error performance of the receiver. Further, enhanced efficiency also comes from operating on successively modulated data; by involving less redundancy in the error correction system, it can be designed with high coding rate. In this paper, we analyze the scheme's capability, by examining computational times and accuracy rates of error correction. bounds on its capability.

A-17-16 Sub-Pixel Estimation of LED Position for Visible Light Communication System using LED Array and High-Speed Camera Reviewed

NAGURA Toru, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

Proceedings of the IEICE General Conference Vol. 2010 page： 244 2010.3

A-4-3 BER Property of Visible Light Communication System Using LED Array and High-Speed Camera Reviewed

SHIRAKI Yasutake, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

Proceedings of the IEICE General Conference Vol. 2010 page： 76 2010.3

B-17-15 A Weight Combination Scheme for Sequential-Test-Based Cooperative Spectrum Sensing Systems Reviewed

Mitsuya Shohei, Yamazato Takaya, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2010 ( 1 ) page： 664 2010.3

B-3-33 Improvement of Spectrum Efficiency by Dynamic Resource Allocation for Satellite Terrestrial Integrated Mobile Communication System Reviewed

AMAN Tomohiro, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2010 ( 1 ) 2010.3

An Access Control Method for Multipoint Cyclic Data Gathering over a PLC Network Reviewed

Y. Ohtomo, T. Yamazato, M. Katayama

IEEE International Symposium on Power Line Communications and Its Applications page： - 2010.3

Language：English

This paper proposes a media access control method for a multipoint cyclic data gathering system, in which each node transmits its data to the base-station periodically. In such condition, by broadcasting ACK/NACK signals from the base-station, the proposed method ensures assignment of a time slot for each node once the node succeeds to transfer its data. It is confirmed that the proposed scheme reduces packet collisions and outperforms conventional slotted-ALOHA scheme in throughput of data even with ACK/NACK errors. Furthermore the proposed scheme realizes adaptive slot assignment under cyclostationary channel environment.

Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication

N. Hiraiwa, T. Yamazato, M. Katayama

Technical Report of IEICE page： - 2010.3

Language：Japanese

In this paper, we propose a kalman channel estimator for MC-CDMA based Inter-Vehicle Communication(IVC). In IVC, the channel characteristic of each car is different among pilot signals because of a doppler shift, a multipath fading, and the difference of receiving power. Our proposed kalman channel estimator uses a kalman filter to track the channel fluctuation and implements a pilot-based channel estimation which interpolates among pilot signals by using an interpolation polynomial into our proposed channel estimator to suppress an estimation error. As results, we show that the kalman channel estimator shows better performance than a pilot-based channel estimation.

Wireless Control Scheme with Noisy Channels for Cooperative Motion Systems

T. Kondo, T. Yamazato, M. Katayama

IEICE General Conference page： - 2010.3

BER Property of Visible Light Communication System Using LED Array and High-Speed Camera

Y. Shiraki, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

IEICE General Conference page： - 2010.3

A Weight Combination Scheme for Sequential-Test-Based Cooperative Spectrum Sensing Systems

M.Mitsuya, T. Yamazato, M. Katayama

IEICE General Conference page： - 2010.3

Sub-pixel Estimation of LED Position for Visible Light Communication System using LED Array and High-Speed Camera

T. Nagura, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

IEICE General Conference page： - 2010.3

Introduction of dirty paper coding for the cognitive piggyback overlay systems

J. Naganawa, T. Yamazato, M. Katayama

IEICE General Conference page： - 2010.3

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera Reviewed

OZAWA Toshiyuki, NAGURA Toru, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 109 ( 415 ) page： 53 - 58 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We propose a successive interference cancellation scheme (SIC) for the hierarchical coding parallel optical communication system using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 415 ) page： 47 - 52 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we propose a kalman channel estimator for MC-CDMA based Inter-Vehicle Communication (IVC). In IVC, the channel characteristic of each car is different among pilot signals because of a doppler shift, a multipath fading, and the difference of receiving power. Our proposed kalman channel estimator uses a kalman filter to track the channel fluctuation and implements a pilot-based channel estimation which interpolates among pilot signals by using an interpolation polynomial into our proposed channel estimator to suppress an estimation error. As results, we show that the kalman channel estimator shows better performance than a pilot-based channel estimation.

Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 414 ) page： 47 - 52 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera Reviewed

OZAWA Toshiyuki, NAGURA Toru, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 109 ( 414 ) page： 53 - 58 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We propose a successive interference cancellation scheme(SIC)for the hierarchical coding parallel optical communication system using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

Detection and Tracking of LED Array Transmitter for Visible Light Communications on Driving Situation Reviewed

NAGURA Toru, OZAWA Toshiyuki, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 109 ( 414 ) page： 59 - 64 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on a decoding algorithm for visible light communication systems on driving situation using a LED array transmitter and a high-speed camera receiver. We propose a LED array detection method using M-sequence and a LED array tracking method using inversion signals. We demonstrate that we can distinguish LED array candidates correctly with M-sequence. We also demonstrate that we can suppress the flicker of LED and improve the data rate compared with the conventional method.

Detection and Tracking of LED Array Transmitter for Visible Light Communications on Driving Situation Reviewed

NAGURA Toru, OZAWA Toshiyuki, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

IEICE technical report Vol. 109 ( 415 ) page： 59 - 64 2010.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Detection and Tracking of LED Array Transmitter for Visible Light Communications on Driving Situation

T. Nagura, T. Ozawa, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

Technical Report of IEICE page： - 2010.2

Language：Japanese

An application of regenerative relay to the cognitive piggyback overlay system

J.Naganawa, T.Yamazato, M.Katayama

Technical Report of IEICE, vol.109, no.383 (SR2009-75), pp.9-14 Vol. Vol.109 ( No.383 (SR2009-75) ) page： pp.9-14, 2010.2

Language：Japanese

This manuscript considers a secondary system sharing the spectrum with the primary system at the same time and same frequency. This manuscript proposes a cognitive overlay system, in which the secondary system relays the primary signal and piggybacks its own data on it. As the relay procedure, non-regenerative and regenerative repeaters are considered and performance with them are compared. The result of the analysis shows that the proposed scheme with regenerative relay allows the secondary signal to communicate at the same speed of the primary signal without any harm to it.

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera

T.Ozawa, T.Nagura, T.Yamazato, M.Katayama, T.Yendo T.Fujii, H.Okada

Technical Report of IEICE page： - 2010.2

Language：Japanese

We propose a successive interference cancellation scheme (SIC) for the hierarchical coding parallel optical communicationsystem using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

An Access Control Method for Multipoint Data Gathering with ACK/NACK Errors Reviewed

OHTOMO Yuzo, YAMAZATO Takaya, KATAYAMA Masaaki

Vol. 2010 ( 1 ) page： 21 - 26 2010.1

An application of regenerative relay to the cognitive piggyback overlay system Reviewed

NAGANAWA Jun, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 383 ) page： 9 - 14 2010.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

An access control method for multipoint data gathering with ACK/NACK errors

Y. Ohtomo, T. Yamazato, M. Katayama

The Papers of Technical Meeting on Communications, IEE Japan, pp21-26 page： pp21-26 2010.1

Language：Japanese

This manuscript proposes a media access control method for a multipoint cyclic data gathering system, in witch a base-station collects data generated periodically at each node. In such condition, by broadcasting ACK/NACK signals form the base-station, the proposed method ensures assignment a time slot for each node once the node succeeds to transfer its data. It is confirmed that the proposed method outperforms conventional slotted-ALOHA in throughput of data even with ACK/NACK errors. Furthermore, the proposed method realizes adaptive slot assignment under cyclostationary channel environment.

Nagoya Univeristy OCW

Takaya YAMAZATO

Japanese Society for Engineering Education 57th Annual Conference page： - 2010.1

1-5 Study on parallel visible light communication using visually non-lighting LED Reviewed

MAENO Keita, YENDO Tomohiro, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, YAMAZATO Takaya, OKADA Hiraku, TANIMOTO Masayuki

PROCEEDINGS OF THE ITE ANNUAL CONVENTION Vol. 2010 ( 0 ) page： 1-5-1 - _1-5-2_ 2010

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

The proposed visible light communication method uses visually non-lighting LED, which enable us to communicate by using tail lamps of cars. In addition, this method can communicate with visually non-lighting traffic lights.

DOI： 10.11485/iteac.2010.0_1-5-1

A study on joint channel decoding using spatial correlation of sensor observations according to ADC bit levels Reviewed

Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC page： 485 - 490 2010

Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/PIMRCW.2010.5670522

An access control method for multipoint cyclic data gathering over a PLC network Reviewed

Yuzo Ohtomo, Takaya Yamazato, Masaaki Katayama

IEEE ISPLC 2010 - International Symposium on Power Line Communications and its Applications page： 285 - 290 2010

Language：English Publishing type：Research paper (international conference proceedings)

This paper proposes a media access control method for a multipoint cyclic data gathering system, in which each node transmits its data to the base-station periodically. In such condition, by broadcasting ACK/NACK signals from the basestation, the proposed method ensures assignment of a time slot for each node once the node succeeds to transfer its data. It is confirmed that the proposed scheme reduces packet collisions and outperforms conventional slotted-ALOHA scheme in throughput of data even with ACK/NACK errors. Furthermore the proposed scheme realizes adaptive slot assignment under cyclostationary channel environment. ©2010 IEEE.

DOI： 10.1109/ISPLC.2010.5479914

Error-correcting scheme based on chaotic dynamics and its performance for noncoherent chaos communications Reviewed

Dynamic Bandwidth Allocation of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

Yamazato Takaya, Aman Tomohiro, Katayama Masaaki

2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010 2010

Arai Shintaro, Nishio Yoshifumi, Yamazato Takaya

Nonlinear Theory and Its Applications, IEICE Vol. 1 ( 1 ) page： 196 - 206 2010

Publishing type：Research paper (scientific journal) Publisher：一般社団法人電子情報通信学会

DOI： 10.1587/nolta.1.196

Dynamic Bandwidth Allocation of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

Takaya Yamazato, Tomohiro Aman, Masaaki Katayama

2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010 page： 1 - 5 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/GLOCOM.2010.5683362

Inband and outband spectrum analysis of the BFDM and BFDM/OQAM signals with truncated Gaussian pulses Reviewed

Experimental Validation of TOA UWB Positioning with Two Receivers Using Known Indoor Features Reviewed

Kietlinski-Zaleski Jan, Yamazato Takaya, Katayama Masaaki

2010 IEEE-ION POSITION LOCATION AND NAVIGATION SYMPOSIUM PLANS page： 748 - 752 2010

Bayarpurev Mongol, Takaya Yamazato, Masaaki Katayama

ISITA/ISSSTA 2010 - 2010 International Symposium on Information Theory and Its Applications page： 743 - 746 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Pulse-shaping OFDM, or more generally BFDM and BFDM/OQAM, systems are originally proposed to combat inter-carrier interference (ICI) caused by time-variance of the channel. The main property that makes these signals robust against ICI is that they allow to employ time-frequency well localized pulses, particularly Gaussian pulse which has the best time-frequency localization. However, this property also suppresses the outband or inband spectral leakage of the BFDM and BFDM/OQAM signal, making them attractive physical layer modulation scheme for cognitive radio. In this paper we analyze the power density spectra of the BFDM and BFDM/OQAM signals and numerically evaluate the inband and outband spectra for truncated Gaussian pulses. © 2010 IEEE.

DOI： 10.1109/ISITA.2010.5649641

Improvement of sequential-test-based cooperative spectrum sensing systems in band limited control channels Reviewed

Shohei Mitsuya, Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

ISCIT 2010 - 2010 10th International Symposium on Communications and Information Technologies page： 968 - 973 2010

Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/ISCIT.2010.5665127

Improved Decoding Methods of Visible Light Communication System for ITS using LED Array and High-Speed Camera Reviewed

Toru Nagura, Takaya Yamazato, Masaaki Katayama, Tomohiro Yendo, Toshiaki Fujii, Hiraku Okada

2010 IEEE 71ST VEHICULAR TECHNOLOGY CONFERENCE page： 1 - 5 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we consider visible light communication system using LED array as a transmitter and high-speed camera as a receiver for Intelligent Transport System (ITS). Previously, we have proposed the hierarchical coding scheme which allocates data to spatial frequency components of the image depending on the priority. This scheme is possible to receive information of the high-priority even if communication distance is long. However, we need to distinguish multi-valued data from the received image by using a hierarchical coding. In this paper, we propose two improved decoding methods, and demonstrate to distinguish multi-valued data more correctly in the experiment.

DOI： 10.1109/VETECS.2010.5493958

High-speed-camera Image Processing Based LED Traffic Light Detection for Road-to-vehicle Visible Light Communication Reviewed

Improved Decoding Methods of Visible Light Communication System for ITS using LED Array and High-Speed Camera Reviewed

Nagura Toru, Yamazato Takaya, Katayama Masaaki, Yendo Tomohiro, Fujii Toshiaki, Okada Hiraku

2010 IEEE 71ST VEHICULAR TECHNOLOGY CONFERENCE 2010

H. Chinthaka N. Premachandra, Tomohiro Yendo, Mehrdad Panahpour Tehrani, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Masayuki Tanimoto

2010 IEEE INTELLIGENT VEHICLES SYMPOSIUM (IV) page： 793 - 798 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

As one of ITS technique, a new visible light road-to-vehicle communication system at intersections is proposed. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter, and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light in high frequency and those emitting LEDs are captured by the high-speed camera for making communication. Here, the luminance value of LEDs in the transmitter should be captured in consecutive frames to achieve effective communication. For this purpose, first the transmitter should be found, then it should be tracked in consecutive frames by processing the images from the high-speed camera. In this paper, we propose new effective algorithms for finding and tracking the transmitter, which result in a increased communication speed, compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

DOI： 10.1109/IVS.2010.5548097

High-speed-camera Image Processing Based LED Traffic Light Detection for Road-to-vehicle Visible Light Communication Reviewed

Premachandra H. Chinthaka N., Yendo Tomohiro, Tehrani Mehrdad Panahpour, Yamazato Takaya, Okada Hiraku, Fujii Toshiaki, Tanimoto Masayuki

2010 IEEE INTELLIGENT VEHICLES SYMPOSIUM (IV) page： 793 - 798 2010

Experimental Validation of TOA UWB Positioning with Two Receivers Using Known Indoor Features Reviewed

Jan Kietlinski-Zaleski, Takaya Yamazato, Masaaki Katayama

2010 IEEE-ION POSITION LOCATION AND NAVIGATION SYMPOSIUM PLANS page： 748 - 752 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal Time of Arrival (ToA) positioning, at least three receivers with unblocked direct path to the transmitter are required. This requirement is not always met. In this work, a novel algorithm for ToA positioning using only two receivers is presented and validated using data from a measurement campaign. Positioning with two receivers is possible by exploiting the knowledge of some of the indoor features, namely positions of big flat reflective surfaces, for example ceiling and walls.

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera Reviewed

OZAWA Toshiyuki, NAGURA Toru, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

ITE Technical Report Vol. 34 ( 0 ) page： 53 - 58 2010

Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

We propose a successive interference cancellation scheme (SIC)for the hierarchical coding parallel optical communication system using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

DOI： 10.11485/itetr.34.6.0_53

Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

ITE Technical Report Vol. 34 ( 0 ) page： 47 - 52 2010

Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

In this paper, we propose a kalman channel estimator for MC-CDMA based Inter-Vehicle Communication (IVC). In IVC, the channel characteristic of each car is different among pilot signals because of a doppler shift, a multipath fading, and the difference of receiving power. Our proposed kalman channel estimator uses a kalman filter to track the channel fluctuation and implements a pilot-based channel estimation which interpolates among pilot signals by using an/interpolation polynomial into our proposed channel estimator to suppress an estimation error. As results, we show that the kalman channel estimator shows better performance than a pilot-based channel estimation.

DOI： 10.11485/itetr.34.6.0_47

Optimal cluster partitioning for wireless sensor networks with cooperative MISO scheme Reviewed

Zheng Huang, Takaya Yamazato, Masaaki Katayama

6th Advanced International Conference on Telecommunications, AICT 2010 page： 323 - 328 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE Computer Society

The paper discusses the optimal cluster partitioning for wireless sensor networks deployed in continuous areas. Both single-hop and multi-hop transmissions with cooperative Multi-Input Single-Output (MISO) scheme are considered for inter-cluster communications. The effects of cluster size in the energy consumption of intra-cluster communication and the amount of fused data are included in calculation. As a result, the dominant factors of the maximal network lifetimes are listed as: the cluster farthest from base station in single-hop transmission and the closest cluster in multi-hop transmission. In addition, the maximal network lifetimes of single-hop and multi-hop transmissions are compared and it is found that there exists a threshold of network size that determines which transmission is the better candidate. © 2010 IEEE.

DOI： 10.1109/AICT.2010.67

Performance evaluation of the cognitive piggyback overlay systems with dirty paper coding Reviewed

Jun Naganawa, Kentaro Kobayashi, Masaaki Katayama, Takaya Yamazato

ISCIT 2010 - 2010 10th International Symposium on Communications and Information Technologies page： 974 - 979 2010

Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/ISCIT.2010.5665130

Performance Evaluation of Error-Correcting Scheme Without Redundancy Code for Noncoherent Chaos Communications Reviewed

Shintaro Arai, Yoshifumi Nishio, Takaya Yamazato, Shinji Ozawa

2010 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS page： 2458 - 2461 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/ISCAS.2010.5537140

Tracking an LED array transmitter for visible light communications in the driving situation Reviewed

Performance Evaluation of Error-Correcting Scheme Without Redundancy Code for Noncoherent Chaos Communications Reviewed

Arai Shintaro, Nishio Yoshifumi, Yamazato Takaya, Ozawa Shinji

2010 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS page： 2458 - 2461 2010

Toru Nagura, Takaya Yamazato, Masaaki Katayama, Tomohiro Yendo, Toshiaki Fujii, Hiraku Okada

Proceedings of the 2010 7th International Symposium on Wireless Communication Systems, ISWCS'10 page： 765 - 769 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/ISWCS.2010.5624361

A-5-17 Wireless Control Scheme with Noisy Channels for Cooperative Motion Systems Reviewed

KONDO Tsugunori, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 119 2010

B-17-3 Introduction of dirty paper coding for the cognitive piggyback overlay systems Reviewed

Naganawa Jun, Yamazato Takaya, Katayama Masaaki

Proceedings of the IEICE General Conference 2010

お熱いのがお好き Reviewed

山里敬也

電子情報通信学会　通信ソサイエティマガジン Vol. 2010 ( 15 ) page： 15_79 - 15_79 2010

UWB Positioning Using Known Indoor Features - Environment Comparison Reviewed

Jan Kietlinski-Zaleski, Takaya Yamazato

2010 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal Time of Arrival (TOA) positioning, at least three receivers with unblocked direct path to the transmitter are required. A requirement that is not always met. In our previous work [1] we presented a novel 3D TOA UWB indoor positioning method that uses only two receivers. This is possible by exploiting the knowledge of some of the indoor features, namely ceiling and walls. In this work, we verify the usability of the method using measurement results in three environments: a lecture room, a cluttered laboratory and a corridor. By comparing the results of the method for three environments, we draw conclusions about its strengths and weaknesses.

Detection and Tracking of LED Array Transmitter for Visible Light Communications on Driving Situation Reviewed

UWB Positioning Using Known Indoor Features - Environment Comparison Reviewed

Kietlinski-Zaleski Jan, Yamazato Takaya

2010 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION 2010

NAGURA Toru, OZAWA Toshiyuki, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

ITE Technical Report Vol. 34 ( 0 ) page： 59 - 64 2010

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

DOI： 10.11485/itetr.34.6.0_59

Traffic prediction scheme for resource assignment of satellite/terrestrial frequency sharing mobile communication system Reviewed

TOA UWB position estimation with two receivers and a set of known reflectors Reviewed

Kietlinski-Zaleski J.

Proceedings - 2009 IEEE International Conference on Ultra-Wideband, ICUWB 2009 page： 376 - 380 2009.12

Aman T.

IWSSC'09 - 2009 International Workshop on Satellite and Space Communications - Conference Proceedings page： 40 - 44 2009.12

On-Vehicle Receiver for Road-to-Vehicle Communication System Reviewed

OKADA Satoshi, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 323 ) page： 77 - 82 2009.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We consider an on-vehicle receiving system for long-distance and high-speed visible light communication. There are several problems associated with applying visible light communication to the field of ITS. It is necessary to receive information from long distance. And tracking the transmitter for a certain moving distance of the vehicle is also important. We applied an imaging optics to receive information over long distance, and two cameras are used to solve the relationship between the transmitter and the receiver position changes with time, and vibrational correction technique is also fixed to the system to minimize vibrational affections.

On-Vehicle Receiver for Road-to-Vehicle Communication System Reviewed

OKADA Satoshi, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 322 ) page： 77 - 81 2009.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

On-vehicle receiver for distant visible light road-to-vehicle communication Reviewed

Okada S.

IEEE Intelligent Vehicles Symposium, Proceedings page： 1033 - 1038 2009.11

Channel estimation and tracking schemes for the pulse-shaping OFDM systems Reviewed

Mongol B.

IEEE International Conference on Communications 2009.11

Encoding system based on spatial frequency characteristics of road-vehicle communication Reviewed

MASUDA Takato, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 266 ) page： 71 - 76 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper we propose a method for analyzing spatial frequency characteristics of road-vehicle communication. In the proposed communication, we use LED traffic lights as transmitter and high-speed camera on car as receiver. So the distance between LED traffic lights and high-speed camera change from far to near, and as the distance is farther, received pictures are smaller. Therefore it is thought that high frequencies of sending data deteriorate, and Moire occurs in received pictures. In this paper, we analyze the deterioration and confirm improvement of communication using simulation.

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes : Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 248 ) page： 95 - 100 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In wireless sensor networks, a large number of sensor nodes are densely deployed for reliable environmental sensing. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on joint channel decoding utilizing the spatial correlation of multiple sensor observations. Our proposed scheme makes use of an estimation of the correlation according to ADC bit levels of the sensor observations. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes : Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 246 ) page： 121 - 126 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In wireless sensor networks, a large number of sensor nodes are densely deployed for reliable environmental sensing. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on joint channel decoding utilizing the spatial correlation of multiple sensor observations. Our proposed scheme makes use of an estimation of the correlation according to ADC bit levels of the sensor observations. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

An access control scheme for passengers wireless communication systems considering the passing of an opposite train Reviewed

YAMAMOTO Masahiro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 229 ) page： 89 - 93 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This manuscript discusses on a wireless cellular communication system for railroad passengers, in which base stations are placed along the railroad. In this system, all users or passengers are on trains. Thus there is high concentration in user distribution, and a group of the users on a train move to the same direction with the same speed. In such a system, when two opposite trains enter in the same cell before they pass each other, the number of users in the cell abruptly increases, and forced terminations of communication, i.e. call dropping, may occur due to the concentration of traffic. This paper proposes access control methods that mitigate the probability of the dropping, by limiting the number of channels allowed to use on each train dynamically or statically before the two trains enter the same cell. As a result, it is shown that the probability of the forced termination of an existing call can be decreased with the cost of increase in blocking probability. It is also confirmed that the dynamic access control method can inhibit increasing of the rejection of newly arrived calls compared to the static access control method when the control duration is enough large. In conclusion, the proposed methods provide lower dropping probability than the conventional (no-control) system, under the same blocking probability.

M-ary Modulation Scheme Using Separation of Chaotic Dynamics for Noncoherent Chaos-Based Communications Reviewed

S. ARAI, Y. NISHIO, T. YAMAZATO, S. OZAWA

2009 International Symposium on Nonlinear Theory and its Applications page： - 2009.10

Language：English

This paper proposes a new M-ary modulation scheme for noncoherent chaos-based communications. A chaotic sequence is successive based on the chaotic dynamics. Without the successive sequence based on the chaotic dynamics, general noncoherent systems are very difficult to demodulate the data. However, we consider that the systematic separation and the reconstruction of the chaotic dynamics can be applied as additional information. Namely, M-ary data symbols can be expressed by separating the chaotic dynamics purposely. We carry out computer simulations of the proposed scheme and confirm that a saving of over 3-4 dB is realized in transmitter energy by increasing M.

*Visible Light Communications using LED Array and High-Speed Camera for ITS Applications Invited

T. Yamazato

IEICE Fundamental Review, Vol.3, No.2, pp.45-53 Vol. Vol.3 ( No.2 ) page： pp.45-53 2009.10

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes - Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data -

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE, vol.USN2009-42, pp.95-100 Vol. Vol.USN2009-42 page： pp.95-100 2009.10

Language：Japanese

In wireless sensor networks, a large number of sensor nodes are densely deployed for reliable environmental sensing. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on joint channel decoding utilizing the spatial correlation of multiple sensor observations. Our proposed scheme makes use of an estimation of the correlation according to ADC bit levels of the sensor observations. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

Decoding of Separately Encoded Multiple Correlated Sources Transmitted over Noisy Channels Reviewed

K. Kobayashi, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals, vol.E92-A, no.10, pp.2402-2410 Vol. Vol.E92-A ( No.10 ) page： pp.2402-2410 2009.10

Language：English Publishing type：Research paper (scientific journal)

We propose an iterative channel decoding scheme for two or more multiple correlated sources. The correlated sources are separately turbo encoded without knowledge of the correlation and transmitted over noisy channels. The proposed decoder exploits the correlation of the multiple sources in an iterative soft decision decoding manner for joint detection of each of the transmitted data. Simulation results show that achieved performance for the more than two sources is also close to the Shannon and Slepian-Wolf limit and large additional SNR gain is obtained in comparison with the case of two sources. We also verify through simulation that no significant penalty results from the estimation of the source correlation in the decoding process and the code with a low error floor achieves good performance for a large number of the correlated sources.

Phase Compensation for Narrowband PLC Channels with Cyclic Time-Varying Features Reviewed

Y. Sugiura, T. Yamazto, M. Katayama

Third Workshop on Power Line Communications page： - 2009.10

Language：English

Phase transfer functions of power-line channels often show sharp and periodic variation synchronous to the (double of) mains frequency. This is a result of impedance change of nonlinear devices connected to the power-lines. This manuscript proposes a phase estimation strategy for phase compensation at a receiver under such environment. In the proposed method, phase estimates are calculated using cyclic observation (average) of the channel phase. The numerical examples under periodic phase variation of the channel and cyclostationary noise show that the receiver with the proposed phase estimation scheme outperforms that with the conventional phase estimation, which uses average over the whole observation period without considering the periodic feature of the channel.

The Receiver for visible Light Road-to-Vehicle Communication

S. Okada, T. Yendo, T. Yamazato, Hiraku Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

PCSJ/IMPS 2009 page： - 2009.10

Language：Japanese

In this paper, we propose a road-to-vehicle visible communication system for ITS. In this system, a LED traffic light is used as transmitter and a photodiode is used as receiver. There are several problems associated with applying visible light communication to the field of ITS. It is necessary to receive information from long distance. And tracking the transmitter for a certain moving distance of the vehicle is also important. We applied an imaging optics to receive information over long distance, and two cameras are used to solve the relationship between the transmitter and the receiver position changes with time, and vibrational correction technique is also fixed to the system to minimize vibrational corrections. We developed algorithms to track the transmitter. The experiments were conducted to confirm the proposals.

Traffic Light Detection for Visible Light Communication Image Sensor

D Takasao, T. Yendo, T. Yamazato, H. Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

PCSJ/IMPS 2009 page： - 2009.10

Language：Japanese

The visible light communication used as telecommunications equipment by modulating LED at high speed is researched. And the road-to-vehicle visible light communication applied to the ITS field is researched. In this paper, the visible light communication is done by using a special image sensor. The pixel for the video that can capture video with 30fps and the pixel for the communication that can be communicated at high speed exist in the image sensor. We can detect the position of the traffic light in the image, and communicate by the pixel for the communication. We propose the detection method of the traffic light that makes the best use of the feature of the image sensor.

An access control scheme for passenger wireless communication systems considering the passing of an opposite train

M. Yamamoto, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. Vol.RCS2009-125 page： pp.89-93 2009.10

Language：Japanese

This manuscript discusses on a wireless cellular communication system for railroad passengers, in which base stations are placed along the railroad. In this system, all users or passengers are on trains. Thus there is high concentration in user distribution, and a group of the users on a train move to the same direction with the same speed. In such a system, when two opposite trains enter in the same cell before they pass each other, the number of users in the cell abruptly increases, and forced terminations of communication, i.e. call dropping, may occur due to the concentration of traffic. This paper proposes access control methods that mitigate the probability of the dropping, by limiting the number of channels allowed to use on each train dynamically or statically before the two trains enter the same cell. As a result, it is shown that the probability of the forced termination of an existing call can be decreased with the cost of increase in blocking probability. It is also confirmed that the dynamic access control method can inhibit increase of the rejection of newly arrived calls compared to the static access control method when the control duration is enough large. In conclusion, the proposed methods provide lower dropping probability than the conventional(no-control) system, under the same blocking probability.

Decoding of Separately Encoded Multiple Correlated Sources Transmitted over Noisy Channels Reviewed

Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E92A ( 10 ) page： 2402 - 2410 2009.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1587/transfun.E92.A.2402

Bit and power allocation for power-line communications under nonwhite and cyclostationary noise environment Reviewed

Sawada N.

2009 IEEE International Symposium on Power Line Communications and its Applications, ISPLC 2009 page： 307 - 312 2009.9

Luminance Extraction Method for Visible Light Communication System using LED Array and High-Speed Camera

T. Nagura, T. Yamazato, M. Katayama

Enginnering Sciences Society Conference of IEICE, A-17-17, p.181 Vol. A-17-17 page： p.181 2009.9

Impact of Pilot Interpolation Techniques on a Channel Estimation Scheme for Inter-Vehicle Communication

N. Hiraiwa, T. Yamazato, M. Katayama

Enginnering Sciences Society Conference of IEICE, A-17-15, p.179 Vol. A-17-15 page： p.179 2009.9

A study on transmission speed on visible light communication systems using LED array and high-speed camera

T. Nagura, T. Yamazato, M. Katayama

Proc. of 11th DSPS Educators Conference, pp.45-46 page： pp.45-46 2009.9

A Note on Joint Decoding using Correlation Estimation of Multiple Sources according to ADC Bit-Level

K. Kobayashi, T. Yamazato, M. Katayama

Communications Society Conference of IEICE, B-20-7, p.388 Vol. B-20-7 page： p.388 2009.9

Image Processing for Visible Light Communication Using LED Traffic lights

S. Arai, T. Yamazato, S. Ozawa

Technical meeting of Electronics, Information and Systems [Division C], IEEJ, Sep., 2009. page： - 2009.9

Language：Japanese

In this paper, we focus on a road-to-vehicle visible light communications using LED traffic light (transmitter) and an in-vehicle camera (receiver). As advantages using the camera, the recognition of objects as well as their locations can easily be realized and the reception of LED modulated data is also possible at the same time. Unfortunately, if the receiver is far from the transmitter, the received data pattern degrades due to reduction of pixel size and defocusing of the LED data pattern. This paper discusses these problems from image processing approaches.

TOA UWB Position Estimation with Two Receivers and a Set of Known Reflectors Reviewed

J. KIETLINSKI-ZALESKI, T. YAMAZATO, M. KATAYAMA

ICUWB 2009 pp.376-380, page： - 2009.9

Language：English

Ultra-Wideband is an attractive technology for short range positioning, especially indoors. However, for normal Time of Arrival(ToA) positioning, at least 3 receivers with unblocked direct path to the transmitter are required. A requirement that is not always met. In this work, a novel algorithm for ToA positioning using only 2 receivers is presented. This is possible by exploiting reflections from a set of known flat reflectors, for example ceiling and walls. The proposed algorithm was tested using self-developed UWB propagation simulator testbed.

Traffic Prediction Scheme for Resource Assignment of Satellite/Terrestrial Frequency Sharing Mobile Communication System Reviewed

T. Aman, T. Yamazato, M. Katayama

International Workshop on Satellite and Space Communications page： - 2009.9

Language：English

The recent development of large aperture on-board multi-beam antennas enables a small-size, low-powered and cellular phone like hand-held terminal as a satellite earth terminal. A single mobile terminal can communicate to both mobile satellite systems and terrestrial systems depend upon his location, QoS and availability of resources among satellite and terrestrial communication systems. In this paper, we propose a new traffic prediction scheme for the integrated satellite/terrestrial frequency sharing mobile communication system. The system shares a common frequency bandwidth in order to enhance the total capacity by a dynamic bandwidth allocation. A key for this allocation depends on a traffic prediction scheme of a few hundreds of terrestrial cells under a footprint of a satellite with a large aperture onboard multi-beam antennas. We propose three traffic predictors based on neural networks for dynamic resource allocation. The performances of the proposed schemes are evaluated in terms of the Relative Traffic Prediction Error and Maximum Traffic Prediction Error by the computer simulation. For the evaluation, we adopt the actual traffic statistic published by Ministry of Internal Affairs and Communications of Japan with population density of terrestrial cells based on the actual population of Aichi, Japan. As results, average traffic prediction error of less than 0.25 is achieved for the prediction interval of one hour, enough for dynamic resource allocation.

Cognitive Radio with Relay of a Primary Signal and Piggyback Modulation Reviewed

J. Naganawa, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communication page： - 2009.9

Language：English

This manuscript proposes a cognitive radio system that shares a frequency with an existing primary system. In the proposed method, a secondary transmitter relays the primary signal and piggybacks its own data on it. Symbol error probabilities of the system are derived analytically. The result shows that the proposed system can communicate at a relatively high speed on the same frequency of the primary system without harm to it.

10-219 Nagoya Univeristy OCW Reviewed

Yamazato Takaya

Proceedings of Annual Conference of Japanese Society for Engineering Education Vol. 2009 ( 0 ) page： 416 - 417 2009.8

Detection of LED Traffic Light by Image Processing for Visible Light Communication System Reviewed

H.C. N. Premachandra, T. Yendo, T. Yamazato, T. Fujii, M. Tanimoto, Y. Kimura

Proceedings of 2009 IEEE Intelligent Vehicles Symposium (IV'09), June 2009 page： - 2009.8

Language：English

We propose a visible light road-to-vehicle communication system at intersection for ITS. In this system, the communication between vehicle and a LED traffic light is approached using LED traffic light as the transmitter, and on-vehicle high-speed camera as the receiver. The LEDs in the transmitter are emitted with 500Hz and the images of those emitting LEDs are captured by a high-speed camera for conducting communication. In this communication, it is extremely necessary to find the transmitter and detect it for consecutive frames while vehicle is moving. In this paper, we introduce proposals for finding and detecting it for consecutive frames by image processing. Experimental results using appropriate images showed the effectiveness of the proposal.

巻頭言～創刊５００号を迎えて～和文論文誌Bは優れた通信技術・研究を蓄える

山里敬也

電子情報通信学会論文誌 Vol. Vol. J92-B ( No. 8 ) page： pp. 1211-1211 2009.8

An Access Control Method for Multipoint Data Gatheringh over Power-Line Communications Reviewed

OHTOMO Yuzo, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 144 ) page： 37 - 42 2009.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper proposes a media access control method for a multipoint data gathering system using power-line communications. In large-scale power-line communication systems, it is difficult to use a CSMA scheme because of hidden terminal problem. In such condition, by broadcasting acknowledgements, the proposed method ensures assignment of a time slot for each node once the node succeeds to transfer its data to the base-station. It is confirmed that the proposed scheme reduces packet collisions and outperforms conventional slotted-ALOHA scheme in throughput of data. In addition, proposed scheme provides an adaptive slot assignment under cyclo-stationary channel environment.

An Access Control Method for Multipoint Data Gathering over Power-Line Communications

Y. Ohtomo, T. Yamazato, M. Katayama

Technical Report of IEICE, vol.WBS2009-13, pp.37-42 Vol. Vol.WBS2009-13 page： pp.37-42 2009.7

Language：Japanese

Edge-Based Tracking of an LED Traffic Light for a Road-to-Vehicle Visible Light Communication System Reviewed

H.C. N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, T. Fujii, M. Tanimoto, Y. Kimura

Journal of Broadcast Engineering published by KoSBE, the Korean Society for Broadcast Engineers, Vol. 14, No. 4, pp.475-487, July 2009 Vol. Vol. 14 ( No. 4 ) page： pp.475-487 2009.7

Language：English

We propose a visible light road-to-vehicle communication system at intersection as one of ITS technique. In this system, the communication between vehicle and a LED traffic light is approached using LED traffic light as a transmitter, and on-vehicle high-speed camera as a receiver. The LEDs in the transmitter are emitted in 500Hz and those emitting LEDs are captured by a high-speed camera for making communication. Here, the luminance value of each LED in the transmitter should be found for consecutive frames to achieve effective communication. For this purpose, first the transmitter should be identified, then it should be tracked for consecutive frames while the vehicle is moving, by processing the images from the high-speed camera. In our previous work, the transmitter was identified by getting the subtraction of two consecutive frames. In this paper, we mainly introduce an algorithm to track the identified transmitter in consecutive frames. Experimental results using appropriate images showed the effectiveness of the proposal.

Construction of a Kalman estimator for BFDM/OQAM system in the time-frequency dispersive channels Reviewed

MONGOL Bayarpurev, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 105 ) page： 125 - 130 2009.6

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

BFDM/OQAM allows to employ a gaussian transmitter pulse at maximal spectral efficiency. Thus, it performs well in the time-frequency dispersive channels and is considered to be a promising candidate for the next generation mobile communications modulation scheme. However, in the highly mobile environment the performance deteriorates and channel equalization and estimation schemes became essential for further improvement of BFDM/OQAM systems. This paper proposes a novel adaptive channel estimator based on a Kalman filter. We approximate the channel state with a number of samples of its fading processes at each delay tap. The idea behind our estimator is to employ a linear predictor to derive a process equation for the Kalman filter. To reduce the convergence time the bayesian estimation is employed to provide an initial value for the Kalman filter. The mean-square-error performance of the proposed estimator is evaluated using computer simulation.

Channel Estimation and Tracking Schemes for the Pulse-Shaping OFDM Systems Reviewed

B. Mongol, T. Yamazato, M. Katayama

IEEE International Conference on Communications, SPC-10-4 (in the CD) Vol. SPC-10-4 page： - 2009.6

Language：English

Robust channel estimation scheme is essential for pulse-shaping OFDM systems in the multipath mobile environment. This paper proposes three types of channel estimation schemes for the general class of pulse-shaping OFDM systems. The first two types are suboptimal low-complexity maximum likelihood estimators. The last type is adaptive Kalman filter channel estimator. We numerically evaluate the performance of each estimator using computer simulation.

Evaluation and Performance Improvement of a Cooperative Sensing System with Losses of Information from Sensing Nodes Reviewed

TAKANASHI Makoto, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 61 ) page： 75 - 79 2009.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

At a location and time, there may be frequencies not in use by their licensed (primary) users. Spectrum sharing, in which a secondary radio system uses such white spaces of frequency, is one of advantageous means to mitigate the spectrum scarcity. In order to realize the spectrum sharing, spectrum sensing that detects the presence of a primary user signal is a key technology. For reliable sensing of the primary signal, cooperative sensing where information from multiple sensing nodes is incorporated at a fusion center is currently being investigated by many researchers. Majority of these works consider the imperfectness of the channels between a primary transmitter and sensor nodes under noise and fading environments. On the contrary, this manuscript deals with the transmission between sensor nodes to a fusion center. For a cooperative spectrum sensing system, in which the analog outputs of energy detectors at sensor nodes are transmitted to a fusion center, the influence of losses of information from the nodes on detection performance is derived analytically. In addition, it is shown that the adaptive processing with the consideration of information loss at the fusion center improves system performance.

No Redundant Error-Correcting Scheme Using Chaotic Dynamics for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio, T. Yamazato

Proceedings of 2009 IEEE International Symposium on Circuits and Systems, pp. 2633-2636 page： pp. 2633-2636 2009.5

Language：English

This paper proposes the error-correcting scheme without redundancy sequences based on the chaotic dynamics for noncoherent chaos communications. We generate successive chaotic sequences from the identical chaotic map. And for the next sequence we set the initial value to the end value of the former sequence. By such way we can create the successive chaotic sequences having the same chaotic dynamics. This feature gives the receiver additional information to correctly recover the received noisy signal. Therefore, by analyzing the chaotic dynamics at the receiver, it is possible to improve the error performance without redundancy signal. As results of computer simulations, we confirm about 3 dB gain in BER performance as compared with the conventional suboptimal receiver when using the short chaotic sequence length per 1 bit.

Evaluation and Performance Improvement of a Cooperative Sensing System with Losses of Information from Sensing Nodes

M. Takanashi, T. Yamazato, M. Katayama

Technical Report of IEICE, vol.109, no.61 (SR2009-5), pp.75-79, Vol. Vol.109 ( No.61 (SR2009-5) ) page： - 2009.5

Joint decoding scheme using bit-level correlation of experimentally observed data

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE, vol.MoMuC2009-2, pp.7-12 Vol. Vol.MoMuC2009-2 page： pp.7-12 2009.5

Language：Japanese

In wireless sensor networks, a large number of sensor nodes are densely deployed for a reliable sensing of physical phenomenon. Due to the high density in the sensing field, sensor observations are spatially correlated. In this paper, we focus on joint channel decoding schemes utilizing the correlation of sensor observations. Our proposed scheme makes use of a bit-level correlation property of data observed in the real environment. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

Joint decoding scheme using bit-level correlation of experimentally observed data Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 22 ) page： 7 - 12 2009.4

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Bit and Power Allocation for Power-Line Communications under Nonwhite and Cyclostationary Noise Environment Reviewed

N. Sawada, T. Yamazato, M. Katayama

IEEE International Symposium on Power Line Communications and Its Applications page： - 2009.4

B-20-42 ISOMAC based energy efficient TDMA-MAC protocol for Sensor Networks Reviewed

CHEN Hiroshi, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2009 ( 2 ) 2009.3

1つの既知反射面と2つの受信機によるUWB ToA位置推定 Reviewed

キエトリンスキザレスキヤン, 山里敬也, 片山正昭

電子情報通信学会技術研究報告. WBS, ワイドバンドシステム : IEICE technical report Vol. 108 ( 474 ) page： 211 - 216 2009.3

Publishing type：Research paper (scientific journal) Publisher：一般社団法人電子情報通信学会

UWBは近距離,特に室内での位置推定のための技術として注目を集めている.しかし,通常用いられるTime of Arrival(ToA)による位置推定では,送信機からの直接波が最低でも3つの異なる位置にある受信機で必要になる.一般に,そのような条件が必ず満たされる訳では無い.本稿では,2つの異なる位置にある受信機を用いたToAによる新しい位置推定手法について提案する.提案手法では,例えば天井や壁などの,ある1つの平面に関する情報が既知であると仮定することで位置推定を実現する.提案するアルゴリズムは,新たに作成したUWB伝搬シミュレーターによって評価する.

Phase Compensation for Narrowband Power-Line Communication Channels with Cyclic Time-Varying Features Reviewed

SUGIURA Yoshie, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 473 ) page： 513 - 518 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Phase transfer functions of power-line channels often show sharp and periodic variation synchronous to the (double of) mains frequency. This is a result of impedance change of nonlinear devices connected to the power-lines. This manuscript proposes a phase estimation strategy for phase compensation at a receiver under such environment. In the proposed method, phase estimates are calculated using cyclic observation (average) of the channel characteristics. The numerical examples under periodic phase variation of the channel and cyclostationary noise, show that the receiver with the proposed phase estimation scheme outperforms that with the conventional phase estimation which uses average over the whole observation period without considering the periodic feature of the channel.

Influence of channel errors on a wireless-controlled rotary inverted pendulum Reviewed

KOHINATA Reo, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 472 ) page： 167 - 172 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper discusses the influence of channel features to the performance of a wireless-controlled system. As an example of the system, a rotary inverted pendulum that has wireless connections in its feedback loop between a controller and the controlled system. As for the wireless channels, both a random error model and a burst error model are employed and the effects of transmission rate and errors to the control quality are evaluated. As a result, it is confirmed that the system with transmission errors can keep the pendulum stable when data rate of the communication is enough high and error rate is below a certain level. In addition, it is clarified that that burst errors in wireless channels affect more when the control quality is kept by compensating errors with higher transmission rate.

Influence of channel errors on a wireless-controlled rotary inverted pendulum Reviewed

KOHINATA Reo, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 474 ) page： 167 - 172 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Influence of channel errors on a wireless-controlled rotary inverted pendulum Reviewed

KOHINATA Reo, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 473 ) page： 167 - 172 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Phase Compensation for Narrowband Power-Line Communication Channels with Cyclic Time-Varying Features Reviewed

SUGIURA Yoshie, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 472 ) page： 513 - 518 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Phase transfer functions of power-line channels often show sharp and periodic variation synchronous to the (double of) mains frequency. This is a result of impedance change of nonlinear devices connected to the power-lines. This manuscript proposes a phase estimation strategy for phase compensation at a receiver under such environment. In the proposed method, phase estimates are calculated using cyclic observation (average) of the channel characteristics. The numerical examples under periodic phase variation of the channel and cyclostationary noise, show that the receiver with the proposed phase estimation scheme outperforms that with the conventional phase estimation which uses average over the whole observation period without considering the periodic feature of the channel.

Phase Compensation for Narrowband Power-Line Communication Channels with Cyclic Time-Varying Features Reviewed

SUGIURA Yoshie, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 474 ) page： 513 - 518 2009.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Phase transfer functions of power-line channels often show sharp and periodic variation synchronous to the (double of) mains frequency. This is a result of impedance change of nonlinear devices connected to the power-lines. This manuscript proposes a phase estimation strategy for phase compensation at a receiver under such environment. In the proposed method, phase estimates are calculated using cyclic observation (average) of the channel characteristics. The numerical examples under periodic phase variation of the channel and cyclostationary noise, show that the receiver with the proposed phase estimation scheme outperforms that with the conventional phase estimation which uses average over the whole observation period without considering the periodic feature of the channel.

Traffic Prediction Scheme for Resource Assignment of Satellite/Terrestrial Frequency Sharing Mobile Communication System Reviewed

AMAN Tomohiro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 440 ) page： 55 - 60 2009.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Satellite/Terrestrial Frequency Sharing Mobile Communication System is drawing an attention for interpolation between satellite mobile communication and terrestrial mobile communication and improvement of spectrum utilization efficiency. Spectrum utilization efficiency can be improved in this system by sharing common frequency bands in satellite mobile and terrestrial mobile communication system and using dynamic resource assignment. But it is need to traffic prediction for dynamic resource assignment. This report propose traffic prediction method using neural network.

衛星／地上周波数共用移動通信システムに置ける資源割当てのためのトラヒック予測

阿萬友洋，山里敬也, 片山正昭

電子情報通信学会技術研究報告 page： - 2009.2

Language：Japanese

協力通信は複数の無線ノードが協力して同一の情報を送信することにより伝送距離を延長し，各ノードの消費電力を低減できる．本稿では，複数のクラスタに分割された無線センサネットワークに協力通信を適用することを考える．クラスタ間協力通信を行うには同一クラスタ内の複数のノードで情報を共有しなければならず，そのためにはクラスタヘッドに選出されたノードがクラスタ内に情報をブロードキャストする必要がある．しかし，このクラスタヘッドの選出手法によりネットワーク全体の消費電力が左右される．そこで，センサネットワークの稼働時間の延長を目的とし，各ノードの残余電力を考慮したクラスタヘッドの選出手法を提案する．結果より，提案手法はセンサノード稼働率，Outage確率共に改善可能であることを示す．

Cluster-based Cooperative Transmission considering the Residual Power of Wireless Sensor Nodes Reviewed

TAKESHIMA Koki, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 399 ) page： 83 - 87 2009.1

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Cooperative transmission can extend the transmission range by transmitting the same data from multiple wireless nodes, and consequently can reduce the consumed power of each node. In this paper, we apply the cooperative transmission to a wireless sensor network where the sensor nodes are organized into multiple clusters. To perform the cluster-based cooperative transmission, it has to choose a cluster head which broadcasts its decoded data to other nodes in a cluster. The overall dissipation power is, however, governed by the cluster head selection criterion. In this paper, we propose a simple cluster head selection criterion considering the residual power of each sensor node, and aim to extend the network lifetime. As results, the proposed scheme shows the best in the active sensor node rate and outage probability.

Turbo Equalization for Inter-Vehicle Communication Based on MC-CDMA Reviewed

HIRAIWA Noriaki, SAKATA Atsunori, YAMAZATO Takaya, KATAYAMA Masaaki

The IEICE transactions on communications B Vol. 92 ( 1 ) page： 367 - 369 2009.1

Tracking an LED Array Using Optical Flow for Visible Light Communication System

H. Chinthaka N. Premachandra, T. Yendo, M. P. Tehrani, T. Yamazato, H. Okada, T. Fujii, M. Tanimoto

2009 ITE Winter Annual Convention page： - 2009.1

Language：Japanese

We propose a visible light road-to-vehicle communication system at intersection as one of ITS technique. In this system, the communication between vehicle and an LED array is approached using LED array as a transmitter, and on-vehicle high-speed camera as a receiver. The LEDs in the transmitter are emitted in 500Hz and those emitting LEDs are captured by a high-speed camera for making communication. Here, the luminance value of LEDs in the transmitter should be captured in consecutive frames to achieve effective communication. For this purpose, first the transmitter should be identified, then it should be tracked in consecutive frames while the vehicle is moving, by processing the images from the high-speed camera. In this paper, we mainly introduce an algorithm to track the transmitter using optical flow and edge information.

Cluster-based Cooperative Transmission considering Residual Power of Wireless Sensor Nodes

K. Takeshima, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. USN2008-76 page： 83-87 2009.1

Turbo Equalization for Inter-Vehicle Communication based on MC-CDMA Reviewed

N. Hiraiwa, A. Sakata, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J92-B ( 1 ) page： 367-369 2009.1

4-5 Tracking an LED Array Using Optical Flow for Visible Light Communication System Reviewed

PREMACHANDRA H. Chinthaka N., YENDO Tomohiro, Panahpour TEHRANI Mehrdad, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, TANIMOTO Masayuki

PROCEEDINGS OF THE ITE WINTER ANNUAL CONVENTION Vol. 2009 ( 0 ) page： _4-5-1_ - 5-1_ 2009

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

DOI： 10.11485/itewac.2009.0__4-5-1_

Channel Estimation and Tracking Schemes for the Pulse-Shaping OFDM Systems Reviewed

Mongol Bayarpurev, Yamazato Takaya, Katayama Masaaki

2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8 page： 3076 - 3080 2009

Channel Estimation and Tracking Schemes for the Pulse-Shaping OFDM Systems Reviewed

Bayarpurev Mongol, Takaya Yamazato, Masaaki Katayama

2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8 page： 3076 - 3080 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Robust channel estimation scheme is essential for pulse-shaping OFDM systems in the multipath mobile environment. This paper proposes three types of channel estimation schemes for the general class of pulse-shaping OFDM systems. The first two types are suboptimal low-complexity, maximum likelihood estimators. The last type is adaptive Kalman filter channel estimator. We numerically evaluate the performance of each estimator using computer simulation.

DOI： 10.1109/ICC.2009.5198817

Channel estimation and tracking schemes for the pulse-shaping OFDM systems Reviewed

Bayarpurev Mongol, Takaya Yamazato, Masaaki Katayama

IEEE International Conference on Communications 2009

Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/ICC.2009.5198817

Cognitive Radio with Relay of a Primary Signal and Piggyback Modulation Reviewed

Naganawa Jun, Yamazato Takaya, Katayama Masaaki

2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS page： 147 - 151 2009

Cognitive Radio with Relay of a Primary Signal and Piggyback Modulation Reviewed

Jun Naganawa, Takaya Yamazato, Masaaki Katayama

2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS page： 147 - 151 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/PIMRC.2009.5450056

A-17-17 Luminance Extraction Method for Visible Light Communication System using LED Array and High-Speed Camera Reviewed

NAGURA Toru, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the Society Conference of IEICE 2009

No Redundant Error-Correcting Scheme Using Chaotic Dynamics for Noncoherent Chaos Communications Reviewed

Arai Shintaro, Nishio Yoshifumi, Yamazato Takaya

ISCAS: 2009 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS, VOLS 1-5 page： 2633 - + 2009

On-Vehicle Receiver for Road-to-Vehicle Communication System Reviewed

OKADA Satoshi, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

ITE Technical Report Vol. 33 ( 0 ) page： 77 - 81 2009

Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

DOI： 10.11485/itetr.33.55.0_77

Visible Light Communications Using LED Array and High-speed Camera for ITS Applications Reviewed

YAMAZATO Takaya

IEICE ESS Fundamentals Review Vol. 3 ( 2 ) page： 45 - 53 2009

A-17-19 Detection of Luminance for Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

ARAI Shintaro, MASE Shohei, NAGURA Toru, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, TANIMOTO Masayuki, KIMURA Yoshikatsu

Proceedings of the IEICE General Conference Vol. 311 2009

A-17-18 128k Transmission of Visible Light Communication System using LED Array and High-Speed Camera Reviewed

NAGURA Toru, MASE Shohei, ARAI Shintaro, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, TANIMOTO Masayuki, KIMURA Yoshikatsu

Proceedings of the IEICE General Conference Vol. 310 2009

No Redundant Error-Correcting Scheme Using Chaotic Dynamics for Noncoherent Chaos Communications Reviewed

Shintaro Arai, Yoshifumi Nishio, Takaya Yamazato

ISCAS: 2009 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS, VOLS 1-5 page： 2633 - + 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/ISCAS.2009.5118342

On-Vehicle Receiver for Distant Visible Light Road-to-Vehicle Communication Reviewed

Satoshi Okada, Tomohiro Yendo, Takaya Yamazato, Toshiaki Fujii, Masayuki Tanimoto, Yoshikatsu Kimura

2009 IEEE INTELLIGENT VEHICLES SYMPOSIUM, VOLS 1 AND 2 page： 1033 - 1038 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we propose a road-to-vehicle visible communication system for ITS. In this system, a LED traffic light is used as transmitter and a photodiode is used as receiver. There are several problems associated with applying visible light communication to the field of ITS. It is necessary to receive information from long distance. And tracking the transmitter for a certain moving distance of the vehicle is also important. We applied an imaging optics to receive information over long distance, and two cameras are used to solve the relationship between the transmitter and the receiver position changes with time, and vibrational correction technique is also fixed to the system to minimize vibrational affections. We developed algorithms to track the transmitter. The experiments were conducted to confirm the proposals.

A-17-15 Impact of Pilot Interpolation Techniques on a Channel Estimation Scheme for Inter-Vehicle Communication Reviewed

TOA UWB Position Estimation with Two Receivers and a Set of Known Reflectors Reviewed

Kietlinski-Zaleski Jan, Yamazato Takaya, Katayama Masaaki

2009 IEEE INTERNATIONAL CONFERENCE ON ULTRA-WIDEBAND (ICUWB 2009) page： 376 - + 2009

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the Society Conference of IEICE Vol. 179 2009

Traffic Prediction Scheme for Resource Assignment of Satellite/Terrestrial Frequency Sharing Mobile Communication System Reviewed

Tomohiro Aman, Takaya Yamazato, Masaaki Katayama

2009 INTERNATIONAL WORKSHOP ON SATELLITE AND SPACE COMMUNICATIONS, CONFERENCE PROCEEDINGS page： 40 - + 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

The recent development of large aperture on-board multi-beam antennas enables a small-size, low-powered and cellular phone like hand-held terminal as a satellite earth terminal. A single mobile terminal can communicate to both mobile satellite systems and terrestrial systems depend upon his location, QoS and availability of resources among satellite and terrestrial communication systems.
In this paper, we propose a new traffic prediction scheme for the integrated satellite/terrestrial frequency sharing mobile communication system. The system shares a common frequency bandwidth in order to enhance the total capacity by a dynamic bandwidth allocation. A key for this allocation depends on a traffic prediction scheme of a few hundreds of terrestrial cells under a footprint of a satellite with a large aperture on-board multi-beam antennas. We propose three traffic predictors based on neural networks for dynamic resource allocation. The performances of the proposed schemes are evaluated in terms of the Relative Traffic Prediction Error and Maximum Traffic Prediction Error by the computer simulation. For the evaluation, we adopt the actual traffic statistic published by Ministry of Internal Affairs and Communications of Japan with population density of terrestrial cells based on the actual population of Aichi, Japan. As results, average traffic prediction error of less than 0.25 is achieved for the prediction interval of one hour, enough for dynamic resource allocation.

Traffic Prediction Scheme for Resource Assignment of Satellite/Terrestrial Frequency Sharing Mobile Communication System Reviewed

Aman Tomohiro, Yamazato Takaya, Katayama Masaaki

2009 INTERNATIONAL WORKSHOP ON SATELLITE AND SPACE COMMUNICATIONS, CONFERENCE PROCEEDINGS page： 40 - + 2009

TOA UWB Position Estimation with Two Receivers and a Set of Known Reflectors Reviewed

Jan Kietlinski-Zaleski, Takaya Yamazato, Masaaki Katayama

2009 IEEE INTERNATIONAL CONFERENCE ON ULTRA-WIDEBAND (ICUWB 2009) page： 376 - + 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

B-20-7 A Note on Joint Decoding using Correlation Estimation of Multiple Sources according to ADC Bit-Level Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

Proceedings of the Society Conference of IEICE Vol. 388 2009

CDMA slotted ALOHA system with successive interference cancellation for inter-vehicle communications Reviewed

Sakata A.

IEEE International Symposium on Spread Spectrum Techniques and Applications page： 188 - 193 2008.12

Mitigation of Satellite Non-linear Effect Using SLM and Iterative Distortion Compensation for OFDM in Satellite Channel Reviewed

AMAN Tomohiro, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

The IEICE transactions on communications B Vol. 91 ( 12 ) page： 1644 - 1646 2008.12

Energy Efficiency of Cooperative MISO Technique in Multi-hop Wireless Sensor Networks Reviewed

Z. Huang, T. Yamazato, M. Katayama

2008 The Fourth International Conference on Intelligent Sensors, Sensor Networks and Information Processing page： CD-ROM 2008.12

Language：English

In this paper, the energy efficiency of cooperative Multiple-Input Single-Output (MISO) technique for a multi-hop wireless sensor network is investigated and compared with other transmission schemes. Firstly, we present different schemes for data transmission of the cluster farther from base station and calculate their energy consumptions. The results show that the optimal transmission scheme varies with the inter-cluster distance in different networks. Then we explore the lifetime of the network and find that it is not always the optimal to employ the multi-hop transmission and the single-hop transmission outperform the multi-hop under a certain distance threshold. In addition, the effects of the transmission bit rate and the required bit error ratio (BER) on the distance threshold are also clarified.

Mitigation of Satellite Non-linear Effect using SLM and Iterative Distortion Compensation for OFDM in Satellite Channel Reviewed

T. Aman, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. J91-B ( 12 ) page： 1644-1646 2008.12

Energy Efficiency of Cooperative MISO Technique in Multi-hop Wireless Sensor Networks Reviewed

Z. Huang, T. Yamazato, M. Katayama

2008 The Fourth International Conference on Intelligent Sensors, Sensor Networks and Information Processing page： 511-515 2008.12

Language：English

Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Invited Reviewed

Takaya YAMAZATO, Shintaro ARAI, Shohei MASE, Tomohiro YENDO, Toshiaki FUJII, Masayuki TANIMOTO and Yoshikatsu KIMURA

2008 International Workshop on Smart Info-Media Systems in Bangkok (SISB 2008) page： CD-ROM 2008.12

Language：English

In this paper, we present hierarchical coding scheme using LED traffic lights and high-speed camera for Intelligent Transport Systems (ITS) application. If each of LEDs in traffic lights is individually modulated, parallel data transmissions are possible using a camera as a reception device. Such parallel LED-camera channel can be modeled as spatial low-pass filtered channel of which the cut-off frequency varies according to the distance. To overcome, we introduce hierarchical coding scheme based on 2D fast Haar wavelet transform.

Joint Channel Decoding of Spatially and Temporally Correlated Data in Wireless Sensor Networks Reviewed

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

The 2008 International Symposium on Information Theory and Its Applications page： 930-934 2008.12

Language：English

In densely deployed wireless sensor networks, sensor observations are spatially correlated. Furthermore, the nature of physical phenomena constitutes a temporal correlation between transmitted observations of an individual sensor node. In this paper, we propose a joint iterative channel decoding scheme using turbo codes. The proposed decoder exploits the spatial and temporal correlations of two binary data sequences to achieve additional coding gain. Simultaneously exploiting the spatial and temporal correlation, the proposed decoder achieves large performance gain.

Joint Channel Decoding of Spatially and Temporally Correlated Data in Wireless Sensor Networks Reviewed

S. Arai, Y. Nishio, T. Yamazato

Proceedings of IEEE Workshop on Nonlinear Circuit Networks (NCN'08) page： 49-51 2008.12

Language：English

We investigate and evaluate a suboptimal receiver using chaotic sequences with biased values. In our previous research, we investigated a differential chaos shift keying (DCSK) using chaotic sequences with biased values purposely and confirmed its better performance. However, our previous study only performed the computer simulation of DCSK using these chaotic sequences. In this study, we focus on the suboptimal receiver and evaluate its performance with chaotic sequences with biased values.

Energy efficiency of cooperative MISO technique in multi-hop wireless sensor networks Reviewed

Huang Z.

ISSNIP 2008 - Proceedings of the 2008 International Conference on Intelligent Sensors, Sensor Networks and Information Processing page： 511 - 516 2008.12

Error correcting scheme for road-to-vehicle visible light communication using LED array Reviewed

Mase S.

IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC page： 1113 - 1117 2008.12

Feasible study of road-to-vehicle communication system using led array and high-speed camera Reviewed

Arai S.

15th World Congress on Intelligent Transport Systems and ITS America Annual Meeting 2008 Vol. 4 page： 2911 - 2922 2008.12

Joint channel decoding of spatially and temporally correlated data in wireless sensor networks Reviewed

Kobayashi K.

2008 International Symposium on Information Theory and its Applications, ISITA2008 2008.12

*Feasible Study of Road-to-Vehicle Communication System Using LED Array and High-Speed Camera Reviewed

S. Arai, S. Mase, T. Yamazato, T. Yendo, T. Fujii, M. Tanimoto, Y. Kimura

Proceedings of the 15th World Congress on ITS page： CD-ROM 2008.11

Language：English

In this study, we focus attention on the parallel optical wireless communication systems using LED array transmitter and a high-speed camera as the receiver for road-to-vehicle communications in ITS. Previously, we have proposed a hierarchical coding scheme which allocates data to spatial frequency components depending on the priority. This scheme is possible to receive the high priority data even if the receiver is far from the transmitter. However, since vehicles drive on a road in actual road-to-vehicle communications, there are many important works to develop the real-time communication system. For example, it is a difficult to synchronize the timing to release the shutter with the lighting cycle of LEDs, i.e., the sampling of the data. This paper details our road-to-vehicle communication system using the LED array and the high-speed camera and proposes their solutions. Moreover, based on proposed solutions, we perform a driving field trial using the LED array and a vehicle with the high speed camera. As the result, we observe the bit error rate and confirm the reception of the data during the driving.

Energy-aware Protocol for Cluster-based Cooperative Transmission in Wireless Sensor Networks Reviewed

K. Takeshima, T. Yamazato, M. Katayama

Proceedings of International Workshop on Vision, Communications and Circuits (IWVCC'08) page： 149-152 2008.11

Language：English

In this paper, we look at communication protocol designed for cluster-based cooperative transmission. As it can increase the spatial diversity of wireless channel, cluster-based cooperative transmission is effective not only for reliable transmission but also in reduction of the transmitted power. The overall energy dissipation is, however, governed by a cluster head selection criterion. We show that the conventional random cluster head selection, as in low-energy adaptive clustering hierarchy (LEACH), and the best link quality cluster head selection may not be optimal for cluster-based cooperative transmission. Based on our finding, we propose a new energy-aware protocol for cluster-based cooperative transmission that considers not only the link quality but also the residual energy of sensor nodes. As results, our protocol shows the best in the availability ratio of sensor nodes and outage probability for the number of cluster-to-cluster transmissions.

Investigation of Noncoherent Detection Using Chaotic Sequence with Biased Values Reviewed

S. Arai, Y. Nishio, T. Yamazato

Proceedings of International Workshop on Vision, Communications and Circuits (IWVCC'08) page： 221-224 2008.11

Language：English

We investigate the chaotic sequence with biased values in chaos-based communication systems. In our previous research, we investigated the the performance of chaos communications using the sequence with biased values purposely. As results, we concluded that the chaotic dynamics affect the performance of chaos communications greatly. However, our previous study only performed the computer simulation the DCSK system using the chaotic sequence with biased values. In this study, we focus on the suboptimal receiver as one of chaos communication systems and observe its performance with the chaotic sequence with biased values.

Performance evaluation of turbo encoding and joint iterative decoding for multiple correlated sources Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 252 ) page： 51 - 55 2008.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We present a joint iterative decoding scheme for multiple correlated data which are separately turbo encoded and transmitted over noisy channels. The proposed decoder exploits the correlation in an iterative manner for achieving additional coding gain. Simulation results show that close to Shannon and Slepian-Wolf limit performance is achieved, and large SNR gain is achieved in comparison with the standard turbo decoder. We also verify through simulation that the codes with a low error floor is crucial to achieve good performance for a large number of the correlated data and no significant penalty results from the estimation of the correlation in the decoding process.

Performance evaluation of turbo encoding and joint iterative decoding for multiple correlated sources

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. USN2008-47 page： 51-55 2008.10

Language：Japanese

Error Correcting Scheme for Road-to-Vehicle Visible Light Communication using LED Array Reviewed

S. Mase, S. Arai, T. Yamazato, T. Yendo, T. Fujii, M. Tanimoto, Y. Kimura

IEEE International IEEE Conference on Intelligent Transportation Systems page： CD-ROM 2008.10

Language：English

In this paper, we propose an improved coding scheme for optical wireless communication systems using a LED array transmitter and a high-speed camera as the receiver on a vehicle. Previously, we have proposed a hierarchical coding scheme which allocated the data to spatial frequency components depending on the priority. In that scheme, the high-priority data can be received even if the receiver was far from the transmitter. We confirmed the advantage of the hierarchical coding scheme, but the bit error performance was not sufficient. In this paper, we divide the data into spatial frequency components, and use error correcting code for each spatial frequency components' data. Experimental evaluation demonstrates the improvement in BER performance. This improvement implies that the system range increased compared to the previous method.

Measurement of narrowband channel characteristics in single-phase three-wire indoor power-line channels Reviewed

Sugiura Y.

IEEE ISPLC 2008 - 2008 IEEE International Symposium on Power Line Communications and Its Applications page： 18 - 23 2008.9

Performance improvement of downlink MC-CDMA cellular system with an intermittent transmission Reviewed

Fushiki M.

2008 IEEE Radio and Wireless Symposium, RWS page： 275 - 278 2008.9

B-20-6 A note on joint decoding of spatially and temporally correlated sources Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

Proceedings of the Society Conference of IEICE Vol. 2008 ( 2 ) 2008.9

Bit and power allocation for power-line communications under nonwhite and cyclostationary noise environment

N. Sawada, T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. A-5-2 page： 89 2008.9

Error-Correcting Method Based on Chaotic Dynamics for Noncoherent Chaos Communications Reviewed

S. Arai, Y. Nishio, T. Yamazato

Proceedings of International Symposium on Nonlinear Theory and its Applications (NOLTA'08) page： 652-655 2008.9

Language：English

This paper proposes the error-correcting method based on the chaotic dynamics for noncoherent chaos communications. We generate successive chaotic sequences from the identical chaotic map. And for the next sequence we set the initial value to the end value of the former sequence. By such way we can create the successive chaotic sequences having the same chaotic dynamics. This feature gives the receiver additional information to correctly recover the received noisy signal. Therefore, by analyzing the chaotic dynamics at the receiver, it is possible to improve the error performance. In other words, error performance of the receiver can be improved by the utilization of the suboptimal receiver with the analysis of chaotic dynamics of the successive received sequence. As results of computer simulations, we confirm about 3 dB gain in BER performance compared to the conventional suboptimal receiver.

A New SC/MMSE Turbo Equalization for MC-CDMA to use in Inter-Vehicle Communication Reviewed

N. Hiraiwa, A. Sakata, T. Yamazato, M. Katayama

IEEE Vehicular Technology Conference 2008-Fall page： CD-ROM 2008.9

Language：English

In this paper, we propose a new SC/MMSE Turbo equalizer for MC-CDMA to use in inter-vehicle communication (IVC). We modify the weight of the MMSE filter of SC/MMSE Turbo equalizer so that it can combat with frequency-selective fading in highly mobile IVC environment and also can mitigate the effect of multiple access interferences (MAI). As results, we show that better throughput is obtained by the proposed SC/MMSE equalization than the conventional one. The average reception range can be up to 70 [m] and the signals from 16 surrounding cars can be received. While for the conventional scheme, only three signals from the nearest cars are achieved.

Cooperative transmission in distributed sensor networks using visible light communication

K. Kobayashi, K. Nakao, T. Yamazato, M. Katayama

Proc. of 10th DSPS Educators Conference page： 72-73 2008.9

A modulation scheme without channel state information for cognitive radio overlay systems

J. Naganawa, T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. B-17-9 page： 452 2008.9

A note on joint decoding of spatially and temporally correlated sources

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

Communications Society Conference of IEICE Vol. B-20-6 page： 342 2008.9

CDMA slotted ALOHA System with Successive Interference Cancellation for Inter-Vehicle Communications Reviewed

A.Sakata, T.Yamazato, H.Okada, M.Katayama

IEEE International Symposium on Spread Spectrum Techniques and Applications page： 188-193 2008.8

Language：English

This paper compares the throughput performance of orthogonal frequency division multiple access (OFDM) and multicarrier CDMA (MC-CDMA) in inter-vehicle communications (IVC).In particular, we compare the throughputs in a situation where hidden terminals are no longer negligible. We encounter the situation in an intersection where two or more cars are crossing by. Due to the hidden terminal degradation, poor throughput performance is obtained with OFDM scheme. On the other hand, MC-CDMA has a resistance to the hidden terminals as it can support simultaneous packets. However, the transmission data rate is much slow because of the spreading. Thus the total throughput may not be as high as the OFDM. As results, we show that throughput of the OFDM is better than the MC-CDMA in a low traffic region. We found that the OFDM can communicate only with the nearest car. On the contrary, when the traffic is high, the MC-CDMA shows better throughput than the OFDM. In addition, we show that many packets can be received simultaneously in MC-CDMA. These results lead to the conclusion that when we want high-speed communication to a few cars, the OFDM is a good candidate. And when low speed but simultaneous communication with many surrounding cars is our desire, then the MC-CDMA is our choice. As MC-CDMA has a compatibility with an OFDM by setting a spreading factor to one, MC-CDMA system may be the preferable choice for IVC.

Performance Comparison of OFDM and MC-CDMA in Inter-Vehicle Communications Reviewed

SAKATA Atsunori, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 171 ) page： 1 - 6 2008.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper evaluates the packet success rate of aa orthogonal frequency division multiplexing (OFDM), a multicarrier CDMA (MC-CDMA) and a multicarrier orthogonal frequency division multiple access (MC-OFDMA) based on MC-CDMA. In particular, we compare the packet success rate in a high traffic situation where a hidden terminal is no longer negligible. A hidden terminal problem tends to occur in a situation of sight limitation such as intersection. We focus on physical layer and adopt MC-CDMA so that simultaneous reception is possible. This feature gives possible resistance to hidden terminal problem. In this paper, we investigate how the packet success rate performance varies with spreading factor and how to assign subcarrier. As results, we show that MC-OFDMA based on MC-CDMA shows better packet success rate than OFDM.

Improvement of Robustness for Road-to-Vehicle Visible Light Communication using Hiearachical Coding Reviewed

MASE Shohei, ARAI Shintaro, YAMAZATO Takaya, YENDO Tomohiro, FUJII Toshiaki, TANIMOTO Masayuki, KIMURA Yoshikatsu

IEICE technical report Vol. 108 ( 171 ) page： 19 - 24 2008.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

YAMAZATO Takaya, ARAI Shintaro, MASE Shohei, ENDO Tomohiro, FIJII Toshiaki, TANIMOTO Masayuki, KIMURA Yoshikatsu

IEICE technical report Vol. 108 ( 165 ) page： 47 - 52 2008.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

YAMAZATO Takaya, ARAI Shintaro, MASE Shohei, ENDO Tomohiro, FIJII Toshiaki, TANIMOTO Masayuki, KIMURA Yoshikatsu

IEICE technical report Vol. 108 ( 163 ) page： 47 - 52 2008.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Ultrasonic Array Emitter for Automotive Short-range Radar Networks Reviewed

HATANO Hiroyuki, YAMAZATO Takaya, KATAYAMA Masaaki

Vol. 62 ( 7 ) page： 29 - 34 2008.7

*Ultrasonic Array Emitter for Automotive Short-range Radar Networks Invited Reviewed

H. Hatano, T. Yamazato, M. Katayama

Journal of Society of Automotive Engineers of Japan, Vol.62, No.7, pp.29-34 Vol. 62 ( 7 ) page： 19-34 2008.7

Language：Japanese

We consider radar network systems using multiple ultrasonic radars for parking assistance. Our radar network has an ultrasonic array emitter and multiple sensors. The ultrasonic array emitter is composed of multiple ultrasonic emitters and can emit signals to the side area which is the desired monitoring area of parking aid. Target positions are estimated by the data processing form multiple ultrasonic sensors which are set at distributed points of the front bumper. In this paper we especially describe our proposed array emitter.

Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Invited

Takaya Yamazato, Shintaro Arai, Shohei Mase, Tomohiro Yendo (Nagoya Univ.), Toshiaki Fujii (Tokyo Inst. of TEch.), Masayuki Tanimoto (Nagoya Univ.), Yoshikatsu Kimura (Toyota Central R&D Labs.)

Technical Report of IEICE, IEICE Tech. Rep. Vol. SIP2008-76 ( 163 ) page： 47-52 2008.7

Language：Japanese

Performance Comparison of OFDM and MC-CDMA in Inter-Vehicle Communications

A.Sakata, T.Yamazato, H.Okada, M.Katayama

Technical Report of IEICE Vol. ITS2008-8 page： - 2008.7

Language：Japanese

This paper evaluates the packet success rate of aa orthogonal frequency division multiplexing(OFDM) , a multicarrier CDMA(MC-CDMA) and a multicarrier orthogonal frequency division multiple access(MC-OFDMA) based on MC-CDMA. In particular, we compare the packet success rate in a high traffic situation where a hidden terminal is no longer negligible. A hidden terminal problem tends to occur in a situation of sight limitation such as intersection. We focus on physical layer and adopt MC-CDMA so that simultaneous reception is possible. This feature gives possible resistance to hidden terminal problem. In this paper, we investigate how the packet success rate performance varies with spreading factor and how to assign subcarrier. As results, we show that MC-OFDMA based on MC-CDMA shows better packet success rate than OFDM.

Improvement of Robustness for Road-to-Vehicle Visible Light Communication using Hiearachical Coding

Shohei MASE, Shintro ARAI, Takaya YAMAZATO, Tomohiro YENDO, Toshiaki FUJII, Masayuki TANIMOTO, Yoshikatsu KIMURA

Technical Report of IEICE page： - 2008.7

Language：Japanese

A Route Establishment Scheme for Multi-route Coding in Multihop Cellular Networks Reviewed

H. Okada, H. Imai, T. Yamazato, M. Katayama, K. Mase

Academy Publisher Journal of Netowkrs Vol. 3 ( 7 ) page： 34-40 2008.7

Language：English

Since the network topology in multihop cellular networks is flexible, multiple routes from a user station to a base station can be established. To reduce packet reception errors of wireless links, a multi-route coding scheme was proposed. An important issue of the multi-route coding is to develop an efficient route establishment scheme. In this paper, we propose a route establishment scheme for multi-route coding in multihop cellular networks. Our proposed scheme consists of a route selection method based on the bit error rate of each wireless link and a hybrid-type multiple-tree routing protocol. We evaluate the performance of our proposed scheme by a computer simulation and show the resulting improvement in the packet error.

A Route Establishment Scheme for Multi-route Coding in Multihop Cellular Networks Reviewed

H. Okada, H. Imai, T. Yamazato, M. Katayama, K. Mase

Academy Publisher Journal of Netowkrs, vol.3, no.7, pp.34-40 Vol. 3 ( 7 ) page： 34-40 2008.7

Language：English Publishing type：Research paper (scientific journal)

相関のある情報源の分散符号化・統合復号法のEXIT解析

小林健太郎，山里敬也，片山正昭

第4回無線分散ネットワークに関するワークショップ page： - 2008.6

A modulation scheme for a cognitive radio system to overlay on a secondary user Reviewed

NAGANAWA Jun, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 62 ) page： 5 - 10 2008.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

As an answer to increasing demands for frequency spectrum, secondary spectrum licensing, in which a secondary wireless system overlays on the frequency band of an existing primary system, is taking attention. In overlay communications, the secondary system is demanded not to be a cause of performance degradation of the primary system, while the primary system does not considers the secondary system. This manuscript proposes a modulation scheme for such a secondary system. In the proposed scheme, the secondary system modifies its transmitting signal parameters adapting channel states and transmitted signal of the primary system. This set of reference information is also used at the receiver of the secondary system. We derive the symbol error rates of both the systems analytically, and show that it is possble to realize the communication of the secondary system with the same quality as the primary system, which has any degradation by the signal of the secondary system.

Spatial Diversity Scheme with Multiple-Transmit/Receive Antennas and Relay Terminals for Reliable Wireless Control Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J91-B ( 5 ) page： 585-594 2008.5

Language：Japanese Publishing type：Research paper (scientific journal)

In this manuscript, a communication system for wireless control of industrial machines in indoor environment is discussed. In order to combat indoor fading and shadowing, an STBC cooperative relaying scheme, which uses multiple transmit and receive antennas together with multiple relay terminals, is introduced. In the proposed scheme each relay terminal transmits all STBC branch-signals with random phase rotations, and no exchange of information between the relay terminals is required to achieve high diversity order. In numerical evaluations, the proposed scheme is compared with conventional deterministic signal assignment or random branch selection schemes using average and outage probability of the frame-error rate as performance measures. As a result, the impact of the random phase rotations is clarified.

A modulation scheme for a cognitive radio system to overlay on a secondary user

Jun Naganawa, Takaya Yamazato, Masaaki Katayama

Technical Report of IEICE Vol. SR2008-2 page： - 2008.5

Language：Japanese

As an answer to increasing demands for frequency spectrum, secondary spe ctrum licensing, in which a secondary wireless system overlays on the fr equency band of an existing primary system, is taking attention. In ove rlay communications, the secondary system is demanded not to be a cause of performance degradation of the primary system, while the primary syst em does not considers the secondary system. This manuscript proposes a modulation scheme for such a secondary system . In the proposed scheme, the secondary system modifies its transmitting signal parameters adapting channel states and transmitted signal of the primary system. This set of reference information is also used at the r eceiver of the secondary system. We derive the symbol error rates of both the systems analytically, and s how that it is possble to realize the communication of the secondary sys tem with the same quality as the primary system, which has any degradati on by the signal of the secondary system.

Spatial Diversity Scheme with Multiple-Transmit/Receive Antennas and Relay Terminals for Reliable Wireless Control Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J91-B ( 5 ) page： 585-594 - 594 2008.5

Measurement of Narrowband Channel Characteristics in Single-Phase Three-Wire Indoor Power-Line Channels Reviewed

Y. Sugiura, T. Yamazato, M. Katayama

IEEE International Symposium on Power Line Communications and Its Applications page： - 2008.4

Language：English

This manuscript reports the measurement results of narrowband signal propagation of PLC channels. In Japan, in-house wiring is single-phase three-wire, and each branch between an outlet of 100V and the panel board is connected to one of two live conductors and the neutral. Thus a pair of outlets can be classified into three types: connected to different live conductors, connected to the same live conductors by different branches from the panel board, and on the same branch to the same live conductor. It is confirmed that the results of the measurements can be classified by these three types of paths. The results show that frequency responses of narrowband PLC channels are relatively smooth, compared with that of wideband PLC. It is also found that propagation loss in lower frequency range is larger than in higher frequency range. The time independence of narrowband PLC channels are confirmed when no electric appliance is connected to the same live conductor.

A-17-12 CDMA Slotted ALOHA Systems with Successive Interference Cancellation for Inter-Vehicle Communications(A-17. ITS) Reviewed

Sakata Atsunori, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2008 page： 323 2008.3

A-5-18 Adaptive modulation for power-line communications with nonwhite and cyclostationary noise Reviewed

Sawada Naoya, Yamazato Takaya, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2008 page： 145 2008.3

A-2-35 Noncoherent Communication Systems using Chaotic Sequence with Many Biased Values Reviewed

ARAI Shintaro, NISHIO Yoshifumi, YAMAZATO Takaya

Proceedings of the IEICE General Conference Vol. 2008 page： 74 2008.3

Introduction of Fractional Frequency Reuse and Fast Retrial Algorithm for uplink of Multi-Cell OFDMA s-ALOHA systems

K. Kimura T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Iterative joint decoding of multiple correlated sources using Turbo codes

K. Kobayashi, T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Carrier Assignment to Improve the Transmission Efficiency of Edge Terminal in OFDMA Downlink Cellular System

M. Fushiki, T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Autonomous Collision-less Slot Assignment Algorithm for Wireless Sensor Networks

R. Chandradasa, T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

CDMA slotted ALOHA Systems with Successive Interference Cancellation for Inter-Vehicle Communications

A.Sakata, T.Yamazato, H.Okada, M.Katayama

IEICE General Conference page： - 2008.3

Performance Comparison of SC/MMSE Turbo Equalization and MMSE Equalization in Inter-Vehicle Communication using MC-CDMA

N. Hiraiwa, A. Sakata, T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Time Variation of Narrowband Channel Characteristics of Indoor Power-Line Channels

Y. Sugiura T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Adaptive modulation for power-line communications with nonwhite and cyclostationary noise

N. Sawada, T. Yamazato, M. Katayama

IEICE General Conference page： - 2008.3

Performance Improvement of Downlink MC-CDMA Cellular System with an Intermittent Transmission Reviewed

M.Fushiki, T.Yamazato, M.Katayama

IEEE Radio and Wireless Symposium page： - 2008.1

Language：English

Throughput performance of MC-CDMA systems depends on the success in managing interference arising from intercell transmission. In this paper, we propose a new intercell interference mitigation scheme for downlink MC-CDMA scheme. In the proposed scheme, a base station transmits downlink signals intermittently to mobile terminals at the edge of cell. The intercell interference can be seen as a partial interference depend upon the on and off period of the adjacent downlink signals. So it is possible for the channel equalizer to suppress this partial intercell interference by setting the weight changes in accordance with the intercell interference. As results, the frame error rate of the proposed scheme is always better than that of the conventional scheme and good throughput performance is achieved especially when the traffic is high.

A New SC/MMSE Turbo Equalization for MC-CDMA to use in Inter-Vehicle Communication Reviewed

Hiraiwa Noriaki, Sakata Atsunori, Yamazato Takaya, Katayama Masaaki

68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008 page： 1193 - 1197 2008

A route establishment scheme for multi-route coding in multihop cellular networks Reviewed

Hiraku Okada, Hitoshi Imai, Takaya Yamazato, Masaaki Katayama, Kenichi Mase

Journal of Networks Vol. 3 ( 7 ) page： 34 - 40 2008

Language：English Publishing type：Research paper (scientific journal) Publisher：Academy Publisher

Since the network topology in multihop cellular networks is flexible, multiple routes from a user station to a base station can be established. To reduce packet reception errors of wireless links, a multi-route coding scheme was proposed. An important issue of the multi-route coding is to develop an efficient route establishment scheme. In this paper, we propose a route establishment scheme for multi-route coding in multihop cellular networks. Our proposed scheme consists of a route selection method based on the bit error rate of each wireless link and a hybrid-type multipletree routing protocol. We evaluate the performance of our proposed scheme by a computer simulation and show the resulting improvement in the packet error. © 2008 Academy Publisher.

DOI： 10.4304/jnw.3.7.34-40

Bit and Power Allocation for Power-Line Communications under Nonwhite and Cyclostationary Noise Environment Reviewed

Sawada Naoya, Yamazato Takaya, Katayama Masaaki

ISPLC: 2009 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS page： 307 - + 2008

Bit and Power Allocation for Power-Line Communications under Nonwhite and Cyclostationary Noise Environment Reviewed

Naoya Sawada, Takaya Yamazato, Masaaki Katayama

ISPLC: 2009 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS page： 307 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This manuscript discusses the adaptive OFDM system for narrow-band power-line communications with nonwhite and cyclostationary noise environment. The bit and power allocation algorithm is proposed with the considerations on the cyclostationarity of power-line noise. Numerical evaluation shows that the proposed method can improve the average BER performance under PLC noise environment.

Energy Efficiency of Cooperative MISO Technique in Multi-Hop Wireless Sensor Networks Reviewed

Huang Zheng, Yamazato Takaya, Katayama Masaaki

ISSNIP 2008: PROCEEDINGS OF THE 2008 INTERNATIONAL CONFERENCE ON INTELLIGENT SENSORS, SENSOR NETWORKS, AND INFORMATION PROCESSING page： 511 - + 2008

Error Correcting Scheme for Road-to-Vehicle Visible Light Communication using LED Array Reviewed

Shohei Mase, Shintaro Arai, Takaya Yamazato, Tomohiro Yendo, Toshiaki Fujii, Masayuki Tanimoto, Yoshikatsu Kimura

PROCEEDINGS OF THE 11TH INTERNATIONAL IEEE CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS page： 1113 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we propose an improved coding scheme for optical wireless communication systems using a LED array transmitter and a high-speed camera as the receiver on a vehicle. Previously, we have proposed a hierarchical coding scheme which allocated the data to spatial frequency components depending on the priority. In that scheme, the high-priority data can be received even if the receiver was far from the transmitter: We confirmed the advantage of the hierarchical coding scheme, but the bit error performance was not sufficient. In this paper, we divide the data into spatial frequency components, and us: error correcting code for each spatial frequency components' data. Experimental evaluation demonstrates the improvement in BE R performance. This improvement implies that the system range increased compared to the previous method.

Energy Efficiency of Cooperative MISO Technique in Multi-Hop Wireless Sensor Networks Reviewed

Zheng Huang, Takaya Yamazato, Masaaki Katayama

ISSNIP 2008: PROCEEDINGS OF THE 2008 INTERNATIONAL CONFERENCE ON INTELLIGENT SENSORS, SENSOR NETWORKS, AND INFORMATION PROCESSING page： 511 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, the energy efficiency of cooperative Multiple-Input Single-Output (MISO) technique for a multi-hop wireless sensor network is investigated and compared with other transmission schemes. Firstly, we present different schemes or data transmission of the cluster farther from base station and calculate their energy consumptions. The results show that the optimal transmission scheme varies with the inter-cluster distance in different networks. Then we explore the lifetime of the network and find that it is not always the optimal to employ the multi-hop transmission and the single-hop transmission outperform the multi-hop under a certain distance threshold. In addition, the effects of the transmission bit rate and the required bit error ratio (BER) on the distance threshold are also clarified.

Joint Channel Decoding of Spatially and Temporally Correlated Data in Wireless Sensor Networks Reviewed

Kobayashi Kentaro, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3 page： 930 - + 2008

Joint Channel Decoding of Spatially and Temporally Correlated Data in Wireless Sensor Networks Reviewed

Kentaro Kobayashi, Takaya Yamazato, Hiraku Okada, Masaaki Katayama

2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3 page： 930 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Measurement of narrowband channel characteristics in single-phase three-wire indoor power-line channels Reviewed

Sugiura Yoshie, Yamazato Takaya, Katayama Masaaki

IEEE ISPLC: 2008 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS page： 18 - + 2008

Measurement of narrowband channel characteristics in single-phase three-wire indoor power-line channels Reviewed

Yoshie Sugiura, Takaya Yamazato, Masaaki Katayama

IEEE ISPLC: 2008 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS page： 18 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This manuscript reports the measurement results of narrowband signal propagation of PLC channels. In Japan, in-house wiring is single-phase three-wire, and each branch between an outlet of 100V and the panel board is connected to one of two live conductors and the neutral. Thus a pair of outlets can be classified into three types: connected to different live conductors, connected to the same five conductors by different branches from the panel board, and on the same branch to the same live conductor. It is confirmed that the results of the measurements can be classified by these three types of paths. The results show that frequency responses of narrowband PLC channels are relatively smooth, compared with that of wideband PLC. It is also found that propagation loss in lower frequency range is larger than in higher frequency range. The time independence of narrowband PLC channels are confirmed when no electric appliance is connected to the same live conductor.

Performance improvement of downlink MC-CDMA cellular system with an intermittent transmission Reviewed

Fushiki Masashi, Yamazato Takaya, Katayama Masaaki

2008 IEEE RADIO AND WIRELESS SYMPOSIUM, VOLS 1 AND 2 page： 275 - + 2008

Performance improvement of downlink MC-CDMA cellular system with an intermittent transmission Reviewed

Masashi Fushiki, Takaya Yamazato, Masaaki Katayama

2008 IEEE RADIO AND WIRELESS SYMPOSIUM, VOLS 1 AND 2 page： 275 - + 2008

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

A note on EXIT analysis for distributed encoding and joint decoding of correlated sources

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE page： - 2007.12

Language：Japanese

Extrinsic information transfer (EXIT) charts are used to predict the behavior of the iterative decoder by solely looking at the input/output relation of individual constituent decoders. This allows the prediction of turbo cliff region. In the recent research on the distributed coding and joint decoding, there has been a significant interest in utilizing iteratively decodable codes. Hence, it is expected that EXIT analysis can be employed for assessing the convergence behavior of such iterative schemes. In this paper, we present a turbo based iterative joint of two correlated binary sources. The convergence behavior of the proposed system is studied using EXIT charts.

Improvement of Error Performance for Noncoherent Chaos Communications Reviewed

Shintaro ARAI, Yoshifumi NISHIO and Takaya YAMAZATO

Proceedings of IEEE Workshop on Nonlinear Circuit Networks (NCN'07) page： 54-56 2007.12

Language：English

This paper proposes the error-correcting for noncoherent chaos communications. To improve the error performance, we focus attention on the successive chaotic sequence based on the chaotic dynamics. Concretely, error performance of a noncoherent receiver improves by analyzing the chaotic dynamics of the successive received sequence. As results of computer simulations, we confirm about 3 dB gain in BER performance compared to the conventional suboptimal receiver.

A note on EXIT analysis for distributed encoding and joint decoding of correlated sources

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. RCS2007-125 page： 79-83 2007.12

Language：Japanese

Extrinsic information transfer (EXIT) charts are used to predict the behavior of the iterative decoder by solely looking at the input/output relation of individual constituent decoders. This allows the prediction of turbo cliff region. In the recent research on the distributed coding and joint decoding, there has been a significant interest in utilizing iteratively decodable codes. Hence, it is expected that EXIT analysis can be employed for assessing the convergence behavior of such iterative schemes. In this paper, we present a turbo based iterative joint decoding scheme of two correlated binary sources. The convergence behavior of the proposed system is studied using EXIT charts.

Automotive ultrasonic array emitter for short-range targets detection Reviewed

Hatano H., Yamazato T., Katayama M.

Proceedings of 4th IEEE Internatilonal Symposium on Wireless Communication Systems 2007, ISWCS page： 355 - 359 2007.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Proceedings of 4th IEEE Internatilonal Symposium on Wireless Communication Systems 2007, ISWCS

We consider an application of a ultrasonic array emitter to automotive targets detection systems for short-range. Ultrasonic sensors are low cost and widely used. However detectable ranges do not meet the requirements for short-range applications, such as parking aid systems. In this paper, we propose a method which may achieve the emission to a desired area within limited time. We evaluate the expected accuracy of target position estimations by computer simulations. As a result, we show the ability of the ultrasonic sensors for parking aid systems. © 2007 IEEE.

DOI： 10.1109/ISWCS.2007.4392361

Cooperative transmission scheme in distributed sensor network for extension of transmission range Reviewed

Nakao K.

4th International Conference on Networked Sensing Systems, INSS page： 89 - 92 2007.12

Throughput comparison of CSMA and CDMA slotted ALOHA in inter-vehicle communication Reviewed

Sakata A.

ITST 2007 - 7th International Conference on Intelligent Transport Systems Telecommunications, Proceedings page： 52 - 57 2007.12

Indoor Propagation Measurements for Wireless Controls

K. Endou, T. Yamazato, M. Katayama

Technical Report of IEICE page： - 2007.11

Language：Japanese

In order to collect basic reference data for wireless controls of industrial equipments, we have constructed a system to measure the continuous (five seconds) wideband (23MHz) simultaneous propagation characteristics of multiple channels in 2.4GHz band. As a result, the propagation characteristics of two indoor wireless channels measured simultaneously, are expressed as functions of time and frequency. The result shows that the propagation loss considerably exceed its mean value locally in time--frequency plane, and that the probability of this drops of the signal is not negligible. In addition, we show that the probability of the deep fades which continues more than the permissible delay time for the control communication system (20ms) is also non-negligible. Moreover, we clarify that, even when the antennas are separated by several wavelength, still the correlation of the time-varying faded signal levels at the antennas is relatively high and should be taken into account in designing a wireless control systems.

Correlations of noise waveforms at different outlets of power-line network Reviewed

A. Kawaguchi, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals, vol. J90-A, no.11, pp 851-860 Vol. J90-A ( 11 ) page： 851-860 2007.11

Language：Japanese Publishing type：Research paper (scientific journal)

This manuscript discusses the relationships of noise waveforms measured at different outlets in a three-wire single-phase (one neutral and two live conductors) power-line network. As a result of experimental measurements, it is shown that instantaneous noise voltages at two different outlets have high correlations if they are connected to the same live conductor. It is also found that the instantaneous noise powers and cyclic averaged noise powers have large correlations even for a pair of outlets connected to the different live conductors. The correlation coefficients for instantaneous voltages and powers are calculated as the frequency functions.

Correlations of noise waveforms at different outlets of power-line network Reviewed

A. Kawaguchi, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals Vol. J90-A ( 11 ) page： 851-860 2007.11

A Novel Contention-Free Medium Access Control Protocol for Inter-Vehicle Communication Systems Reviewed

M. Masamura, H. Okada, S. Makido, T. Yamazato, M. Katayama

The First International Workshop on Mobile Vehicular Networks at MASS 2007 page： - 2007.10

Language：English

We propose a contention-free medium access control (MAC) protocol for inter-vehicle communication systems that share information for the improvement of safety drive on the highway. In the proposed system, contention-free medium access is achieved by periodical one-way token transmissions. The token contains the frame information about the transmission/reception phase. While the token is relaid by one-way, the vehicle which has the token can send a packet to both up- and down-link. The token transmission interval is set not to be interfered from other transmit vehicles at a receive vehicle. In addition, multiple channels are used and allocated dynamically for every token transmission to reduce the transmission waiting time. We also evaluate the maximum end-to-end transmission delay of the proposed protocol, and clarify that the proposed protocol can guarantee the transmission within allowable delay time.

Automotive Ultrasonic Array Emitter for Short-range Targets Detection Reviewed

H, Hatano, T. Yamazato, M. Katayama

IEEE International Symposium on Wireless Communication Systems page： - 2007.10

Language：English

A Route Selection Scheme for Multi-Route Coding in Multihop Cellular Networks Reviewed

H. Okada, H. Imai, T. Yamazato, M. Katayama, K. Mase

IEEE Vehicular Technology Conference (VTC) page： - 2007.10

Language：English

In the multihop cellular networks, multiple routes from a user station to a base station can be established because of the flexibility of network topology. In order to reduce packet errors of wireless transmissions, we proposed the multi-route coding scheme, in which packets are encoded and divided into subpackets, and they are transmitted on several routes from the user station to the base station. In order to improve the performance of the multi-route coding, a route selection scheme is very important issue. In this paper, we propose the route selection scheme for the multi-route coding in multihop cellular networks. The proposed scheme is based on the bit error rate of wireless links. We also apply the proposed route selection scheme to a hybrid routing protocol and evaluate its performance.

A Route Selection Scheme for Multi-Route Coding in Multihop Cellular Networks Reviewed

H. Okada, H. Imai, T. Yamazato, M. Katayama, K. Mase

IEEE Vehicular Technology Conference page： - 2007.10

Language：English

Automotive Ultrasonic Array Emitter for Short-range Targets Detection Reviewed

H. Hatano, T. Yamazato, M. Katayama

IEEE International Symposium on Wireless Communication Systems, pp.355-359 page： 355-359 2007.10

Language：English

Performance evaluation of cooperative transmission in wireless sensor networks using FPGA

K. Nakao, T. Yamazato, M. Katayama

Technical Report of IEICE page： - 2007.10

Language：Japanese

Since sensor nodes are typically small and power limited, they are only able to achieve short-range transmission with low complexity processing. Therefore, we need to realize extension of the transmission range by cooperative transmission among the distributed nodes. In this paper, we propose a simple cooperative scheme without tight synchronization, i.e., multiplication of random phase in the transmitter before the transmission. Thanks to a strong error correcting code, it is possible to extend the transmission range. We evaluate the performance of this proposed scheme by LED optical communication equivalently using FPGA.

A Novel Contention-Free Medium Access Control Protocol for Inter-Vehicle Communication Systems Reviewed

M. Masamura, H. Okada, S. Makido, T. Yamazato, M. Katayama

The First International Workshop on Mobile Vehicular Networks at MASS 2007 page： - 2007.10

Language：English

Hierarchical Coding Scheme for Optical Wireless Communicaiton using LED Traffic Light and High-Speed Camera Reviewed

K. Masuda, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. Vol.J90A ( 9 ) page： 696-704 2007.9

Language：Japanese Publishing type：Research paper (scientific journal)

LEDs are expected as lightning sources for next generation, and data transmission system using LEDs attract attention. In this paper, we present hierarchical coding scheme using LED traffic lights and high-speed camera for Intelligent Transport Systems (ITS) application. Further, if each of LEDs in traffic lights is individually modulated, parallel data transmissions are possible using a camera as a reception device. Such parallel LED-camera channel can be modeled as spatial low-pass filtered channel of which the cut-off frequency varies according to the distance. To overcome, we propose hierarchical coding scheme based on 2D fast Haar wavelet transform. As results, the proposed hierarchical transmission schemes outperform the conventional on-off keying and the reception of high priority data is guaranteed even LED-camera distance is further.

Distributed Space-Time Block Coding for Large and Undetermined Set of Relay Terminals Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC2007 page： - 2007.9

Language：English

In this manuscript, a spatial diversity scheme with multiple transmit and receive antennas together with multiple relay terminals for packet radio is considered. Correctly received signals at some relay terminals are re-transmitted to the receiver with the spatial diversity by STBC cooperative relaying scheme. To achieve high diversity order with the conventional STBC cooperative relaying scheme, relay terminals which re-transmit the signals are required to exchange signaling information with each another. However, the exchanging of the information causes delay of the signal transmission. Thus, in this manuscript, a novel signaling scheme for the STBC cooperative relaying is proposed. The proposed scheme releases relay terminals exchanging the signaling information. The proposed scheme also saves communication resources to provide flexibility for installation of relay terminals.

Experiment on Hierarchical Transmission Scheme for Visible Light Communication using LED Traffic Light and High-Speed Camera Reviewed

S. Arai, S. Mase, T. Yamazato, T. Endo, T. Fujii, M. Tanimoto, K. Kidono, Y. Kimura, Y. Ninomiya

IEEE International Symposium on Wireless Vehicular Communications (WiVeC'07) page： - 2007.9

Language：English

LEDs are expected as lighting sources for next generation, and data transmission system using LEDs attract attention. In this paper, we present hierarchical coding scheme using LED traffic lights and high-speed camera for Intelligent Transport Systems (ITS) application. Further, if each of LEDs in traffic lights is individually modulated, parallel data transmissions are possible using a camera as a reception device. Such parallel LED-camera channel can be modeled as spatial low-pass filtered channel of which the cut-off frequency varies according to the distance. To overcome, we propose hierarchical coding scheme based on 2D fast Haar wavelet transform. As results, the proposed hierarchical transmission schemes outperform the conventional on-off keying and the reception of high priority data is guaranteed even LED-camera distance is further.

Analysis on Chaotic Sequence with Biased Values for Noncoherent Chaos Communication Reviewed

S. Arai, Y. Nishio, T. Yamazato

International Symposium on Nonlinear Theory and its Applications (NOLTA) Vol. NOLTA2007 page： 144-147 2007.9

Language：English

In this paper, we analyze a chaotic dynamics generating a chaotic sequence with biased values and apply it to noncoherent chaos communications. We examine a behavior of the chaotic dynamics by increasing the slope of the chaotic map and investigate the invariant measure and the correlation function. A high quality performance of noncoherent chaos communications is obtained by controlling the distribution of the chaotic sequence with biased values. Finally we carry out the computer simulation using its sequence and discuss the obtained results and the future problem for chaos communication.

Efficient Channel Estimation Scheme for Pulse-shaping OFDM Systems Reviewed

B.Mongol, T. Yamazato, M. Katayama

International Symposium on Nonlinear Theory and its Applications (NOLTA) Vol. NOLTA2007 page： - 2007.9

Language：Japanese

This paper proposes a low-complexity channel estimation sheme for the pulse-shaping OFDM systems in the highly mobile multipath environment. The estimation scheme is based on the tapped-delay-line model for the channel. The main idea behind our scheme is to approximate the fading process for each tap with finite terms of its Taylor series expansion. The proposed scheme also tracks the channel. We show that the channel can be estimated and tracked with reasonable mismatch error while using considerably short training period.

A study on position estimation method for multiple targets detection for automotive radar networks Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

Transactions of Society of Automotive Engineers of Japan Vol. 38 ( 5 ) page： 191-196 2007.9

Language：Japanese

We research automotive radar networks with multiple radars set in the front of car. Especially, we consider data processing using measured ranges provided by the radars in order to estimate multiple target positions with high accuracy. This paper is composed of three steps. Firstly, we derive a method based on MAP estimation. Secondly, we propose a method which reduces the calculation complexity compared with the above MAP method. Finally, we introduce a method which can detect targets without ghost-targets in case the lacks of measured ranges are happened because of miss-detection. We evaluate the methods with computer simulations.

Performance comparison of CSMA and CDMA slotted ALOHA in Inter-Vehicle communication

A.Sakata, T.Yamazato, H.Okada, M.Katayama

Communications Society Conference of IEICE page： - 2007.9

A Study on Random Access Scheme using Channel Division for Multi-Cell OFDMA uplink

K. Kimura T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. B-5-62 page： 384 2007.9

Experiment on Hierarchical Transmission Scheme for Visible Light Communication using LED Traffic Light and High-Speed Camera Reviewed

S. Arai, S. Mase, T. Yamazato, T. Endo, T. Fujii, M. Tanimoto, K. Kidono, Y. Kimura, Y. Ninomiya

Proceedings of IEEE International Symposium on Wireless Vehicular Communications (WiVeC'07) page： - 2007.9

Language：English

Efficient Channel Estimation Scheme for Pulse-shaping OFDM Systems Reviewed

B.Mongol, T. Yamazato, M. Katayama

International Symposium on Nonlinear Theory and its Applications page： - 2007.9

Language：English

Hierarchical Coding Scheme for Optical Wireless Communicaiton using LED Traffic Light and High-Speed Camera Reviewed

K. Masuda, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J90-A ( 9 ) page： 696-704 - 704 2007.9

A study on position estimation method for multiple targets detection for automotive radar networks Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

Transactions of Society of Automotive Engineers of Japan Vol. 38 ( 5 ) page： 191-196 2007.9

Performance Improvement of Downlink MC-CDMA Cellular System using Different Arrival Time of the Adjacent Cell Signal

M. Fushiki, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. RCS2007-68 page： 87-91 2007.8

Language：Japanese

Performance evaluation of cooperative transmission in distributed sensor networks using FPGA

K. Nakao, T. Yamazato, M. Katayama

Proceedings of 9th DSPS Educators Conference page： 91-92 2007.8

Throughput evaluation of CSMA and CDMA slotted ALOHA in Inter-Vehicle communication

A.Sakata, T.Yamazato, H.Okada, M.Katayama

Technical Report of IEICE Vol. RCS2007-55 page： 13-18 2007.8

Language：Japanese

This paper evaluate the throughput performance of a carrier-sense multiple access (CSMA) scheme that uses an orthogonal frequency division multiple access (OFDM) physical layer and a CDMA slotted ALOHA scheme based on multicarrier CDMA (MC-CDMA) in inter-vehicle communication (IVC). In particular, we compare the throughputs in a situation where a hidden terminal is no longer negligible. We encounter such a situation in an intersection where two or more cars are crossing by. In a hidden terminal situation, the CSMA scheme may degrade throughput. On the other hand, CDMA slotted ALOHA has a resistance to the hidden terminal situation as it can support simultaneous packets. However, the transmission data rate is much slow because of the spreading. Thus the total throughput may not be as high as the CSMA based OFDM even in a hidden terminal situation. As results, we show that the CSMA based OFDM system shows better total throughput than CDMA slotted ALOHA in all region. But, only the signal from the nearest car can be received. On the contrary, CDMA slotted ALOHA can receive many packets simultaneously. This is much preferable feature for safety driving.

Measurement of the Narrowband Channel Characteristics \\in Single-Phase Three-Wire Indoor Power-Line Channels

Y. Sugiura , T. Yamazato, M. Katayama

Technical Report of IEICE page： - 2007.8

Language：Japanese

This manuscript reports the measurement results of narrow-band signal propagation of PLC channels between a pair of outlets. In Japan, in-house wiring is of single-phase three-wire, and each branch between an outlet of 100V and the panel board is connected to one of two live conductors and the neutral. Thus a pair of outlets can be classified into three types: connected to different live conductors, connected to the same live conductors by different branches from the panel board, and on the same branch to the same live conductor. It is confirmed that the results of the measurements are also classified by these three types of paths. The results show that frequency responses of narrow-band PLC channels are relatively smooth, compared with that of wide-band PLC. It is also found that propagation loss in lower frequency range is larger than in higher frequency range. The time independence of narrow-band PLC channels are confirmed when no electric appliance is connected to the same live conductor.

Ultrasonic Array Emitter for Short-range Automotive Targets Detection System

H. Hatano, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. ITS2007-12 page： 15-20 2007.7

Language：Japanese

We consider application of ultrasonic sensor to automotive targets detection system for short-range. The ultrasonic sensors are low cost and widely used. However the detection range is short. In addition, wide detection area is needed. To apply for high functional parking aid system, we propose the array emitter which can emit signals to desired area within desired cycle time. As a result, we show the ability of the ultrasonic sensor for parking aid systems.

A Method for Reducing the Influence of the Interference Considering ADC Nonlinearity in an OFDM Receiver Reviewed

M. Sawada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J90-B ( 6 ) page： 577-584 2007.6

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper we propose an OFDM receiver that mitigates the performance degradation caused by interference. The mitigation process is done all in digital after ADCs. The receiver estimates the reliability of each OFDM symbol based on its number of out-of-range samples. This reliability is then used as the external information in soft Viterbi decoding process. The results of numerical simulations for 16QAM/OFDM show that the proposed receiver is robust to strong interference.

Cooperative Transmission Scheme in Distributed Sensor Network for Extension of Transmission Range Reviewed

K. Nakao, T. Yamazato, H. Okada, M. Katayama

Fourth International Conference on Networked Sensing Systems page： 89-92 2007.6

Language：English

We consider a distributed transmission of data packet to a sink where the distance for a sensor node to the sink is much longer than a sensor node can transmit. We give a simple modification in the transmitter, i.e., multiplication of random phase before the transmission. Thanks to a strong error correcting code, it is possible to extend the transmission range as the received amplitude varies symbol by symbol for our scheme while whole data packet may be lost for the conventional scheme.

Throughput Comparison of CSMA and CDMA slotted ALOHA in Inter-Vehicle Communication Reviewed

A.Sakata, H.Okada, T.Yamazato, M.Katayama

The 7th International Conference on ITS Telecommunications page： 52-57 2007.6

Language：English

This paper compare the throughput performance of a carrier-sense multiple access (CSMA) scheme that uses an orthogonal frequency division multiple access (OFDM) physical layer and a CDMA slotted ALOHA scheme based on multicarrier CDMA (MC-CDMA) in inter-vehicle communication (IVC). In particular, we compare the throughputs in a situation where a hidden terminal is no longer negligible. We encounter such a situation in an intersection where two or more cars are crossing by. In a hidden terminal situation, the CSMA scheme may degrade throughput. On the other hand, CDMA slotted ALOHA has a resistance to the hidden terminal situation as it can support simultaneous packets. However, the transmission data rate is much slow because of the spreading. Thus the total throughput may not be as high as the CSMA based OFDM even in a hidden terminal situation. As a result, we show that the CSMA based OFDM system shows better total throughput than CDMA slotted ALOHA in all region. But, only the signal from the nearest car can be received. On the contrary, CDMA slotted ALOHA can be received many packets simultaneously. This is much preferable feature for safety driving.

Experiments on a Wireless Visible-Light Communication System using an LED Sign Panel

T. Ohtsuji, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. OCS2007-14 page： 25-29 2007.6

Language：Japanese

This manuscript focuses on a wireless visible-light communication system with an LED-back-lighted sign board. Possibilities of the system are confirmed by experiment. In the experimental system, the transmitter uses frequency shift keying (FSK), which has constant envelope to avoid fluctuation of luminance and can be received without carrier phase synchronization. Since the noise and signal propagation in Electric/Optical/Electric channel are not flat in frequency, we introduce a weighting equalization before the decision circuit of the receiver. Experimental results show that this weighting improves bit error rate (BER) performance and extend distance between the transmitter and the receiver.

Channel measurement of a visible light communication system with an LED sign panel

D. Ishida , T. Yamazato, M. Katayama

Technical Report of IEICE Vol. OCS2007-15 page： 31-35 2007.6

Language：Japanese

As one of visible light communications systems, this paper focuses on a system using LED sign panel as a transmitter. The characteristic between the panel (E/O) input and the APD(O/E) output is measured. Linearity, frequency response, and the levels of harmonics of the channel is measured. The effects of the distance between the panel and the APD on the signal level is clarified. After the measurement of noise spectrum caused by an inverter-driven fluorescent lamp, the SNR in frequency is calculated.

A Study on Joint Decoding for Wireless Sensor Networks

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

Proc. of Academia Program, Wireless Technology Park 2007 page： 26-27 2007.4

Language：Japanese

Development of tiny sensor equipped with wireless communication function is remarkable with the advancement of small, light, and high-performance wireless devices. In the near future, we will see tens or hundreds of these nodes deployed in town and inside buildings. In such an environment, since many sensor nodes observe a same target or field, the information observed by each sensor node are correlated. Such correlated information are collected at a fusion center. Our purpose is to reduce channel error by using the correlation properties of observed data at the fusion center. Related works on the distributed encoding and joint decoding are the case of two correlated sources. By using the weighted correlation feedback, we extend the iterative joint decoding scheme for the general case where more than two sensor nodes are employed. We show that when the number of sensor nodes is increased, decoding performance improvement cannot be achieved by simple weighting. For more appropriate weighting, we find the weight that minimizes the bit error rate from the analytical formula of MAP decision and apply it to the case of Turbo code.

A Simple Estimator of Multiple Target Positions for Automotive Short Range Radar Networks Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

IEEE Vehicular Technology Conference (VTC) page： 2511-2515 2007.4

Language：English

For safety applications, automotive radar networks show an interesting potential. Apart from long range radars, networked short range radar systems are under development. Additional applications can be accomplished, such includes precrash detection, parking aid and blind spot surveillance. We research the automotive radar networks using short range radars. The network is built with multiple radars. In this paper, we consider data processing using measured ranges provided by the radars in order to estimate multiple target positions with high accuracy. Firstly, we derive a method based on MAP stimation. Secondly, we propose a method which reduces the calculation complexity compared to the above MAP method. Finally, we introduce a method which can detect targets with low ndetected targets. The case often happens when the measured ranges are lost because of miss-detections.We evaluate the performance th computer simulations.

Visible Light Communication using LED TrafficLight and car equipped with camera

T. Yamazato, M. Katayama

Proc. of Academia Program, Wireless Technology Park 2007 page： 38-39 2007.4

MIMO Equalizer for Pulse-ShapingOFDM Systems in Dispersive Time-Varying Channels

B. Mongol , T. Yamazato, H. Okada, M. Katayama

Proc. of Academia Program, Wireless Technology Park 2007 page： 50-51 2007.4

Language：Japanese

Pulse-shaping OFDM is well-known that it performs well in a mobile environment, i.e. time-varying channel, compared with conventional OFDM. However, as the time-variance becomes higher, the intersymbol and intercarrier interferences (ISI/ICIs) increase and can no longer be neglected. These ISI/ICIs deteriorate the performance of the systems. Proper channel equalization is needed for further improvement of the systems. In this paper, we have proposed a multi-input multi-output (MIMO) transversal filter to equalize the time-frequency dispersive channel. Tap weights are calculated using the zero-forcing (ZF) algorithm. We also have proposed maximum-likelihood channel estimator and its low-complexity version. The proposed system can significantly improve the performance of the pulse-shaping systems in the dispersive time-varying channels.

A-21-25 Noncoherent Detection for Cooperative Transmission in Distributed Sensor Network Reviewed

Nakao Kouji, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2007 page： 416 2007.3

*Nagoya University OpenCourseWare Invited

T. Yamazato

Annals of Nagoya UniversityAnnals of Nagoya University Vol. 第５号 page： 51-55 2007.3

Language：Japanese Publishing type：Research paper (bulletin of university, research institution)

The Nagoya University OpenCourseWare Committee is currently working to make some of the university's teaching materials openly available for instructors, students and self-directed learners around the world via the Internet. In this report, OpenCourseWare activity in Nagoya University is introduced.

Inter-Network Communication Method for Multihop Token Line Protocol

M. Masamura, H. Okada, T. Yamazato, M. Katayama

IEICE General Conference page： - 2007.3

Power-line communication system using correlations of instantaneous noise powers at a transmitter and a receiver

A. Kawaguchi, H. Okada, T. Yamazato, M. Katayama

IEICE General Conference Vol. A-5-22 page： - 2007.3

Performance Improvement of MC-CDMA System using Different Arrival Time of the Other Cell Signal

M. Fushiki, T. Yamazato, H. Okada, M. Katayama

IEICE General Conference page： - 2007.3

Radio Resource Allocation using Priority Based on User Position for Multiuser OFDM

K. Kimura T. Yamazato, M. Katayama

IEICE General Conference Vol. B-5-122 page： 536 2007.3

Noncoherent Detection for Cooperative Transmission in Distributed Sensor Network

K. Nakao, T. Yamazato, H. Okada, M. Katayama

IEICE General Conference Vol. A-21-25 page： 416 2007.3

Coded Modulation in Consideration of State of Signals for M-ary PSK Coherent Signals Reviewed

T. Otake, H. Okada, T. Yamazato, K. Yamazaki, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J90-A ( 3 ) page： 257-261 2007.3

Coded Modulation in Consideration of State of Signals for M-ary PSK Coherent Signals Reviewed

T. Otake, H. Okada, T. Yamazato, K. Yamazaki, M. Katayama

IEICE Transaction on Fundamentals Vol. J90-A ( 3 ) page： 257-261 - 261 2007.3

Compensation Scheme for Nonlinear Distortion with 8PSK/OFDM Transmission in Nonlinear Satellite Channel Reviewed

T. Yamaoka, T. Yamazato, H. Okada, M. Katayama

IEICE Transactions on Communications Vol. J90-B ( 2 ) page： 138-147 2007.2

Language：Japanese Publishing type：Research paper (scientific journal)

This paper discusses 8PSK/OFDM transmission in nonlinear satellite channel. We propose an effective compensation scheme for nonlinear distortion with high coding rate. Proposed compensation scheme is composed by bit-interleaved coded modulation with iterative decoding and original compensation for nonlinear distortion. The proposed scheme has lower complexity by combining two feedback systems and achieves good error performance under large nonlinear distortion in satellite channel.

Compensation Scheme for Nonlinear Distortion with 8PSK/OFDM Transmission in Nonlinear Satellite Channel Reviewed

T. Yamaoka, T. Yamazato, H. Okada, M. Katayama

IEICE Transactions on Communications Vol. J90-B ( 2 ) page： 138-147 - 147 2007.2

Route Characteristic Estimation for Multi-Route Coding in Wireless Multihop Networks Reviewed

H. Okada, M. Umakoshi, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J90-B ( 1 ) page： 93-96 2007.1

Language：Japanese Publishing type：Research paper (scientific journal)

In the multi-route coding, encoded subpackets are transmitted via multiple routes and decoded at a destination node to get diversity gain. Because the characteristic of each route is usually different, the performance will be improved by considering it. In this letter, we propose the estimation scheme of route characteristic.

Routing Protocol for Multi-Route Coding Based on Link Quality in Multihop Cellular Networks

H. Imai, H. Okada, T. Yamazato and M. Katayama

6th Ad-hoc Network Workshop Vol. 5-5 - 5-8 page： - 2007.1

Language：Japanese

Multihop cellular networks using wireless multihop communications for cellular system are considered in this paper. In this networks, we proposed the multi-route coding scheme. In the multi-route coding, packets are encoded and divided into sub packets, and they are transmitted on multiple routes from usernode to multiple base stations. In this paper, we introduce the bit error rate on each route as route selection metrics in a routing protocol for the multi-route coding. We evaluate the performance of the multi-route coding using the bit error rate metric and show that the routing protocol based on its metric improve the packet error rate.

Route Characteristic Estimation for Multi-Route Coding in Wireless Multihop Networks Reviewed

H. Okada, M. Umakoshi, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J90-B ( 1 ) page： 93-96 - 96 2007.1

A new nonlinear distortion compensation scheme for 8PSK/OFDM in satellite channel Reviewed

Yamazato T., Yamaoka T., Okada H., Katayama M.

25th AIAA International Communications Satellite Systems Conference 2007

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：25th AIAA International Communications Satellite Systems Conference

DOI： 10.2514/6.2007-3289

A novel contention-free medium access control protocol for inter-vehicle communication systems Reviewed

Mitsuru Masamura, Hiraku Okada, Satoshi Makido, Takaya Yamazato, Masaaki Katayama

2007 IEEE INTERNATIONAL CONFERENCE ON MOBILE AD-HOC AND SENSOR SYSTEMS, VOLS 1-3 page： 995 - + 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/MOBHOC.2007.4428733

A simple estimator of multiple target positions for automotive short range radar networks Reviewed

Hatano Hiroyuki, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6 page： 2511 - + 2007

A route selection scheme for multi-route coding in multihop cellular networks Reviewed

Hiraku Okada, Hitoshi Imai, Takaya Yamazato, Masaaki Katayama, Kenichi Mase

2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5 page： 6 - + 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/VETECF.2007.18

A route selection scheme for multi-route coding in multihop cellular networks Reviewed

Okada Hiraku, Imai Hitoshi, Yamazato Takaya, Katayama Masaaki, Mase Kenichi

2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5 page： 6 - + 2007

Automotive ultrasonic array emitter for short-range targets detection Reviewed

Hatano Hiroyuki, Yamazato Takaya, Katayama Masaaki

2007 FOURTH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS, VOLS 1 AND 2 page： 582 - 586 2007

Automotive ultrasonic array emitter for short-range targets detection Reviewed

Hiroyuki Hatano, Takaya Yamazato, Masaaki Katayama

2007 FOURTH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS, VOLS 1 AND 2 page： 582 - 586 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Distributed space-time block coding for large and undetermined set of relay terminals Reviewed

Cooperative transmission scheme in distributed sensor network for extension of transmission range Reviewed

Nakao Koji, Yamazato Takaya, Katayama Masaaki, Okada Hiraku

INSS 07: PROCEEDINGS OF THE FOURTH INTERNATIONAL CONFERENCE ON NETWORKED SENSING SYSTEMS page： 89 - + 2007

Experiment on hierarchical transmission scheme for visible light communication using LED traffic light and high-speed camera Reviewed

Arai Shintaro, Mase Shohei, Yamazato Takaya, Endo Tomohiro, Fujii Toshiaki, Tanimoto Masayuki, Kidono Kiyosumi, Kimura Yoshikatsu, Ninomiya Yoshiki

2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5 page： 2174 - + 2007

Ryosuke Uchida, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9 page： 2727 - + 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this manuscript, a decode-and-forward cooperative diversity scheme for wireless packet transmission network with large and undetermined set of relay terminals is considered. Correctly received signals at some relay terminals are retransmitted to the receiver with the STBC-based cooperative relaying scheme. For large and undetermined set of relay terminals, performance of the conventional STBC-based cooperative diversity is known to be degraded due to the loss of the diversity gain and increasement of decoding complexity. In this manuscript, we propose a signaling scheme to reduce the performance loss. Our proposed scheme is based on the linear transformation of the STBC matrix by a signature vector, which has more degrees of freedom for the assignment of signals compared to the conventional STBC-based cooperative diversity.

DOI： 10.1109/PIMRC.2007.4394668

Experiment on hierarchical transmission scheme for visible light communication using LED traffic light and high-speed camera Reviewed

Distributed space-time block coding for large and undetermined set of relay terminals Reviewed

Uchida Ryosuke, Okada Hiraku, Yamazato Takaya, Katayama Masaaki

2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9 page： 2727 - + 2007

Shintaro Arai, Shohei Mase, Takaya Yamazato, Tomohiro Endo, Toshiaki Fujii, Masayuki Tanimoto, Kiyosumi Kidono, Yoshikatsu Kimura, Yoshiki Ninomiya

2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5 page： 2174 - + 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

LEDs are expected as lighting sources for next generation, and data transmission system using LEDs attract attention. In this paper, we present hierarchical coding scheme using LED traffic lights and high-speed camera for Intelligent Transport Systems (ITS) application. Further, if each of LEDs in. traffic lights is individually modulated, parallel data transmissions are possible using a camera as a reception device. Such parallel LED-camera channel can be in deled as spatial low-pass filtered channel of which the cut-off frequency vanes according to the distance. To overcome, we propose hierarchical coding scheme based on 2D fast Haar wavelet transform. As results, the proposed hierarchical transmission schemes outperform the conventional on-off keying and the reception of high priority data is guaranteed even LED-camera distance is further.

DOI： 10.1109/VETECF.2007.456

Improvement of transmission quality using correlation of observational data in sensor networks Reviewed

Kentaro Kobayashi, Takaya Yamazato, Hiraku Okada, Masaaki Katayama

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 90 ( 11 ) page： 1 - 10 2007

Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

In sensor networks, many of the sensor nodes are often positioned in clusters, and there is a correlation between the data obtained at the various sensor nodes by observation. This kind of observational data is collected at fusion centers. In this paper, we study the observation precision at fusion centers from the viewpoint of the Kullback-Leibler (KL) information. In particular, we consider transmission path errors arising when transmission is made from each sensor node via wireless communication paths, as a factor in the deterioration of the KL information, or in other words, observation precision, and study its effects and methods for reducing it. In this paper, We Study the KL information obtained in fusion centers when there have been transmission path errors in cases where the correlation between observational data is all equal, and where the correlation is random. We show that the deterioration of the KL information can be reduced in fusion centers by using the correlation of observational data in the estimates of error data. In addition, we present examples of estimating the correlation between observational data in fusion centers that use correlation, and of estimating error data using correlation. (C) 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3. 90(11): 1-10, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).

DOI： 10.1002/ecjc.20250

Route diversity effect of joint decoding using correlation between observed data sequences in sensor networks Reviewed

Performance analysis of UWB impulse radar receiver using parallel IPCP Reviewed

Hatano Hiroyuki, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 90 ( 7 ) page： 1 - 14 2007

Hiraku Okada, Kentaro Kobayashit, Takaya Yamazato, Kenichi Mase

2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6 page： 217 - 221 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In sensor networks, because of densely deployment of sensor nodes, sensing area of each sensor node is overlapped with each other and its observed data sequence is correlated. The joint decoding scheme that uses the correlation between the observed data sequences can reduce bit errors in the wireless channel. In this paper, we extend the joint decoding to the case of more than two-hop transmission. For such extension, selection of fusion scheme is very important issue. If the global fusion scheme is employed and the observed data sequence of each sensor node is transmitted on an independent route, route diversity effect could be obtained by using the correlation between observed data sequences. We compare the bit error rate performance of local and global fusion schemes and clarify the route diversity effect.

DOI： 10.1109/VETECS.2007.57

Throughput comparison of CSMA and CDMA slotted ALOHA in inter-vehicle communication Reviewed

Sakata Atsunori, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

2007 7TH INTERNATIONAL CONFERENCE ON ITS TELECOMMUNICATIONS, PROCEEDINGS page： 52 - + 2007

A novel contention-free medium access control protocol for inter-vehicle communication systems Reviewed

Masamura Mitsuru, Okada Hiraku, Makido Satoshi, Yamazato Takaya, Katayama Masaaki

2007 IEEE INTERNATIONAL CONFERENCE ON MOBILE AD-HOC AND SENSOR SYSTEMS, VOLS 1-3 page： 995 - + 2007

Iterative channel decoding scheme using the correlation of transmitted information sequences in sensor networks Reviewed

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J89-A ( 12 ) page： 1044-1056 2006.12

Language：Japanese Publishing type：Research paper (scientific journal)

In sensor networks, many sensor nodes are densely deployed and observation data obtained by each sensor node are correlated. The observation data are encoded and transmitted from each sensor node. Such observation data are collected at a fusion center. In this paper, we extend the iterative channel decoding scheme using the correlation of transmitted information sequences to the case of more than two sensor nodes. An approach to use practical channel codes for more than two correlated data is still not presented. A problem in the extension to cases of more than two sensor nodes is how to use the information of correlation obtained from observation data. In this paper, we propose an iterative channel decoding scheme that uses them with weighting. We show that when the number of sensor nodes is increased, decoding performance improvement cannot be achieved by simple weighting, and so a more appropriate weight is needed. We find the weight that minimizes the bit error rate from the analytical formula for uncoded BPSK and apply it to the case of Turbo code.

Influence of ADC Nonlinearity on the Performance of an OFDM Receiver Reviewed

M. Sawada, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. E89-B ( 12 ) page： 3250-3256 2006.12

Language：English Publishing type：Research paper (scientific journal)

This paper discusses the influence of the nonlinearity of analog-to-digital converters (ADCs) on the performance of orthogonal frequency division multiplexing (OFDM) receivers. We evaluate signal constellations and bit error rate performances while considering quantization errors and clippings. The optimum range for an ADC input amplitude is found as a result of the trade-off between quantization error and the effects of clipping. In addition, it is shown that the peak-to-average power ratio (PAPR) of the signal is not a good measure of the bit error rate (BER) performance, since the largest peaks occur only with very low probabilities. The relationship between the location of a subcarrier and its performance is studied. As a result, it is shown that the influence of the quantization error is identical for all subcarriers, while the effects of clipping depend on the subcarrier frequency. When clipping occurs, the BER performance of a subcarrier near the center frequency is worse than that near the edges.

Iterative Channel Decoding Scheme Using Correlation between Transmitting Data Sequences for Fading Channels

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

Technical Report of IEICE Vol. SN2006-45 page： 45-51 2006.12

Language：Japanese

Influence of Characteristics of Wireless Channels on Quality of Wireless Control Systems Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J89-A ( 12 ) page： 1104-1107 2006.12

Language：Japanese Publishing type：Research paper (scientific journal)

In this manuscript, the employment of wireless data transmission for control of industrial machines in an indoor fading environment is considered. The relationship between the performance of the wireless control and that of the wireless transmission is studied in two types of the systems: the system with wireless transmission both for a control signal to a controlled target and a feedback signal from a sensor at the target; and the system that employs wireless transmission only for a control signal. As a result, it is shown that the performance of the systems can be improved by increasing the transmission rate as well as decreasing the error rate. The fact suggests how the wireless transmission should be designed to maintain high quality in wireless-controlled systems.

Channel estimation for BFDM/OQAM system in dispersive time-varying channels Reviewed

Mongol B.

3rd International Symposium on Wireless Communication Systems 2006, ISWCS'06 page： 159 - 163 2006.12

Influence of ADC nonlinearity on the performance of an OFDM receiver Reviewed

Manabu Sawada, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E89B ( 12 ) page： 3250 - 3256 2006.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1093/ietcom/e89-b.12.3250

Throughput evaluation of ARQ scheme for multi-route coding in wireless multi-hop networks Reviewed

Okada H.

IEEE Vehicular Technology Conference Vol. 2 page： 668 - 672 2006.12

Iterative channel decoding scheme using the correlation of transmitted information sequences in sensor networks Reviewed

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J89-A ( 12 ) page： 1044-1056 - 1056 2006.12

Influence of Characteristics of Wireless Channels on Quality of Wireless Control Systems Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals Vol. J89-A ( 12 ) page： 1104-1107 - 1107 2006.12

MIMO Zero-forcing Equalizer for BFDM/OQAM Systems in the Time-Frequency Dispersive Channels Reviewed

B. Mongol, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E89-A ( 11 ) page： 3114-3122 2006.11

Language：English Publishing type：Research paper (scientific journal)

Pulse-shaping OFDM is well-known that it performs well in a mobile environment compared with conventional OFDM. However, in a highly mobile environment intersymbol and intercarrier interferences (ISI/ICIs) increase and can no longer be neglected. These ISI/ICIs deteriorate the performance of the systems. Proper channel equalization is needed for further improvement of the systems. In this paper, a more general case, namely Biorthogonal Frequency Division System based on Offset QAM (BFDM/OQAM) is considered. We propose a multi-input multi-output (MIMO) transversal filter to equalize the time-frequency dispersive channel. Tap weights are calculated using the zero-forcing (ZF) algorithm. We also propose maximum-likelihood channel estimator and its low-complexity version. The proposed system can significantly improve the performance of BFDM/OQAM systems in the highly mobile environment.

MIMO Zero-forcing Equalizer for BFDM/OQAM Systems in the Highly Mobile Environments Reviewed

B. Mongol, T. Yamazato, H. Okada, M. Katayama

IEEE Global Communications Conference page： - 2006.11

Language：English

Pulse-shaping OFDM is well-known that it performs well in a mobile environment comparing with conventional OFDM. However, in highly mobile environment intersymbol and intercarrier interferences (ISI/ICIs) increase and can no longer be neglected. These ISI/ICIs deteriorate the performance of the systems. Proper channel equalization is needed for further improvement of the systems. In this paper, more general case, namely Biorthogonal Frequency Division System based on Offset QAM (BFDM/OQAM) is considered. We propose a multi-input multi-output (MIMO) transversal filter to equalize the time-frequency dispersive channel. Tap weights are calculated using the zero-forcing (ZF) algorithm. We also propose maximum-likelihood channel estimator and its low-complexity version. The proposed system can significantly improve the performance of BFDM/OQAM systems in the highly mobile environment.

Influence of Transmit and Receive Correlations on Performance of the MIMO System with Multiple Antennas and Relay Terminals

R. Uchida, H. Okada, T. Yamazato, M. Katayama

MObile Radio Interdisciplinary Workshop (MORI Workshop) page： - 2006.11

A study on the Method for Reducing the Influence of the Interference Considering ADC Nonlinearity in an OFDM Receiver

M. Sawada, T. Yamazato, M. Katayama

Symposium on Information Theory and Its Applications (SITA) Vol. 2 page： 691-694 2006.11

Language：Japanese

MIMO zero-forcing equalizer for BFDM/OQAM systems in time-frequency dispersive channels Reviewed

Bayarpurev Mongol, Takaya Yamazato, Hiraku Okada, Masaaki Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E89A ( 11 ) page： 3114 - 3122 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

DOI： 10.1093/ietfec/a89-a.11.3114

MIMO zero-forcing equalizer for BFDM/OQAM systems in time-frequency dispersive channels Reviewed

Mongol Bayarpurev, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E89A ( 11 ) page： 3114 - 3122 2006.11

A study on route selection metrics for the multiple-route packet combining scheme in wireless multihop networks Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J89-B ( 10 ) page： 2047-2051 2006.10

Iterative Joint Channel-Decoding Scheme Using the Correlation of Transmitted Information Sequences Reviewed

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

The 2006 International Symposium on Information Theory and Its Applications page： 808-813 2006.10

Language：English

In this study, we consider joint channel decoding of Turbo code for multiple correlated data that are observed by sensor nodes densely deployed in a sensor field. We focus on the correlation properties of observation data and try to reduce decoding error by an iterative procedure. An approach to use practical channel codes for more than two correlated data is still not presented. A problem in the extension to cases of more than two sensor nodes is how to use the information of correlation obtained from observation data. In this study, we propose an iterative channel decoding scheme that uses them with weighting. We show that when the number of sensor nodes is increased, decoding performance improvement cannot be achieved by simple weighting, and so a more appropriate weight is needed. We find the optimum weight that minimizes the bit error rate from the analytical formula for uncoded BPSK and apply it to the case of Turbo code.

Influence of Transmit and Receive Correlations on Performance of the MIMO System with Multiple Antennas and Relay Terminals Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

The 2006 International Symposium on Information Theory and Its Applications page： 454-459 2006.10

Language：English

In this manuscript, spatial diversity for in-factory environments is considered. The proposed scheme uses multiple antennas at a transmitter and a receiver, and also multiple relay terminals to provide diversity gain against fading and shadowing. If the separation of antennas at the transmitter or the receiver is not enough, then diversity gain is influenced by correlation at the transmitter or the receiver. This manuscript shows the analytical and numerical results of the effects of transmit and receive correlations on bit error performance of the proposed spatial diversity scheme.

A Study on Blind Cooperative Relaying Scheme with Space-Time Block Coding

R. Uchida, H. Okada, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. RCS2006-142 page： 55-60 2006.10

Language：Japanese

In this manuscript, a spatial diversity scheme with multiple transmit and receive antennas together with multiple relay terminals for packet radio is considered. Correctly received signals at relay terminals are re-transmitted to the base station with the spatial diversity by STBC cooperative relaying scheme. To achieve high diversity order with the conventional STBC cooperative relaying scheme, the relay terminals are required to exchange signaling information with each other. In this manuscript, a novel signaling scheme for the STBC cooperative relaying is proposed. The proposed scheme releases relay terminals exchanging of the signaling information and saves the communication rosource to provide flexibility for installation of relay terminals. As a benchmark to the proposed scheme, optimum signaling case is also considered.

Foreword: Special section on information theory and its applications Reviewed

Morita H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E89-A ( 10 ) page： 2457 - 2458 2006.10

A study on route selection metrics for the multiple-route packet combining scheme in wireless multihop networks Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J89-B ( 10 ) page： 2047-2051 - 2051 2006.10

A-21-15 A Study on Fusion Schemes for Joint Decoding Using Correlation between Observed Data Sequences Reviewed

Okada Hiraku, Kobayashi Kentaro, Yamazato Takaya, Mase Kenichi

Proceedings of the Society Conference of IEICE Vol. 2006 page： 227 2006.9

A study on the reduction of the influence of the interference using ADC nonlinearity in an OFDM receiver

M. Sawada, T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. B-17-5 page： 515 2006.9

A Correlation Tolerant Relaying Scheme for the Spatial Diversity with Multiple Transmit and Receive Antennas

R. Uchida, H. Okada, T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. B-5-122 page： 482 2006.9

Channel Estimation for BFDM/OQAM System in Dispersive Time-Varying Channels Reviewed

B. Mongol, T. Yamazato, H. Okada, and M. Katayama

International Symposium on Wireless Communication Systems page： - 2006.9

Language：English

Pulse-shaping OFDM is well-known that it performs well in a mobile environment comparing with conventional OFDM. However, in highly mobile environment intersymbol and intercarrier interferences (ISI/ICIs) increase and can no longer be neglected. These ISI/ICIs deteriorate the performance of the systems. Practically, proper channel equalization and estimation are needed for further improvement of the systems. In this paper, more general case, namely Biorthogonal Frequency Division System based on Offset QAM (BFDM/OQAM) is considered. We first derive analytical equations for the channel statistics. Further, we propose maximum-likelihood channel estimator and its low-complexity versions. The performance analysis shows that the estimators are robust against Doppler spread of the channels.

The Effect of Multipath Hybrid Routing Protocol in Multihop Cellular Networks Reviewed

H. Imai, H. Okada, T. Yamazato, M. Katayama

The 17th Annual IEEE International Symposium on Personal Indoor and Mobile Radio Communication page： - 2006.9

Language：English

This paper examines multihop cellular networks. There are some issues in these networks, such as route loss due to topological change and packet errors due to wireless nodes relay. To overcome these issues, we use a multiple route coding scheme in which packets are transmitted on multiple routes from a user node to multiple base stations. This scheme can achieve a diversity gain by combining packets that are transmitted along multiple routes. Some challenges must be met to establish multiple routes for this scheme. In this paper, we propose a routing protocol for multiple route coding. The key idea of this proposed scheme is using a hybrid routing protocol. This can mitigate an increase in control packets and multiple disjoint routes can be constructed. We evaluate the performance of this proposed scheme.

Optical Wireless Communicaiton using LED Traffic Light and High-Speed Camera

T. Yamazato, K. Masuda, H. Okada, M. Katayama

Technical Report of IEICE Vol. SIP2006-58 page： 25-30 2006.7

Language：Japanese

A Mathematical Model of Noise in Narrowband Power-Line Communication Systems Reviewed

M. Katayama, T. Yamazato, H. Okada

IEEE Journal on Selected Areas in Communications Vol. 24 ( 7 ) page： 1267-1275. 2006.7

Language：English Publishing type：Research paper (scientific journal)

This manuscript introduces a mathematically tractable and accurate model of narrowband power-line noise based on experimental measurements. In this paper, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power-line noise can be described in close form. The periodic function that represents the variance is then approximated with a small number of parameters. The noise waveform generated with this model shows good agreement with that of actually measured noise. Noise waveforms generated by different models are also compared to that of the proposed mode.

A mathematical model of noise in narrowband power line communication systems Reviewed

Masaaki Katayama, Takaya Yamazato, Hiraku Okada

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 24 ( 7 ) page： 1267 - 1276 2006.7

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This manuscript introduces a mathematically tractable and accurate model of narrowband power line noise based on experimental measurements. In this paper, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power line noise can be described in close form. The periodic function that represents the variance is then approximated with a small number of parameters. The noise waveform generated with this model shows good agreement with that of actually measured noise. Noise waveforms generated by different models are also compared with that of the proposed model.

DOI： 10.1109/JSAC.2006.874408

Peformance analysis of UWB Impulse Radar Receiver using Parallel IPCP Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Communications Vol. J89-A ( 6 ) page： 544-556 2006.6

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we consider two novel inter-period correlation processing (IPCP) receivers for UWB impulse radar. The conventional IPCP receiver uses the signal periodicity of signals, so it avoids estimation of unknown parameters determined by the targets. However, its accuracy of measurement is poor because the interval of receiver outputs is restricted to a code length. We propose a parallel IPCP receiver to improve accuracy. When there are multiple targets, the conventional IPCP receiver needs multiple thresholds to detect. This results in complexity of the receiver. So, we propose a parallel differential IPCP receiver. We present the analysis of proposed receivers.

An Inter-Vehicle Two-Way Communication System

M. Masamura, H.Okada, S. Makido, T. Yamazato, M. Katayama

4th Ad-hoc Network Workshop Vol. 4-21 - 4-24 page： - 2006.6

Language：Japanese

We propose an inter-vehicle two-way communication system for safety applications. The proposed system synchronizes with transmission timings mong cars by one-direction token transmissions in a linear network. The token contains the frame information about transmission/reception phase. The token transmission interval is set so that adjacent reception cars do not affect interference from other cars. Moreover, multiple channels are used in order to make the same transmission delays despite of their transmission directions and reduce them. This system can adapt changes of the network structure by allocating channels dynamically for every token.

An Analysis on Influence of Transmit and Receive Correlations on Performance of the MIMO System with Relay Terminals

R. Uchida, H. Okada, T. Yamazato, and M. Katayama

Technical Report of IEICE Vol. RCS2006-46 page： 65-70 2006.6

Language：Japanese

In this manuscript, a spatial diversity scheme with multiple transmit and receive antennas and relay terminals for indoor factory fading/shadowing environment is considered. The scheme uses multiple transmit and receive antennas and relay terminals to provide diversity gain against the fading and shadowing. However, if the separations of antennas at a transmitter or a receiver are not enough, then the signals of the diversity branches may be influenced by transmit or receive correlation. This manuscript shows the analytical and numerical results of the effect of the transmit and receive correlations on the performance of the spatial diversi ty scheme.

Performance Analysis of ARQ Scheme for Multi-route Coding in Wireless Multi-hop Networks Reviewed

H. Okada, T. Wada, K. Ohuchi, M. Saito, T. Yamazato, M. Katayama

IEEE Vehicular Technology Conference (VTC) page： - 2006.5

Language：English

For reduction in bit errors on wireless channels, we proposed the multi-route coding scheme on multiple routes for wireless multi-hop networks. In this paper, we introduce ARQ to the multi-route coding. In the multi-route coding, the destination node combines and decodes sub packets which are encoded and divided by the source node. The intermediate node relays a sub packet, that is, only a part of a packet. Therefore, the intermediate node cannot detect packet errors, and only the destination node can do after combining and decoding sub packets. We propose the ARQ scheme between the source node and the destination node. We analyze the proposed ARQ scheme and evaluate the throughput performance.

Iterative channel decoding scheme using the correlation of transmitted information sequences - Extension to the case of more than two sensor nodes -

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

Technical Report of IEICE Vol. SN2006-32 page： 91-97 2006.5

Language：Japanese

In sensor networks, many sensor nodes are densely deployed and observation data obtained by each sensor node is correlated. The observation data is encoded and transmitted from each sensor node. Such observation data are collected at a fusion center. In this paper, we consider a channel decoding scheme using the correlation of observation data. Related works on the encoding and decoding scheme using the correlation of observation data are for the case of two correlated sources. An approach for more than two sources is still not presented. In this paper, we extend the iterative channel decoding scheme using the correlation of transmitted information sequences to the case of more than two sensor nodes. A problem in the extension to the case of more than two sensor nodes is how to use the information of correlation obtained from other sequences. Specifically, it is needed to use them with weighting to minimize the bit error rate. In this paper, we find the optimum weight that minimizes the BER from the analytical formula in the case of uncoded BPSK and apply it to the case of Turbo code.

Throughput Evaluation of ARQ Scheme for Multi-route Coding in Wireless Multi-hop Networks Reviewed

H. Okada, T. Wada, K. Ohuchi, M. Saito, T. Yamazato, M. Katayama

IEEE Vehicular Technology Conference (VTC) page： 668-672 2006.5

Language：English

A study on the mitigation of the influence of ADC nonlinearity in an OFDM receiver

M. Sawada, H. Okada, T. Yamazato, M. Katayama

DENSO TECHNICAL REVIEW Vol. 11 ( 1 ) page： 115-120 2006.5

Language：Japanese

An orthogonal frequency division multiplexing (OFDM) scheme, with highly spectrum efficiency and robustness against frequency selective fading, is applied to IEEE802.11a/g for high-speed wireless local area network (LAN) systems and digital terrestrial television broadcasting (DTTB) systems. The OFDM signal has large fluctuation in its amplitude, large dynamic range and high linearity are required for its transmitter and receiver. In the receiver, the Bit Error Rate (BER) performance is degraded by analog-to-digital converter (ADC) nonlinearity. We propose a new scheme to mitigate the influence of ADC nonlinearity in an OFDM receiver. In the proposed receiver, the weight for the soft Viterbi decoder is controlled based on the ADC output amplitude. We evaluate the BER performance for the proposed receiver when the control errors occur in the AGC amplifier. As a result, the effect of the proposed receiver on the BER performance is shown.

Multi-route Coding in Wireless Multi-hop Networks Reviewed

H. Okada, N. Nakagawa, T. Wada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. E89-B ( 5 ) page： 1620-1626 2006.5

Language：English Publishing type：Research paper (scientific journal)

Wireless multi-hop networks have drawn much attention for the future generation mobile communication systems. These networks can establish multiple routes from a source node to a destination node because of flexible construction of network topology. The transmission by multiple routes has enough capability to achieve reliable communication because we can expect to obtain diversity gain by multiple routes. In this paper, we propose the multi-route coding scheme. At first, we discuss a channel model in multi-hop networks employing regenerative relay, which we named the virtual channel model. By using the virtual channel model, a packet is encoded on multiple routes as follows; a bit sequence of a packet is encoded and divided into subpackets, and each subpacket is transmitted on each route. We evaluate its packet error rate performance, and clarify effectiveness of the proposed scheme. In general, we should face degradation of a route condition such as the case when a subpacket does not reach a destination node. Hence, we have to consider the influence of subpacket loss. We also investigate it, and show tolerance of the proposed scheme over that.

A study on position estimation method based on MAP estimation for multiple targets in car radar networks

H. Hatano, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE Vol. ITS2006-3 page： 39402 2006.5

Language：Japanese

In this paper, we consider radar networks for cars. The radar networks are the networks built with multiple radars. Using measured ranges provided by radars, target positions are estimated. The measured ranges include measurement errors. The estimation method of the target positions using a MAP stimation is an optimum method. However, when the number of targets increases, the MAP estimation method becomes complex. So we introduce the simpler methods based on the MAP estimation method. The performance is evaluated by computer simulations.

Cooperative transmission scheme using coded FSK

K. Nakao, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE Vol. SN2006-28 page： 67-72 2006.5

Language：Japanese

In sensor networks, many sensor nodes are distributed. The observation data are collected at a fusion center. They are transmitted to a fusion center by direct or multihop transmission. In this paper, we consider the situation that the transmission by those ways is not possible (e.g. a helicopter collects the data). We realize the transmission by a cooperative transmission among the nodes. An approach proposed for cooperative transmission is assumed coherent propagation or multi-channel, or applied to only a few nodes. In this paper, we propose a scheme to achieve the cooperative co-channel transmission only coding by multiplying a random phase per symbol.

Peformance analysis of UWB Impulse Radar Receiver using Parallel IPCP Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J89-A ( 6 ) page： 544-556 2006.5

Multi-route coding in wireless multi-hop networks Reviewed

Hiraku Okada, Nobuyuki Nakagawa, Tadahiro Wada, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E89B ( 5 ) page： 1620 - 1626 2006.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Wireless multi-hop networks have drawn much attention for the future generation mobile communication systems. These networks can establish multiple routes from a source node to a destination node because of flexible construction of network topology. Transmissions by multiple routes have enough capability to achieve reliable communication because we can expect to obtain diversity gain by multiple routes. In this paper, we propose the multi-route coding scheme. At first, we discuss a channel model in multi-hop networks employing regenerative relay, which we named the virtual channel model. By using the virtual channel model, a packet is encoded on multiple routes as follows; a bit sequence of a packet is encoded and divided into subpackets, and each subpacket is transmitted on each route. We evaluate its packet error rate performance, and clarify effectiveness of the proposed scheme. In general, we should face degradation of a route condition such as the case when a subpacket does not reach a destination node. Hence, we have to consider the influence of subpacket loss. We also investigate it, and show tolerance of the proposed scheme over that.

DOI： 10.1093/ietcom/e89-b.5.1620

MIMO Zero-forcing Equalizer for BFDM/OQAM Systems in the Highly Mobile Environments Reviewed

Reliable Robust Radio for Wireless Control of Industrial Machines

R. Uchida, H. Okada, T. Yamazato, M. Katayama

Proc. of Academia Program, Wireless Technology Park 2006 page： - 2006.4

Language：Japanese

Wireless control of industrial machines in factories has a lots of advantages over wired control. To achieve wireless control safely, high reliability of the wireless transmission system is required. In this manuscript, wireless transmission system with high reliability in indoor environment is considered. In indoor environment, transmitted signal fluctuates due to fading and shadowing. To combat the fading and shadowing, macro / micro spatial diversity can be used as an effective countermeasure. In this manuscript, macro / micro diversity is achieved by multiple wireless relay terminals, which is convenient in setting and moving the macro diversity branches. In the proposed scheme, channel between the transmitter and the receiver through relay terminals is considered as a MIMO channel and separation of the signals re-transmitted from the relay terminals is not required. This feature makes it possible to have higher order diversity without the cost of bandwidth inefficiency. By numerical calculations, performance of the proposed scheme is evaluated and the improvement of the reliability of the transmission system is confirmed.

Automotive radar network technique for short range

H. Hatano, T. Yamazato, H. Okada, M. Katayama

Proc. of Academia Program, Wireless Technology Park 2006 page： 34-35 2006.4

Language：Japanese

We consider a radar system for vehicles in order to detect obstacles in a short range (up to 10m). In comparison with a long range radar, a short range radar needs wide angular range. Therefore a radar network which is set at front of a vehicle with multiple radars is being considered. The short range radar system also needs estimating obstacle positions with high accuracy. Therefore, by this research, we consider improving accuracy of the position estimation with the radar network. We use MMSE (Minimum Mean Square Error) and estimate parameters to get accurate positions from ranges measured by multiple radars. For MMSE, we consider three methods which differ in terms of objective functions to minimize or parameters to estimate. For these methods, we evaluate position estimation characteristics using computer simulations. We show that each method has characteristic performance at environment of use of cars.

A-21-19 Joint Decoding of Convolutional Codes using the Correlation of Transmitted Information Sequences in Sensor Networks Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2006 page： 367 2006.3

Robust BFDM/OQAM Receiver for Time-Frequency Dispersive Channels

B. Mongol, T. Yamazato, H. Okada, and M. Katayama

Technical Report of IEICE Vol. WBS2005-112 page： 19-24 2006.3

Language：English

Biorthogonal Frequency Division Multiplexing based on Offset QAM (BFDM/OQAM) system is one of the pulse-shaping versions of Orthogonal Frequency Division Multiplexing (OFDM) systems. It allows optimal Gaussian transmitting pulse at critical sampling i.e., maximum spectral efficiency. In this paper we propose a robust receiver for BFDM/OQAM systems in highly mobile environment. The idea behind our approach is to employ Multi-Input Multi-Output zero-forcing (MIMO-ZF) transversal filter to equalize the channel. The equalizer requires knowledge of the channel status. The channel is estimated by using Maximum-Likelihood method. We evaluate the error rate performance of the proposed system in the time-frequency dispersive channels.

Correlations of noise waveforms at different outlets in a power-line network Reviewed

A. Kawaguchi, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Power Line Communications and Its Applications page： - 2006.3

Language：English

This manuscript discusses the relationships of noise waveforms measured at different outlets in a three-wire single-phase (one neutral and two live conductors) power-line network. As a result of experimental measurements, it is confirmed that instantaneous noise voltages at two different outlets have high correlations if the outlets are connected to the same live conductor in a distribution board, while the outlets for the different live conductors provide noise waveforms with low correlations. It is also shown that the instantaneous noise powers and cyclic averaged noise powers as time functions have large correlations even at a pair of outlets connected to the different live conductors. The correlation coefficients for instantaneous voltages and powers are also calculated as the frequency functions.

An Implementation of Multiple Route Coding Scheme in Wireless Multihop Networks

M.Umakoshi,H.Okada,K.Suzuki,T.Yamazato,M.Katayama

IEICE General Conference Vol. B-21-9 page： 569 2006.3

A method to mitigate the influence of ADC nonlinearity in an OFDM receiver

M. Sawada, H. Okada, T. Yamazato, M. Katayama

IEICE General Conference Vol. B-17-4 page： 583 2006.3

A Study on Signal Separation Scheme for Wideband Software-defined Radio Base Station

Toru KITAYABU, Hiraku OKADA, Takaya YAMAZATO, Masaaki KATAYAMA

IEICE General Conference Vol. B-17-6 page： 585 2006.3

A Study on Effects of Transmit/Receive Correlations on Performance of Diversity with Multiple Antennae/Relay Terminals

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE General Conference Vol. B-5-161 page： 514 2006.3

Joint Decoding of Convolutional Codes using the Correlation of Transmitted Information Sequences in Sensor Networks

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

IEICE General Conference Vol. A-21-19 page： 367 2006.3

Performance Evaluation of Packet Combining and ARQ Schemes of Multiple Route Coding in Wireless Multihop Networks

H. Okada, M. Saito, T. Wada, K. Ohuchi, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. RCS2005-207 page： 175-180 2006.3

Language：Japanese

For reduction in bit errors on wireless channels, we proposed the multi-route coding scheme on multiple routes for wireless multi-hop networks. In this paper, we introduce packet combining and ARQ to the multi-route coding. In the multi-route coding, the destination node combines and decodes sub packets which are encoded and divided by the source node. The intermediate node relays a sub packet, that is, only a part of a packet. Therefore, the intermediate node cannot detect packet errors, and only the destination node can do after combining and decoding sub packets. We propose the ARQ scheme between the source node and the destination node, and evaluate the performance of the proposed scheme.

Experiment on Hierarchical Coding Scheme for Parallel Optical Wireless Communications

K. Masuda, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE Vol. WBS2005-91 page： 75-79 2006.3

Language：Japanese

In this paper, we evaluate the performance of hierarchical transmission scheme using LED traffic lights and high-speed camera for ITS application. By using camera as a receiving device, parallel data transmissions are possible if each of LEDs in traffic lights is individually modulated. In such parallel LED-camera channel, if a receiver is far from a transmitter the received data pattern degrade and it is hard to distinguish adjacent LEDs. To overcome, we have proposed hierarchical coding schemes. Experimental results show that the proposed hierarchical coding schemes outperform the conventional on-off keying(OOK) if LED-camera distance is further.

Applying OFDM modulation to Simple Regenerative Repeating Process of Broadband Satellite

T. Yamazato, H. Kuwamura, A. Ogawa

Technical Report of IEICE Vol. SAT2005-53 page： 23-28 2006.2

Language：Japanese

The authors have been working on the simple regenerative repeater for satellite communication systems that omit the process of error-correction-decoding and re-encoding in the satellite side. We have implemented coded QAM system to FPGA board and confirmed the effectiveness till now. If a header part is common by this simple regenerative, transmission is theoretically possible with a signal of any kind of signal format. In this study, we introduce the FPGA implementation of OFDM signal and show the effectiveness of regenerative repeating process for OFDM transmission.

A Proposal of Iterative Nonlinear Distiortion Compensation Scheme for OFDM Trandmission in Satellite Channel

T. Yamaoka, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE Vol. SAT2005-56 page： 37-42 2006.2

An Error Control Scheme for the Control Signal Onboard the Simplified Satellite Repeater

S. Saiki, H. Kuwamura, A. Ogawa, T. Yamazato

Technical Report of IEICE Vol. SAT2005-54 page： 29-32 2006.2

Language：Japanese

This paper is concerned with performance evaluation for error control of the routing information onboard the simplified satellite repeater for broadband satellite communications. The necessary information for the onboard routing is carried on the preamble portion placed at the top of the packet and modulated with the differential binary PSK. In this paper, we adopt simplified two dimensional parity check code for the routing information onboard the simplified satellite repeater. It is decoded by iterated soft decision decoding, then the error correction is performed together with error detection. We describe the results obtained by computer simulation in terms of the block error rate.

An Effct of Nonlinerity Onboard the Simplified Satellite Repeater for OFDM Signal Transmission

H. Kuwamura, A. Ogawa, T. Yamazato

Technical Report of IEICE Vol. SAT2005-55 page： 33-36 2006.2

Language：Japanese

This paper is concerned with performance evaluation for an experimental model of a repeater for broadband satellite communications. For the purpose of realizing a high speed and flexible internet satellite communication system, we propose a simplified configuration of satellite regenerative repeater. In this repeater, the amount of signal processing is limited so that the input signal is only AD converted and stored, but a complex function of error control is left to the earth stations. While the information data are modulated with multi-level QAM based on OFDM, the necessary information for the onboard routing is carried on the preamble potion placed at the top of the packet and modulated with the differential binary PSK .In this paper, measured results of the bit error rate for this simplified regenerative repeater are described.

A note on error correct decoding scheme using the correlation of transmitted information sequences in sensor networks

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

Technical Report of IEICE Vol. SN2006-10 page： 59-64 2006.1

Language：Japanese

Routing Protocol for Multiple Route Coding in Multihop Cellular Networks

H. Imai, H. Okada, T. Yamazato and M. Katayama

Ad-hoc Network Workshop Vol. 7-5 - 7-8 page： - 2006.1

Language：Japanese

Multihop cellular network using wireless multihop communications for cellular system are considered in this paper. In this networks, there are some issues such as the route loss due to topological change and packet errors due to wireless nodes delay. To overcome these issues, we use the multiple route coding scheme in which packets are transmitted on multiple route from usernode to multiple base stations. In this paper, we propose a routing protocol for multiple route coding. The key idea of the proposed scheme is to employ the hybrid routing protocol. It can mitigate the increase in control packets and construct multiple disjoint routes. We evaluate the performance of the proposed scheme.

Channel estimation for BFDM/OQAM system in dispersive time-varying channels Reviewed

Mongol Bayarpurev, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

2006 3RD INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS, VOLS 1-2 page： 159 - + 2006

Correlations of noise waveforms at different outlets in a power-line network Reviewed

Kawaguchi A.

2006 IEEE International Symposium on Power Line Communications and Its Applications, ISPLC'06 page： 92 - 97 2006

MIMO Zero-forcing Equalizer for BFDM/OQAM Systems in the Highly Mobile Environments Reviewed

Mongol Bayarpurev, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

GLOBECOM 2006 - 2006 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE 2006

Bayarpurev Mongol, Takaya Yamazato, Hiraku Okada, Masaaki Katayama

GLOBECOM 2006 - 2006 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE 2006

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/GLOCOM.2006.620

Performance analysis of multiroute packet combining scheme for real-time communications in wireless multihop networks Reviewed

Y Hirayama, N Nakagawa, H Okada, T Yamazato, M Katayama

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 89 ( 1 ) page： 34 - 44 2006

Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

In this research, real-time packet cornmunications on wireless multihop networks is considered. Since the communications quality is substantially degraded by packet delay in real-time packet communications, packet retransmission is not usually used. In order to suppress the effect of packet errors in the Communications channel on communications quality in such cases, this paper proposes an application of a multiroute packet combining scheme on a wireless multihop network. The performance of the proposed scheme depends on the time required for transmission of a packet on each route and the start time of packet combining at the destination node, in addition to the number of transmitted duplicate packets at the source node. In order to evaluate the constantly changing system performance from the viewpoint of the quality of service (QoS) required in real-time communications, the distribution function of the time needed for attaining a certain required packet error rate and the average packet error rate attainable at a certain time are analytically derived. From numerical examples, it is proven that there exists a number of transmitted duplicate packets minimizing the required time for attaining the required packet error rate, and also a number of transmitted duplicate packets minimizing the average packet rate attainable within an allowed delay time. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/ecja.20238

Single-user MAP based soft-in/soft-output parallel interference canceler utilizing retransmission diversity Reviewed

Y Tadokoro, H Okada, T Yamazato, M Katayama

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 89 ( 6 ) page： 1 - 12 2006

Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

In packet communications, packets whose transmission Fails are retransmitted. If the likelihood information on a failed packet is used, the demodulation of the retransmitted packets and the operation of interference cancellation can be performed more accurately. Hence, several interference cancellation techniques using such retransmission diversify have been proposed. However, in these methods, the algorithm for interference cancellation is identical to the conventional one. Only the matched filter outputs of the packets with failed packet are combined at the output of the interference canceler. In the present research, the likelihood information on the failed packets is used and an interference cancellation algorithm is proposed that maximizes the a posteriori probability. As a result of performance evaluation, it is found that the newly transmitted packets in addition to the retransmitted packets can be sent successfully in the proposed interference cancellation method. (c) 2006 Wiley Periodicals, Inc.

DOI： 10.1002/ecjc.20217

Throughput Evaluation of ARQ Scheme for Multi-route Coding in Wireless Multi-hop Networks Reviewed

Hiraku Okada, Tadahiro Wada, Kouji Ohuchi, Masato Saito, Takaya Yamazato, Masaaki Katayama

2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6 page： 668 - + 2006

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/VETECS.2006.1682908

Throughput Evaluation of ARQ Scheme for Multi-route Coding in Wireless Multi-hop Networks Reviewed

Okada Hiraku, Wada Tadahiro, Ohuchi Kouji, Saito Masato, Yamazato Takaya, Katayama Masaaki

2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6 page： 668 - + 2006

The effect of multipath hybrid routing protocol in multihop cellular networks Reviewed

Hitoshi Imai, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC page： 1 - 5 2006

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/PIMRC.2006.254216

Target Position Estimation using MMSE for A Radar Network Reviewed

H.Hatano, T. Yamazato, H. Okada, and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J88-A ( 12 ) page： - 2005.12

An improvement of the transmission quality using the correlation of the observation data in sensor networks Reviewed

An improvement of the transmission quality using the correlation of the observation data in sensor networks

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J88-A ( 12 ) page： - 2005.12

Language：Japanese Publishing type：Research paper (scientific journal)

In sensor networks, many sensor nodes are densely deployed and observation data obtained by each sensor node is correlated. Such observation data are collected at a fusion center. In this paper, we discuss the observation accuracy at the fusion center from the viewpoint of the amount of Kullback-Leibler (KL) information. Especially, we consider channel error caused when data are transmitted from sensor nodes through wireless communication channels. The channel error deteriorates the observation accuracy. We discuss this influence and a method to decrease it. In this paper, we consider a case when all the correlation between the observation data is equal and when the correlation is uniformly distributed. In both cases, we discuss degradation of KL information under the influence of channel errors. We show that it possible to avoid such degradation using the correlation between the observation data by a estimation of correct value of the erroneous data. In addition, we show a method to estimate the correlation between the observation data and an example of estimating a correct value from erroneous data using correlation.

Ultra-Wideband Chaotic Radar and Clutter Reduction Methods Reviewed

N. Dake, Y. Uwate, Y. Nishio, T. Yamazato

Journal of Signal Processing Vol. 9 ( 6 ) page： 473-478 2005.12

Language：English Publishing type：Research paper (scientific journal)

Chaos could generate nonperiodic sequences with infinite lengths theoretically. In this paper, we propose a UWB (ultra-wideband) chaotic radar, whose transmitted signal is generated by a chaotic map. Since it is important to remove various noises called clutter in a radar, we focus mainly on the removal of clutter by applying three clutter reduction methods. We derive the probability density function of power, the distances between the transmitted signals and the recovered signals, and the detection probability, using computer simulations, and the performance of the proposed radar is evaluated.

A mathematical model of narrowband power-line noise based on measurements Reviewed

Katayama M., Yamazato T., Okada H.

2005 International Symposium on Power Line Communications and Its Applications, ISPLC 2005 Vol. 2005 page： 152 - 156 2005.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：2005 International Symposium on Power Line Communications and Its Applications, ISPLC 2005

This manuscript introduces a mathematically tractable and accurate model of narrowband power-line noise based on experimental measurements. In this model, the noise is expressed as the sum of cyclostationary Gaussian processes. The non-stationary features of power-line noise are represented with a small number of parameters, and the noise waveforms generated with the model achieve good agreement with those of actually measured noise. © 2005 IEEE.

DOI： 10.1109/ISPLC.2005.1430486

Successive interference cancellation for hierarchical parallel optical wireless communication systems Reviewed

On the second-order statistics of the channel parameters for BFDM/OQAM systems Reviewed

Mongol B.

2nd International Symposium on Wireless Communications Systems 2005, ISWCS 2005 - Conference Proceedings Vol. 2005 page： 534 - 538 2005.12

Okada H.

2005 Asia-Pacific Conference on Communications Vol. 2005 page： 788 - 792 2005.12

An improvement of the transmission quality using the correlation of the observation data in sensor networks Reviewed

K. Kobayashi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J88-A ( 12 ) page： 1442-1451 - 1451 2005.12

Target Position Estimation using MMSE for A Radar Network Reviewed

H.Hatano, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J88-A ( 12 ) page： 1456-1459 - 1459 2005.12

[Invited Talk] Information Theory Providing Fundamentals of Sensor Networks Invited

T. Yamazato

Technical Report of IEICE Vol. IT2005-62 page： 17-26 2005.11

Language：Japanese

Despite the known objective, to achieve advance sensing by connecting many sensing devices by an information and communication networks, sensor networks may give a significant impact throughout the field of information and communication technology and may become a basis of the information revolution. Applications of sensor networks ranges from environmental observations, security, building of intelligent space, to disaster rescue, amusement and so on. The unique feature of Sensor Networks is that the sensing nodes must operate under a set of unique constraints and requirement that network itself is unstable and unreliable. The limited amount of energy available to wireless sensors has a significant impact on all aspects of wireless sensor networks, from the amount of information that the node can process, to the volume of wireless communication it can carry across. In this paper, information theory that providing fundamentals of sensor networks is addressed, especially its theoretical outline and issues are introduced.

Introduction on Nagoya University Open Courseware

T. Egawa, T. Yamazato

2005 Conference on Education for Information Processing page： - 2005.11

A Study on Route Selection Metrics for the Multiple-Route Packet

Y. Hirayama, H. Okadaa, T. Yamazato, and M. Katayama

Symposium on Information Theory and Its Applications (SITA) Vol. 1 page： 151-154 2005.11

Language：Japanese

The multiple-route packet combining (MRPC) is a diversity combining and error correction scheme for wireless multihop networks. In this scheme, multiple replicas of a coded packet are transmitted along different disjoint routes from a source node. These replicas are received, combined and decoded by the destination. If a conventional multipath routing protocol, such as MDSR, is employed, smaller hop routes tend to be selected to transmit packets. However, the performance of MRPC depends on the packet reception probability and the bit error rate of each route. It is therefore expected that the performance improves if these statics are utilized as a route selection metric. In this paper, we compare the packet error performance of MRPC for different route selection metrics. Three different metrics are considered, that is, the log-likelihood ratio (LLR), the packet reception probability, and the number of hops of a route. From the performance comparison, we show that LLR is the best metric when packet decoding errors are dominant over packet losses.

A study on the mitigation of the influence of ADC nonlinearity in an OFDM receiver

M. Sawada, H. Okada, T. Yamazato, M. Katayama

Symposium on Information Theory and Its Applications (SITA) Vol. 1 page： 143-146 2005.11

Channel Coding for M-Ary Coherent-State Signals with Signal Constellations in Consideration of Signal States

T. Otake, H. Okada, T. Yamazato, K. Yamazaki, and M. Katayama

Symposium on Information Theory and Its Applications (SITA) Vol. 1 page： 203-206 2005.11

Language：Japanese

In quantum communication systems, the optimum detection process for M-ary PSK coherent-state signals which minimizes symbol error probability is Square-root Measurement(SRM). To minimize the bit error probability of the M-ary PSK coherent-state signals, it is effective to consider the allocation of the code words to the signals. In this paper, we show that the average bit error probability for such coded signals improves more than that of the uncoded signals which have the same information rate as the coded signals.

The Faculty Inventory for Student Involvement in Web-Enhanced Learning -The Online Survey of WebCT Users-

T. Yamazato, T. Nakai, H. Nakajima, H. Okada, M. Omura

3rd WebCT Conference page： 73-77 2005.11

Performance evaluation of route coding scheme in wireless multi-hop networks Reviewed

Okada H.

IEEE Vehicular Technology Conference Vol. 61 ( 5 ) page： 3092 - 3096 2005.10

Outage Probability of a Macro and Micro MIMO Diversity Scheme in an Indoor Fading and Shadowing Environment Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E88-A ( 10 ) page： 2945-2951 2005.10

Language：English Publishing type：Research paper (scientific journal)

In this manuscript, a layered macro / micro diversity scheme is introduced at the receiver side of a MIMO STBC wireless control system under fading and shadowing environment. The combination of the outputs of micro diversity is based on soft-decision values, while the macro diversity branches are combined based on hard decision values. As a measure of the reliability of the system, the outage probability of frame-error rate is employed. The performance of the proposed system is analytically and numerically evaluated and the impact of the macro diversity in the outage probability is clarified.

Successive Interference Cancellation for Hierarchical Parallel Optical Wireless Communication Systems Reviewed

H. Okada, K. Masuda, T. Yamazato, M. Katayama

The 11th Asia-Pacific Conference on Communications page： 788-792 2005.10

Language：English

A parallel optical wireless communication system using two-dimensional LED array (2D LED array) and two-dimensional image sensor (2D image sensor) was proposed for the visible light communication systems. In this system, each LED of the 2D LED array is individually modulated, and the 2D image sensor recognizes each LED modulated data. However, the received data pattern will be degraded due to reduction of pixel size and/or defocussing of the LED data pattern. This phenomenon corresponds to the degradation of high spatial frequency components of the received data pattern. To overcome, we employ a hierarchical transmission scheme at a transmitter and a successive interference cancellation at a receiver. By allocating high priority data to low frequency components and low priority data to high frequency components, the reception of high priority data can be guaranteed. We also attempt to apply interference cancellation to overcome the degradation of high spatial frequency components of the received data pattern. By evaluating the bit error rate, we clarify the effect of the proposed system.

A Note on the Simple Regenerative Repeating Process for Communication Satellite

T. Yamazato, A. Ogawa

Technical Report of IEICE Vol. SAT2005-21 page： 27-32 2005.10

Language：English

We have been working on a relay process of communication satellite. We omit the regenerative process at the satellite. Only routing and other necessary operation are performed at satellite. Simple configuration and signal processing may promise robust and long-lasting operations in space. We call it simple regenerating repeater. However, an issue is how to realize the reliable transmission even if we omit the error correcting and detecting process at the satellite. To overcome this issue, we propose to place the error detection code prior to QAM mapping. Using the status of error detector, it is possible to give accuracy to the received signal so we can improve the performance by soft decoding. The FPGA experimental boards of the system are also introduced

Characterization of a simplified regenerative repeater for broadband satellite communications

H. Kuwamura, A. Ogawa, T. Yamazato

Technical Report of IEICE Vol. SAT2005-22 page： 33-35 2005.10

Outage probability of a macro and micro MIMO diversity scheme in an indoor fading and shadowing environment Reviewed

R Uchida, H Okada, T Yamazato, M Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E88A ( 10 ) page： 2945 - 2951 2005.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this manuscript, a layered macro/micro diversity scheme is introduced at the receiver side of a MIMO STBC wireless control system under fading and shadowing environment. The combination of the outputs of micro diversity is based on soft-decision values, while the macro diversity branches are combined based on hard decision values. As a measure of the reliability of the system, the outage probability of frame-error rate is employed. The performance of the proposed system is analytically and numerically evaluated and the impact of the macro diversity in the outage probability is clarified.

DOI： 10.1093/ietfec/e88-a.10.2945

Application of successive interference cancellation to a packet-recognition/code-acquisition scheme in CDMA unslotted ALOHA systems Reviewed

A-21-5 PERFORMANCE ANALYSIS OF A MULTI-ROUTE PACKET COMBINING SCHEME IN SENSOR NETWORKS Reviewed

Nakao Kouji, Yamazato Takaya, Okada Hiraku, Hirayama Yasuhiro, Katayama Masaaki

Proceedings of the Society Conference of IEICE Vol. 2005 page： 274 2005.9

A MIMO System with Relay Terminals for Reliable Wireless Control Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

The 16th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communication page： - 2005.9

Language：English

In this manuscript, wireless communication system for reliable wireless control of industrial machines in indoor environment is considered. In indoor environment, transmitted signal fluctuates due to fading and shadowing. To combat the fading and shadowing, macro / micro spatial diversity can be used as an effective countermeasure. In this manuscript, macro / micro diversity is achieved by multiple wireless relay terminals, which is convenient in setting and moving the macro diversity branches. In the proposed scheme, channel between the transmitter and the receiver through relay terminals is considered as a MIMO channel and separation of the signals re-transmitted from the relay terminals is not required. This feature makes it possible to have higher order diversity without the cost of bandwidth inefficiency. In numerical examples, the performance of the proposed scheme is evaluated by average frame-error rate and outage probability of frame-error rate. With two relay terminals, the diversity gain of the proposed scheme is about 5-6 dB, which is 1 dB higher than that of conventional macroscopic diversity.

A Simple Regenerative Repeating Process for Broadband Communication Satellite Reviewed

T. Yamazato, A. Ogawa

23rd AIAA International Communications Satellite Systems Conference (ICSSC-2005) Vol. MOD-1-1 page： - 2005.9

Language：English

In this paper, we focus on relay process of broadband communication satellite. We omit the demodulation, error decoding and re-encoding process at the satellite. Just store the received signal as it is and then forward it to the destination in which the information is extracted from the header. We discuss the issue of analog-to-digital converter for this relay process. For given quantization level, reduction of signal accuracy can improve the transmission rate as we can adopt higher order of QAM. However, the degradation occurred due to the reduction of available quantized bit for accuracy. To overcome this issue, we propose to place the error detection code prior to QAM mapping. Using the status of error detector, it is possible to give an accuracy to the received signal so we can improve the performance by soft decoding.

Performance Analysis of a Multi-Route Packet Combining Sheme in Sensor Networks

K. Nakao, Y. Hirayama, T. Yamazato, H. Okada, and M. Katayama

Communications Society Conference of IEICE Vol. A-21-5 page： 274 2005.9

A New Coded QAM Modulation Scheme for Broadband Satellite Communication Reviewed

T. Yamazato, T. Yamaoka, H. Okada, M. Katayama, A. Ogawa

23rd AIAA International Communications Satellite Systems Conference (ICSSC-2005) Vol. MOD-3-3 page： - 2005.9

Language：English

In this paper, we propose a new multi-rate coded QAM for broadband satellite communication system. The overall coding rate is (m?2)/2 and Turbo code is adopted. The mapping is similar to bit-interleaved coded modulation (BICM) systems; unlike BICM mapping, we only assign four of Turbo coded bits. This brings a set-partitioning. We also consider the effect of quantization bits. Actually we try to realize high-order QAM by using the available quantization bits, which reduces the signal accuracy so the performance may degrade. As results, our proposed scheme achieve good performance even when the available quantization bits are less.

Effects of Error Rate and Transmission Rate on the Performance of Wireless Control Systems

R. Uchida, H. Okada, T. Yamazato, and M. Katayama

Communications Society Conference of IEICE Vol. B-5-156 page： 556 2005.9

A Study on ARQ Schemes of Multiple Route Coding for Wireless Multihop Networks

H. Okada, M. Saito, T. Wada, K. Ohuchi, T. Yamazato, M. Katayama

Communications Society Conference of IEICE Vol. B-5-149 page： 549 2005.9

A Study on Effects of Variations of Transmitter LED's Luminance for Hierarchical Coding in Parallel Optical Wireless Communication Systems

K. Masuda, T. Yamazato, H. Okada, and M. Katayama

Communications Society Conference of IEICE Vol. B-8-17 page： 209 2005.9

On the Second-order Statistics of the Channel Parameters for BFDM/OQAM Systems Reviewed

B. Mongol, T. Yamazato, H. Okada, M. Katayama

2nd International Symposium on Wireless Communication Systems page： 534-538 2005.9

Language：English

Recently, there has been increased interest in using multicarrier systems in rapidly time-varying multipath environment. Biorthogonal Frequency Division Multiplexing based on Offset QAM (BFDM/OQAM) is an attractive modulation method since it allows time-frequency well-localized pulses even at critical sampling (i.e. maximum spectral ef ciency). BFDM/OQAM system is naturally strong against intersymbol and intercarrier interference (ISI/ICI). However, for further improvement of the system a study on the channel statistics is needed. In this paper we analytically examine the channel parameters for BFDM/OQAM and derive their second-order statistics.

A New Coded QAM Modulation Scheme for Broadband Satellite Communication Reviewed

T. Yamazato, T. Yamaoka, H. Okada, M. Katayama, A. Ogawa

23rd AIAA International Communications Satellite Systems Conference (ICSSC-2005) Vol. MOD-3-3 page： - 2005.9

Language：English

Influence of the Nonlinearity of the ADC in an OFDM Receiver Reviewed

M. Sawada, H. Okada, T. Yamazato, and M. Katayama

The 10th International OFDM-Workshop 2005 page： 220-224 2005.8

Language：English

This paper discusses the influence of the nonlinearity of an analog-to-digital converter (ADC) in an orthogonal frequency division multiplexing (OFDM) receiver. We evaluate a signal constellation and a bit error rate (BER) performance with the consideration of quantization errors and clippings. As a result, the trade off between the quantization error and the clipping and the optimum range for an ADC input amplitude are shown. In addition, it is shown that the peak to average power ratio (PAPR) of the signal is not a good measure of the BER performance, since the peaks occur only with very low probabilities.

Target position detection using MMSE in radar networks

H.Hatano, T. Yamazato, H. Okada, and M. Katayama

Technical Report of IEICE Vol. ITS2005-15 page： 45-49 2005.7

[Technical Exhibition] Software Defined Receiver with SFQ Digital Devices

A. Sekiya, Y. Nishido, H. Akaike, H. Okada, M. Inoue, T. Yamazato, A. Fujimaki, M. Katayama

Technical Report of IEICE Vol. SR2005-34 page： 91-96 2005.7

Single-user MAP Based Soft-in/Soft-output Parallel Interference Canceler Utilizing Retransmission Diversity Reviewed

Y. Tadokoro, H. Okada, T. Yamazato, and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J88-A ( 6 ) page： 739-750 2005.6

Language：English Publishing type：Research paper (scientific journal)

In packet communication systems, unsuccessful packets should be retransmitted. By exploiting the information on the unsuccessful packets such as log-likelihood ratio(LLR), the retransmitted packets may be correctly demodulated. Some authors have proposed the interference cancellation schemes using such a retransmission diversity technique. However, these schemes uses the traditional approach of interference cancellation. In addition, the received signals are just combined at the output of the canceler. This paper develops the novel interference cancellation scheme which maximize a posteriori probability utilizing the LLR on unsuccessful packets. Performance evaluation shows that not only retransmitted packets but also new-generated packets can be successfully transmitted in the proposed scheme.

Performance Evaluation of Route Coding Scheme in Wireless Multi-hop Networks Reviewed

H. Okada, T. Wada, K. Ohuchi, M. Saito, T. Yamazato, M. Katayama

IEEE Vehicular Technology Conference (VTC) page： 3092-3096 2005.6

Language：English

Wireless multi-hop networks have been much attention for the future generation mobile communication systems. Due to the possibility of flexible construction in the wireless multi-hop networks, multiple routes from a source node to a destination node can be established. In this paper, we propose the route coding scheme in the wireless multi-hop networks. In the proposed scheme, a packeted data sequence is encoded by the convolutional code at the source node. Each digit of the code word is assigned to sub-packets on multiple routes. At the intermediate nodes, the sub-packets are regenerated-relayed to the next node. The sub-packets transmitted via multiple routes are decoded by the Viterbi decoder with the modified metric computation at the destination node. We also evaluate the system performance, and clarify the improvement of the packet error rate by the proposed scheme. Furthermore, we investigate the influence of the route loss due to topological change or recognizing failure.

Target position estimation using MMSE for UWB IPCP receivers Reviewed

H. Hatano, T. Yamazato, H. Okada, M. Katayama

The 5th International Conference on ITS Telecommunications page： 131-134 2005.6

Language：English

In this work, we present target position estimation methods using minimum mean-square error (MMSE) algorithm for short-range radar systems. We consider UWB IPCP (inter-period correlation processor) receiver and improve target position accuracy by using a set of measured ranges. Depend on how we set the objective functions for MMSE, we propose three methods. And we evaluate the performance of position estimations using computer simulations.

Faculty Inventories for Student Involvement in Web-Enhanced Learning

H. Nakajima, H. Okada, T. Nakai, T. Yamazato

Webct User Conference page： 109-113 2005.6

Performance Analysis of Multiple-route Packet Combining Scheme for Real-time Communications in Wireless Multihop Networks

Y. Hirayama, H. Okada, T. Yamazato, and M. Katayama

Proc. of Cooperation Industry Academia Government 2005 page： 92-93 2005.6

Application of Successive Interference Cancellation to a Packet-Recognition/Code-Acquisition Scheme in CDMA Unslotted ALOHA Systems Reviewed

Y. Tadokoro, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E88-A ( 6 ) page： 1605-1612 2005.6

Language：English Publishing type：Research paper (scientific journal)

Packet-recognition/code-acquisition (PR/CA) is one of the most important issues in packet communication systems. In a CDMA Unslotted ALOHA system, Multiple Access Interference (MAI) may bring about error in PR/CA. The MAI mainly stems from already recognized packets and newly arriving packets under the execution of PR/CA. This characteristic of asynchronous transmission in CDMA U-ALOHA systems implies that only one or a few packets arrive at the receiver within a short interval of a execution. Furthermore, newly arriving packets are recognized and code-acquired by using a short preamble part. Consequently, the MAI from the packets under the execution of the PR/CA will be small. Focusing on that point, this paper proposes applying the IC scheme in order to suppress the MAI from the already recognized and code-acquired packets. A performance evaluation demonstrates that such an application is valid due to the small amount of MAI from the packets under the execution of PR/CA. In addition, we demonstrates that the scheme reduces false recognition rather than mis-recognition. Such a scheme improves the performance of not only PR/CA, but also the throughput.

Research on relation between error performance of coded QAM and qauntized bits --Proposal of multi-rate coded QAM--

T.Yamaoka,T.Yamazato,H.Okada,M.Katayama and A.Ogawa

Technical Report of IEICE Vol. SAT2005-9 page： 19-23 2005.6

A Macro and Micro Diversity Scheme with Relay Terminals for Reliable Wireless Control

R. Uchida, H. Okada, T. Yamazato, and M. Katayama

Technical Report of IEICE Vol. RCS2005-28 page： 39275 2005.6

Language：Japanese

In this manuscript, wireless communication system for reliable wireless control of industrial machines in indoor environment is considered. In indoor environment, transmitted signal fluctuates due to fading and shadowing. To combat the fading and shadowing, macro / micro spatial diversity can be used as an effective countermeasure. In this manuscript, macro / micro diversity is achieved by multiple wireless relay terminals, which is convenient in setting and moving the macro diversity branches. In the proposed scheme, channel between the transmitter and the receiver through relay terminals is considered as a MIMO channel and separation of the signals re-transmitted from the relay terminals is not required. This feature makes it possible to have higher order diversity without the cost of bandwidth inefficiency. By numerical calculations, performance of the proposed scheme is evaluated and the improvement of the reliability of the communication system is confirmed.

Improvement of the estimation quality using the correlation of the observation data - When sensor nodes are uniformly distributed -

K. Kobayashi, T. Yamazato, H. Okada and M. Katayama

Technical Report of IEICE Vol. SN2005-5 page： 15-20 2005.6

Evaluation of the Channel Parameter Statistics for BFDM/OQAM System in Multipath Time-Varying Channels

B. Mongol, H. Okada, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. RCS2005-33 page： 35-40 2005.6

Language：English

Recently, there has been increased interest in using Orthogonal Frequency Division Modulation (OFDM) systems in rapidly time-varying multipath environment. The performance of the systems in such time-frequency dispersive channels, depends critically on the time-frequency localization of the transmitter pulse. Biorthogonal Frequency Division Multiplexing based on Offset QAM (BFDM/OQAM) is attractive modulation method since it allows time-frequency well-localized pulses at critical sampling (i.e. maximum spectral efficiency). In this paper we consider BFDM/OQAM system with Gaussian transmitter pulse and evaluate channel parameter statistics in multipath time-varying channels.

Y Tadokoro, H Okada, T Yamazato, M Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E88A ( 6 ) page： 1605 - 1612 2005.6

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Packet-recognition/code-acquisition (PR/CA) is one of the most important issues in packet communication systems. In a CDMA Unslotted ALOHA system, Multiple Access Interference (MAI) may bring about errors in PR/CA. The MAI mainly stems from already recognized packets and newly arriving packets under the execution of PR/CA. This characteristic of asynchronous transmission in CDMA U-ALOHA systems implies that only one or a few packets arrive at the receiver within a short interval of a execution. Furthermore, newly arriving packets are recognized and code-acquired by using a short preamble part. Consequently, the MAI from the packets under the execution of the PR/CA will be small. Focusing on that point, this paper proposes applying the IC scheme in order to suppress the MAI from the already recognized and code-acquired packets. A performance evaluation demonstrates that such an application is valid due to the small amount of MAI from the packets under the execution of PR/CA. In addition, we demonstrates that the scheme reduces false recognition rather than mis-recognition. Such a scheme improves the performance of not only PR/CA, but also the throughput.

DOI： 10.1093/ietfec/e88-a.6.1605

Special section on papers selected from 2004 International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2004) Reviewed

Kikuchi H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E88-A ( 6 ) 2005.6

再送ダイバーシチを用いて事後確率を最大にする軟入力/軟出力並列型干渉除去法 Reviewed

田所幸浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会論文誌 A Vol. J88-A ( 6 ) page： 739 - 750 2005.6

Activity Report of Information Security Promotion Agency, Nagoya University

Y. Takeuchi, Y. Yamaguchi, N. Kawaguchi, T. Yamazato, A. Hasegawa, T. Sakabe

IPSJ SIG Technical Report Vol. 2005-CSEC-29(1) page： 39088 2005.5

Language：Japanese

The Informaton Security Promotion Agency (ISPA), Nagoya University was established in November, 2003. It is an expert group of information security and technology operation as promptly and actively as possible to respond information security incidents. There are two missions in ISPA. One is to engage in educational activities on information security for all members in Nagoya University. The other is to respond information security incidents as promptly and actively. In this report, we describe information security training, building of information security incident database, investigation of wireless LAN and information security audit. We also report security incidents which occur in our university.

A Mathematical Model of Narrowband Power-Line Noise Based on Measurements Reviewed

M. Katayama, T. Yamazato, H. Okada

9th International Symposium on Power-Line Communications and Its Applications page： 152-156 2005.4

Language：English

A-5-26 A Study on Hierarchical Coding for Parallel Optical Wireless Communication Systems Reviewed

Masuda Kyoichiro, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2005 page： 142 2005.3

An Adaptive Receiver for Power-Line Communications with the Estimation of Instantaneous Noise Power Reviewed

HIRAYAMA Yuichi, OKADA Hiraku, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE Transactions on Fundamentals, A Vol. 88 ( 3 ) page： 755 - 760 2005.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

The noise on power-lines is non-stationary, while the instantaneous noise power in different frequency bands are dependent. Under such noise environments, the instantaneous noise power in a frequency band can be estimated by observing the noise in other frequency bands. In this paper, we propose a receiver structure which uses the estimated instantaneous noise power in the decoding process and show its superiority in BER performance to conventional systems.

An adaptive receiver for power-line communications with the estimation of instantaneous noise power Reviewed

An Analysis of the Maximum Throughput on CDMA Packet Communication Systems Employing Successive Interference Cancellation Reviewed

Y. Tadokoro, H. Okada, T. Yamazato, and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J88-A ( 3 ) page： 429-433 2005.3

Language：English Publishing type：Research paper (scientific journal)

This letter analyzes the maximum throughput on CDMA packet communication systems employing successive interference cancellation. This analysis is performed in terms of received signal-power distribution. The optimum received signal-power distribution which achieves the maximum throughput is shown to be the optimum one on BER with the limitation of packet transmission.

Research on Clutter Reduction Methods of a UWB Chaotic Radar Reviewed

Dake, Y. Uwate, Y. Nishio, T. Yamazato

2005 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP05) page： - 2005.3

A course enhanced by WebCT Invited

T. Yamazato

Nagoya Journal of Higher Education Vol. 第５号 page： 49-64 2005.3

Language：Japanese Publishing type：Research paper (bulletin of university, research institution)

WebCT (Web Course Tools) is a course management systems (CMS) that have been developed at British Columbia University to support faculty members for designing, developing and managing his/her class. The WebCT offers many useful tools, such as displaying html-files, discussion board, e-mail, online-quiz, and so on. After using WebCT for several years, I found that it is possible to teach dynamically and interactively. Some of experiences I have learned using WebCT are reported, such includes a dynamic course administration, discussions among students, extensive study contents, and so on. As a conclusion, a need of faculty support is essential to enhance teaching and learning in Nagoya University especially for those using WebCT.

A Simplified Regenerative Repeater for Satellite Communications

H. Kuwamura, S. Saiki, A. Ogawa, T. Yamazato, S. Kawai

IEICE General Conference Vol. B-3-17 page： 345 2005.3

Performance Evaluation of Multi-route Turbo Coding using Parity Check Codes

N. Nakagawa, H. Okada, T. Wada, T. Yamazato, M. Katayama

IEICE General Conference Vol. B-5-141 page： 590 2005.3

A Study on Hierarchical Coding for Parallel Optical Wireless Communication Systems

K. Masuda, T. Yamazato, H. Okada, and M. Katayama

IEICE General Conference Vol. A-5-26 page： 142 2005.3

A Study on Successive Interference Cancellation for Hierarchical Coding in Parallel Optical Wireless Communication Systems

H. Okada, K. Masuda, T. Yamazato, M. Katayama

IEICE General Conference Vol. A-5-25 page： 141 2005.3

An Adaptive Receiver for Power-Line Communications with the Estimation of Instantaneous Noise Power Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E88-A ( 3 ) page： 755-760 2005.3

Language：English Publishing type：Research paper (scientific journal)

A Prototype for a Broadband Software-Defined Base Station Which Processes Signals with Widely Differing Intensity

T. Kitayabu, H. Okada, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. SR04-23 page： 17-22 2005.3

Language：Japanese

This paper discusses the preliminary examinations of a broadband software-defined base station receiver. The authors have been concentrating on the concept of Intelligent Super Base-station (ISB), which processes multiple signals with different modulation schemes at the same time. For the receiver of the ISB, the introduction of a superconductive analog to digital converter (ADC), which has a large bandwidth and high sensitivity, has been proposed. For the realization of such a receiver, as the first step, we designed a prototype receiver with a semi-conductive ADC, which receives and demodulates two FM broadcasting signals at the same time. As a result of the experimentations, influence of the difference of the signal level is clarified, and importance of signal selection algorithm is confirmed.

Y Hirayama, H Okada, T Yamazato, M Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E88A ( 3 ) page： 755 - 760 2005.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

The noise on power-lines is non-stationary, while the instantaneous noise power in different frequency bands are dependent. Under such noise environments. the instantaneous noise power in a frequency band can be estimated by observing the noise in other frequency bands. In his paper, we propose a receiver structure which uses the estimated instantaneous noise power in the decoding process and show its superiority in BER performance to conventional systems.

DOI： 10.1093/ietfec/e88-a.3.755

逐次型干渉除去法を用いたCDMAパケット通信システムにおける最大スループットの解析 Reviewed

田所幸浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会論文誌 A Vol. J88-A ( 3 ) page： 429 - 433 2005.3

An Adaptive Receiver for Power-Line Communications with the Estimation of Instantaneous Noise Power Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E88-A ( 3 ) page： 755-760 2005.2

Language：English Publishing type：Research paper (scientific journal)

*A Tutorial on Multiple Access Technologies for Beyond 3G Mobile Networks Invited Reviewed

A. Jamalipour, T. Yamazato, T. Wada

IEEE Communication Magazine Vol. 43 ( 2 ) page： 110-117 2005.2

Authorship：Lead author Language：English

Beyond third-generation (B3G) wireless cellular systems are recognized as systems that can achieve high data-rate transmission beyond those currently provided by the second- and third-generation (2G/3G) wireless cellular systems and are capable of delivering multiple services to users at different locations under very diverse channel conditions. B3G systems should provide services comparable to those offered by wired networks for a variety of applications such as interactive multimedia, VoIP (voice over Internet protocol), network games, videoconferencing, etc. The current trend is that B3G will be based on IP technology, and therefore, all-IP [1] architecture design has been an important research topic in the past few years. Those systems will need to support multiple services ubiquitously in different types of environment including indoor, outdoor (with low and high velocity), and up to global broadband access (satellite). Thus, they would be deployed in a heterogeneous environment of various physical access networks of wireless and wired systems. The network heterogeneity means that the physical access network underlying the B3G system will support different levels of data rates and different mobility and traffic management techniques govern individual systems. In this context, the B3G mobile systems will face at least two predominant constraints: a) heterogeneity in physical access network, and b) change of application types from commonly low data rates into more bandwidth demanding real-time and multimedia ones. In such situation, providing quality of service to users would become even more difficult that what we are currently dealing. One of the main issues involved in the development of B3G systems is the choice of multiple access (MA) technology that could efficiently share the available bandwidth to large number of users. The choice of MA technique could significantly enhance or damage the service quality delivered to end users. It is known that the existin

A tutorial on multiple access technologies for beyond 3G mobile networks Reviewed

A Jamalipour, T Wada, T Yamazato

IEEE COMMUNICATIONS MAGAZINE Vol. 43 ( 2 ) page： 110 - 117 2005.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In this article some fundamental technical concepts of the main multiple access schemes for wireless mobile systems are reviewed, and a path for development of appropriate multiple access technologies for next-generation mobile networks, or so-called beyond 3G (B3G), is established. We first review the multiple access technologies in second- and third-gene ration wireless cellular systems from historical and technical points of view. This review is followed by a novel formulization of the multiple access schemes through mathematical expressions that could simplify the process of development of new multiple access schemes for B3G wireless cellular systems. We then list the most important features of multiple access schemes in 3G mobile systems. Finally, we conclude the article by reviewing the most promising multiple access technologies for B3G mobile cellular systems.

DOI： 10.1109/MCOM.2005.1391509

Time-dependent analysis of the multiple-route packet combining scheme in wireless multihop networks Reviewed

A tutorial on multiple access technologies for beyond 3G mobile networks Reviewed

Jamalipour A, Wada T, Yamazato T

IEEE COMMUNICATIONS MAGAZINE Vol. 43 ( 2 ) page： 110 - 117 2005.2

Performance analysis of multi-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Y. Hirayama, N. Nakagawa, H. Okada, T. Yamazato, and M. Katayama

IEICE Transactions on Communications Vol. J88-B ( 1 ) page： 269-279 2005.1

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we consider real-time packet communications in wireless multihop networks. In real-time packet communications, packet retransmission cannot be used because it may produce undesired delays. In this case, it is necessary to be employed a technique which can reduce the influence of packet errors. We propose to apply a multi-route packet combining scheme to wireless multihop networks. We analyze two characteristics of the proposed system. One is the average packet error probability, which is obtained as a function of a elapsed time. The other is the required time for achieving a required packet error probability.

Time-Dependent Analysis of the Multiple-Route Packet Combining Scheme in Wireless Multihop Networks Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

International Journal of Wireless Information Networks Vol. 12 ( 1 ) page： 35-45 2005.1

Language：English Publishing type：Research paper (scientific journal)

In this paper, we apply the multiple-route packet combining scheme to wireless multihop networks in order to support delay-sensitive applications. The performance of the system is time-dependent and is greatly affected by network-level performance. Therefore, it is necessary to develop an analytical framework to evaluate the per- formance of the system with taking into account its time-dependency. We use queuing theory to analyze the performance of the system. From numerical results, it is shown that the performance degradation of the system is mainly caused by the increase of packet delay, which is due to the increase of the traffic intensity. To prevent the increase of traffic,we propose a packet discarding scheme. We analyze the average packet error probability of the proposed system with the equilibrium point analysis (EPA). Numerical results show that the packet discarding scheme can improve the average packet error probability under heavy traffic conditions.

Clutter reduction methods of a UWB chaos radar

Natsumi Dake, Yoshifumi Nishio, Takaya Yamazato

Technical Report of IEICE Vol. NLP2004-108 page： 49-52 2005.1

Language：Japanese

We have proposed a UWB chaos radar, whose transmitted signal is generated by a chaotic map. If the feature of chaos is exploited, a radar with outstanding performance can be expected. It is important to remove various noises called clutter in a radar. In this study, we focus mainly on removal of clutters by employing two noise reduction methods. We use the Minimum Distance Approximation method and Maximum Likelihood Decodings method to remove the clutter.

Yasuhiro Hirayama, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

International Journal of Wireless Information Networks Vol. 12 ( 1 ) page： 35 - 45 2005.1

Language：English Publishing type：Research paper (scientific journal)

In this paper, we apply the multiple-route packet combining scheme (In Proceedings of the 1st International Symposium on Wireless Communication Systems, pp. 183-187, Mauritius, 2004) to wireless multihop networks in order to support delay-sensitive applications. The performance of the system is time-dependent and is greatly affected by network-level performance. Therefore, it is necessary to develop an analytical framework to evaluate the performance of the system with taking into account its time-dependency. We use queuing theory to analyze the performance of the system. From numerical results, it is shown that the performance degradation of the system is mainly caused by the increase of packet delay, which is due to the increase of the traffic intensity. To prevent the increase of traffic, we propose a packet discarding scheme. We analyze the average packet error probability of the proposed system with the equilibrium point analysis (EPA). Numerical results show that the packet discarding scheme can improve the average packet error probability under heavy traffic conditions. © 2005 Springer Science+Business Media, Inc.

DOI： 10.1007/s10776-005-5161-6

On the Second-order Statistics of the Channel Parameters for BFDM/OQAM Systems Reviewed

B. Mongol, T. Yamazato, H. Okada, M. Katayama

2nd International Symposium on Wireless Communication Systems page： 534-538 2005

Language：English

A MIMO system with relay terminals for reliable wireless control. Reviewed

Ryosuke Uchida, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

Proceedings of the IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, Berlin, Germany, September 11-14, 2005 page： 1626 - 1630 2005

A study of wireless TCP access with base station diversity Reviewed

K Naito, H Okada, T Yamazato, M Katayama

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 88 ( 9 ) page： 49 - 61 2005

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

It is known that performance is degraded in Internet access using TCP in a wireless environment, making communications almost impossible. This study proposes a cellular system in which a wireless terminal evaluates its own wireless environment and TCP performance and connects to multiple base stations. The TCP performance in the proposed system is evaluated and it is found to be greatly improved by applying base station diversity. By applying the proposed procedure for selecting the base station to which it will connect, the unnecessary use of wireless resources can be avoided. It is shown that in order to improve TCP performance, the cell radius should be set appropriately for the required TCP performance. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/ecja.20169

A simple data relay process and turbo code application to wireless sensor networks Reviewed

On the second-order statistics of the channel parameters for BFDM/OQAM systems Reviewed

Mongol B, Yamazato T, Okada H, Katayama M

2ND INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS 2005 (ISWCS 2005) page： 534 - 538 2005

Performance evaluation of route coding scheme in wireless multi-hop networks Reviewed

Okada H, Wada T, Ohuchi K, Saito M, Yamazato T, Katayama M

VTC2005-SPRING: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, PROCEEDINGS page： 3092 - 3096 2005

Successive interference cancellation for hierarchical parallel optical wireless communication systems Reviewed

Okada H, Masuda K, Yamazato T, Katayama M

2005 ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC), VOLS 1& 2 page： 788 - 792 2005

Yamazato T., Okada H., Katayama M., Ogawa A.

1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04 page： 398 - 402 2004.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04

In this study, we focus on relay process of intermediate node of wireless sensor networks. In conventional wireless sensor networks, the intermediate node performs the regenerative repeating process such that error correction, detection and re-encoding are processed. This is reliable, but it requires a lot of processing effort and may take much energy. To reduce a burden of relay process, we propose to omit error decoding and/or reencoding process at the intermediate nodes. Farther, we propose a method that realizes soft-decision decoding for hard-detected signals. With this method, we can employ Turbo code to wireless sensor networks. As results, we show that though omitting the decoding and re-encoding process at the intermediate node may not affect much to the performance. © 2004 IEEE.

A study on error correcting and diversity combiner scheme on multiple routes in wireless multi-hop networks Reviewed

Okada H., Koie N., Nakagawa N., Yamazato T., Katayama M.

1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04 page： 183 - 187 2004.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04

Wireless multi-hop networks have been much attention for the possibility of flexible construction of the network topology. One of the important and interesting techniques for multi-hop networks is a multi-path routing. By using the multi-path routing, multiple routes from a source node to a destination node can be established. In this paper, we propose the error correcting and diversity combiner scheme on multiple routes in wireless multi-hop networks to reduce bit errors. The diversity combiner outputs the likelihood information from the packets transmitted via multiple routes. By feeding the likelihood information into the Viterbi decoder, the diversity gain can be obtained. We evaluate the packet error rate and the total traffic. As a result, the packet error rate can be improved. Furthermore, the total traffic can be reduced in the low Eb/N0 in spite of the traffic increase due to transmission via redundant routes. © 2004 IEEE.

Performance analysis of MC-CDMA system with and without guard interval in two-path channel Reviewed

Yamamoto H.

IEEE International Symposium on Spread Spectrum Techniques and Applications page： 67 - 71 2004.12

Performance analysis of UWB impulse radar using parallel IPCP receiver Reviewed

Hatano H.

1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04 page： 115 - 119 2004.12

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Hirayama Y.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC Vol. 1 page： 140 - 144 2004.12

The optimum received signal-power distribution for CDMA packet communication systems employing successive interference cancellation Reviewed

Tadokoro Y.

IEEE International Symposium on Spread Spectrum Techniques and Applications page： 37 - 41 2004.12

Hierarchical transmission of DCT coefficients using multi-code DS/SS modulation Reviewed

Honjo M, Makido S, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E87A ( 11 ) page： 3001 - 3007 2004.11

Hierarchical transmission of DCT coefficients using multi-code DS/SS modulation Reviewed

Honjo M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E87-A ( 11 ) page： 3001 - 3007 2004.11

Hierarchical transmission of DCT coefficients using multi-code DS/SS modulation Reviewed

M Honjo, S Makido, T Yamazato, H Okada, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E87A ( 11 ) page： 3001 - 3007 2004.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We propose a novel hierarchical transmission method of DCT coefficients using multi-code DS/SS modulation. For low resolution image transmission over noisy channel, an error resilient and graceful degradation technique is necessary. Here, the DCT coefficients are divided into each stratum (a branch of multi-code DS/SS) and transmitted simultaneously through a noisy channel. By assigning an appropriate transmission energy that corresponds to their source energy variances, energy assignment, it is possible to maintain picture quality effectively even in a noisy channel. Analysis of this method was performed using an image data model, 2-D Gauss-Markov random field, which showed that picture quality is maintained even in the noisy channel condition.

[Invited Paper] Information and Signal Processing for Sensor Networks Invited Reviewed

A. Ogawa, T. Yamazato, T. Ohtsuki

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E87-A ( 10 ) page： 2599-2606 2004.10

Language：English Publishing type：Research paper (scientific journal)

Sensor networks, in which a large number of sensor nodes are connected with each other through communication networks, are potential to provide extensive new applications with various research and technical challenges and attracting much attention all over the world. In this paper we describe information and signal processing for sensor networks with emphasis on the concepts of collaboration and fusion as one of the most important issues for the sensor networks. We also review some basic aspects of sensor networks in terms of their features and the network architecture.

A Macro and Micro MIMO Diversity Scheme for a Shadowing Environment Reviewed

R. Uchida, H. Okada, T. Yamazato, M. Katayama

The 2004 International Symposium on Information Theory and Its Applications page： 1535-1539 2004.10

Performance Evaluation for Error Correcting Scheme on Multiple Routes in Wireless Multi-hop Networks Reviewed

N. Nakagawa, H. Okada, T. Wada, T. Yamazato, M. Katayama

The 2004 International Symposium on Information Theory and Its Applications page： 1535-1539 2004.10

Language：English

In this paper, we consider the improvement of packet error rate on wireless multi-hop networks. One of the important and interesting techniques for wireless multi-hop networks is multi-path routing. By using multi-path routing, multiple routes can be established from a source node to a destination node. In this paper, we propose the error correcting scheme in which the coded different packets are transmitted using multiple routes on wireless multi-hop networks. Hence, we can achieve a coding gain for multiple routes and expect the improvement of performance. In wireless multi-hop networks, the route loss due to topological change or recognizing failure may be happened. From the above discussion, we evaluate the proposed scheme by packet error rate in consideration of the influence of the route loss.

Information and signal processing for sensor networks Reviewed

Ogawa A, Yamazato T, Ohtsuki T

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E87A ( 10 ) page： 2599 - 2606 2004.10

Information and signal processing for sensor networks Reviewed

Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E87-A ( 10 ) page： 2599 - 2606 2004.10

Information and signal processing for sensor networks Reviewed

A Ogawa, T Yamazato, T Ohtsuki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E87A ( 10 ) page： 2599 - 2606 2004.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Performance analysis of CDMA Unslotted ALOHA system employing successive interference cancellation Reviewed

Performance Analysis of MC-CDMA System with and without Guard Interval in Two-Path Channel Reviewed

H. Yamamoto, T. Yamazato, H. Okada, and M. Katayama

IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA) page： 67-71 2004.9

Performance Analysis of UWB Impulse Radar Using Parallel IPCP Receiver Reviewed

H. Hatano, H. Okada, T. Yamazato, M. Katayama

1st International Symposium on Wireless Communication Systems page： 115-119 2004.9

Language：English

UWB impulse radar has high accuracy of measurement because it uses a transmitted signal whose pulse length is below some nanosecond. In this paper, we propose two novel inter-period correlation processing (IPCP) receivers for UWB impulse radar. The conventional IPCP receiver uses the signal periodicity of signals, so it avoids estimation of unknown parameters determined by the targets and propagation. However, its accuracy of measurement is poor because the time resolution is restricted to a signal periodicity. We propose a parallel IPCP receiver to improve accuracy. When there are multiple targets, the conventional IPCP receiver needs multiple thresholds to detect. This results in complexity of the receiver. So, we propose a parallel differential IPCP receiver. We present the analysis of the outputs, and the performance of proposed receivers.

A Study on Error Correcting and Diversity Combiner Scheme on Multiple Routes in Wireless Multi-hop Networks Reviewed

H. Okada, N. Koie, N. Nakagawa, T. Yamazato, M. Katayama

1st International Symposium on Wireless Communication Systems page： 183-187 2004.9

Language：English

A Simple Data Relay Process and Turbo Code Application to Wireless Sensor Networks Reviewed

T. Yamazato, H. Okada, M. Katayama, A. Ogawa

1st International Symposium on Wireless Communication Systems page： 398-402 2004.9

Language：English

In this study, we focus on relay process of intermediate node of wireless sensor networks. In conventional wireless sensor networks, the intermediate node performs the regenerative repeating process such that error correction, detection and re-encoding are processed. This is reliable, but it requires a lot of processing effort and may take much energy. To reduce a burden of relay process, we propose to omit error decoding and/or re-encoding process at the intermediate nodes. Further, we propose a method that realizes soft-decision decoding for hard-detected signals. With this method, we can employ Turbo code to wireless sensor networks. As results, we show that though omitting the decoding and re-encoding process at the intermediate node may not affect much to the performance.

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Y. Hirayama, N. Nakagawa, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC2004 page： - 2004.9

Language：English

In real-time packet communications, packet retransmission is generally not used because it may produce undesired delays. In this case, however, packet errors caused by a channel may lead to a loss of transmitted information directly. Then, it is necessary to employ a technique which can reduce the influence of packet errors. We propose to employ a multiple-route packet combining scheme in real-time communications on wireless multihop networks. The scheme can achieve a diversity gain by combining multiple copies of the same packet that are transmitted along different routes. We analyze two characteristics of the proposed system. One is the average packet error probability, which is obtained as a function of elapsed time after transmission requests for copied packets are generated. The other is the required time for achieving a required packet error probability. The results are evaluated from a quality of service (QoS) point of view. From numerical results, it is shown that for a given tolerable delay, there exists a number of multiple routes that minimizes the achievable average packet error probability. Moreover, if the number of multiple routes is selected appropriately, the required time for achieving a required packet error probability can be minimized.

The Optimum Received Signal-Power Distribution for CDMA Packet Communication Systems Employing Successive Interference Cancellation Reviewed

Y. Tadokoro, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA) page： 37-41 2004.9

Language：English

In CDMA packet communication systems employing Successive Interference Cancellation(SIC) scheme, the suppression of MAI depends on the received signal-power distribution, in addition to the cross-correlation characteristic of spreading sequences and the number of transmitted packets. Some works have been done about discovering the received signal-power distribution which makes MAI be suppressed effectively. This distribution minimizes the averaged Bit Error Rate(BER). However, in packet communication systems, it is dominant to the performance if packets can be transmitted successfully or not. Even if the averaged BER is high, many packets can be correctly transmitted. It implies that the optimum distribution on averaged BER does not give the best performance of packet transmission.In this paper, the received signal-power distribution which gives the best performance of packet transmission is derived. Such a distribution will make clear the limit of performance improvement using SIC.

Assisted Highway System Using Reference Course Information and Inter-Vehicle Communications Reviewed

D. Yamakage, T. Yamazato, H. Okada, M. Katayama

The 4th International Workshop on ITS Telecommunications page： 181-185 2004.7

Language：English

In this paper, we propose AHS system using DGPS, RVC and IVC. And, we evaluate the system performance in simulation. From simulation results, we find that if the RVC bit error rate is about 10^-5, it is possible to accomplish the same tracking performance as the case that RVC bit error does not occur. Moreover, we confirm that when IVC packet error rate is less than 10^-3, it can be enough to achieve ideal platooning performance.

A Study for Wireless TCP Access with Base Station Diversity Reviewed

K. Naito, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J87-B ( 4 ) page： 512-523 2004.4

Language：Japanese Publishing type：Research paper (scientific journal)

The performance of TCP degrades and it can not communicate each other in a wireless environment. In this paper, we propose a new base station diversity cellular system which evaluates the relations between wireless environments and TCP characteristics. From our result, the proposed system can improve the TCP characteristics without over consumption of wireless resource. Further, it is important to consider a cell radius from a view point of required TCP characteristics.

A Study for Wireless TCP Access with Base Station Diversity Reviewed

Katsuhiro Naito, Hiraku Okada, Takaya Yamazato, Masaaki Katayama

IEICE Transaction on Communications (Japanese) Vol. J87-B ( 4 ) page： 512 - 523 2004.4

B-17-17 Influence of the Sampling Jitter on the Performance of a Software-Defined Receiver Reviewed

Suzuki Kensuke, Okada Hikaru, Yamazato Takaya, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2004 ( 1 ) page： 852 2004.3

An Adaptive PLC Receiver with the Estimation of Instantaneous Noise Power Reviewed

Y. Hirayama, H. Okada, T. Yamazato and M. Katayama

8th International Symposium on Power-Line Communications and Its Applications page： 116-121 2004.3

Language：English

Performance evaluation for a diversity decoding scheme under multipath environment with OFDM Reviewed

H. Shibata, A. Ogawa, T. Yamazato

2004 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP04) page： 25-28 2004.3

Language：English

This paper is concerned with the performance evaluation for the diversity decoding scheme in which space diversity technique and iterative decoding for non systematic convolutional error-correcting code are effectively combined. The concept of the diversity decoding is applied to an OFDM system (e.g. the digital terrestrial TV broadcasting system). This paper shows the performance evaluation for the diversity decoding scheme under multipath environment with OFDM.

A study of adaptive MMSE receiver operating in thefrequency domain for CDMA system Reviewed

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

2004 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP04) page： 57-60 2004.3

A study on error correcting and diversity combiner scheme on multiple routes in wireless multi-hop networks Reviewed

Okada H, Koie N, Nakagawa N, Yamazato T, Katayama M

1ST INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS 2004, PROCEEDINGS page： 183 - 187 2004

Y Tadokoro, H Okada, T Yamazato, M Katayama, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 87 ( 6 ) page： 32 - 43 2004

Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

Multiple access interference (MAI) occurs in the CDMA Unslotted ALOHA system and is a significant factor for degradation of performances. Further, in this system, there are frequent situations in which the received signal power becomes inhomogeneous so that the effect of the MAI is enhanced. Presently, an interference cancellation technique is developed as a way to Suppress the MAI. However, this method mainly deals with a system that transmits and receives signals continuously in time. The evaluation of the performances is also by means of the bit error rate. In the packet communication system, success or failure of the transmission of each packet rather than of the transmission of each bit is the key to system performances. Hence, in the present study, a system is proposed that uses a successive interference cancellation as one of the interference cancellation techniques to the CDMA Unslotted ALOHA system. The throughput performance is analytically derived for performance evaluation. Also, in general, the performances under the situation of unequal received signal power are worse than those for equal received power. However, in the proposed system, performance can be better in an unequal received power environment than in the equal power case. (C) 2004 Wiley Periodicals, Inc.

DOI： 10.1002/ecjc.10116

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Performance analysis of UWB impulse radar using parallel IPCP receiver Reviewed

Hatano H, Okada H, Yamazato T, Katayama M

1ST INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS 2004, PROCEEDINGS page： 115 - 119 2004

Y Hirayama, N Nakagawa, H Okada, T Yamazato, M Katayama

2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS page： 140 - 144 2004

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In real-time packet communications, packet retransmission is generally not used because it may produce undesired delays. In this case, however, packet errors caused by a channel may lead to a loss of transmitted information directly. Then, it is necessary to employ a technique which can reduce the influence of packet errors. We propose to employ a multiple-route packet combining scheme in real-time communications on wireless multihop networks. The scheme, which is proposed in [1], can achieve a diversity gain by combining multiple copies of the same packet that are transmitted along different routes. We analyze two characteristics of the proposed system. One is the average packet error probability, which is obtained as a function of elapsed time after transmission requests for copied packets are generated. The other is the required time for achieving a required packet error probability. The results are evaluated from a quality of service (QoS) point of view. From numerical results, it is shown that for a given tolerable delay, there exists a number of multiple routes that minimizes the achievable average packet error probability. Moreover, if the number of multiple routes is selected appropriately, the required time for achieving a required packet error probability can be minimized.

DOI： 10.1109/PIMRC.2004.1370852

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Hirayama Y, Nakagawa N, Okada H, Yamazato T, Katayama M

2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS page： 140 - 144 2004

SNIR Analysis of Asynchronous MC-CDMA System in Frequency Selective Fading Channel Reviewed

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J86-A ( 12 ) page： 1426-1430 2003.12

SNIR Analysis of Asynchronous MC-CDMA System in Frequency Selective Fading Channel Reviewed

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J86-A ( 12 ) page： 1426-1430 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

This paper presents the signal to noise plus interference ratio(SNIR) analysis of the asynchronous Multicarrier (MC)-CDMA system with multipath fading channel. We derive the SNIR of the MC-CDMA system and compared with that of the DS-CDMA. We found that the SNIR of the MC-CDMA is equal to that of the band-limited DS-CDMA system under the same bandwidth and the same spreading factor.

Reducing Peak Power of Coded OFDM Systems with Multiple Symbol Mapping Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J86-A ( 10 ) page： 1058-1067 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we propose a novel coding scheme to reduce a peak envelope power (PEP) of convolutionally coded orthogonal frequency devision multiplex (OFDM) signals. In this system, convolutionally coded bits are mapped into symbol sequence. The symbol sequence have multiple symbols which are adjusted so as to show low PEP. Also, applying a set partition to the symbol sequence enable to enlarge an Euclidean distance between each sequence. We evaluate the performance of proposed system under the effect of nonlinear amplifier.

Reducing Peak Power of Coded OFDM Systems with Multiple Symbol Mapping Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. J86-A ( 10 ) page： 1058-1067 2003.10

基地局ダイバシチを用いたTCPによる無線インターネット接続に関する一検討

内藤克浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会ネットワークシステム研究会 Vol. 103 ( 204 ) page： 31 - 36 2003.7

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E86-A ( 6 ) page： 1541-1549 2003.6

Language：English Publishing type：Research paper (scientific journal)

In an attempt to improve the performance under frequency selective fading environment, we develope in this paper an orthogonal frequency division multiplex (OFDM) system in which adaptive interleaving is applied. The adaptive interleaving is a method that assigns symbols adaptively to the subcarriers in order to cope with frequency selective fading based on a channel state information (CSI) sent back from the reception end. The concept of adaptive interleaving is to maximize a free Euclidean distance in the limited interleave size. In this paper, we extend the method by an introduction of bit interleaving and multiple trellis coded modulation (MTCM). MTCM assigns two or more symbols to one trellis branch and shows good performance in frequency selective fading. If we could assign those set of symbols with an aid of the adaptive interleaving, the performance improvement can be expected. Another improvement method considered in this paper is the use of bit interleaving. The bit interleaving techniques randomize the effect of channel more efficiently compared to the case of symbols interleaving. Thus the further performance improvement is expected. One draw back is that since the interleaving process is done in bit level, bit interleaving can not be applied to TCM nor MTCM. In this paper, we mainly focus on adaptive bit and symbol interleaving and discuss the performance from the point of interleaving effect, and the error correcting code (convolutional code and MTCM).

Performance improvement for coded OFDM systems with adaptive interleaving in frequency selective fading channel Reviewed

Harada M, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E86A ( 6 ) page： 1541 - 1549 2003.6

Harada M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E86-A ( 6 ) page： 1541 - 1549 2003.6

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Fundamentals Vol. E86-A ( 6 ) page： 1541-1549 - 1549 2003.6

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In an attempt to improve the performance under frequency selective fading environment, we develop in this paper an orthogonal frequency division multiplex (OFDM) system in which adaptive interleaving is applied. The adaptive interleaving is a method that assigns symbols adaptively to the subcarriers in order to cope with frequency selective fading based on a channel state information (CSI) sent back from the reception end. The concept of adaptive interleaving is to maximize a free Euclidean distance in the limited interleave size. In this paper, we extend the method by an introduction of bit interleaving and multiple trellis coded modulation (MTCM). MTCM assigns two or more symbols to one trellis branch and shows good performance in frequency selective fading. If we could assign those set of symbols with an aid of the adaptive interleaving, the performance improvement can be expected. Another improvement method considered in this paper is the use of bit interleaving. The bit interleaving techniques randomize the effect of channel more efficiently compared to the case of symbols interleaving. Thus the further performance improvement is expected. One draw back is that since the interleaving process is done in bit level, bit interleaving can not be applied to TCM nor MTCM. In this paper, we mainly focus on adaptive bit and symbol interleaving and discuss the performance from the point of interleaving effect, and the error correcting code (convolutional code and MTCM).

A study on linear filtering in frequency domain for DS-CDMA systems Reviewed

TAKEUCHI Hiroshi, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2003 page： 154 2003.3

A Study on Turbo Soft-Decision Decoding for Hard-Detected Optical Communication signals Reviewed

ZHENG Chen, YAMAZATO Takaya, OKADA Hikaru, KATAYAMA Masaaki, OGAWA Akira

IEICE Trans. Communication, B Vol. 86 ( 3 ) page： 1022 - 1030 2003.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We propose a method to realize soft-derision decoding for hard-detected signals. In this paper, a novel concept is introduced as "error-deleeled reliability." The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of If 10^<〜11> can be achieved by serial concatenation of a ReedSolomon code and a turbo code for Q-factor lower than 8.0dB with a bandwidth expansion ratio of 33.3%.

A Study on Turbo Soft-Decision Decoding for Hard Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022-1030 2003.3

Language：English Publishing type：Research paper (scientific journal)

We propose a method to realize soft-decision decoding for hard-detected signals. In this paper, a novel concept is introduced as error-detected reliability. The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of 10-11 can be achieved by serial concatenation of a Reed-Solomon code and a turbo code for Q-factor lower than 8.0 dB with a bandwidth expansion ratio of 33.3%.

Noise analysis on wide-band PLC with high sampling rate and long observation time Reviewed

Y. Hirayama, H. Okada, T. Yamazato and M. Katayama

7th International Symposium on Power-Line Communications and Its Applications page： 142-147 2003.3

Language：English

This manuscript reports the results of the measurement of wide-band PLC noise with high speed (50MHz) sampling and long (10.4s) observation duration. The measured noise is divided in frequency, and stochastic properties of the noise waveforms in each frequency bands, such as autocorrelations, probability density functions, and correlation coefficients between noise waveforms of different frequency bands are discussed. Cyclostationary features of the noise in each band is confirmed. It is found that the amplitude distribution in each band is different, and that Gaussian noise model is not a good approximation in higher frequency bands.

Soft-Decision Decoding of Low-Density Parity-Check Codes for Hard-Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1132-1135 2003.3

Language：English Publishing type：Research paper (scientific journal)

A soft-decision decoding scheme of low-density parity-check codes (LDPC) is proposed for hard-detected signals of optical fiber communication (OFC) systems. Based on the error detection, the proposed scheme converts the received hard-decision into soft reliability for the input of the LDPC decoder, and soft-decision decoding is performed. Simulation results under OFC channels are shown and superior performance is obtained by using the proposed decoding scheme of the LDPC codes.

A Study on Turbo Soft-Decision Decoding for Hard Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022-1030 - 1135 2003.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

A soft-derision decoding scheme of low-density parity-check codes (LDPC) is proposed for hard-detected signals of optical fiber communication (OFC) systems. Based on the error detection, the proposed scheme converts the received hard-decision into soft reliability for the input of the LDPC decoder, and soft-decision decoding is performed. Simulation results under OFC channels are shown and superior performance is obtained by using the proposed decoding scheme of the LDPC codes.

A study on turbo soft-decision decoding for hard-detected optical communication signals Reviewed

A study on turbo soft-decision decoding for hard-detected optical communication signals Reviewed

Zheng C, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E86B ( 3 ) page： 1022 - 1030 2003.3

Zheng C., Yamazato T., Okada H., Katayama M., Ogawa A.

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022 - 1030 2003.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Communications

We propose a method to realize soft-decision decoding for hard-detected signals. In this paper, a novel concept is introduced as "error-detected reliability." The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of 10-11 can be achieved by serial concatenation of a Reed-Solomon code and a turbo code for Q-factor lower than 8.0 dB with a bandwidth expansion ratio of 33.3%.

Soft-decision decoding of low-density parity-check codes for hard-detected optical communication signals Reviewed

Soft-decision decoding of low-density parity-check codes for hard-detected optical communication signals Reviewed

Zheng C, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E86B ( 3 ) page： 1132 - 1135 2003.3

Zheng C.

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1132 - 1135 2003.3

Comparison of multiple access schemes in multibeam Non-GEO satellite communication systems Reviewed

Ichikawa N, Katayama M, Okada H, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E86B ( 2 ) page： 785 - 791 2003.2

Comparison of multiple access schemes in multibeam non-GEO satellite communication systems Reviewed

Ichikawa N.

IEICE Transactions on Communications Vol. E86-B ( 2 ) page： 785 - 791 2003.2

Comparison of Multiple Access Schemes in Multibeam Non-GEO Satellite Communication Systems Reviewed

N. Ichikawa, M. Katayama, H. Okada, T. Yamazato, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 2 ) page： 785-791 2003.2

逐次型干渉除去法を用いたCDMA Unslotted ALOHA方式の特性評価 Reviewed

田所幸浩, 岡田啓, 山里敬也, 片山正昭, 小川明

電子情報通信学会論文誌 A Vol. J86-A ( 2 ) page： 168 - 178 2003.2

Performance Analysis of CDMA Unslotted ALOHA System \\Employing Successive Interference Cancellation Reviewed

Yukihiro TADOKORO, Hiraku OKADA,\\ Takaya YAMAZATO, Masaaki KATAYAMA,

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences page： - 2003.1

Language：Japanese Publishing type：Research paper (scientific journal)

In a CDMA Unslotted ALOHA system, multiple access interference(MAI) has a great influence on the system performance. The unequalness of signals' power (e.x. Rayleigh fading) makes the influence more serious. The MAI may be suppressed by using interference cancellation technique. Such a technique has been considered in the system in which signals are transmitted continuously. In addition, the performance is evaluated by bit error rate. However, in a packet system, the performance depends on whether packets are successfully transmitted or not. In this paper, to suppress the MAI, CDMA Unslotted ALOHA system employing successive interference cancellation is proposed. The throughput performance of the proposed system is analyzed and evaluated. As the result, the performance is improved, and the performance under Rayleigh fading is better than that in the case of equal signals' power.

Soft-Decision Decoding of Low-Density Parity-Check Codes for Hard-Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

IEICE Transactions on Communications page： - 2003.1

Language：English Publishing type：Research paper (scientific journal)

Medium Access Control Protocol Based on Estimation ofMultimedia Traffic with an Adaptive Algorithm in CDMA PacketCommunications Reviewed

Y. Hirayama, H. Okada, T. Yamazato, and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences page： - 2002.12

A Study on the Application of Error Concealment Technique to Real-Time Parallel Video Decoder Reviewed

M. Honjo, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences page： - 2002.12

Language：Japanese Publishing type：Research paper (scientific journal)

As high error resilience and low delay decoding technique, RT-PVD (real-time parallel video decoder) has been proposed[1]. In this paper, we consider the performance of the RT-PVD in which error concealment (EC) technique is included. Ordinary, even if the EC was applied, secondary error propagation would be eventually caused. But in the RT-PVD, the random block noise was replaced by appropriate block of the reference frame sequence. So we could establish high PSNR gain and good perceptual quality without error propagation.

A Study on Turbo Soft-Decision Decoding for Hard Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications page： - 2002.12

Language：English Publishing type：Research paper (scientific journal)

We propose a method to realize soft-decision decoding for hard-detected signals. In this paper, a novel concept is introduced as ``error-detected reliability''. The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of $10^{-11}$ can be achieved by serial concatenation of a Reed-Solomon code and a turbo code for Q-factor lower than $8.0$ dB with a bandwidth expansion ratio of $33.3\%$.

A study on statistical characteristic of bit-error rate with transmitter diversity in fading channels

R. Uchida, H. Okada, T. Yamazato, and M. Katayama

Symposium on Information Theory and Its Applications (SITA) page： - 2002.12

Language：Japanese

In this paper, we analize a characteristic of wireless communication system from a viewpoint of probability distribution of bit-error rate (BER) for aiming to guarantee the reliability of wireless communication systems. A single transmission space diversity (time space repetitional coding) with M transmit antennas through independent slow Rayleigh fading channels is considered. The influence of combining method of the receiver, and the number of transmit antennas, to the BER distribution is clarified.

Medium access control protocol based on estimation of multimedia traffic with an adaptive algorithm in CDMA packet communications Reviewed

Hirayama Y, Okada H, Yamazato T, Katayama M

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E85A ( 12 ) page： 2868 - 2876 2002.12

Medium access control protocol based on estimation of multimedia traffic with an adaptive algorithm in CDMA packet communications Reviewed

Hirayama Y.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E85-A ( 12 ) page： 2868 - 2876 2002.12

Medium Access Control Protocol Based on Estimation of Multimedia Traffic with an Adaptive Algorithm in CDMA Packet Communications Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals Vol. E85-A ( 12 ) page： 2868-2876 - 2876 2002.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we propose a medium access control (MAC) protocol for multimedia code division multiple access (CDMA) communications. In the proposed protocol, a base station (BS) estimates the instantaneous number of simultaneously transmitted packets in the future slots with exploiting a stochastic property of traffic. In order to carry out this estimation, we employ an adaptive algorithm. We evaluate the performance of the proposed protocol by comparing that with two different cases. One is no estimation case and the other is perfect estimation case. From these results, we clarify the advantage of the proposed MAC protocol.

Performance improvement of OFDM system with consideration on the characteristics of power-line noise Reviewed

Performance improvement of OFDM system with consideration on the characteristics of power-line noise Reviewed

Sugimoto K, Okada H, Yamazato T, Katayama M

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E85A ( 12 ) page： 2822 - 2829 2002.12

Sugimoto K.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E85-A ( 12 ) page： 2822 - 2829 2002.12

Performance Improvement of OFDM System with Consideration on the Characteristics of Power-Line Noise Reviewed

K. Sugimoto, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals Vol. E85-A ( 12 ) page： 2822-2829 - 2829 2002.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In narrow band power-line communication (PLC) systems, which use frequency band below a few hundred kHz, the noise on power-line is non-white and non-stationary. Under such environment, the performance of Orthogonal Frequency Division Multiplex (OFDM) modulation system is analyzed, and time and frequency dependence of bit error rate (BER) is clarified. In addition, the possibility of performance improvement with the symbol level repetition coding employing cyclo-stationary feature of power-line noise is presented.

A Study on the Application of Error Concealment Technique to Real-Time Parallel Video Decoder Reviewed

M. Honjo, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. J85-A ( 12 ) page： 1463-1468 2002.12

Calculation of Mobile Location using a Statistical Scatterer

N. J. Thomas, H. Okada, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. SST2002-34 page： 45-50 2002.10

Language：English

A statistical technique to calculate the location of a signal source, e.g. a mobile phone, in a multipath, non--line of sight environment, is proposed. The technique relies on angular spread and relative time of arrival measurements of multipath signals received at a base station antenna array. The source location is estimated using an a priori known statistical model for the distribution of single bounce multipath scatterers around the signal source, and fitting the measured channel impulse response received at the base station to this model. Further improvement in location estimation accuracy is demonstrated using the Kalman filter, or time average filter on the time sequence of location estimates in a moving scenario.

Spread Sequence for Multicarrier CDMA under the Effect of Nonlinear Amplifier Reviewed

M. Harada, T. Yamazato, H. Okada, and M. Katayama

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA2002 page： - 2002.10

Decoding of low-density parity-check codes for hard-detected optical fiber communication signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA2002 page： - 2002.10

Language：English

A soft-decision decoding scheme of low-density parity-check codes (LDPC) is proposed for hard-detected signals of optical fiber communication (OFC) systems. The scheme converts the received hard-decision into soft reliability for the input of the LDPC decoder, and soft-decision decoding is performed. Simulation results under OFC channels are shown and superior performance is obtained by using the proposed decoding scheme of the LDPC codes.

An access control protocol based on estimation of multimedia traffic with an adaptive algorithm in CDMA packet network Reviewed

Y. Hirayama, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC2002 page： 619-623 2002.9

Language：English

In multimedia wireless communications, various types of traffic are handled. Generally, each of these traffic has a different stochastic property. An access control protocol for multimedia wireless communications, therefore, are required to adopt a stochastic property of multimedia traffic. Conventional access control protocols, however, do not consider such characteristics of multimedia traffic. In this paper, we propose an access control protocol for multimedia CDMA packet communications. The proposed protocol controls the data packet transmissions based on the estimation of the instantaneous number of simultaneously transmitted voice and video packets. This estimation exploits the stochastic property of multimedia traffic. To carry out such estimation, we employ an adaptive algorithm as an estimation method. We evaluate the performance of the proposed protocol by comparing it with the performance in the case where a stochastic property of traffic is not considered.

Effect of Interleaving and FEC on the Throughput of CDMA Unslotted ALOHA System with Adaptive Multiuser Receiver Reviewed

H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC2002 ( 2 ) page： 941-945 2002.9

Language：English

A CDMA unslotted ALOHA system is a connectionless-type of CDMA packet communication system. In this system, a user station can transmit a packet asynchronously and randomly, and so the packet birth/death event is one of the most important problems for multiuser detection. We have proposed the CDMA unslotted ALOHA system using an adaptive filter receiver based on minimum mean square error criterion in [8], and shown the improvement in the throughput performance even considering the effect of birth/death event. The ensemble-averaged squared error, however, increases at the point of packet birth. In this paper, we employ interleaving and forward error correction (FEC) coding techniques to mitigate the momentary increase in ensemble-averaged squared error. The use of FEC, however, causes the increase in MAI due to redundancy bits of FEC. Moreover, signal power is reduced under the condition that the energy of an information bit is the same. In such cases, whether an adaptive filter can operate effectively or not interests us. We evaluate the system performance and show that the improvement in throughput is achieved with interleaving and FEC techniques.

A Proposal of OFDM Synchronization Scheme with Subtraction Operation Reviewed

T. Shibata, N. Itoh, M. Fujimoto, N. Suzuki, A. Ogawa, T. Yamazato, M. Harada

7th International-OFDM Workshop 2002 page： 237-240 2002.9

BER Performance of Asynchronous Multicarrier-CDMA System and Asynchronous DS-CDMA System in Frequency Selective Fading Reviewed

H. Takeuchi, T. Yamazato, H. Okada, and M. Katayama

7th International-OFDM Workshop 2002 page： 26-30 2002.9

Reduced Peak Power Transmission for Convolutionally Coded OFDM Signals Reviewed

M. Harada, T. Yamazato, H. Okada, and M. Katayama

7th International-OFDM Workshop 2002 page： 102-106 2002.9

Language：English

In this paper, we propose a novel coding scheme to reduce a peak envelope power of convolutionally coded orthogonal frequency devision multiplexing (OFDM) signals. In this system, convolutionally coded bits are mapped onto symbol sequence. The symbol sequence have multiple symbols which are adjusted so as to show low peak envelope power. Also, applying a set partition to the symbol sequence enable to enlarge an Euclidean distance between each sequence. We evaluate the performance of proposed system under the effect of nonlinear amplifier.

Turbo Decoding for Hard-Detected Signals of Fiber Optical Communications Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

IASTED Wireless and Optical Communications 2002 (WOC 2002) Conference page： - 2002.7

Language：English

We propose a method to realize the soft-decision decoding for the hard-detected signals. In this paper, a novel concept is introduced as error-detected reliability. The method is very useful for fiber optical communication systems as hard detection is the only detection method for the systems. We demonstrate our proposed method using the turbo code in which the soft information is required for the decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding. Moreover, the bit error rate of $10^{-11}$ can be achieved by serial Concatenation of Reed-Solomon and turbo code for Q-factor lower than $8.0$ dB with the bandwidth expansion ratio of $33.3\%$.

Transmitting/Receiving Diversity Method using Single-phase Three-wire Power-Line for Power-Line Communication

H. Furukawa, H. Okada, T. Yamazato, and M. Katayama

Technical Report of IEICE Vol. SST2002-14 page： 13-17 2002.7

Language：Japanese

The low voltage distribution power-lines from the distribution transformer to the fuse box are single-phase and three-wire type and the In-house power-lines are single-phase and two-wire type in Japan. The two-wire type power-lines are constructed of a pair of wires of the three-wire type power-lines. And the two-wire type power-lines are used as 200V or 100V AC. Under this condition, there is mutual coupling between different pair of power-lines. Therefore it is possible to improve performance of the power-line for communication by using the Space-Frequency Coding when the transmitter or receiver is on at least two pairs of power-lines. In this paper, the transmitting/receiving diversity method using the Space-Frequency Code for Power-Line communication is proposed and the effectiveness of this method has been confirmed by experiments.

New Analytical Model for TCP in wireless Environments Reviewed

K. Naito, H. Okada, M. Saito, T. Yamazato, and M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E85-A ( 7 ) page： pp.1501-1510 2002.7

Language：English Publishing type：Research paper (scientific journal)

We propose a new analytical model of Transmission Control Protocol (TCP) in wireless environments where transmission errors occur frequently. In our proposed model, we consider the exponential increase of a congestion window and the exponential increase of a timeout back-off. Finally, we have clarified the behavior of TCP mechanisms of different versions and TCP throughput characteristics analytically. From our result, the behavior of TCP mechanisms is different in each implementation version. These differences mean that the required characteristics of wireless links are different in each implementation version. Therefore, our proposed model is a base analysis of designing wireless link mechanisms.

An Access Control Protocol Based on Estimation of Traffic with an Adaptive Algorithm in Multimedia CDMA Packet Communications

Y. Hirayama, H. Okada, T. Yamazato, and M. Katayama

Technical Report of IEICE Vol. 102 ( 204 ) page： 55-60 2002.7

Language：Japanese

In a multimedia communication, various types of traffic are handled. Generally, each traffic in a multimedia communication has a different stochastic property. Conventional access control protocols do not consider such characteristics of multimedia traffic. We propose a new access control protocol for multimedia CDMA packet communications in which stochastic properties of multimedia traffic is considers. The proposed protocol controls packet transmissions based on estimation of the instantaneous number of simultaneously transmitted packets. This estimation is carried out by an adaptive algorithm. Simulation results show the advantage of the proposed protocol over the protocol which does not estimate the number of simultaneously transmitted packets

Statistical Noise Characterization for Wide Band Power Line

Y. HIRAYAMA, H. OKADA, T. YAMAZATO, and M. KATAYAMA

Technical Report of IEICE Vol. SST2002-13 page： 7-12 2002.7

Language：Japanese

The wide band power-line communication system (PLC) has been drawing much attention as an alternative communication system. To realize reliable high-speed data transmissions, it is essential to understand the noise feature on the power-line. Noise characteristics of the narrow band PLC have been discussed in previous papers, however, there is few report on the wide band PLC noise. In this paper, we prepare a noise measurement system and discuss on the measured noise characteristics in wide band. As a result, we show that the noise characteristics differ greatly dependents on frequency.

New analytical model for TCP in wireless environments Reviewed

Naito K, Okada H, Saito M, Yamazato T, Katayama M

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E85A ( 7 ) page： 1501 - 1510 2002.7

New analytical model for TCP in wireless environments Reviewed

Naito K.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E85-A ( 7 ) page： 1501 - 1510 2002.7

New Analytical Model for TCP in Wireless Environments Reviewed

Katsuhiro Naito, Hiraku Okada, Masato Saito, Takaya Yamazato, Masaaki Katayama

IEICE Transactions on Fundamentals Vol. E85-A ( 7 ) page： 1501 - 1510 2002.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Performance Evaluation of PredictionError Based MAP Receiver for DCT Compressed Image Transmission Reviewed

A Study on Handover and Channel Allocation Scheme using Linear Shift Property of the Servicearea in Low Earth-Orbital Satellite

K.Nisihara, H.Okada, T.Yamazato, and M.Katayama

Technical Report of IEICE Vol. 102 ( 144 ) page： 15-18 2002.6

Language：Japanese

In this paper, we discuss the handover and channel allocation scheme for cellular systems of Low Earth-Orbital (LEO) satellite. By using the linear sift property of LEO satellite, we propose the handover scheme in which a user use the same channel even if a handover occurs. Furthermore, we propose the dynamic channel allocation scheme taking account of the centralized cellular system of LEO Satellite. In this scheme, a channel is assigned according to the objective function which is calculated by user and channel distribution. From comparison of numerical results, we show that the proposed scheme can improve the blocking probability.

A study on SOVA based Turbo-decoding with threshold Reviewed

M. Matsui, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J85-A ( 5 ) page： pp.606-609 2002.5

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we propose a new SOVA based Turbo-decoding scheme which applys a variable threshold to the output of each of the component decoder. The value of the threshold is determined accoding to the distribution of the observed output of each of the component decoder. We show that our proposed scheme gives the better BER performance than conventional one.

Performance Evaluation of PredictionError Based MAP Receiver for DCT Compressed Image Transmission Reviewed

S. Makido, M. Honjo, T. Yamazato, H. OKada, M. Katayama, A. Ogawa

The Journal of the Institute of Television Engineers of Japan Vol. 56 ( 5 ) page： pp.842-845 2002.5

S. Makido, M. Honjo, T. Yamazato, H. OKada, M. Katayama, A. Ogawa

The Journal of the Institute of Television Engineers of Japan Vol. 56 ( 5 ) page： 842-845 - 845 2002.5

Potentiality of Campus Portal

T. Yamazato, S. Kajita, H. Okada

IEICE General Conference Vol. KD-1-2 page： 257-258 2002.3

BER Performance Analysis of Multicarrier-CDMA Systems in Multipath Fading Channel

H.takeuchi, T.yamazato, H.okada and M.katayama

Technical Report of IEICE Vol. SST2001-171 page： pp.13-18 2002.3

Language：Japanese Publishing type：Research paper (scientific journal)

This paper presents the BER analysis of the asynchronous Multicarrier (MC)-CDMA system in multipath fading channel. We derive the BER of the MC-CDMA and compared with that of the DS-CDMA. We found that the BER of the MC-CDMA is a little worse than that of the band-limited DS-CDMA under the same bandwidth and the same spreading factor, and when the number of multipath is infinity, the BER of both systems are regarded as being that for the case without fading channel. However, if the number of multipath is more than the number of finger of Rake receiver, the MC-CDMA system can perform better than the DS-CDMA system.

A study on Iterative Decoding and Diversity Scheme for Correlated Rayleigh Fading Signals

R. Chang, C. Zheng, T. Yamazato, M. Katayama, A. Ogawa

IEICE General Conference Vol. B-5-221 page： p.672 2002.3

CDMA Packet Recognition and Signal Acquisition using LMS-based Adaptive Receiver Reviewed

T. Kume, T. Yamazato, K. Ban, H. Okada, and M. Katayama

IEEE Wireless Communications and Networking Conference Vol. 1 page： pp.379-383 2002.3

Language：English Publishing type：Research paper (scientific journal)

In this paper, we propose a new packet recognition and signal acquisition scheme with an adaptive linear filter based on an Least Mean Square (LMS) algorithm for code-division multiple access (CDMA) packet systems. In CDMA systems, conventional receivers with matched filtering suffer from the near-far problem due to multiple access interference (MAI). In general, closed-loop power control is used in order to reduce the influence of the near-far problem. However, closed-loop power control is unsuitable for packet systems. Hence, in order to eliminate the influences of the near-far problem, we focus on an adaptive receiver based on an LMS algorithm for a packet recognition and signal acquisition in CDMA packet systems.

Effect of Nonlinear Amplifiers of Transmitters in Multicarrier CDMA Systems Reviewed

H. Muramatsu, M. Harada, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J85-A ( 3 ) page： pp.340-348 2002.3

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we compare Multicarrier(MC-) CDMA systems with DS-CDMA systems in the asynchronous uplink channel. First, we analysis signal to noise inteference ratio (SNIR) of asynchronous MC-CDMA systmes in AWGN channel, in order to show the basic performance of MC-CDMA systems. Then, we discuss the effect of nonlinear amplifiers of trnasmitters in MC-CDMA systems, which are usually required using in the mobile terminals for the uplink. We evaluate bit error rate preformance taking account of out-of-band emission.

Effect of Nonlinear Amplifiers of Transmitters in Multicarrier CDMA Systems Reviewed

H. Muramatsu, M. Harada, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J85-A ( 3 ) page： 340-348 2002.3

Comparison of Multiple Access Schemes in Multibeam Non-GEO Satellite Communication Systems Reviewed

N. Ichikawa, M. Katayama, H. Okada, T. Yamazato, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 2 ) page： 785-791 2002.2

Language：English Publishing type：Research paper (scientific journal)

This paper describes an analytical method to estimate the amount of interference in multibeam non-geostationary satellite systems. The performance of CDMA is compared with that of FDMA (or TDMA) by employing the maximum acceptable number of users per cell in uplink as a measure. Numerical examples shows that the maximum acceptable number of users in FDMA (or TDMA) systems varies according to the altitude of the satellites, while the performance is insensitive to the altitude in CDMA systems. Then, it is found that the superior multiple access scheme depends on the altitude of the satellite.

The Real-Time Parallel Video Decoder Considered on the Complexity and Delay of Error Correcting Decoding Reviewed

M. Honjo, S. Makido, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J85-A ( 2 ) page： pp.214-230 2002.2

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, a new video decoding scheme integrating error correcting decoder is proposed. In video data transmission, some error correcting code should be equipped to keep video data quality. But in many cases it would need much complex calculation and delay at the decoder when high quality of video data is required. Then, we prepare the two error correcting decoders against one error correcting encoder, where they are different in the delay and the reliability. Due to reconstructing output frame and reference frame separately with two outputs, less delay and less degradation is accomplished. The video quality is analyzed with the 3-D DPCM parallel decoder. Here we show that the degradation of output frame is minimized when no error exists in the reference frame. And we evaluate the simulation results using concatenating code as an example of two output error correcting decoder. Here we show that it is possible to maintain the video quality and achieves graceful degradation in low channel energy, especially in Rayleigh fading channel. Furthermore in the subjective evaluation, we can confirm that the degradation seems to less impression than general decoding in the same PSNR.

The Real-Time Parallel Video Decoder Considered on the Complexity and Delay of Error Correcting Decoding Reviewed

M. Honjo, S. Makido, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. J85-A ( 2 ) page： 214-230 2002.2

An access control protocol based on estimation of multimedia traffic with an adaptive algorithm in CDMA packet network Reviewed

Hirayama Y, Okada H, Yamazato T, Katayama M

13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS page： 619 - 623 2002

CDMA packet recognition and signal acquisition using LMS-based adaptive receiver Reviewed

T Kume, Yamazato, I, K Ban, H Okada, M Katayama

WCNC 2002: IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE RECORD, VOLS 1 & 2 Vol. 1 page： 379 - 383 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we propose a new packet recognition and signal acquisition scheme with an adaptive linear filter based on an Least Mean Square (LMS) algorithm for code-division multiple access (CDMA) packet systems. In CDMA systems, conventional receivers with matched filtering suffer from the near-far problem due to multiple access interference (MAI). In general, closed-loop power control is used in order to reduce the influence of the near-far problem, However, closed-loop power control is unsuitable for packet systems. Hence, in order to eliminate the influences of the near-far problem, we focus on an adaptive receiver based on an LMS algorithm for a packet recognition and signal acquisition in CDMA packet systems.

DOI： 10.1109/WCNC.2002.993525

An access control protocol based on estimation of multimedia traffic with an adaptive algorithm in CDMA packet network Reviewed

Y Hirayama, H Okada, T Yamazato, M Katayama

13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS Vol. 2 page： 619 - 623 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/PIMRC.2002.1047296

Effect of interleaving and FEC on the throughput of CDMA unslotted aloha system with adaptive multiuser receiver Reviewed

H Okada, T Yamazato, M Katayama

13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS Vol. 2 page： 941 - 945 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

A CDMA unslotted ALOHA system is a connectionless-type of CDMA packet communication system. In this system, a user station can transmit a packet asynchronously and randomly, and so the packet birth/death event is one of the most important problems for multiuser detection. We have proposed the CDMA unslotted ALOHA system using an adaptive filter receiver based on minimum mean square error criterion in [8], and shown the improvement in the throughput performance even considering the effect of birth/death event. The ensemble-averaged squared error, however, increases at the point of packet birth. In this paper, we employ interleaving and forward error correction (FEC) coding techniques to mitigate the momentary increase in ensemble-averaged squared error. The use of FEC, however, causes the increase in MAI due to redundancy bits of FEC. Moreover, signal power is reduced under the condition that the energy of an information bit is the same. In such cases, whether an adaptive filter can operate effectively or not interests us,,. We evaluate the system performance and show that the improvement in throughput is achieved with interleaving and FEC techniques.

DOI： 10.1109/PIMRC.2002.1047360

A new packet detection scheme in CDMA unslotted ALOHA system with successive interference cancellation Reviewed

Effect of interleaving and FEC on the throughput of CDMA unslotted aloha system with adaptive multiuser receiver Reviewed

Okada H, Yamazato T, Katayama M

13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS page： 941 - 945 2002

Turbo decoding for hard-detected signals of fiber optical communications Reviewed

Zheng C, Yamazato T, Okada H, Katayama M, Ogawa A

PROCEEDINGS OF THE IASTED INTERNATIONAL CONFERENCE ON WIRELESS AND OPTICAL COMMUNICATIONS page： 125 - 130 2002

A Study on Reducing Peak Power of MTCM OFDM Systems

M. Harada, T. Yamazato, H. Okada, and M. Katayama

Symposium on Information Theory and Its Applications (SITA) Vol. 1 page： 71-74 2001.12

Tadokoro Y., Okada H., Yamazato T., Katayama M., Ogawa A.

Conference Record / IEEE Global Telecommunications Conference Vol. 5 page： 3173 - 3177 2001.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Conference Record / IEEE Global Telecommunications Conference

A packet detection is one of the most important problems in packet communication systems. In a CDMA Unslotted ALOHA system, which is one of the wireless packet communication systems, Multiple Access Interference(MAI) makes the performance of the packet detection worse. To reduce the effect of MAI, we propose a new packet detection scheme in this paper. In this scheme, Successive Interference Cancellation(SIC) is applied. The packet's signal is detected after the cancellation of MAI using SIC. This proposed scheme gives good performance of the packet detection.

Hierarchical transmission of video signal using multi-code DS/SS modulation based on DCT coefficients Reviewed

Honjo M.

Conference Record / IEEE Global Telecommunications Conference Vol. 6 page： 3395 - 3399 2001.12

A New Packet Detection Scheme in CDMA Unslotted ALOHA System with Successive Interference Cancellation Reviewed

Y. Tadokoro, H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE Global Communications Conference Vol. 5 page： pp.3173-3177 2001.11

Language：English

Spread Spectrum Techniques and its Applications --CDMA, bluetooth, 2.4GHz Wireless LAN and the latest topics-- Invited

Takaya Yamazato

MST2001 Vol. D-4 page： 39-59 2001.11

Hierarchical Transmission of Video Signal Using Multi-Code DS/SS Modulation Based on DCT Coefficients Reviewed

M. Honjo, S. Makido, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEEE Global Communications Conference Vol. 6 page： pp.3395-3399 2001.11

Language：English

In this paper, we propose a hierarchical transmission of video signal using multi-code DS/SS modulation. Assigning an appropriate distribution of transmission energy to DCT coefficients, it is possible to control the picture quality depending on the channel quality. We consider a hierarchical structure based on the variance of DCT coefficient and transmit each coefficient using multi-code DS/SS modulation. The analysis is carried out to show the effectiveness of our scheme using 2-D Gauss-Markov random field, which represents image data. It is shown that by an appropriate energy assignment to each stratum (a branch of multi-code DS/SS), it is possible to maintain picture quality even in bad channel quality

A Study on the Packet Detection Scheme Using Successive Interference Cancellation on CDMA Unslotted ALOHA System

Y.Tadokoro, H.Okada, T.Yamazato, M.Katayama and A.Ogawa

Technical Report of IEICE Vol. SST2001-41 page： 1-6 2001.10

Language：English

In wireless packet communication systems, it is well known that the system performance(throughput) depends on the errors of packet detection. Moreover, in a CDMA Unslotted ALOHA system, Multiple Access Interference(MAI) has much influence on the performance of packet detection, and the system performance. Our aim is to improve the system performance. To achieve it, we study the new packet detection scheme to reduce the effect of MAI on packet detection in this paper. In the proposed scheme, the effect is reduced by Successive Interference Cancellation(SIC) and the received signal with less MAI is left. The packet's signal is detected for the received signal with less MAI. This scheme gives good performance of the packet detection and throughput.

A Connection Service for Personal Terminals via LAN Sockets/Wireless LAN at CIMS, Nagoya University

H. Okada, T. Yamazato

IPSJ SIG Notes page： 31-36 2001.10

Language：Japanese

Center for Information Media Studies (CIMS) in Nagoya University was established with the aim of development of information education systems. We aim not only at the fulfillment of the computer literacy education, but also at the educational breakthrough by utilizing the multi-media technologies. More than 800 terminals are located campus wide in Nagoya University. In the future, it is expected that many students take their own computer to the campus, connect it to the information education network, and take lessons. To realize this plan, a connection service for personal terminals via LAN sockets/wireless LAN has been in experimental operation since May 2000. In this report, we describe a brief summary about this system, and discuss the issue of the system.

DS-CDMA v.s. MC-CDMA Invited

T. Yamazato, M. Harada, H. Muramatsu, H. Okada and M. Katayama

Technical Report of IEICE Vol. SST2001-47 page： 37-44 2001.10

Language：Japanese

In this paper, we compare Multicarrier (MC-) CDMA systems with DS-CDMA systems in the asynchronous uplink channel. First, we analysis signal to noise inteference ratio (SNIR) of asynchronous MC-CDMA systmes in AWGN channel, in order to show the basic performance of MC-CDMA systems. Then, we discuss the effect of nonlinear amplifiers of trnasmitters in MC-CDMA systems, which are usually required using in the mobile terminals for the uplink. We evaluate bit error rate preformance taking account of out-of-band emission.

A Study on Digital Signal Processing in Frequency Domain for a Broadband Software-Defined Base Station

T. Morikami, H. Okada, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. SR01-17 page： 71-77 2001.10

Language：Japanese

In this study, we consider a broadband software-defined base station receiver, which simultaneously processes signals of different modulation and multiple access schemes. For such a system, division/selection of individual signals is an important task. In this manuscript,discrete Fourier transform (DFT) is employed for this purpose, and after the separation of signals, they are processed all in frequency domain. In addition, we discuss the influence of key parameters of DFT to BER performance.

A Study for TCP Throughput in a wireless CDMA system

K. Naito, H. Okada, T. Yamazato and M. Katayama

Communications Society Conference of IEICE page： - 2001.9

BER Analysis of Orthogonal Multi-carrier DS-CDMA with Multi-rate Traffic Reviewed

A. Sandouk, M. Harada, H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E84-B ( 7 ) page： pp.1723-1731 2001.7

BER analysis for multi-carrier DS CDMA with multi-rate traffic Reviewed

Sandouk A, Harada M, Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E84A ( 7 ) page： 1723 - 1731 2001.7

BER analysis for multi-carrier DS CDMA with multi-rate traffic Reviewed

Sandouk A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E84-A ( 7 ) page： 1723 - 1731 2001.7

BER Analysis for Multi-carrier DS CDMA with Multi-rate Traffic Reviewed

A. Sandouk, M. Harada, H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Fundamentals Vol. E84-A ( 7 ) page： 1723-1731 - 1731 2001.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this letter, we present bit error analysis(BER) of orthogonal multi-carrier direct sequence code division multiple access(DS-CDMA) system with multi-rate (multimedia) traffic. Analysis is carried out with random signature codes for an AWGN channel. Interference in such a system is severe because all users of all media transmit over the same assigned sub-carriers. This makes the analysis difficult. In our analysis, we divide this interference into different types and carry out our analysis to obtain the BER taking into account all these types. We show that the performance of the system is improved as the number of assigned sub-carriers M increases until a limit where the improvement does not continue even when M increases more. This is because of, as we show, the interference due to other sub-carriers becomes constant even in the case of M → ∞, and the interference in a multi-rate multi-carrier system is bigger than that in a single-carrier (M = 1) by a factor of π^2/3.

QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks Reviewed

A. Sandouk, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E84-B ( 6 ) page： 1588-1595 2001.6

Language：English Publishing type：Research paper (scientific journal)

In this letter, performance evaluation of a system that combines between Code-Division Multiple Access (CDMA) and ALOHA protocol in multimedia networks is presented. In our analysis, we compare the performance between the two basic techniques of ALOHA protocol, i.e., Slotted-ALOHA (S-ALOHA) and Unslotted-ALOHA (U-ALOHA), when combined with CDMA scheme to support voice and data users operating in same CDMA channel. The quality of service (QoS) required for voice and data media is completely taken care of. We obtain the throughput of data media, and the outage probability for voice considering both voice and data offered loads. Throughput performance of S-ALOHA technique is almost twice of that of U-ALOHA. However, we show in this letter that when we combine CDMA with the two basic techniques of ALOHA to accomplish multimedia transmission, both techniques have almost same performance. And, thus, CDMA U-ALOHA can be a good candidate for multimedia networks.

QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks Reviewed

Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E84B ( 6 ) page： 1588 - 1595 2001.6

QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks Reviewed

Sandouk A.

IEICE Transactions on Communications Vol. E84-B ( 6 ) page： 1588 - 1595 2001.6

A MAP Receiver Based on Prediction Error Reviewed

S. Makido, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

The Journal of the Institute of Television Engineers of Japan Vol. 55 ( 6 ) page： 886-893 - 893 2001.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

A MAP (Maximum A posteriori Probability) receiver is described that is designed for Markovian sources in a wireless environment. A MAP receiver, a well-known efficient receiver, uses the stochastic characteristics of the source in the decision procedure. However, it is very difficult to implement a MAP algorithm at the front of the receiver because of its calculation costs. To reduce these costs we introduce a source predictor in the receiver. With the aid of the predictor, the MAP detector can be operated with a small calculation cost. Experimental PCM (Pulse Coded Modulation) image transmission demonstrated the feasibility of the proposed receiver. Simulation of the receiver's performance showed it had better MSE (Mean Squared Error) performance in spite of its implementation simplicity.

DOI： 10.3169/itej.55.886

Other Link： https://jlc.jst.go.jp/DN/JALC/00075825751?from=CiNii

New Analytical Model for the TCP Throughput in Wireless Environment Reviewed

Katsuhiro Naito, Hiraku Okada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEEE Vehicular Technology Conference (VTC-Spring 2001) Vol. 3 2001.5

SNIR Analysis of Asynchronous Multicarrier CDMA Systems Reviewed

MURAMATSU Hiroki, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2001 page： 181 2001.3

A STUDY ON MAP RECEIVER DESIGN FOR IMAGE COMMUNICATIONS Reviewed

Makido Satoshi, Honjo Masaru, Yamazato Takaya, Okada Hiraku, Katayama Masaaki, Ogawa Akira

Proceedings of the IEICE General Conference Vol. 2001 page： 186 2001.3

Joint Multi-dimensional Channel Parameter Estimation Schemes for DS-CDMA Systems Using a Modified version of the SAGE Algorithm Reviewed

Youssef R. Senhaji, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E84-B ( 3 ) page： 511-519 2001.3

Language：Japanese Publishing type：Research paper (scientific journal)

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths when calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

A Study on MAP Receiver Design for Image Communications

S. Makido, M. Honjo, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE General Conference Vol. A-6 ( 4 ) page： 186 2001.3

Adaptive Subcarrier Assignment Schemes for OFDM Systems with Transmit Diversity

H. Shi, M. Katayama, T. Yamazato, H. Okada, A. Ogawa

IEICE General Conference Vol. SB-139 page： 17-18 2001.3

SNIR Analysis of Multicarrier CDMA Systems

H. Muramatsu, T. Yamazato, H.Okada, M. Katayama

IEICE General Conference Vol. A-5 ( 22 ) page： 181 2001.3

Generation of Sets of Sequences Suitable for MulticodeTransmission in Quasi-Synchronous CDMA Systems Reviewed

M. Saito, H. Okada, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transactions on Communications Vol. EB-84 ( 3 ) page： 576-580 2001.3

Language：English Publishing type：Research paper (scientific journal)

In this letter, we present a method to generate sets of sequences suitable for multicode transmission in quasi-synchronous (QS) CDMA systems. We focus on Gold code but extension to orthogonal Gold code is straightforward. We show that by appropriate classification of sequences, it is possible to have sets whose cross correlation is small in QS situations.

Generation of sets of sequences suitable for multicode transmission in quasi-synchronous CDMA systems Reviewed

Saito M, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E84B ( 3 ) page： 576 - 580 2001.3

Joint multi-dimensional channel parameter estimation schemes for DS-CDMA systems using a modified version of the SAGE algorithm Reviewed

YR Senhaji, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E84B ( 3 ) page： 511 - 519 2001.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths wizen calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

Generation of sets of sequences suitable for multicode transmission in quasi-synchronous CDMA systems Reviewed

Joint multi-dimensional channel parameter estimation schemes for DS-CDMA systems using a modified version of the SAGE algorithm Reviewed

Senhaji YR, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E84B ( 3 ) page： 511 - 519 2001.3

Generation of Sets of Sequences Suitable for MulticodeTransmission in Quasi-Synchronous CDMA Systems Reviewed

M. Saito, H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E84-B ( 3 ) page： 576-580 2001.3

Saito M.

IEICE Transactions on Communications Vol. E84-B ( 3 ) page： 576 - 580 2001.3

Throughput Performance of CDMA Slotted ALOHA Systems Based on Average Packet Success Probability Considering Bit-to-Bit Dependence Reviewed

M. Saito, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. EA-84 ( 2 ) page： 653-659 2001.2

Language：English Publishing type：Research paper (scientific journal)

We propose the analytical calculation method of average packet success probability of CDMA slotted ALOHA systems, which derives accurate probability, and that is applicable to the system with any spreading codes and any amplitude distributions. In the method, we consider the bit-to-bit dependence of amplitude of signals, used spreading sequences, relative timing delays, and relative carrier phases. This bit-to-bit dependence is the case that the parameters above mentioned are constant for a slot time. By using the method to obtain the average packet success probability, we derive useful throughput performance of CDMA slotted ALOHA systems on fading channel, and show that the normalized throughput becomes worse in the case of larger spreading factor.

Throughput performance of CDMA slotted ALOHA systems based on average packet success probability considering bit-to-bit dependence Reviewed

Saito M, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E84A ( 2 ) page： 653 - 659 2001.2

Throughput performance of CDMA slotted ALOHA systems based on average packet success probability considering bit-to-bit dependence Reviewed

M Saito, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E84A ( 2 ) page： 653 - 659 2001.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We propose the analytical calculation method of average packet success probability of CDMA Slotted ALOHA systems, which derives accurate probability, and that is applicable to the system with any spreading codes and any amplitude distributions. In the method, we consider the bit-to-bit dependence of amplitude of signals, used spreading sequences, relative timing delays, and relative carrier phases. This bit-to-bit dependence is the case that the parameters above mentioned are constant for a slot time. By using the method to obtain the average packet success probability, we derive useful throughput performance of CDMA Slotted ALOHA systems on fading channel, and show that the normalized throughput becomes worse in the case of larger spreading factor.

Throughput performance of CDMA slotted ALOHA systems based on average packet success probability considering bit-to-bit dependence Reviewed

M. Saito, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Fundamentals Vol. E84-A ( 2 ) page： 653 - 659 2001.2

Language：English Publishing type：Research paper (scientific journal) Publisher：電子情報通信学会

We propose the analytical calculation method of average packet success probability of CDMA Slotted ALOHA systems, which derives accurate probability, and that is applicable to the system with any spreading codes and any amplitude distributions. In the method, we consider the bit-to-bit dependence of amplitude of signals, used spreading sequences, relative timing delays, and relative carrier phases. This bit-to-bit dependence is the case that the parameters above mentioned are constant for a slot time. By using the method to obtain the sverage packet success probability, we derive useful throughput performance of CDMA Slotted ALOHA systems on fading channel, and show that the normalized throughput becomes worse in the case of larger spreading factor.

Study on TCP throughput with FEC and ARQ in a wireless link Reviewed

K. Naito, H. Okada, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J84-A ( 1 ) page： 122-126 2001.1

Language：English Publishing type：Research paper (scientific journal)

It is reported that the performance of the TCP is very poor in wireless environments. In this paper, we attempt FEC or ARQ to better performance of the TCP in a wireless link, and clarify the TCP throughput. As shown in results, it is necessary for better performance of the TCP to apply FEC or ARQ, which suited to occurrence distribution of transmission errors.

Study on TCP Throughput with FEC and ARQ in a Wireless Link Reviewed

Katsuhiro Naito, Hiraku Okada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEICE Transaction on Fundamentals (Japanese) Vol. J84-A ( 1 ) page： 122 - 126 2001.1

An Adaptive Antenna Selection Scheme for Transmit Diversity in OFDM Systems Reviewed

H. Shi M. Katayama T. Yamazato H.Okada and A.Ogawa

IEEE Vehicular Technology Conference (VTC) page： - 2001

Language：English

We consider an adaptive antenna selection scheme for transmit diversity in OFDM systems. In the proposed system, the mapping of the subcarriers to antennas is adaptively operated by transmitter according to the Channel State Information(CSI). The performance of the system is improved greatly with this scheme even in slow fading environment. In addition, major modification is necessary only at the transmitter. This is very advantageous for systems with small terminals.

マルコフ情報源に対する予測器を用いた高能率MAP受信機の提案

牧戸知史，本庄勝，山里敬也，岡田啓，片山正昭，小川明

電気学会東海支部平成１２年度第２回「マルチメディア情報通信のための信号処理技術」若手セミナー page： - 2001

A Study on Multi-carrier DS-CDMA Systems with Multi-rate Traffic

A. Sandouk, M. Harada, H. OKada, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE Vol. SST2000 ( 87 ) page： 137-142 2001

Language：English

In this work, orthogonal multi-carrier direct sequence code division multiple access (DS-CDMA) system with multi-rate traffic is presented. Interference in such a system is severe because all users of all media transmit over the same assigned sub-carriers. We divide this interference into different types and analyze the system to obtain the bit error rate (BER) with random signature codes for an AWGN channel taking into account all interference types.

The influence of analog to digital conversion on the performance of a broadband software-defined base station

M. Okuma, T. Yamazato, H.Okada, M.Katayama

Technical Report of IEICE Vol. SR01 ( 2 ) page： 39340 2001

Language：Japanese

In this study, we consider a broadband software-defined base station receiver, which emploies superconductive analog to digital converter (ADC) and simultaneously processes signals of different modulation and multiple access schemes. In such a system, we show the influence of the key parameters of an ADC (such as a number of bits per sample, and full-scale-range) on the bit error rate performance for various conditions.

A novel signal recognition and detection scheme for CDMA packet systems

T.Kume, T.Yamazato, K.Ban, H.Okada, and M.Katayama

Technical Report of IEICE ( 27 ) page： 33-38 2001

Language：Japanese

In this paper, a novel signal recognition and acquisition scheme with an adaptive filter is proposed for direct-sequence code-division multiple access (DS-CDMA) packet systems. In CDMA systems, conventional matched filter receivers suffer from the near-far problem due to multiple access interference (MAI). In general, closed-loop power control is used in order to reduce the influence of the near-far problem. However, in packet systems, closed-loop power control is unsuitable. Hence, we focus on an adaptive receiver with an adaptive linear filter based on LMS algorithm, which eliminate the influences of MAI and the near-far problem, for a signal recognition and acquisition in CDMA packet systems.

Performance of an OFDM Communication Systemunder a Frequency and Time Dependent Power-Line Channel Reviewed

K. Sugimoto, M. Katayama, T. Yamazato, H. Okada

5th International Symposium on Power-line Communications and Its Applications page： 35-40 2001

Language：English

In this manuscript, we employ OFDM (Orthogonal Frequency Division Multiplexing) modulator with the cyclo-stationary Gaussian model for power-line noise. Under this environment, the relation of the bit error rate (BER) to time and frequency is analyzed. In addition, we introduce guaranteed BER as a measure of the performance and show performance improvement by changing the number of sub-carriers and omitting a part of data from transmission.

Fundamentals of CDMA Invited Reviewed

Takaya Yamazato

2001 Karuizawa Workshop, Karuizawa, Nagano, Japan page： - 2001

A Design of Source Matched MAP Receiver for Image Transmission Reviewed

S. Makido, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

IEEE International Symposium on Circuit and Systems ( IV ) page： 136-139 2001

Language：English

In this paper we will discuss the MAP receiver design for the reception of the image signal. It is impractical to use the MAP algorithm for the source detection because of its huge calculation costs. To solve this problem we propose a novel MAP receiver structure, where the receiver contains a predictor within it. With an aid of the predictor we can reduce the calculation. Furthermore we can approximate the a priori probability by the prediction error distribution.

New Analytical Model for the TCP Throughput in Wireless Environment Reviewed

K. Naito, H. Okada, T. Yamazato, M. Katayama, and A. Ogawa

IEEE Vehicular Technology Conference (VTC) page： - 2001

Language：Japanese

In this paper, we propose a new analytical model for the TCP, and analyze the bulk throughput performance of different versions of TCP Transmission Control Protocol), viz., Tahoe, Reno and NewReno. We focus on the performance of a single wireless TCP connection which has random segment losses. In our analytical model, we model the TCP mechanisms as a Markov chain. In our result, we found that TCP Tahoe, Reno and NewReno have similar performance with random segment losses. This will lead us to design a lower layer mechanisms.

A MAP Receiver Based on Prediction Error Reviewed

S. Makido, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

The Journal of the Institute of Television Engineers of Japan, vol.55, no.6, pp.886-893, June 2001 Vol. 55 ( 6 ) page： - 2001

Language：Japanese Publishing type：Research paper (scientific journal)

A MAP (Maximum A posteriori Probability) receiver is described that is designed for Markovian sources in a wireless environment. A MAP receiver, a well-known efficient receiver, uses the stochastic characteristics of the source in its calculation costs. To reduce these costs we introduce a source predictor in the receiver. With the aid of the predictor, the MAP detector can be operated with a small calculation cost. Experimental PCM (Pulse Coded Modulation) image transmission demonstrated the feasibility of the proposed receiver. Simulation of the receiver's performance showed it had better MSE (Mean Squared Error) performance in spite of its implementation simplicity.

Hierarchical Transmission of DCT Coefficients Using Multi-Code DS/SS Modulation

M. Honjo, S. Makido, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

Technical Report of IEICE Vol. SST2001 ( 17 ) page： - 2001

Language：Japanese

In this paper, we propose a hierarchical transmission of image signal using multi-code DS/SS modulation. DCT is originally invoked in the image coding at the aim of compacting the input variance and compressing efficiently. We achieve an error torelant transmission system by using this property in transmit energy. We introduce the energy assingment (EA) to reduce the channel noise in hierarchical transmission. Assigning an appropriate transmitt energy corresponding to its variance, we show that it is possible to maintain the picuture quality even in low channel condition. The analysis is carried out to show the effectiveness of our scheme using 2-D Gauss-Markov random field in the case of MC DS/SS modulation used. We also verify the same characteristic in several sample movies.

Comparison of CDMA and FDMA/TDMA in non-GEO Satellite Systems Reviewed

N. Ichikawa, M. Katayama, H. Okada, T. Yamazato, and Akira Ogawa

IEEE International Conference on Communications (ICC2001) Vol. G76.5 page： - 2001

Language：English

We compare CDMA and FDMA (or TDMA) schemes in multi-beam non-geostationary satellite systems, taking the effects of antenna patterns on inter-cell interference into consideration. The maximum acceptable number of users per cell in uplink is employed as a measure of the system capacity. We have found that in FDMA (or TDMA) systems the maximum acceptable number of users varies according to the altitude of the satellites, while the performance is insensitive to the altitude in CDMA systems. For this reason, the altitude of the satellites is found to be an important factor for selecting multiple access schemes in non-geostationary satellite systems.

A Study on High Rate Serially Concatenated Coding Scheme for Optical Communication Systems Reviewed

C. Zheng, T. Yamazato, M. Katayama and A. Ogawa

International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC), Tokushima, Japan page： - 2001

Language：English

In this work, a serially concatenated coding scheme of an outer Reed-Solomon code and an inner high rate Turbo code is proposed for the optical communication systems. The simulation results show the reduction of the ``error floor'' influence of the Turbo code. This reduction is due to the outer cascaded Reed-Solomon decoding process and the increase of the interleaver size of the inner Turbo code. The effect of quantization is also considered for inner Turbo decoder. As results, 4-bit quantization is satisfied.

Communication System for Time and Frequency Dependent Power-Line Channel

K.Sugimoto, H.Okada, T.Yamazato, M.Katayama

Technical Report of IEICE page： - 2001

Language：Japanese

In power-line communication, channel characteristics and the man-made noise from appliances are time and frequency dependent. This noise is known to be modeled by colored cyclo-stationary Gaussian noise. In consideration of frequency dependence of noise, in this manuscript, we employ OFDM signaling scheme. Under this environment, the space spanned by time and frequency can be subdivided into small cells by symbol duration and sub-carriers of OFDM. The bit error rate (BER) of each cell is analytically derived. In addition, we consider performance improvement by combining some cells (transmitting same information in some cells with iterative coding) according to the knowledge on stochastic features of the cyclo-stationary power-line channel.

An access control protocol based on correlation of multimedia traffic for CDMA ALOHA

Y. Hirayama, H. Okada, T. Yamazato, and M. Katayama

Technical Report of IEICE page： - 2001

Language：Japanese

In this paper, we consider wireless multimedia packet communications which support voice, video, and data traffic. Multimedia traffic includes various types of traffic which has different characteristics of packet generation. We propose a new access control protocol for multimedia traffic. This protocol controls data packet transmission based on estimation of number of packets which will generate in future. This estimation is derived from correlation of voice packet traffic. We evaluate the performance of proposed protocol when it applied to the CDMA slotted ALOHA. Simulation results show that proposed protocol can maintain the data packet throughput and the packet loss rate at a certain level when the offered load of data increases.

A design of source matched MAP receiver for image transmission Reviewed

Makido S., Yamazato T., Okada H., Katayama M., Ogawa A.

Materials Research Society Symposium - Proceedings Vol. 626 2001

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium - Proceedings

A new packet detection scheme in CDMA unslotted ALOHA system with successive interference cancellation Reviewed

Tadokoro Y, Okada H, Yamazato T, Katayama A, Ogawa A

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 page： 3173 - 3177 2001

An adaptive antenna selection scheme for transmit diversity in OFDM systems Reviewed

Shi H, Katayama M, Yamazato T, Okada H, Ogawa A

IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001, VOLS 1-4, PROCEEDINGS page： 2168 - 2172 2001

An adaptive antenna selection scheme for transmit diversity in OFDM systems Reviewed

H Shi, M Katayama, T Yamazato, H Okada, A Ogawa

IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001, VOLS 1-4, PROCEEDINGS page： 2168 - 2172 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In wireless communication systems, as one of effective techniques for combating fading, transmit diversity has attracted much attention, especially when receive diversity is expensive or impractical due to the constraint of terminal size. In this study we consider an adaptive carrier-by-carrier basis antenna selection scheme for transmit diversity, in OFDM systems under the assumption that a transmitter has priori knowledge of the Channel State Information(CSI). In the proposed schemes transmit antennas are selected adaptively for each subcarrier according to CSI.

DOI： 10.1109/VTC.2001.957128

An adaptive antenna selection scheme for transmit diversity in OFDM systems Reviewed

Shi H., Katayama M., Yamazato T., Okada H., Ogawa A.

IEEE Vehicular Technology Conference Vol. 4 ( 54ND ) page： 2168 - 2172 2001

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEE Vehicular Technology Conference

In wireless communication systems, as one of effective techniques for combating fading, transmit diversity has attracted much attention, especially when receive diversity is expensive or impractical due to the constraint of terminal size. In this study we consider an adaptive carrier-by-carrier basis antenna selection scheme for transmit diversity in OFDM systems under the assumption that a transmitter has priori knowledge of the Channel State Information(CSI). In the proposed schemes transmit antennas are selected adaptively for each subcarrier according to CSI.

Comparison of CDMA and FDMA/TDMA in non-GEO satellite systems Reviewed

Ichikawa N.

IEEE International Conference on Communications Vol. 10 page： 3167 - 3172 2001

Comparison of CDMA and FDMA/TDMA in non-GEO satellite systems Reviewed

N Ichikawa, M Katayama, H Okada

2001 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-10, CONFERENCE RECORD page： 3167 - 3171 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/ICC.2001.937256

Throughput performance of CDMA Slotted ALOHA systems based on average packet success probability considering bit-to-bit dependence Reviewed

Hierarchical transmission of video signal using multi-code DS/SS modulation based on DCT coefficients Reviewed

Honjo M, Makido S, Yamazato T, Okada H, Katayama M, Ogawa A

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 page： 3395 - 3399 2001

New analytical model for the TCP throughput in wireless environment Reviewed

Naito K.

IEEE Vehicular Technology Conference Vol. 3 ( 53ND ) page： 2128 - 2132 2001

New analytical model for the TCP throughput in wireless environment Reviewed

Naito K, Okada H, Yamazato T, Katayama M, Ogawa A

IEEE VTC 53RD VEHICULAR TECHNOLOGY CONFERENCE, SPRING 2001, VOLS 1-4, PROCEEDINGS page： 2128 - 2132 2001

Saito M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E84-A ( 2 ) page： 653 - 659 2001

A new packet detection scheme in CDMA unslotted ALOHA system with successive interference cancellation Reviewed

Y Tadokoro, H Okada, T Yamazato, A Katayama, A Ogawa

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 page： 3173 - 3177 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

DOI： 10.1109/GLOCOM.2001.966012

Modified HPSK Modulation Scheme for Wideband CDMA Systems Invited Reviewed

A. Fujiwara, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J83-A ( 12 ) page： 1552-1557 2000.12

OFDM systems with multiple trellis coded modulation Reviewed

Harada M.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC Vol. 2 page： 814 - 818 2000.12

An Access Control Protocol for a Heterogeneous Traffic with a Multi-Code CDMA Scheme Reviewed

SANDOUK Abbas, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE Transactions on Fundamentals, A Vol. 83 ( 11 ) page： 2085 - 2092 2000.11

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss the access control in multimedia CDMA ALOHA protocol. We introduce a new algorithm for the access control based on Modified Channel Load Sensing Protocol (MCLSP) in an integrated voice and two different classes of data users, high bit rate and low bit rate, exist in a multi-code CDMA Slotted ALOHA system. With our new algorithm, we show that the throughput of high bit rate data users, as well as, the total throughput of the data medium can be optimized and take a maximum value even at high values of offered loads. We also investigate the performance when voice activity detection (VAD) is consideraed in voice transmission.

An Initial Code Acqusition Scheme for Indoor Packet DS/SS Systems with Macro/Micro Antenna Diversity Reviewed

Y. Ikai, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 11 ) page： 2072-2077 2000.11

Language：English Publishing type：Research paper (scientific journal)

In this paper, we study macro/micro diversity techniques for code acquisition of a direct-sequence spread-spectrum signal in an indoor packet communication system. In the system discussed, the base station has several radio ports each with a cluster of antennas, and the terminal also has multiple antennas. The performance in the uplink of this system is analyzed under Lognormal shadowing and flat Rayleigh fading. The numerical results show great performance improvements by proposed diversity techniques. In addition, it is clarified that the mean acquisition time, which is often used as the measure of performance, is not suitable for packet radio systems as it underestimates the necessary preamble length for initial code acquisition.

Efficient Channel Parameter Estimators for DS-CDMA Systems in Slow Time-Varying Channels Using a Modified version of the SAGE Algorithm Reviewed

Y. R. Senhaji, T. Yamazato, M. Katayama, and A. Ogawa

IEEE Global Communications Conference (Globecom2000) Vol. 3 ( 3 ) page： 1483-1487 2000.11

Language：Japanese

A modified version of the SAGE algorithm applied for joint estimation of delays, incidence azimuths and attenuation parameters characterizing the channel is presented. The modifications are based on using different observation intervals in optimizing the parameters and using time correlation in estimating delays, for the purpose of a further reduction in SAGE's computational weight, and improving its accuracy in delay estimation. We show analytically that short observation intervals are sufficient for optimizing the delays and the azimuths, and verify through simulation the reliability of using time correlation. Two other estimators are proposed combining the modified SAGE with a sequential estimation of the attenuation parameters suitable for slowly varying channels.

An Access Control Protocol for a Heterogenous Traffic with a Multi-Code CDMA Scheme Reviewed

A. Sandouk, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 11 ) page： 2085-2092 2000.11

Language：English Publishing type：Research paper (scientific journal)

An access control protocol for a heterogeneous traffic with a multi-code CDMA scheme Reviewed

Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E83A ( 11 ) page： 2085 - 2092 2000.11

An initial code acquisition scheme for indoor packet DS/SS systems with macro/micro antenna diversity Reviewed

Ikai Y, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E83A ( 11 ) page： 2070 - 2077 2000.11

An initial code acquisition scheme for indoor packet DS/SS systems with macro/micro antenna diversity Reviewed

Y Ikai, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E83A ( 11 ) page： 2070 - 2077 2000.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

An access control protocol for a heterogeneous traffic with a multi-code CDMA scheme Reviewed

A Sandouk, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E83A ( 11 ) page： 2085 - 2092 2000.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we discuss the access control in multimedia CDMA ALOHA protocol. We introduce a new algorithm for the access control based on Modified Channel Load Sensing Protocol (MCLSP) in an integrated Voice and two different classes of data users, high bit rate and low bit rate, exist in a multi-code CDMA Slotted ALOHA system. With our new algorithm, we show that the throughput of high bit rate data users, as well as, the total throughput of the data medium can be optimized and take a maximum value even at high values of offered loads. We also investigate the performance when voice activity detection (VAD) is considered in voice transmission.

A Study on Reducing tne Nonlinear Distortion in Multicarrier Systems Reviewed

HARADA Masaaki, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE Trans. Fundamentals, A Vol. 83 ( 10 ) page： 1992 - 1995 2000.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on the realization of reduced peak power transmission for the multicarrier systems. Since the signals have large amplitude fluctuations in conventional multicarrier systems, signals amplified by a nonlinear amplifier are greatly distorted, resulting in severe performance degradation. In order to avoid this large amplitude fluctuation, we propose a scheme for reducing the nonlinear distortion by using the set of the signal point series which show low peak to mean envelope power ratio(PMEPR)value. In this system, one symbol is transmitted with multicarriers and the received signal is detected with maximum likelihood sequence detection.

An Study on Reducing the Nonlinear Distortion on Multicarrier Systems Reviewed

M. Harada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 10 ) page： 1992-1995 2000.10

Language：English Publishing type：Research paper (scientific journal)

In this paper, we discuss on the realization of reduced peak power transmission for the multicarrier systems. Since the signals have large amplitude fluctuations in conventional multicarrier systems, signals amplified by a nonlinear amplifier are greatly distorted, resulting in severe performance degradation. In order to avoid this large amplitude fluctuation, we propose a scheme for reducing the nonlinear distortion by using the set of the signal point series which show low peak to mean envelope power ratio (PMEPR) value. In this system, one symbol is transmitted with multicarriers and the received signal is detected with maximum likelihood sequence detection.

A study on reducing the nonlinear distortion in multicarrier systems Reviewed

Harada M, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E83A ( 10 ) page： 1992 - 1995 2000.10

Influence of two kinds of Packet Existence Detection Error on CDMA Unslotted ALOHA System Reviewed

TADOKORO Yukihiro, OKADA Hiraku, SAITO Masato, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

Proceedings of the Society Conference of IEICE Vol. 2000 page： 145 2000.9

Joint optimization of transmitter/receiver with multiple transmit/receive antennas in band-limited channels Reviewed

Ban K, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 8 ) page： 1697 - 1704 2000.8

Joint optimization of transmitter/receiver with multiple transmit/receive antennas in band-limited channels Reviewed

K Ban, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 8 ) page： 1697 - 1704 2000.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We study the joint optimization problem of a transmitter with multiple transmit antennas and a receiver with multiple receive antennas in a narrow-band communication system. We discuss the problem of designing a pre-filter at the transmitter, a post-filter at the receiver, and a bit allocation pattern to multiple symbols in the sense of minimizing the average bit error rate. With the optimized filters and the bit allocation, we could realize high efficiency and high data rate in band-limited channels.

Adaptive Transmit Permission Probability Control in CDMA Cellular Packet Communications with Site Diversity Reviewed

MORI Kazuo, KOBAYASHI Takehiko, YAMAZATO Takaya, OGAWA Akira

IEICE transactions on communications Vol. 83 ( 7 ) page： 1445 - 1453 2000.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Site diversity causes unfairness in packet reception that depends on the location of the mobile stations in the uplink of CDMA cellular packet communication systems.This paper proposes an adaptive transmit permission probability control scheme that reduces this unfairness in CDMA cellular slotted-ALOHA systems with site diversity.The proposed scheme adaptively controls the transmit permission probability according to the offered load and the location of the mobile stations.Successful packet reception rate, fairness coefficient and throughput performance are evaluated in fading environments with imperfect power control.Computer simulation shows that adaptive transmit permission probability control improves fairness of service for all mobile stations and throughput performance across all channel loads compared with the conventional scheme.

Adaptive transmit permission probability control in CDMA cellular packet communications with site diversity Reviewed

Mori K, Kobayashi T, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 7 ) page： 1445 - 1453 2000.7

Adaptive transmit permission probability control in CDMA cellular packet communications with site diversity Reviewed

K Mori, T Kobayashi, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 7 ) page： 1445 - 1453 2000.7

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Site diversity causes unfairness in packet reception that depends on the location of the mobile stations in the uplink of CDMA cellular packet communication systems. This paper proposes an adaptive transmit permission probability control scheme that reduces this unfairness in CDMA cellular slotted-ALOHA systems with site diversity. The proposed scheme adaptively controls the transmit permission probability according to the offered load and the location of the mobile stations. Successful packet reception rate, fairness coefficient and throughput performance are evaluated in fading environments with imperfect power control. Computer simulation shows that adaptive transmit permission probability control improves fairness of service for all mobile stations and throughput performance across all channel loads compared with the conventional scheme.

Hierarchical Channel Structure to Improve Handover Performance of LEOS Communication Systems

T.Hara, M.Katayama, H.Okada, T.Yamazato, and A.Ogawa

Technical Report of IEICE Vol. SAT page： - 2000.6

Hierarchical Channel Structure to Improve Handover Performance of LEOS Communication Systems

N. Ichikawa, M. Katayama, H. Okada, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT2000 page： - 2000.6

Effects of cell structure on quality of service of LEOS communication systems Reviewed

Ono K, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 4 ) page： 782 - 790 2000.4

Effects of cell structure on quality of service of LEOS communication systems Reviewed

K Ono, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E83B ( 4 ) page： 782 - 790 2000.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we analytically study the effects of overlap and overlay structure on the quality of service (QoS) of Low Earth-Orbital Satellite (LEOS) communication systems. We consider two-layered overlay of cells and intentional overlap of neighboring small cells. In order to measure the QoS, the probabilities of rejection of a newly arrived call (blocking) and Forced termination due to failure of a handover (call dropping) are derived. In addition to these measures, the largest traffic intensity which guarantees the required blocking and dropping probabilities is also used.

An access control protocol for a heterogeneous traffic with a multi-code CDMA scheme Reviewed

Performance Evaluation of the CDMA Unslotted ALOHA System Employing Successive Interference Cancellation Considering Packet Detection Error

K. Tadokoro, H. Okada, M. Saito, T. Yamazato, M. Katayama and A. Ogawa

2000 IEICE General Conference page： - 2000.3

A Study on Approximation Effects of TCP Analysis

K. Naito, H. Okada, M. Saito, T. Yamazato, M. Katayama and A. Ogawa

2000 IEICE General Conference Vol. B-5-185 page： 570 2000.3

無線環境下におけるTCPのスループット解析に関する一検討

内藤克浩, 岡田啓, 斎藤将人, 山里敬也, 片山正昭, 小川明

電子情報通信学会無線通信システム研究会 Vol. 99 ( 638 ) page： 107 - 113 2000.2

Modeling of Cyclostationary and Frequency Dependent Power-Line Channels for Communications Reviewed

M. Katayama, S. Itou, T.Yamazato, A. Ogawa

THE 4th International Symposium on Power-Line Communications and its Applications, Limerick, Ireland Vol. ISPC page： - 2000

A Study on Approximation Effects of TCP Analysis

K.Naito, H.Okada, T.Yamazato, M.katayama and A.Ogawa

Communications Society Conference of IEICE page： - 2000

Influence of two kinds of Packet Existence Detection Error on CDMA Unslotted ALOHA System Employing Successive Interference Cancellation

Y.Tadokoro, H.Okada, M.Saito, T.Yamazato, M.Katayama and A.Ogawa

Enginnering Sciences Society Conference of IEICE page： - 2000

An Initial Code Acqusition Scheme for Indoor Packet DS/SS Systems with Macro/Micro Antenna Diversity Reviewed

Y. Ikai, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 11 ) page： - 2000

A Study on Cross-Correlation Property in Orthogonal Multi-Code CDMA Systems Reviewed

A. Fujiwara, T. Wada, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J83 ( 5 ) page： 589-593 2000

Adaptive Transmit Permission Probability Control in CDMA Cellular Packet Communications with Site Diversity Reviewed

K. Mori, T. Kobayashi, T. Yamazato, A. Ogawa

IEICE Transaction on Communications. Vol. E83-B ( 7 ) page： - 2000

Effects of Cell Structure on Quality of Service of LEOS Communication Systems Reviewed

K.Ono, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E83-B ( 4 ) page： 782-790 2000

Service Fairness in CDMA Cellular Packet Systems with Site Diversity Reception, Reviewed

K. Mori, T. Kobayashi, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E82-B ( 12 ) page： 1964-1973 2000

Throughput Analysis of TCP in Wireless Environment

K. Naito, H. Okada, M. Saito, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS99-232 page： 107-113 2000

Evaluation of Interference between UP- and Down-Links on CDMA Cellular Packet Systems Employing a Shared-TDD Scheme

K. Mori, T. Kobayashi, T. Yamazato, and A. Ogawa

General Conference of IECIE Vol. SB-3-2 page： 739 2000

A Study on Noise Enhancement and Cross Correlation in Synchronous CDMA Systems with Decorrelating Detector

Masato Saito, Hiraku Okada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

Technical Report of IEICE Vol. SST page： - 2000

Chip by Chip Turbo Coded CDMA System

T. Yamazato

YRP Telecom Summit, YRP, Yokosuka, Japan Vol. YRP page： - 2000

A Note on a Transmit Adaptive Array Antennas and its Capacity Enhancementin a cellular CDMA

T. Yamazato, Youssef. Senhaji, H. Okada, M. Katayama, A. Ogawa

Technical Report of IEICE Vol. SST-2000-20 page： 39275 2000

Influence of Beam Pattern on the Capacity of LEOS Communication Systems Reviewed

N. Ichikawa, M. Katayama T. Yamazato and A. Ogawa

ISCOM'99, Kaohsiung, Taiwan Vol. ISCOM'99 page： - 2000

Code Acquisition of a DS/SS Signal with Transmit and Receive Antenna Diversity Reviewed

Y. Ikai, M. Katayama,T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E82-A ( 12 ) page： 2728-2734 2000

OFDM Systems with Reduced Nonlinear Effect Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, and A. Ogawa

IEEE Vehicular Technology Conference (VTC Fall) Vol. VTC2000 page： - 2000

OFDM Systems with Multiple Trellis Coded Modulation Reviewed

M. Harada, T. Yamazato, M. Katayama, and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC2000 page： - 2000

Adaptive Array Antennas for the Base Station of a Multi Processing Gain CDMA System Reviewed

A. Morimoto, M. Katayama,T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E82-A ( 12 ) page： 2687-2696 2000

A Study on Constant Amplitude Transmission for Orthogonal Multicode Systems Reviewed

T. Wada, and T. Yamazato

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA2000 page： 576-579 2000

Language：English

In this paper, we deal with the constant amplitude orthogonal multicode systems. The constant amplitude transmission has the advantage of the high power efficiency because the high power amplifier which has non-linear characteristic can be applied for the amplification of the signals. In this paper, we show the bent sequences can achieve the constant amplitude transmission and also show the effectiveness of the constant amplitude transmission in terms of symbol error rate.

A Study on Weight Control Scheme of Adaptive Array Antennas with Interference Canceler

Takayuki Suzuki, Masaaki Katayama, Takaya Yamazato, Akira Ogawa

Technical Report of IEICE Vol. RCS page： - 2000

Throughput Performance of CDMA Unslotted ALOHA System with Successive Interference Cancellation considering Detection Error of Packet Existance Reviewed

Y. Tadokoro, H. Okada, M. Saito, T. Yamazato, M. Katayama, A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA2000 page： 728-731 2000

Language：English

In CDMA ALOHA system, Multiple Access Interference(MAI) is in existence and it has large influence on the system performance. To suppress the influence, we proposed new system in which SIC is applied to CDMA Unslotted ALOHA. But because of random access and time-short packets, it is very difficult to detect packet existence perfectly. So, in this paper, we evaluate the influence of detection error of packet existence in proposed system by throughput performance.

A New Diversity Reception and Decoding Scheme for Convolutional Encoded Signal Reviewed

W.Z. Wang, T. Yamazato, C. Zheng, H. Okada, M. Katayama, and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA2000 page： 964-967 2000

Language：English

In this paper, we propose a new diversity reception and decoding scheme for a convolutionally encoded signal. Aiming at obtaining an additional gain by combining diversity reception and decoding technique, we extend notion of space diversity technique to error correction coded signal and consider an iterative decoding. As a result, we have found $2.0$ dB coding gain in 2 path Rayleigh fading channels at BER $=10^{-5}$ after 6 iterations. This reception technique is particularly useful when used in mobile communications.

A Symbol Detection Scheme for OFDM Signals with Subtraction Operation Reviewed

Shibata T.

The Journal of The Institute of Image Information and Television Engineers Vol. 54 ( 12 ) page： 1788 - 1791 2000

Sandouk A., Yamazato T., Katayama M., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 11 ) page： 2085 - 2092 2000

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

Adaptive transmit permission probability control in CDMA cellular packet communications with site diversity Reviewed

Mori K., Kobayashi T., Yamazato T., Ogawa A.

IEICE Transactions on Communications Vol. E83-B ( 7 ) page： 1445 - 1452 2000

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Communications

Site diversity causes unfairness in packet reception that depends on the location of the mobile stations in the uplink of CDMA cellular packet communication systems. This paper proposes an adaptive transmit permission probability control scheme that reduces this unfairness in CDMA cellular slotted-ALOHA systems with site diversity. The proposed scheme adaptively controls the transmit permission probability according to the offered load and the location of the mobile stations. Successful packet reception rate, fairness coefficient and throughput performance are evaluated in fading environments with imperfect power control. Computer simulation shows that adaptive transmit permission probability control improves fairness of service for all mobile stations and throughput performance across all channel loads compared with the conventional scheme.

An initial code acquisition scheme for indoor packet DS/SS systems with macro/micro antenna diversity Reviewed

Ikai Y., Katayama M., Yamazato T., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 11 ) page： 2070 - 2077 2000

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

In this paper, we study macro/micro diversity techniques for code acquisition of a direct-sequence spreadspectrum signal in an indoor packet communication system. In the system discussed, the base station has several radio ports each with a cluster of antennas, and the terminal also has multiple antennas. The performance in the uplink of this system is analyzed under Lognormal shadowing and flat Rayleigh fading. The numerical results show great performance improvements by proposed diversity techniques. In addition, it is clarified that the mean acquisition time, which is often used as the measure of performance, is not suitable for packet radio systems as it underestimates the necessary preamble length for initial code acquisition.

An OFDM system with reduced non-linear effect Reviewed

M Harada, T Yamazato, H Okada, M Katayama, A Ogawa

IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2000, VOLS 1-6, PROCEEDINGS page： 1794 - 1798 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we discuss on the realization of reduced peak power transmission for the OFDM systems. Since the signals have large amplitude fluctuations in conventional OFDM systems, signets amplified by a non-linear amplifier Pre greatly distorted, resulting in severe performance degradation, In order to avoid this large amplitude fluctuation, we propose a scheme for reducing the nonlinear distortion by using the set of the signal point series which show low Penk-to-Mean-Envelope-Power-Ratio (PMEPR) value. In this system, one symbol is transmitted with multicarriers and the received signal is detected with maximum likelihood sequence (MLS) detection.

An OFDM system with reduced non-linear effect Reviewed

Harada M, Yamazato T, Okada H, Katayama M, Ogawa A

IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2000, VOLS 1-6, PROCEEDINGS page： 1794 - 1798 2000

A study on reducing the nonlinear distortion in multicarrier systems Reviewed

Harada M., Yamazato T., Katayama M., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E83-A ( 10 ) page： 1992 - 1995 2000

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

In this paper, we discuss on the realization of reduced peak power transmission for the multicarrier systems. Since the signals have large amplitude fluctuations in conventional multicarrier systems, signals amplified by a nonlinear amplifier are greatly distorted, resulting in severe performance degradation. In order to avoid this large amplitude fluctuation, we propose a scheme for reducing the nonlinear distortion by using the set of the signal point series which show low peak to mean envelope power ratio (PMEPR) value. In this system, one symbol is transmitted with multicarriers and the received signal is detected with maximum likelihood sequence detection.

Efficient channel parameter estimators for DS-CDMA systems in slow time-varying channels using a modified version of the SAGE algorithm Reviewed

YR Senhaji, T Yamazato, M Katayama, A Ogawa

GLOBECOM '00: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1- 3 page： 1483 - 1487 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

A modified version of the SAGE algorithm applied for joint estimation of delays, incidence azimuths and attenuation parameters characterizing the channel is presented. The modifications are based on using different observation intervals In optimizing the parameters and using time correlation in estimating delays, for the purpose of a further reduction in sAGE's computational weight, and Improving its accuracy in delay estimation. We show analytically that short observation intervals are sufficient for optimizing the delays and the azimuths, and verify through simulation the reliability of using time correlation.
Two other estimators are proposed combining the modified SAGE with a sequential estimation of the attenuation parameters suitable for slowly varying channels.

DOI： 10.1109/GLOCOM.2000.891887

Joint optimization of transmitter/receiver with multiple transmit/receive antennas in band-limited channels Reviewed

Efficient channel parameter estimators for DS-CDMA systems in slow time-varying channels using a modified version of the SAGE algorithm Reviewed

Senhaji YR, Yamazato T, Katayama M, Ogawa A

GLOBECOM '00: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1- 3 page： 1483 - 1487 2000

Effects of cell structure on quality of service of LEOS communication systems Reviewed

Ono K.

IEICE Transactions on Communications Vol. E83-B ( 4 ) page： 782 - 789 2000

Ban K.

IEICE Transactions on Communications Vol. E83-B ( 8 ) page： 1697 - 1703 2000

OFDM systems with Multiple Trellis Coded Modulation Reviewed

Harada M, Yamazato T, Katayama M, Ogawa A

PIMRC 2000: 11TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1 AND 2, PROCEEDINGS page： 814 - 818 2000

Performance evaluation of modified HPSK for Wideband CDMA Reviewed

T Yamazato, A Fujiwara, M Katayama, A Ogawa

2000 IEEE SIXTH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES AND APPLICATIONS, PROCEEDINGS, VOL 1 AND 2 page： 751 - 755 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In mobile communications, power is a very important factor and non-linear amplification of power amplifier cannot be avoided due to their high power efficiency. HPSK modulation scheme has been proposed as the spreading technique for W-CDMA and cdma2000. HPSK is a complex spreading scheme that is designed to minimize the zero-crossing signal transition. However, there is a possibility that signal transition of HPSK go through zero.
In this paper, we propose a new modulation scheme for W-CDMA and cdma2000. The scheme is based on HPSK, but we modified the complex scrambling to avoid zero-crossing. We call it as modified HPSK (m-HPSK), It is shown that m-HPSK outperforms HPSK in the presence of non-linear amplification.

Performance evaluation of modified HPSK for Wideband CDMA Reviewed

Yamazato T, Fujiwara A, Katayama M, Ogawa A

2000 IEEE SIXTH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES AND APPLICATIONS, PROCEEDINGS, VOL 1 AND 2 page： 751 - 755 2000

Performance Analysis of an Integrated Voice and Data CDMA System Reviewed

Sato T.

Electronics and Communications in Japan, Part II: Electronics (English translation of Denshi Tsushin Gakkai Ronbunshi) Vol. 83 ( 4 ) page： 61 - 70 2000

Performance analysis of an integrated voice and data CDMA system Reviewed

T Sato, A Sandouk, T Yamazato, M Katayama, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS Vol. 83 ( 4 ) page： 61 - 70 2000

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

This research is an analysis of the mixed system of data packets and CDMA voice signals transmitted by the channel load sensing protocol. The voice signal is a medium requiring instantaneous action to complete the transmission within a certain time whereas the data packet is a medium requiring high reliability but allows temporal delay. The blocking probability and Erlang capacity are derived for the voice signal while the throughput is derived for the data packet. The characteristics in the system using CDMA strongly depend on the number of simultaneously transmitting stations. In particular, in the present system, due to the mixture of different media, the effect of traffic on each medium needs to be considered. In regard to this point, this paper analyzes the effect of traffic on each medium from the relationship of the required quality of the media and the number of simultaneously transmitting stations. Then the optimization of the system with two kinds of media is considered. Further, the system capacity is derived as a guideline for the system optimization. The data offered load is derived to make maximally efficient use of the channel. (C) 2000 Scripta Technica.

Performance analysis of an integrated voice and data CDMA system Reviewed

Sato T, Sandouk A, Yamazato T, Katayama M, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS Vol. 83 ( 4 ) page： 61 - 70 2000

OFDM systems with Multiple Trellis Coded Modulation Reviewed

M Harada, T Yamazato, M Katayama, A Ogawa

PIMRC 2000: 11TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1 AND 2, PROCEEDINGS page： 814 - 818 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In an attempt to improve the performance under frequency selective fading environment, we propose in this paper an Orthogonal-Frequency-Division-Multiple-Access (OFDM) system in which MTCM (Multiple Trellis Coded Modulation) is applied to a set of multiple subcarriers. The code is designed to enlarge the summation of the Euclidean distance and the product distance. We also propose a scheme for assigning the symbols to subcarriers adaptively based on the channel state information (CSI) fed back from the reception receive end, and evaluate the performance applying these two codes and the proposed scheme under a multipath Rayleigh fading environment.

DOI： 10.1109/PIMRC.2000.881535

Throughput evaluation in CDMA/shared-TDD packet systems in a cellular environment Reviewed

K Mori, T Kobayashi, T Yamazato, A Ogawa

WCNC: 2000 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, VOLS 1-3 page： 321 - 326 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper examines the inter-cell interference between uplinks and downlinks when a shared-TDD scheme is applied to CDMA packet communication systems in cellular environments. The CDMA/shared-TDD cellular packet systems experience two additional types of interference: one is the interference between base stations and the other is between mobile stations. The effect of these interferences on the throughput performance Is evaluated. Computer simulation demonstrated that interference between base stations rarely degrades uplink throughput, but interference between mobile stations substantially degrades downlink throughput.

DOI： 10.1109/WCNC.2000.904650

Transmission power control for downlinks in CDMA/shared-TDD cellular packet systems Reviewed

K Mori, T Kobayashi, T Yamazato, A Ogawa

PIMRC 2000: 11TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1 AND 2, PROCEEDINGS page： 1520 - 1524 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper proposes a transmission power control scheme for downlinks in CDMA/shared-TDD cellular packet systems that experience inter-cell interference between uplinks and downlinks. The proposed scheme increases the downlink transmission power for re-transmission packets and thus improves the signal-to-interference ratio for the packets. Simulation results show that the proposed scheme improves downlink throughput without sacrificing the uplink throughput.

DOI： 10.1109/PIMRC.2000.881672

Adaptive Array Antennas for the Base Station of a Multi Processing Gain CDMA System Reviewed

MORIMOTO Akihito, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira

IEICE Trans. Fundamentals Vol. 82 ( 12 ) page： 2687 - 2696 1999.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper discusses the employment of adaptive array antennas at the base station of a Multi Processing Gain (MPG) CDMA system. It is shown that the adaptive array antenna with the weight control scheme based on the signal before despreading procedure does not increase but even decreases the performance than that with an omni-directional antenna, and the cause of this serious performance degradation is revealed. Then it is shown that the performance with the weight control scheme based on the signal after despreading procedure is always better than that with an omni-directional antenna. Furthermore, the possibilities of performance improvement by the combination of adaptive array antenna and interference cancellation techniques are mentioned.

The Performance of MTCM Coded Multicarrier System

M. Harada, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA99 page： 563-566 1999.12

A study on SOVA based Turbo-decoding with threshold

M. Matsui, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA99 ( 1 ) page： 13-16 1999.12

Adaptive array antennas for the base station of a multi processing gain CDMA system Reviewed

Morimoto A, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2687 - 2696 1999.12

Adaptive array antennas for the base station of a multi processing gain CDMA system Reviewed

A Morimoto, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2687 - 2696 1999.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Chip-by-chip turbo coding for DS/SS systems Reviewed

Zheng C, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2751 - 2757 1999.12

Chip-by-chip turbo coding for DS/SS systems Reviewed

C Zheng, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2751 - 2757 1999.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Most of error correcting codes applying to DS/SS systems are such that information data is first (bit-by-bit) encoded and then spread by pseudo noise (PN) sequence. Thus, coding; gain achieved by such systems are mainly due to the error correcting codes and the redundancy produced by the spreading codes shows no effect on the coding gain. In this paper, a chip-by-chip Turbo coding for DS/SS systems is proposed. The input information data is first spread by PN sequence and then fed into the Turbo-encoder which operates in chip timing. As the Turbo-encoder operates in chip timing, a large interleaving size would be obtained, which improves the performance. As results, superior performances with coding gain of more than 3.0 dB and 5.0 dB for AWGN and Rayleigh-fading channel, respectively, were found with short frame size of information data.

Code acquisition of a DS/SS signal with transmit and receive antenna diversity Reviewed

Ikai Y, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2728 - 2734 1999.12

Decorrelating detector for multi-processing gain CDMA systems Reviewed

Hiraiwa H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 12 ) page： 2774 - 2777 1999.12

Decorrelating detector for multi-processing gain CDMA systems Reviewed

Hiraiwa H, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2774 - 2777 1999.12

Code acquisition of a DS/SS signal with transmit and receive antenna diversity Reviewed

Y Ikai, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 12 ) page： 2728 - 2734 1999.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we propose the introduction of space diversity techniques to the code acquisition of a direct-sequence spread-spectrum signal. In this scheme, both a transmitter and a receiver have multiple antennas and the signals corresponding to all the combinations of the transmitter and receiver antennas are combined at the acquisition circuit of the receiver. The performance is evaluated for an indoor packet radio communication system from the viewpoints of the average time for acquisition, the probability of success of acquisition, and the necessary preamble length. As the result, we show great performance improvements by the proposed scheme under slow and Rat Rayleigh fading environment.

Service Fairness in CDMA Cellular Packet Systems with Site Diversity Reception Reviewed

Kazuo MORI, Takehiko KOBAYASHI, Takaya YAMAZATO, Akira OGAWA

IEICE Transactions on Communications Vol. Vol. E82-B, No. 12 page： 1964 - 1973 1999.12

Service Fairness in CDMA Cellular Slotted-ALOHA Packet Systems Reviewed

Kazuo MORI, Takehiko KOBAYASHI, Takaya YAMAZATO, Akira OGAWA

Proc. of IEEE 1999 Global Telecommunications Conference (GLOBECOM'99) Vol. Vol. 1b page： 655 - 660 1999.12

Control of Transmit Permission Probability to Improve Service Fairness in CDMA Cellular Packet Communications Reviewed

K. Mori, T. Kobayashi, T. Yamazato, and A. Ogawa,

The 6th IEEE International Workshop on Mobile Multimedia Communications (MOMUC'99) Vol. MOMUC'99 page： 35-42 1999.11

Language：English

In the INTERNET, TCP (Transmission Control Protocol) is used for a reliable transport protocol. Originally, the TCP has been designed for wired networks, and not for wireless ones. It is reported that the performance of TCP is very poor in wireless environments. In this paper, we propose a new analytical model of the TCP, where the congestion window is modeled as a Markov chain. In the presence of random bit errors on a wireless link, we analyze the throughput of the TCP for the proposed model. Also, in a wireless link, we attempt to employ Reed Solomon code as FEC or Go-Back-N as ARQ, and discuss about throughput of TCP with FEC or ARQ.

A Synopsis of CIMS at Nagoya University

T. Yamazato, S. Kajita, T. Hamaguchi, S. Yuen

IPSJ SIG Technical Report Vol. DMS99 ( 16 ) page： 55-60 1999.11

The Influence of an ADC on Bit Error Rate Performance of a Software-Defined Base Station

K. Matsubara, M. Katayama, T. Yamazato, A. Ogawa

Technical Report of IEICE Vol. SR99 ( 19 ) page： 67-72 1999.11

A Study on OFDM Synchronization Scheme with Subtraction Operation

T. Shibata, N. Itoh, M. Fujimoto, H. Itoh, N. Suzuki, K. Ohtsuka T. Yamazato, A. Ogawa

Technical Report of IEICE Vol. RCS99 ( 135 ) page： 97-101 1999.10

An integrated voice/data CDMA packet communications with multi-code CDMA scheme Reviewed

Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 10 ) page： 2105 - 2114 1999.10

An integrated voice/data CDMA packet communications with multi-code CDMA scheme Reviewed

A Sandouk, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E82A ( 10 ) page： 2105 - 2114 1999.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we consider an integrated voice and data system over CDMA Slotted-ALOHA (CDMA S-ALOBA). We investigate its performance when multi-code CDMA (MC-CDMA) is applied as a multi-rate scheme to support users which require transmission with different bit rates. Two different classes of data users are transmitted together with voice. Performance measurement is obtained in respect of throughput for data and outage probability for voice. Moreover, we consider the Modified Channel Load Sensing Protocol (MCLSP) as a traffic control to improve the throughput of data. As a result, we show that the MC-CDMA technique is an effective one to obtain good throughput for data users at an acceptable voice outage probability. Furthermore, we show that with MCLSP, the throughput of data can be improved to reach a constant value even at a high offered load of data users.

A new acquisition scheme of a DS/SS signal with transmit and receive antenna diversity Reviewed

A Scheme for Throughput Improvement in Voice/Data CDMA Packet Communications Reviewed

A. Sandouk, T. Yamazato, M. Katayama, and A. Ogawa

IEEE Vehicular Technology Conference (VTC Fall) Vol. IEEE VTC'102 Fall page： - 1999.9

A Study on Multiple Trellis Coded Modulation for Multicarrier Systems

M. Harada, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE Vol. SST99 ( 32 ) page： 13-18 1999.9

Chip-by-chip Turbo coded DS/SS systems

T. Yamazato, C. Zheng, M. Katayama, A. Ogawa

1999 IEICE General Conference page： - 1999.9

Chip-by-chip Turbo coded DS/SS systems Reviewed

YAMAZATO Takaya, Zheng Cheng, KATAYAMA Masaaki, OGAWA Akira

Proceedings of the Society Conference of IEICE Vol. 1999 ( 0 ) page： 97 1999.8

Permission Probability Control to Improve Service Fairness in CDMA Cellular ALOHA Systems

K. Mori, T. Kobayashi, T. Yamazato, A. Ogawa

Technical Report of IEICE Vol. RCS99 ( 91 ) page： 29-36 1999.8

A Study for the Throughput Performance of CDMA Slotted ALOHA Systems

M. Saito, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE Vol. SST99 ( 21 ) page： 37-42 1999.7

Throughput Performance of CDMA ALOHA (invited) Invited

A. Ogawa, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE Vol. SAT99-41 page： 99 1999.6

A Study of Chip-by-Chip Turbo Coding for DS-CDMA Systems

C. Zheng, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE Vol. SST99-8 page： 49-54 1999.6

Effect of Beam Pattern on Capacity of Multibeam LEOS Communication Systems

N. Ichikawa, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SAT99 ( 39 ) page： 83-90 1999.6

Performance Improvements applying an Adaptive Array Antenna for Transmission at a Mobile Station

Y. R. Senhaji, T. Yamazato, M. Katayama, and A. Ogawa

1999 IEICE General Conference Vol. B ( 5 ) page： 37 1999.3

Application of ARQ Scheme to Inter-frame Picture Decoding

M. Honjo, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

1999 IEICE General Conference Vol. B ( 5-243 ) page： 594 1999.3

A Study of Error Correcting Codes Applied to OFDM Systems

W. Wang, C.Zheng, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. IT98 ( 75 ) page： 49-54 1999.3

A Study on Decorrelating Detector for Multi-Processing Gain CDMA Systems

H. Hiraiwa, M. Katayama, T. Yamazato and A. Ogawa

1999 IEICE General Conference Vol. B ( 5-111 ) page： 462 1999.3

A Study on the Error Control Scheme in Data Transmission for Positioning of Sea Turtles

Y. Amano, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE Vol. SANE99 ( 64 ) page： 105-108 1999.2

Effect of Beam Pattern on Capacity of Multibeam LEOS Communication Systems

N. Ichikawa, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE, vol.SAT99-39, pp.83-90 (1999.6) Vol. SAT99 ( 39 ) page： 83-90 1999

A Study of Error Correcting Codes Applied to OFDM Systems

W. Wang, C.Zheng, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE, vol.IT98-75, pp.49-54 (1999-03) Vol. IT98 ( 75 ) page： 49-54 1999

Application of ARQ Scheme to Inter-frame Picture Decoding

M. Honjo, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

1999 IEICE General Conference, vol.B-5-243, p.594 (1999-3) Vol. B ( 5 ) page： 243 1999

A Study on the Error Control Scheme in Data Transmission for Positioning of Sea Turtles

Y. Amano, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE, vol.SANE99-64, pp.105-108 (1999-02) Vol. SANE99 ( 64 ) page： 105-108 1999

A Study on Decorrelating Detector for Multi-Processing Gain CDMA Systems

H. Hiraiwa, M. Katayama, T. Yamazato and A. Ogawa

1999 IEICE General Conference, vol.B-5-111, p.462 (1999-03) Vol. B ( 5 ) page： 111 1999

A Scheme for Throughput Improvement in Voice/Data CDMA Packet Communications Reviewed

A. Sandouk, T. Yamazato, M. Katayama, and A. Ogawa

IEEE Vehicular Technology Conference (VTC Fall) Vol. IEEE VTC'100 Fall page： - 1999

A New Acquisition Scheme of a DS/SS Signal with Transmit and Receive Antenna Diversity Reviewed

Y. Ikai, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Conference on Communications (ICC99) Vol. ICC'99 page： - 1999

Throughput Improvement of a Dual-Class Multi-code CDMA ALOHA System with Modified Channel Load Sensing Protocol Reviewed

A. Sandouk, H. Okada, T. Yamazato, M. Katayama, and A. Ogawa

IEEE International Conference on Communications (ICC99) Vol. ICC'99 page： - 1999

Performance Improvements applying an Adaptive Array Antenna at both the Base and Mobile Stations in Cellular CDMA Reviewed

Youssef R. Senhaji, H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC99 page： - 1999

Acquisition of a DS/SS Signal with Macro/Micro Antenna Diversity under Raylgh Fading and Log-normal Shadowing Reviewed

Y. Ikai, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC99 page： - 1999

Transmitter Precoding with Multiple Transmit/Receive Antennas for High Data Rate Communication in Bandwidth-Limited Channels

K. Ban, M. Katayama, T. Yamazato, and A. Ogawa

IEEE VTC'99 Fall Vol. VTC'99 page： - 1999

A Study on the Error Control Scheme in Data Transmission for Positioning of Sea Turtles

Y. Amano, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE, vol.SANE99-64, pp.105-108 (1999-02) Vol. SANE99 ( 64 ) page： 105-108 1999

A New Acquisition Scheme of a DS/SS Signal with Transmit and Receive Antenna Diversity Reviewed

Y. Ikai, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Conference on Communications (ICC99) Vol. ICC'99 page： - 1999

Chip-by-Chip Turbo Coding for DS/SS Systems Reviewed

C. Zheng, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Communications Vol. E82-A ( 12 ) page： 2751-2757 1999

Decorrelating Detector for Multi-Processing Gain CDMA Systems Reviewed

H. Hiraiwa, M. Katayama,T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 12 ) page： 2751-2757 1999

Applying Successive Interference Cancellation to CDMA Unslotted ALOHA System

Y. Tadokoro, H. Okada, M. Saito, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE Vol. SST99 ( 34 ) page： 25-30 1999

A Study on Multiple Trellis Coded Modulation for Multicarrier Systems

M. Harada, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE, vol.SST99-32, pp.13-18 (1999-9) Vol. SST99 ( 32 ) page： 13-18 1999

Throughput Performance of CDMA ALOHA (invited)

A. Ogawa, T. Yamazato, H. Okada, M. Katayama

Technical Report of IEICE, vol.SAT99-41, p.99 (1999-6) Vol. SAT99 ( 41 ) page： 99 1999

Error Resilient Video Coding System for Wireless Communication -Using Motion Compensted Field Reviewed

M. Honjo, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

WPMC'99, Amsterdam, Netherlands Vol. WPMC'99 page： - 1999

Transmitter Precoding with Multiple Transmit/Receive Antennas for High Date Rate Communication in Bandwidth-limited Channels Reviewed

K. Ban, M. Katayama, T. Yamazato, and A. Ogawa

IEEE Vehicular Technology Conference (VTC Fall) Vol. IEEE VTC'101 Fall page： - 1999

Throughput Performance of CDMA Slotted ALOHA Systems with Accurate Packet Success Probability Reviewed

M. Saito, T. Yamazato, M. Katayama, and A. Ogawa

WPMC'99, Amsterdam, Netherlands Vol. WPMC'99 page： - 1999

Acquisition of a DS/SS Signal with Macro/Micro Antenna Diversity under Rayleigh Fading and Log-normal Shadowing Reviewed

Y. Ikai, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC99 page： - 1999

Throughput Improvement of a Dual-Class Multi-code CDMA ALOHA System with Modified Channel Load Sensing Protocol Reviewed

A. Sandouk, H. Okada, T. Yamazato, M. Katayama, and A. Ogawa

IEEE International Conference on Communications (ICC99) Vol. ICC'99 page： - 1999

Performance Improvements applying an Adaptive Array Antenna at both the Base and Mobile Stations in Cellular CDMA Reviewed

Youssef R. Senhaji, H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC99 ( 3 ) page： 982-986 1999

A Study for the Throughput Performance of CDMA Slotted ALOHA Systems

M. Saito, T. Yamazato, M. Katayama, A. Ogawa

Technical Report of IEICE, vol.SST99-21, pp.37-42 (1999-7) Vol. SST99 ( 21 ) page： 37-42 1999

Service Fairness in CDMA Cellular Slotted-ALOHA Packet Systems Reviewed

K. Mori, T. Kobayashi, T. Yamazato and A. Ogawa

IEEE Global Communications Conference (Globecom1999) Vol. Globecom'99 page： 655-660 1999

Ikai Y., Katayama M., Yamazato T., Ogawa A.

IEEE International Conference on Communications Vol. 2 page： 1256 - 1261 1999

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEE International Conference on Communications

We propose the introduction of space diversity techniques to the code acquisition of a direct-sequence spread-spectrum signal. In this scheme, both a transmitter and a receiver have multiple antennas and the signals corresponding to all the combinations of the transmitter/receiver antennas are combined at the acquisition circuit of the receiver. The performance is evaluated for indoor packet radio communication systems from the viewpoints of average time for acquisition, probability of success of acquisition, and necessary preamble length. As the result, we show great performance improvements by the proposed scheme under slow and flat Rayleigh fading environment.

DOI： 10.1109/ICC.1999.765524

A scheme for throughput improvement in voice/data CDMA packet communications Reviewed

Abbas Sandouk, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEEE Vehicular Technology Conference Vol. 50 ( 1 ) page： 362 - 366 1999

Language：English Publishing type：Research paper (international conference proceedings)

In this paper, voice and data users with different bit rales are integrated in multi-code CDMA slotted ALOHA (MC-CDMA S-ALOHA) system. Performance measurement is obtained in the respect of throughput for data and outage probability for voice. Moreover, we consider the Modified Channel Load Sensing Protocol (MCLSP) as a traffic control to improve the throughput of data. We show that the MC-CDMA technique is an effective one to obtain a good throughput for data at an acceptable voice outage probability. We also show that the throughput of data can be improved with MCLSP. © 1999 IEEE.

DOI： 10.1109/VETECF.1999.797157

Adaptive array antennas for the base station of a multi processing gain CDMA system Reviewed

Morimoto A., Katayama M., Yamazato T., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 12 ) page： 2687 - 2695 1999

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

An integrated voice/data CDMA packet communications with multi-code CDMA scheme Reviewed

Sandouk A., Yamazato T., Katayama M., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 10 ) page： 2105 - 2113 1999

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

In this paper, we consider an integrated voice and data system over CDMA Slotted-ALOHA (CDMA S-ALOHA). We investigate its performance when multi-code CDMA (MC-CDMA) is applied as a multi-rate scheme to support users which require transmission with different bit rates. Two different classes of data users are transmitted together with voice. Performance measurement is obtained in respect of throughput for data and outage probability for voice. Moreover, we consider the Modified Channel Load Sensing Protocol (MCLSP) as a traffic control to improve the throughput of data. As a result, we show that the MC-CDMA technique is an effective one to obtain good throughput for data users at an acceptable voice outage probability. Furthermore, we show that with MCLSP, the throughput of data can be improved to reach a constant value even at a high offered load of data users.

Chip-by-chip turbo coding for DS/SS systems Reviewed

Zheng C.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 12 ) page： 2751 - 2756 1999

Code acquisition of a DS/SS signal with transmit and receive antenna diversity Reviewed

Ikai Y.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E82-A ( 12 ) page： 2728 - 2733 1999

Performance of a LEOS communication system with overlaid and overlapped cell arrangement Reviewed

Ono K, Katayama M, Yamazato T, Ogawa A

MOBILE AND PERSONAL SATELLITE COMMUNICATIONS 3 page： 131 - 145 1999

Performance of a LEOS communication system with overlaid and overlapped cell arrangement Reviewed

K Ono, M Katayama, T Yamazato, A Ogawa

MOBILE AND PERSONAL SATELLITE COMMUNICATIONS 3 page： 131 - 145 1999

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG LONDON LTD

The performance of a Low Earth-Orbital Satellite communication System with large overlap of neighboring cells and the layered cell structure is discussed. The rejection of a newly arrived call (call blocking) and the forced termination of a call which requests handover(call dropping) are used as the performance measures and simple one-dimensional model is introduced in order to analyze the performance. As the result, performance improvement by overlapping, overlaying, and the combination of them are shown. In addition, it is found that there are optimum parameters or combinations of them, which makes the performances best.

Throughput improvement of a dual-class multi-code CDMA ALOHA system with modified channel load sensing protocol Reviewed

Service fairness in CDMA cellular packet systems with site diversity reception Reviewed

Mori K.

IEICE Transactions on Communications Vol. E82-B ( 12 ) page： 1964 - 1972 1999

Sandouk A.

IEEE International Conference on Communications Vol. 2 page： 1079 - 1083 1999

Transmitter precoding with multiple transmit/receive antennas for high data rate communication in bandwidth-limited channels Reviewed

Koichiro Ban, Masaaki Katayama, Takaya Yamazato, Akira Ogawa

IEEE Vehicular Technology Conference Vol. 50 ( 3 ) page： 1946 - 1950 1999

Language：English Publishing type：Research paper (international conference proceedings)

We develop a new concept of a multichannel transmission scheme utilizing multiple transmit/receive antennas in narrow-band communication systems. We study the problem to design a pre-filter at the transmitter, a post-filter at the receiver, and a signal mapping operation before pre-filtering. With this new concept, we could expect extremely high data rate and high efficiency communication systems. © 1999 IEEE.

DOI： 10.1109/VETECF.1999.801737

Multimedia Packet Transmission using CDMA

T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST98 ( 42 ) page： 39339 1998.12

Hierarchical Transmission of Huffman Code Using Multi-Code/Multi-Rate DS/SS Modulation with appropriate Power Control Reviewed

A. Makido, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Communications Vol. E81-B ( 12 ) page： 2283-2289 1998.12

Hierarchical transmission of Huffman code using multi-code/multi-rate DS/SS modulation with appropriate power control Reviewed

Makido S, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E81B ( 12 ) page： 2283 - 2289 1998.12

Hierarchical transmission of Huffman code using multi-code/multi-rate DS/SS modulation with appropriate power control Reviewed

S Makido, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E81B ( 12 ) page： 2283 - 2289 1998.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

For transmission of video signals, it is important that the system allows a certain degree of flexibility in bit rate as well as quality, depending upon the requirements of media and channel conditions. In this paper, we discuss the hierarchical transmission of Huffman code using multi-code/multi-rate DS/SS system to realize flexible transmission. We first discuss and show that the structure of Huffman code tree directly expresses hierarchical structure, and that parallel transmission of Huffman code can achieve hierarchical transmission. By assigning different transmission data rate to the bits in each stratum, it is possible to transmit different amount of information from each stratum. Further, we show the quality of each of the stratum can easily controlled by an appropriate power distribution to each parallel transmission branch.

A Channel Control Scheme Considering Channel Response for Multi-carrier Transmission Reviewed

T. Shibata, N. Suzuki, M. Fujimoto, K. Nishikawa, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. J81-B-I ( 11 ) page： 700-708 1998.11

Initial acquisition of code timings and carrier frequencies of CDM down-link signals in multiple-LEO-satellite communication systems Reviewed

Ishizu M, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 11 ) page： 2281 - 2290 1998.11

Initial acquisition of code timings and carrier frequencies of CDM down-link signals in multiple-LEO-satellite communication systems Reviewed

M Ishizu, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 11 ) page： 2281 - 2290 1998.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we discuss the initial acquisition of the code division multiplexed DS/SS down-link signals at a user terminal of multiple LEO mobile satellite communication systems. In LEO systems, a receiver generally receives signals from plural satellites for soft hand-off and for satellite diversity as a countermeasure to shadowing. In this situation, the signal from each satellite becomes the interference to the signals from other satellites. In addition to this inter-satellite interference, we have to consider the intra-satellite interference from user channels to a pilot channel because of the loss of orthogonality of channels at initial acquisition stage especially under frequency offsets due to Doppler effect. Thus in this paper, we analytically evaluate the performance of an initial acquisition scheme, taking the intra/inter-satellite interference under Doppler shift into account.

New quasi-synchronous sequences for CDMA slotted ALOHA systems Reviewed

Saito M, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 11 ) page： 2274 - 2280 1998.11

New quasi-synchronous sequences for CDMA slotted ALOHA systems Reviewed

M. Saito, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transactions on Fundamentals Vol. E81-A ( 11 ) page： 2274 - 2280 1998.11

Language：English Publishing type：Research paper (scientific journal) Publisher：電子情報通信学会

One of unique features of CDMA slotted ALOHA (CDMA S-ALOHA) is that user must synchronize his transmission to give slot. thus orthogonal sequence as spreading sequence would achieve ideal throughput if each of packets accomplish perfect synchronization. In ths presence of any ambiguity in synchronizations, however, quasi-synchronous (QS) sequences suit well with CDMA S-ALOHA system. In this paper, we introduce new QS-sequences obtained from the orthogonal Gold sequences and discuss their performance when applying to CDMA S-ALOHA systems. As a result, withstanding to access timing error, good performance is ensured with this sequence under the environment of AWGN, MAI (multiple access interference) and frequency non-selective fading, that is, micro or pico cellular systems and indoor wireless LANs.

Performance evaluation of DS/CDMA communications systems modulated with pi/2-shift BPSK over multipath Rayleigh fading channels Reviewed

Galib MMA, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 11 ) page： 2304 - 2310 1998.11

Performance evaluation of DS/CDMA communications systems modulated with pi/2-shift BPSK over multipath Rayleigh fading channels Reviewed

MMA Galib, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 11 ) page： 2304 - 2310 1998.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In mobile communications, power is a very important factor and nonlinear amplification of power amplifiers cannot be avoided due to their high power efficiency. This article presents the performance of pi/2-shift BPSK modulation scheme used in DS/SS/CDMA wireless communications over multipath Rayleigh fading channel and compares the performance with the performance of conventional BPSK and offset QPSK CDMA systems. The performance parameters: Out-of-Band power, average Bit Error Rate (BER) and Spectral Efficiency have been evaluated. In order to obtain improved performance on fading channels, a RAKE receiver has been employed. Finally it is shown that pi/2-shift BPSK outperforms conventional BPSK and offset QPSK in the presence of nonlinear amplification.

A Study on the Throughput of Multi-Code CDMA ALOHA System with Modified Channel Load Sensing Protocol

M. Saito, H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST98 ( 40 ) page： 61-68 1998.10

Parallel Transmission of Huffman Code Under Fading Environment

S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. CS98 ( 117 ) page： IE98-96 1998.10

Performance of a LEOS Communication System with Overlaid and Overlapped Cell Arrangement

K. Ono, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT98 ( 42 ) page： 39090 1998.10

Handoff Performance of LEO Satellite Communication Systems with Overlapped-Cell Arrangement

K. Ono, M. Katayama, T. Yamazato and A. Ogawa

1998 IEICE General Conference Vol. SB-3 ( 13 ) page： 556-557 1998.10

Error correcting capability of constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 10 ) page： 2166 - 2169 1998.10

Queueing analysis of CDMA unslotted ALOHA systems with finite buffers Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 10 ) page： 2083 - 2091 1998.10

Queueing Analysis of CDMA Unslotted ALOHA Systems with Finite Buffers Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. E81-A ( 10 ) page： 2083-2091 - 2091 1998.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE

CDMA unslotted ALOHA system with finite size of quenueing buffers is discussed in this paper. We introduce an analytical model in which the system is divided into two Markov chains; one is in the user part, and the other is in the channel part. In the user part, we can model the queueing behavior of the user station as an M/G/1/B queue. In the channel part, we can consider the number of simulataneously transmitted packets as an M_1+M_2/D/∞//K queue. We analyze the queueing system by using this analytical model, and evaluate the effect of buffer capacity in terms of the throughput, the rejection probability and the average delay. As a result, increase in the buffer size brings about an improvement in the grade of service in terms of higher throughput and lower rejection probability.

Throughput Performance of QS-CDMA Slotted ALOHA System on 2-path Rayleigh Fading Environment Reviewed

SAITO Masato, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

Proceedings of the Society Conference of IEICE Vol. 1998 page： 99 1998.9

Performance of Transmit/Receive Antenna Diversity with FEC Coding under Correlated Rician Fading Channels

K. Ban, M. Katayama, T. Yamazato and A. Ogawa

1998 IEICE General Conference Vol. A-5 ( 8 ) page： 98 1998.9

Throughput Performance of QS-CDMA Slotted ALOHA System on 2-path Rayleigh Fading Environment

M. Saito, T. Yamazato, M. Katayama and A. Ogawa

1998 Society Conference of IEICE Vol. A-5-9 page： 99 1998.9

A Study on Reducing the Nonlinear Distortion in OFDM Systems

M. Harada, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE Vol. RCS98 ( 61 ) page： 25-30 1998.7

Throughput Analysis for CDMA Unslotted ALOHA Systems with Finite Population Assumption Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J81-A ( 7 ) page： 1089-1092 1998.7

CDMA slotted ALOHA system with finite buffers Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E81A ( 7 ) page： 1473 - 1478 1998.7

CDMA Slotted ALOHA System with Finite Buffers Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. E81-A ( 7 ) page： 1473-1478 - 1478 1998.7

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE

In this paper, CDMA slotted ALOHA system with finite size of buffers is proposed. To analyze the system performance, we use the linear approximate solution based on restricted occupancy urn models. We evaluate the system performance in terms of throughput, average delay, and rejection probability and clarify the effect of buffer capacity.

Throughput Analysis for CDMA Unslotted ALOHA Systems with Finite Population Assumption Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. J81-A ( 7 ) page： 1089-1092 1998.7

An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

Ishiguro T, Yamazato T, Katayama M, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 81 ( 6 ) page： 51 - 60 1998.6

An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

Ishiguro T., Yamazato T., Katayama M., Ogawa A.

Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi) Vol. 81 ( 6 ) page： 51 - 60 1998.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)

The CDMA system using DS/SS/GMSK modulation can realize a high spectral efficiency by using the constant-envelope property of GMSK modulation, even if the signal is band-limited and the transmitter is nonlinear. This paper discusses the optimization of a receiver in order to further improve spectral efficiency. The idea is to apply optimal weights to the despreading matrix. Using the signal-to-noise power ratio based on a linear approximation to the DS/SS/GMSK waveform, the weights that minimize the signal-to-noise power ratio are determined. The performance is compared to that of the conventional receiver, in terms of the signal-to-noise power ratio after despreading, the bit error rate, and the spectral efficiency. As a result, we show that performance is improved by applying optimal weights to the despreading matrix. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(6): 51-60, 1998.

DOI： 10.1002/(sici)1520-6424(199806)81:6<51::aid-ecja6>3.3.co;2-h

An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

T Ishiguro, T Yamazato, M Katayama, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 81 ( 6 ) page： 51 - 60 1998.6

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

The Effect of Channel Error on H.263 Image Transmission

M. Honjo, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

1998 IEICE General Conference, vol.B-5-234, p.598 (1998-3) Vol. B-5 ( 234 ) page： 598 1998.3

A Channel Control Scheme using Channel State Information in Multi-Carrier Transmission

T. Shibata, M. Fujimoto, N. Suzuki, K. Nishikawa, T. Yamazato and A. Ogawa

1998 IEICE General Conference Vol. B-5 ( 23 ) page： 387 1998.3

Performance Analysis of a Multi Processing-Gain CDMA System with Adaptive Array Antenna at Base Station

L. Zhang, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. A・P97 ( 215 ) page： 101-108 1998.2

A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed

Okuda S, Katayama M, Yamazato T, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 81 ( 2 ) page： 24 - 33 1998.2

A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed

S Okuda, M Katayama, T Yamazato, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 81 ( 2 ) page： 24 - 33 1998.2

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

This paper considers the direct-sequence spread-spectrum (DS/SS) communication system, and proposes an initial acquisition scheme for the spread signal in an environment where a large frequency offset is included in the carrier. By the proposed scheme, not only is the initial acquisition of the spread signal realized, but also the carrier frequency offset can be estimated to some extent. The proposed configuration assumes acquisition by digital signal processing, using the fast Fourier transform (FFT). Numerical examples are shown for the mean acquisition time and the frequency synchronization characteristics by the proposed scheme, and it is shown that the proposed scheme can realize excellent acquisition performance even if there exists a large frequency offset in the carrier. (C) 1998 Scripta Technica.

A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed

Okuda S., Katayama M., Yamazato T., Ogawa A.

Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi) Vol. 81 ( 2 ) page： 24 - 33 1998.2

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)

DOI： 10.1002/(sici)1520-6440(199802)81:2<24::aid-ecjc3>3.0.co;2-5

Hierarchical transmission of huffman code using multi-code/multi-rate DS/SS modulation with appropriate power control Reviewed

CDMA slotted ALOHA system with finite buffers Reviewed

Okada H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 7 ) page： 1473 - 1478 1998.1

Queueing analysis of CDMA unslotted aloha systems with finite buffers Reviewed

Okada H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 10 ) page： 2083 - 2091 1998.1

Performance Analysis of a Multi Processing-Gain CDMA System with Adaptive Array Antenna at Base Station

A. Morimoto, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. A・P97-215 page： 101-108 1998

Performance of a LEOS Communication System with Overlaid and Overlapped Cell Arrangement Reviewed

K.Ono, M.Katayama, T.Yamazato and A.Ogawa

EMPS'98 Vol. 1 page： 131-145 1998

New Quasi-Synchronous Sepuences for CDMA Slotted ALOH Systems Reviewed

M. Saito, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 11 ) page： 2274-2280 1998

Inittial Acquisition of Code Timings and Carrier Frequencies of CDMA Downlink Signals in Multiple-LEO-Satellite Communication Systems Reviewed

M. Ishizu, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 11 ) page： 2281-2290 1998

A Channel Control Method for Multi-Carrier Transmission Considering Channel Response Reviewed

T. Shibata, N. Suzuki, M. Fujimoto, K. Nishikawa, T. Yamazato and A. Ogawa

APMC'98 Vol. 3 page： 853-856 1998

An Integrated Voice and Multi-Code CDMA Data System for CDMA Slotted-ALOHA with Modified Channel Load Sensing Protocol

A. Sandouk, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. 2 page： 523-526 1998

Application of TURBO Code to Band-limited VIDEO Signal Transmission

M. Honjo, M. Matsui, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. 26.7,2 page： 619-622 1998

A Study on Parallel Decording of Turbo-Codes Using Soft-output Viterbi Decorder

M. Matsui, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. IT98 ( 21 ) page： 17-22 1998

A Study on Cross-Correlation Property in Orthogonal Multi-Code SYstems

A. Fujiwara, T. Wada, T. Yamazato, M. Katayama, and A. Ogawa

Technical Report of IEICE Vol. SST98-13 page： 19-24 1998

Weight Control Scheme of Adaptive Array Antennas in CDMA Systems

A. Morimoto, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. CS98-56 page： 39277 1998

A New Acquisition Scheme of DS/SS Signals using Space Diversity Techniques

Y. Ikai, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST98-24 page： 53-60 1998

Tutorial : Introduction to CDMA Invited Reviewed

T. Yamazato, A. Ogawa, M. Katayama and A. Jamalipour

1998 IEEE Global Telecommunications Conference/Tutorial Note Vol. Globecom98 ( TI-13 ) page： - 1998

CDMA Unslotted ALOHA Systems with Finite Buffers Reviewed

H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE ICUCP'98 Vol. ICUPC98 ( 2 ) page： 1143-1147 1998

An Access Control Scheme Based on Transmit Power for CDMA ALOHA System under a Cellular Environment Reviewed

Y. Asai, T. Yamazato, M. Katayama and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA98 ( 2 ) page： 491-494 1998

Hierarchical Transmission System using Multi-Code/Multi-Rate DS/SS Modulation Reviewed

T. Yamazato, S. Makido, M. Katayama and A. Ogawa

1998 IEEE Global Telecommunications Conference Vol. Globecom98 ( 4 ) page： 2147-2152 1998

A Control Scheme of Multi-Carrier Transmission Considering Channel Channel Response for Mobile Communication Reviewed

T. Shibata, N. Suzuki, M. Fujimoto, K. Nishikawa, T. Yamazato and A. Ogawa

APCC'98 Vol. APCC98 ( 2 ) page： 543-546 1998

Performance Evaluation of DS/CDMA Communications Systems Modulated with pi/2-Shift BPSK over Multipath Rayleigh Fading Channels Reviewed

A. Galib, T. Yamazato, M. Katayama and A. Ogawa

1998 IEEE Global Telecommunications Conference/Communications Theory Mini Conference Vol. Globecom98 page： - 1998

Error Correcting Capability of Constant Amplitude Coding for Orthgonal Multi-Code CDMA Systems Reviewed

T. Wada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E-81-A ( 10 ) page： 2166-2169 1998

Queueing Analysis of CDMA Slotted ALOHA Systems with Finite Buffer and Finite Population Assumptions Reviewed

H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Conference on Communications (ICC98) Vol. ICC98 ( 1 ) page： 407-411 1998

Problems of Implementing Adaptive Array Antennas in CDMA Systems Reviewed

A. Morimoto, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC98 ( 3 ) page： 1422-1426 1998

Effect of Nonlinear Amplification on Multi-Code DS/SS System Reviewed

T. Yamazato, A. Fujiwara, M. Katayama, A. Ogawa

International Symposium on Nonlinear Theory and its Applications (NOLTA) Vol. NOLTA98 page： - 1998

Quase-Synchronous CDMA Slotted ALOHA System Through Flat Fading Channel Reviewed

Masato Saito, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

The 1998 International Symposium on Information Theory and its Applications(ISITA'98) Vol. FA4-3,2 ( 2 ) page： 487-490 1998

Access Control Techniques for CDMA ALOHA Reviewed

T. Yamazato, H. Okada,M. Katayama and A. Ogawa

IEEE Fifth International Symposium on Spread Spectrum Techniques & Applications Vol. ISSSTA98 ( 1 ) page： 293-297 1998

Queueing Analysis of CDMA Unslotted ALOHA Systems with Finite Buffers Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 10 ) page： 2083-2091 1998

Wireless Transmission of Huffman Code Using Parallel Weighted DS/SS Modulation

S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST97-117 page： 19-24 1998

Wireless Transmission of Huffman Code using DS/SS Modulation Reviewed

S. Makido, T. Yamazato, M. Katayama, A. Ogawa

TJCOM'98, Taiwan Vol. TJCOM98 ( 2 ) page： 37-42 1998

CDMA Slotted ALOHA System with Finite Buffers Reviewed

H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 7 ) page： 1473-1478 1998

Evaluation of the Interference with Small Number of Users in Orthogonal Multi-Code CDMA Systems Reviewed

A. Fujiwara, T. Wada, T. Yamazato, M. Katayama and A. Ogawa

WPMC'98 Vol. 1 page： 422-427 1998

Access control techniques for CDMA ALOHA Reviewed

Yamazato T, Okada H, Katayama M, Ogawa A

1998 IEEE 5TH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES AND APPLICATIONS - PROCEEDINGS, VOLS 1-3 page： 293 - 297 1998

CDMA unslotted ALOHA systems with finite buffers Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

ICUPC '98 - IEEE 1998 INTERNATIONAL CONFERENCE ON UNIVERSAL PERSONAL COMMUNICATIONS, VOLS 1 AND 2 Vol. 1-2 page： 1143 - 1147 1998

CDMA unslotted ALOHA systems with finite buffers Reviewed

Okada H.

ICUPC 1998 - IEEE 1998 International Conference on Universal Personal Communications, Conference Proceedings Vol. 2 page： 1143 - 1147 1998

Makido S.

IEICE Transactions on Communications Vol. E81-B ( 12 ) page： 2283 - 2289 1998

Hierarchical transmission system using multi-code/multi-rate DS/SS modulation Reviewed

Yamazato T, Makido S, Katayama M, Ogawa A

GLOBECOM 98: IEEE GLOBECOM 1998 - CONFERENCE RECORD, VOLS 1-6 page： 2147 - 2152 1998

NeW Quasi-Synchronous Sequences for CDMA Slotted ALOHA Systems Reviewed

Saito M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 11 ) page： 2274 - 2280 1998

Performance Evaluation of DS/CDMA communications systems modulated with f -shift bpsk over multipath rayleigh fading channels Reviewed

Asadullah Galib M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E81-A ( 11 ) page： 2304 - 2310 1998

Problems of implementing adaptive array antennas in CDMA systems Reviewed

A Morimoto, M Katayama, T Yamazato, A Ogawa

NINTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-3 page： 1422 - 1426 1998

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we discuss the performance of a system in which multi processing gain(MPG) spread spectrum signals are transmitted to a base station within the same bandwidth. At the receiver of the base station, an adaptive array antenna is employed. We evaluate the system performance in terms of Signal to Interference-and-Noise Ratio(SINR) and also of outage probability of low-rate users. We find that the employment of the adaptive array antenna may result in serious degradation of the outage probability of low-rate users. We then show that the cause of this serious degradation is the inadequate guidelines of conventional adaptive array antennas.

Queueing analysis of CDMA slotted ALOHA systems with finite buffer and finite population assumptions Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

ICC 98 - 1998 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS VOLS 1-3 page： 407 - 411 1998

A Constant Amplitude Coding for Orthogonal Multi-Code CDMA Systems Reviewed

WADA Tadahiro, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE TRANS. FUNDAMENTALS, A Vol. 80 ( 12 ) page： 2477 - 2484 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we present orthogonal multi-code CDMA systems with the constant amplitude transmission. In general, the dynamic range of the amplitude of the transmitting signal is very large in the case of orthogonal multi-code CDMA systems. In order to realize the constant amplitude transmission for orthogonal multi-code CDMA systems, we propose a constant amplitude coding. First, we show the basic concept of the constant amplitude coding. And then, we show that the constant amplitude transmission can be realized by the combination of the conventional orthogonal multi-code CDMA and the constant amplitude coding. Finally, the effectiveness of the proposed method is evaluated in terms of the bit error rate performance and it is shown that the proposed method is robust to the non-linear distortion caused by a high power amplifier(HPA).

A Spread-Spectrum System with Dual Processing Gains Designed for Cyclic Noise in Power Line Communications Reviewed

NIWA Hisashi, OONO Osamu, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira, ISAKA Noriyuki

IEICE Trans. Fundamentals, A Vol. 80 ( 12 ) page： 2526 - 2533 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We propose a spread-spectrum power line communication system considering the cyclic features of the noise in the lines. For this purpose, we model the noise as the sum of a time-invariant stationary process and two cyclostationary processes, i.e., cyclic continuous noise and cyclic impulsive noise. The proposed system employs two different countermeasures to each of these two classes of cyclic noise. For the cyclic continuous noise, it uses multiple-processing-gain spread spectrum technique: the smaller processing gains are assigned for the periods with lower instantaneous noise power and the larger ones for the periods of higher noise power. Considering the cyclic impulsive noise, convolutional coding with interleaving is applied. In order to analyze the performance improvement, due to the employment of multiple processing gains, we introduce a simple model of the continuous noise. The overall performance is evaluated by computer simulation with the actual noise wave-form measured in power lines.

A Simple Transmit/Receive Antenna Diversity for Indoor DS/CDMA Wireless Communication Systems Reviewed

BAN Koichiro, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira

IEICE Trans. Commun. Vol. 80 ( 12 ) page： 1790 - 1796 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This paper proposes a direct-sequence spread spectrum (DS/SS) communication system with a new diversity technique designed for indoor multi-path fading channels where path diversity isn't available. In this system, the transmitter sends a same signal from multiple antennas at the same time with intentional time delays, which allows the receiver to distinguish and combine the signals from different antennas. We also consider the combination of this scheme with the conventional receiving antenna diversity for additional diversity gain. Furthermore, it is found that the use of the multiple transmitting antennas decreases the effect of the multiple access interference.

Q uasi-Synchronous CDMA ALOHA System Using the Sequences Generated from Orthogonal Gold Sequences

Masato Saito, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA97 ( 5-4-5 ) page： 589-592 1997.12

Performance Analysis of CDMA ALOHA Systems with Finite Buffer

Hiraku Okada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA97 ( 4-3-6 ) page： 409-412 1997.12

A Study on Error Correcting Capability of Constant Amplitude Coding for Orthogonal Multi-Code CDMA Systems

Tadahiro Wada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA97 ( 5-4-6 ) page： 593-596 1997.12

A constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2477 - 2484 1997.12

A simple transmit/receive antenna diversity for indoor DS/CDMA wireless communication systems Reviewed

Ban K, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E80B ( 12 ) page： 1790 - 1796 1997.12

A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

Niwa H, Oono O, Katayama M, Yamazato T, Ogawa A, Isaka N

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2526 - 2533 1997.12

CDMA for personal communications based on low Earth-orbital satellite systems Reviewed

Ogawa A, Katayama M, Yamazato T, Jamalipour A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2347 - 2356 1997.12

Effects of transmission control in an integrated voice and data CDMA system Reviewed

Sato T, Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2509 - 2516 1997.12

Multi-antenna transmission scheme for convolutionally coded DS/CDMA system Reviewed

Ban K, Katayama M, Stark WE, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2437 - 2444 1997.12

A constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2477 - 2484 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

H Niwa, O Oono, M Katayama, T Yamazato, A Ogawa, N Isaka

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2526 - 2533 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We propose a spread-spectrum power line communication system considering the cyclic features of the noise in the lines. For this purpose, we model the noise as the sum of a time-invariant stationary process and two cyclostationary processes, i.e., cyclic continuous noise and cyclic impulsive noise. The proposed system employs two different countermeasures to each of these two classes of cyclic noise. For the cyclic continuous noise, it uses multiple-processing-gain spread spectrum technique: the smaller processing gains are assigned for the periods with lower instantaneous noise power and the larger ones for the periods of higher noise power, Considering the cyclic impulsive noise, convolutional coding with interleaving is applied. In order to analyze the performance improvement due to the employment of multiple processing gains, we introduce a simple model of the continuous noise. The overall performance is evaluated bu computer simulation with the actual noise wave-form measured in power lines.

A simple transmit/receive antenna diversity for indoor DS/CDMA wireless communication systems Reviewed

K Ban, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E80B ( 12 ) page： 1790 - 1796 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper proposes a direct-sequence spread spectrum (DS/SS) communication system with a new diversity technique designed for indoor multi-path Fading channels where path diversity isn't available. In this system, the transmitter sends a same signal from multiple antennas at the same time with intentional time delays, which allows the receiver to distinguish and combine the signals from different antennas. We also consider the combination of this scheme with the conventional receiving antenna diversity for additional diversity gain. Furthermore, it is found that the use of the multiple transmitting antennas decreases the effect of the multiple access interference.

An Initial Acquisition Method for M-ary Spread-Spectrum Signals Using Hadamard Code Sequences Reviewed

WADA Tadahiro, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE Trans. Fundamentals Vol. 80 ( 11 ) page： 2172 - 2179 1997.11

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we examine a new initial symbol acquisition method for M-ary spread-spectrum (M-ary/SS) signals that are affected by large carrier frequency offset. By the effect of the carrier frequency offset, preamble signal energy is dispersed to the undesired outputs. The proposed method is based on the collection of such dispersed signal energies by using reference patterns. The reference patterns are constructed by using the characteristic of Hadamard code sequences. The effectiveness of the proposed method is evaluated in terms of mean acquisition time.

An initial acquisition method for M-ary spread-spectrum signals using Hadamard code sequences Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 11 ) page： 2172 - 2179 1997.11

An initial acquisition method for M-ary spread-spectrum signals using Hadamard code sequences Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 11 ) page： 2172 - 2179 1997.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Performance Analysis of the CDMA Unslotted ALOHA Systems with Finite Population and Fixed Packet Length

H. Okada, T. Yamazato, M. Katayama and A. Ogawa

1997 IEICE General Conference Vol. A-5-11 page： 112 1997.9

A Study on the Capacity of a Multi Processing-Gain SSMA System

L. Zhang, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 59 ) page： 19-24 1997.9

A study on the performance of CDMA ALOHA system under a cellular environment

Y. Asai, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 57 ) page： 39275 1997.9

pi/2-shift BPSK - A modulation scheme robust to nonlinear amplification for CDMA mobile communications Reviewed

Kashyap K, Wada T, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 9 ) page： 1634 - 1639 1997.9

A Study on Wireless Transmission of MPEG Encoded Image Signals Using DS/SS Modulation

S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. DSP97 ( 66 ) page： 37-42 1997.7

A Study on CDMA-Unslotted ALOHA with Data Packets Over CDMA Voice Signals

A. Sandouk, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 27 ) page： 43-48 1997.7

A Modeling of the Noise for Power Line Communication Systems

O. Ohno, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. DSP97 ( 61 ) page： 39275 1997.7

Prospective Performance of LEO Satellite Systems Employing Spread-Spectrum Techniques

A. Jamalipour, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 18 ) page： 31-38 1997.6

Multi-Antenna Transmission Scheme for a Convolutionally Coded DS/CDMA System

K. Ban, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 1 ) page： 39088 1997.6

A Study on Orthogonal Multi-Code CDMA Systems Using Constant Amplitude Coding

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS97 ( 35 ) page： 19-24 1997.6

Influence of Multiple-Access Interference in a Multi Processing-Gain SSMA System

H. Hiraiwa, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 2 ) page： 39275 1997.6

Simultaneous Acquisition of DS/SS Signals with Doppler Shift in Multi-LEO-Satellite Communication Systems

M. Ishizu, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SANE97 ( 6 ) page： 35-40 1997.4

An Initial Acquisition Method for Observing Ecology of Sea Animals Using LEO Satellite

T. Tokuyasu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SANE97 ( 8 ) page： 45-50 1997.4

The Effect of Throughput Performance in the CDMA Unslotted ALOHA with Optimal Access Control Protocol by Access Timing Delay

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

1997 IEICE General Conference Vol. B-5 ( 39 ) page： 426 1997.3

Throughput Analysis of CDMA-Unslotted ALOHA System With Voice and Data Packets

Abbas SANDOUK, Takeshi SATO, Takaya YAMAZATO, Masaaki KATAYAMA, and Akira OGAWA

1997 IEICE General Conference Vol. A-5-14 page： - 1997.3

An Integration of Voice and Data in CDMA Unslotted ALOHA with Channel Load Sensing

T. Sato, A. Sandouk, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST96 ( 105 ) page： 43-48 1997.3

An Analytically Estimation of DS/SS/CDMA Using GMSK Reviewed

T. Ishiguro, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Communications Vol. J80-B-II ( 1 ) page： 131-136 1997.1

Bit Interleaved Trellis Coded 16DAPSK on Fading Channels Reviewed

H. Nakagawa, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Communications Vol. J80-B-II ( 1 ) page： 39091 1997.1

An Improvement of Performance of DS/SS/CDMA with GMSK Reviewed

T. Ishiguro, T. Yamazato, M. Katayama, and A. Ogawa

IEICE Transaction on Communications Vol. J80-B-II ( 1 ) page： 18-26 1997.1

Throughput improvement of CDMA slotted ALOHA systems Reviewed

Saito M, Okada H, Sato T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E80B ( 1 ) page： 74 - 80 1997.1

Throughput Improvement of CDMA Slotted ALOHA System Reviewed

M. Saito, H. Okada, T. Sato, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Communications Vol. E80-B ( 1 ) page： 74-80 1997

低軌道周回衛星を用いた海亀生態観測システムの一検討

徳安朋浩、山里敬也、片山正昭、小川明

1997年電気関係学会東海支部連合大会 page： 505 1997

Performance Analysis of CDMA-Unslotted ALOHA Operating over CDMA Voice Signals Reviewed

A. Sandouk, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

IEEE Pacific Rim Conference on Communication and Signal Processing (PACRIM) Vol. PACRIM97 ( 2 ) page： 603-606 1997

Effect of Non-uniform Traffic and Power Control on CDMA Unslotted ALOHA system Reviewed

T. Yamazato, Y. Asai, M. Katayama and A. Ogawa

1997 International Technical Conference on Circuits/Systems, Computers And Communications, Okinawa Vol. 2 page： 857-860 1997

Simultaneous Estimation of Code and Frequency of DS/SS Signals of Multiple-LEO-Satellite Communication Systems Reviewed

M. Ishidu, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC97 ( 2 ) page： 1019-1027 1997

π/2-shift BPSK- A Modulation Scheme Robust to Nonlinear Amplification for CDMA Mobile Communication Reviewed

K. Kashyap, T. Wada, M. Katayama, T .Yamazato, A .Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 9 ) page： 1634-1639 1997

Performance Analysis of Integrated Voice and Data System in CDMA Unslotted ALOHA with Channel Load Sensing Reviewed

T. Sato, S. Abbas, T. Yamazato, M. Katayama and A. Ogawa

1997 International Technical Conference On Circuits/Systems, Computers And Communications, Okinawa Vol. 2 page： 853-856 1997

A Proposal of SS Communication System Using LEO Satellite for Observing Ecology of Sea Turtle Reviewed

T. Tokuyasu, T. Wada, T. Yamazato, M. Katayama and A. Ogawa

1997 IEEE Global Communications Conference, Phoenix Vol. Globecom97 ( 2 ) page： 1157-1161 1997

Convolutionally Coded DS/CDMA System using Multi-Antenna Transmission Reviewed

K.Ban, M.Katayama, W.E.Stark, T.Yamazato and A.Ogawa

1997 IEEE Global Telecommunications Conference, Phoenix Vol. Globecom97 ( 1 ) page： 92-96 1997

Effects of Transmission Control Considering Voice Activation in an Integrated Voice and Data CDMA System Reviewed

T. Sato, S. Abbas, T. Yamazato, M. Katayama and A. Ogawa

1997 Fourth European Conference on Satellite Communications, Roma Vol. 1 page： 176-181 1997

System Capacity of an Integrated Voice and Data CDMA Network in Channel Load Sensing Protocol Reviewed

T. Sato, S. Abbas, T. Yamazato, M. Katayama and A. Ogawa

1997 IEEE Global Telecommunications Conference, Phoenix Vol. Globecom97 ( 2 ) page： 899-903 1997

Constant Amplitude Orthogonal Multi-Code CDMA System Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

APCC'97, Sydney Vol. APCC97 ( 1 ) page： 362-366 1997

An Initial Acquisition Method for M-ary Spread-Spectrum Signals Using Hadamard Code Sequences

T. Wada, T. Yamazato, M. Katayama,A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 11 ) page： 2172-2179 1997

A Spread-Spectrum System with Dual Processing Gains Designed for Cyclic Noise in Power Line Communications Reviewed

H. Niwa, O. Oono, M. katayama, T. Yamazato, A. Ogawa, N. Isaka

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2526-2533 1997

Influence of Multiple-Access Interference in a Multi Processing-Gain SSMA System Reviewed

H. Hiraiwa, M. Katayama, T. Yamazato and A. Ogawa

APCC'97, Sydney Vol. APCC97 ( 3 ) page： 1611-1615 1997

Effects of Transmission Control in an Integrated Voice and Data CDMA System Reviewed

T. Sato, S. Abbas, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2500-2516 1997

Multi-Antenna Transmission Scheme for Convolutionally Coded DS/CDMA System Reviewed

K. Ban, M. Katayama, W .E .Stark, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2437-2444 1997

A Simple Transmit/Receive Antenna Diversity for Indoor DS/CDMA Wireless Communication Systems Reviewed

K. Ban, M. Katayama, T. yamazato and A. Ogawa

IEICE Transaction on Communications Vol. E80-B ( 12 ) page： 1790-1796 1997

A Constant Amplitude Coding for Orthogonal Multi-Code CDMA Systems Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2477-2484 1997

[Invited Paper] CDMA for Personal Communications Based on Low Earth Orbital Satellite Systems Invited Reviewed

A. Ogawa, M. Katayama, T. Yamazato, A. Jamalipour

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2347-2356 1997

低軌道周回衛星を用いた海亀生態観測システムにおける海亀搭載送信用アンテナ

天野良晃、徳安朋浩、山里敬也、片山正昭、小川明

1997年電気関係学会東海支部連合大会 page： 507 1997

低軌道周回衛星を用いた海亀生態観測システムにおける海亀搭載データ処理装置

北村唯夫、徳安朋浩、山里敬也、片山正昭、小川明

1997年電気関係学会東海支部連合大会 page： 506 1997

レイリーフェージング下におけるスペクトル拡散信号のダイバシチ同期補捉手法の提案

猪飼洋平、片山正昭、山里敬也、小川明

1997年電気関係学会東海支部連合大会 page： 508 1997

マルチコードCDMA方式における振幅変動の影響

藤原昭博、山里敬也、片山正昭、小川明

1997年電気関係学会東海支部連合大会 page： 509 1997

A proposal of SS communication system using LEO satellite for observing ecology of sea turtles Reviewed

Tokuyasu T, Wada T, Yamazato T, Katayama M, Ogawa A

GLOBECOM 97 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, CONFERENCE RECORD, VOLS 1-3 page： 1157 - 1161 1997

CDMA for personal communications based on low earth-orbital satellite systems Reviewed

Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2347 - 2355 1997

Convolutionally coded DS/CDMA system using multi-antenna transmission Reviewed

Ban K, Katayama M, Stark WE, Yamazato T, Ogawa A

GLOBECOM 97 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, CONFERENCE RECORD, VOLS 1-3 page： 92 - 96 1997

Performance analysis of CDMA-unslotted ALOHA operating over CDMA voice signals Reviewed

A Sandouk, T Sato, T Yamazato, M Katayama, A Ogawa

1997 IEEE PACIFIC RIM CONFERENCE ON COMMUNICATIONS, COMPUTERS AND SIGNAL PROCESSING, VOLS 1 AND 2 page： 603 - 606 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In this paper, we analyse system performance of CDMA data terminals operating over CDMA voice signals. Outage probability for voice users and throughput for data users are evaluated taking into account the effect of interference from both media. Since we have two different media with different characteristics, the analysis is rather difficult because the behavior of the system will be dependent on both voice and data offered loads. We get over this difficulty profiting from the characteristics of both media. Consequently, we obtain the performance of both media by using the queueing theory.

Simultaneous estimation of code and frequency of DS/SS signals of multiple-LEO-satellite communication systems Reviewed

M Ishizu, M Katayama, T Yamazato, A Ogawa

PIMRC '97 - EIGHTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS: WAVES OF THE YEAR 2000+, TECHNICAL PROGRAM, PROCEEDINGS, VOLS 1-3 page： 1019 - 1023 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In this manuscript, we consider a receiver with satellite diversity by using DS/SS signals from different LEO satellites. Since the signals from the different LEO satellites may have different frequency offsets due to Doppler effect, we propose an acquisition scheme which can estimate code timings and carrier frequencies of these signals at once. We evaluate characteristics of the proposed scheme by mean acquisition time.

System capacity of an integrated voice and data CDMA network in channel load sensing protocol Reviewed

T Sato, A Sandouk, T Yamazato, M Katayama, A Ogawa

GLOBECOM 97 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, CONFERENCE RECORD, VOLS 1-3 page： 899 - 903 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In this paper, we analyze an integrated voice and data system over a CDMA Unslotted ALOHA with Channel Load Sensing Protocol, considering the effect of each traffic. We can And that the threshold for the number of data transmissions is very effective to improve both performances of the throughput for data and the Erlang capacity for voice users. Furthermore, to optimize this system, we define the system capacity. As a result. we obtain an optimum threshold for data to make the;best use of the channel capacity.

A constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

Wada T., Yamazato T., Katayama M., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2477 - 2483 1997

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

Niwa H., Oonq O., Katayama M., Yamazato T., Ogawa A., Isaka N.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 12 ) page： 2526 - 2532 1997

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

We propose a spread-spectrum power line communication system considering the cyclic features of the noise in the lines. For this purpose, we model the noise as the sum of a time-invariant stationary process and two cyclostationary processes, i.e., cyclic continuous noise and cyclic impulsive noise. The proposed system employs two different countermeasures to each of these two classes of cyclic noise. For the cyclic continuous noise, it uses multiple-processing-gain spread spectrum technique: the smaller processing gains are assigned for the periods with lower instantaneous noise power and the larger ones for the periods of higher noise power. Considering the cyclic impulsive noise, convolutional coding with interleaving is applied. In order to analyze the performance improvement due to the employment of multiple processing gains, we introduce a simple model of the continuous noise. The overall performance is evaluated by computer simulation with the actual noise wave-form measured in power lines.

A simple transmit/receive antenna diversity for indoor DS/CDMA wireless communication systems Reviewed

Ban K., Katayama M., Yamazato T., Ogawa A.

IEICE Transactions on Communications Vol. E80-B ( 12 ) page： 1790 - 1796 1997

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Communications

A proposal of SS communication system using LEO satellite for observing ecology of sea turtles Reviewed

T Tokuyasu, T Wada, T Yamazato, M Katayama, A Ogawa

GLOBECOM 97 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, CONFERENCE RECORD, VOLS 1-3 page： 1157 - 1161 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we examine the system for observing ecology of sea animals by means of a low earth orbital observatory satellite. We consider the system performance in the uplink, which is the communication link from the animal stations to the observatory satellite. Since the up-link condition is much severe, we employ the M-ary/SS with CDMA ALOHA as a multiple access scheme. A key issue to realize the system depends on an acquisition technique which is robust to the effect of large Doppler shift caused by the rapid movement of the low earth orbital satellite. Ih this paper, we discuss code-acquisition and estimation of carrier frequency considering the M-ary/SS/CDMA technique to realize this observatory system.

An initial acquisition method for M-ary spread-spectrum signals using hadamard code sequences Reviewed

Wada T., Yamazato T., Katayama M., Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E80-A ( 11 ) page： 2172 - 2179 1997

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences

Effects of transmission control considering voice activation in an integrated voice and data CDMA Reviewed

T Sato, A Sandouk, T Yamazato, M Katayama, A Ogawa

ECSC-4: 4TH EUROPEAN CONFERENCE ON SATELLITE COMMUNICATIONS page： 176 - 181 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ASSOC ELETTROTECHNICA ED ELETTRONICA ITALIANA

In this paper, we focus on an integrated voice and data system over unslotted CDMA system. We propose a method to accommodate the data packet into the silence period of voice signal by using a traffic control based on the channel load sensing protocol. We evaluate the system by the throughput and delay performance for data packet, the blocking probability for voice users. From the results, we show the advantages of the proposed system.

Approximation Method for CDMA Unslotted ALOHA Systems with Fixed Packet Length

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST96 ( 61 ) page： 13-18 1996.12

Throughput of CDMA ALOHA in Cellular Environment

T. Yamazato, Y. Asai, A. Jamalipour, M. Katayama, A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA96 ( D-4-2 ) page： 313-316 1996.12

CDMA ALOHA systems with modified channel load sensing protocol for satellite communications Reviewed

Okada H, Saito M, Sato T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E79A ( 12 ) page： 2035 - 2042 1996.12

DS/SS/GMSK with differential detection over multipath Rayleigh fading channels Reviewed

Wakaki I, Ishiguro T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E79A ( 12 ) page： 1957 - 1962 1996.12

Quasi-synchronous code division multiple access (CDMA) with binary shift-register sequences Reviewed

S Kuno, T Yamazato, M Katayama, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE Vol. 79 ( 12 ) page： 71 - 81 1996.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

This paper discusses the quasi-synchronous code-division multiple access system (QS-CDMA), where the time error in the synchronized access is allowed for a certain range, based on the spread-spectrum communication technique. The Gold sequence and the M sequence, which are the binary shift-register sequences, are used to derive the set of quasi-synchronous spread sequences (QS-sequence) considering the auto- and cross-correlation characteristics, realizing a wide tolerable range for the timing error.
The QS-CDMA system using such QS-sequence is investigated, and the effectiveness is examined. As a result, it is seen that the performance is improved greatly by using the QS-sequence presented in this paper, compared to the asynchronous CDMA system. It is shown also that the tolerable range for the access timing error is enlarged compared to the synchronous CDMA system.

Transmit permission control on spread ALOHA packets in LEO satellite systems Reviewed

A Jamalipour, M Katayama, T Yamazato, A Ogawa

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 14 ( 9 ) page： 1748 - 1757 1996.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

A transmit permission control method for improving the throughput characteristics of a low earth orbit (LEG) satellite communication system employing spread-slotted ALOHA multiple-access scheme is proposed, Both nonfading and fading satellite links are considered, The basic idea of the proposed scheme is to decrease the level of interference at each satellite and, hence, to increase the probability of packet success, by prohibiting the packet transmission from the users with relatively high propagation loss to their connecting satellites, It is shown that the method has the ability to improve the throughput performance in heavy traffic loads and the peak value of the throughput, significantly, It is also shown that the average delay performance of the system employing the proposed scheme is superior to that of the conventional system at heavy traffic loads.

DOI： 10.1109/49.545697

A Study of the Receiver for Observing Ecology of Sea Animals Utilizing Low Orbit Satellite

T. Tokuyasu, T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SANE96 ( 64 ) page： 67-72 1996.10

A New M-ary Spread-Spectrum Multiple-Access Scheme in the Presence of Carrier Frequency Offset Reviewed

WADA Tadahiro, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE transactions on fundamentals of electronics, communications and computer sciences Vol. 79 ( 9 ) page： 1415 - 1422 1996.9

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

The performance of an M-ary spread-spectrum multiple-access (Al-ary/SSMA) scheme in the presence of carrier frequency offset is discussed in this paper. The influence of carrier frequency offset on the non-coherent reception of M-ary/SSMA signals is examined and it is shown that the carrier frequency off-set degrades the performance remarkably, yet, this influence has a distinctive property. Making use of this property, we propose a new M-ary/SSMA scheme that can mitigate the influence of the carrier frequency offset. The scheme is based on the assignment of two distinctive Hadamard codes to in-phase and quadrature components of the transmitted signal. The effect of simultaneous transmission is evaluated in terms of bit-error-rate performance with the carrier frequency offset. As the result, it is observed that the satisfactory bit-error-rate performance can be achieved in the presence of carrier frequency offset.

A Study of The System for Observing Ecology of Sea Animals Utilizing Low Orbit Satellite

T. Tokuyasu, T. Yamazato, M. Katayama and A. Ogawa

1996 Society Conference of IEICE Vol. SB-2 ( 12 ) page： - 1996.9

A new M-ary spread-spectrum multiple-access scheme in the presence of carrier frequency offset Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E79A ( 9 ) page： 1415 - 1422 1996.9

Coordinate interleaved trellis coded QPSK with T-algorithm on Rayleigh fading channel Reviewed

Nakamura H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E79B ( 9 ) page： 1248 - 1255 1996.9

Effects of the access timing delay on CDMA unslotted ALOHA with channel load sensing Reviewed

Sato T, Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E79B ( 9 ) page： 1339 - 1345 1996.9

Effects of multiple access interference in a multi-rate SSMA system Reviewed

Ichiba M, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E79B ( 9 ) page： 1333 - 1338 1996.9

A new M-ary spread-spectrum multiple-access scheme in the presence of carrier frequency offset Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E79A ( 9 ) page： 1415 - 1422 1996.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

The performance of an M-ary spread-spectrum multiple-access (M-ary/SSMA) scheme in the presence of carrier frequency offset is discussed in this paper. The influence of carrier frequency offset on the non-coherent reception of M-ary/SSMA signals is examined and it is shown that the carrier frequency offset degrades the performance remarkably, yet, this influence has a distinctive property. Making use of this property, we propose a new M-ary/SSMA scheme that can mitigate the influence of the carrier frequency offset. The scheme is based on the assignment of two distinctive Hadamard codes to in-phase and quadrature components of the transmitted signal. The effect of simultaneous transmission is evaluated in terms of bit-error-rate performance with the carrier frequency offset. As the result, it is observed that the satisfactory bit-error-rate performance can be achieved in the presence of carrier frequency offset.

DS/SS/GMSK with Differential Detection over Multipath Rayleigh Fading Channels

I. Wakaki, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST96 ( 34 ) page： 37-42 1996.7

CDMA unslotted ALOHA systems with packet retransmission control Reviewed

Okada H, Sato T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E79A ( 7 ) page： 1004 - 1010 1996.7

A Study on an Initial Acquisition Method for M-ary Spread-Spectrum Signals with Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST96 ( 14 ) page： 81-86 1996.6

Throughput analysis of DS/SSMA unslotted ALOHA system with fixed packet length Reviewed

T Sato, H Okada, T Yamazato, M Katayama, A Ogawa

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 14 ( 4 ) page： 750 - 756 1996.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Throughput analysis of direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA with fixed packet length is presented. As the levels of multi-user interference fluctuate during the packet transmission, we calculate the packet error probability and the throughput by considering not only the number of overlapped packets but also the amount of time overlap, On the assumption that packet generation is Poisson, the system can be thought as the queueing system M/D/infinity. With Gaussian approximation of multi-user interference, we obtain the throughput as the function of the number of chips in a bit, the packet length, and the offered load of the system, We also analyze the channel load sensing protocol (CLSP), and obtain the optimum threshold pf CLSP.

DOI： 10.1109/49.490426

Adaptive Transmit Permission Control on Spread-Slotted Aloha Packets Applicable in LEOS Systems Reviewed

JAMALIPOUR Abbas, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira

IEICE transactions on communications Vol. 79 ( 3 ) page： 257 - 265 1996.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

A new transmit permission control scheme applicable in multi-cell communication systems is proposed. In this scheme, by prohibiting the transmissions from the users with relatively high propagation loss to their connecting hub stations, level of multiple access interference is decreased, and hence throughput characteristics are improved. Moreover, we continue our discussion to propose two adaptive forms of the transmit permission control scheme, in which the prohibition condition becomes more intelligent by considering the level of the offered traffic loads to hub stations. These methods are utilized in a slotted Aloha random transmission of the spread spectrum packets, and on the uplinks of a low earth orbit satellite communication system as an example of the multi-cell systems. It is shown that the adaptive schemes exhibits significantly improved characteristics at all offered traffic loads in these systems.

Throughput Analysis of CDMA ALOHA System in Fading Channel with Near-Far Problem

K. Nishida, H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

1996 IEICE General Conference Vol. SA-5 ( 4 ) page： 472 1996.3

A Study of Multiple Access Interference Using M-ary/SS/CDMA Signals

H. Kojima, T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 141 ) page： 65-70 1996.3

A Study on Code Division Duplex (CDD) for Distributed CDMA Networks

H. Asada, K. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 145 ) page： 89-94 1996.3

A study on the performance of the CDMA system using pi/4-shift QPSK and pi/2-shift BPSK

K. Kashyap, T. Wada, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 127 ) page： 95-100 1996.3

Throughput Performance of CDMA Unslotted ALOHA using Error Correcting Code

T. Yamazato, K. Nishida, T. Sato, H. Okada, M. Katayama and A. Ogawa

1996 IEICE General Conference Vol. SA-5 ( 3 ) page： - 1996.3

The DS/SS System using Transmission Diversity for Indoor Wireless Communications

K. Ban, M. Katayama, T. Yamazato and A. Ogawa

1996 IEICE General Conference Vol. A-235 page： - 1996.3

A differential positioning scheme with a single satellite to be incorporated into mobile communications Reviewed

Yabumoto Y, Katayama M, Yamazato T, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 79 ( 3 ) page： 73 - 82 1996.3

Adaptive transmit permission control on spread-slotted Aloha packets applicable in LEOS systems Reviewed

Jamalipour A, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E79B ( 3 ) page： 257 - 265 1996.3

A differential positioning scheme with a single satellite to be incorporated into mobile communications Reviewed

Y Yabumoto, M Katayama, T Yamazato, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 79 ( 3 ) page： 73 - 82 1996.3

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA PUBL

The case in which the radio determination capability is integrated into a mobile satellite communication system is investigated and a positioning scheme is proposed which operates with a single satellite. In the proposed scheme, each mobile terminal is designed to be equipped with the minimum additional function for positioning, aiming at the integration of communication functions with low cost. It is not necessary to transmit the correction signal for range error although a differential technique is applied to improve positioning accuracy. To evaluate the feasibility of the proposed scheme, we calculate the horizontal dilution of precision (HDOP) and available area taking account of the time period required for positioning and satellite altitude.

A differential positioning scheme with a single satellite to be incorporated into mobile communications Reviewed

Yabumoto Y., Katayama M., Yamazato T., Ogawa A.

Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi) Vol. 79 ( 3 ) page： 73 - 82 1996.3

DOI： 10.1002/ecja.4410790308

Adaptive transmit permission control on spread-slotted Aloha packets applicable in LEOS systems Reviewed

A Jamalipour, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E79B ( 3 ) page： 257 - 265 1996.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A new transmit permission control scheme applicable in multi-cell communication systems is proposed. Tn this scheme, by prohibiting the transmissions from the users with relatively high propagation loss to their connecting hub stations, level of multiple access interference is decreased, and hence throughput characteristics are improved. Moreover, we continue our discussion to propose two adaptive forms of the transmit permission control scheme, in which the prohibition condition becomes more intelligent by considering the level of the offered traffic loads to hub stations. These methods are utilized in a slotted Aloha random transmission of the spread spectrum packets, and on the uplinks of a low earth orbit satellite communication system as an example of the multi-cell systems. it is shown that the adaptive schemes exhibits significantly improved characteristics at all offered traffic loads in these systems.

Quasi-Synchronous CDMA with Binary Shift-Register Sequences Reviewed

S. Kuno, T. Yamazato,M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J79-A ( 1 ) page： 105-114 1996.1

Parallel Acquisition of a Direct-Sequence Spread-Spectrum Signal with Frequency Offset Reviewed

M. Mizutani, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J79-A ( 1 ) page： 98-104 1996.1

DS/SS/GMSK with Differential Detection over Multipath Rayleigh Fading Channels Reviewed

I. Wakaki, T. Ishiguro, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E79-A ( 12 ) page： 1957-1962 1996

Transmit Permission Control on Spread ALOHA Packets in LEO Satellites Systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato, A. Ogawa

IEEE Journal on Selected Areas in Communications Vol. 14 ( 9 ) page： 1748-1757 1996

Transmission Characteristics of Band-Limited Signals for DS/SS/CDMA Reviewed

A. Ogawa, K. Kashyap, T. Wada, M. Katayama and T. Yamazato

Asia-Pacific Microwave Conference Vol. 4 ( E12 ) page： INV2,1329-1332 1996

CDMA ALOHA Systems with Modified Channel Load Sensing Protocol for Satellite Communications Reviewed

H. Okada, M. Saito, T. Sato, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E79-A ( 12 ) page： 2035-2042 1996

Throughput Analysis of DS/SSMA Unslotted ALOHA System with Fixed Packet Length Reviewed

T. Sato, H. Okada, T. Yamazato,M. Katayama, A. Ogawa

IEEE Journal on Selected Areas in Communications Vol. 14 ( 4 ) page： 750-756 1996

Throughput Performance Improvement of Spread-Slotted Aloha in Mobile Satellite Communications Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Conference on Communications (ICC'96) Vol. ICC96 page： 1740-1744 1996

A Novel Access Control Method for CDMA Unslotted ALOHA Systems Reviewed

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

2nd International Workshop on Multi-Dimensional Mobile Communications, Seoul Vol. MDMC96 page： 391-395 1996

CDMA Unslotted ALOHA Systems with Packet Retransmission Control Reviewed

H. Okada, T. Sato, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E79-A ( 7 ) page： 1004-1010 1996

On the Average Delay-Throughput Performance Improvement of LEO Satellite Systems by Adaptive Transmit Permission Control Scheme Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

Proc. of the XXVth General Assembly of the International Union of Radio Science, Lille Vol. C8 ( 3 ) page： 157 1996

Effects of Multiple Access Interference in a Multi-Rate SSMA System Reviewed

M. Ichiba, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E79-B ( 9 ) page： 1333-1338 1996

Effects of the Access Timing Delay on CDMA Unslotted ALOHA with Channle Load Sensing Reviewed

T. Sato, H. Okada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Communications Vol. E79-B ( 9 ) page： 1339-1345 1996

A New M-ary Spread-Spectrum Multiple-Access Scheme in the Presence of Carrier Frequency Offset Reviewed

T. Wada, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E79-A ( 9 ) page： 1415-1422 1996

Coordinate Interleaving Trellis Coded QPSK with T-algorithm on Rayleigh Fading Cannels Reviewed

H. Nakamura, T. Yamazato, M. Katayama, A. Ogawa

IEICE Transaction on Communications Vol. E79-B ( 9 ) page： 1248-1255 1996

Performance of Bit-by-Bit Interleaved Trellis Coded 16DAPSK on Rayleigh Fading Channel Reviewed

T. Yamazato, H. Nakagawa, M. Katayama and A. Ogawa

IEEE International Conference on Universal Personal Communications Vol. ICUPC96 page： 543-547 1996

Performance Degradation due to the Access Timing Delay on CDMA Unslotted ALOHA with Channel Load Sensing Reviewed

T. Sato, H. Okada, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Conference on Universal Personal Communications Vol. ICUPC96 page： 111-114 1996

A Spread-Spectrum System with Dual Processing Gains Designed for Cysric Noise in Power line Communications Reviewed

H. Niwa, M. Katayama, T. Yamazato, A. Ogawa and N. Isaka

IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA) Vol. ISSSTA96 page： 816-820 1996

DS/SS/GMSK with Differential Detection over Multipath Rayleigh Fading Channels Reviewed

I. Wakaki, T. Ishiguro, T. Yamazato, M. Katayama, A. Ogawa

IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA) Vol. ISSSTA96 page： 399-403 1996

Throughput of CDMA Unslotted-ALOHA System in Cellular Environment Reviewed

A. Ogawa, T. Yamazato, K. Nishida, H. Okada, T. Sato and M. Katayama

Proc. of the Japan-Canada International Workshop on Multimedia Wireless Communications and Computing, Victoria page： 23-24 1996

A New Initial Acquisition Methods for M-ary Spread-Spectrum Communication Systems Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA96 page： 770-773 1996

A New Acquisition Scheme for the DS/SS Signal with Large Carrier Frequency Offset Reviewed

S. Okuda, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J79-A ( 10 ) page： 1725-1733 1996

The DS/CDMA System using Transmission Diversity for Indoor Wireless Communications Reviewed

K. Ban, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal Indoor and Mobile Radio Communications Vol. PIMRC96 page： 802-812 1996

Throughput Improvemnt on CDMA Slotted ALOHA Systems by Modified Channel Load Sensing Protocol Reviewed

M. Saito, H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Personal Indoor and Mobile Radio Communications Vol. PIMRC96 page： 103-107 1996

The Receiver with an Adaptive Array Antenna and Satellite Diversity for Low Earth-Orbital Multiple Satellite Communication Systems Reviewed

H. Sumino, M. Katayama, T. Yamazato and A. Ogawa

Proc. of the Second European Workshop on Mobile/Personal Satcoms, Roma page： 180-194 1996

The Performance of CDMA System Using π/4-shift QPSK and π/2-shift BPSK with the Nonlinearity of HPA Reviewed

K. Kashyap, T. Wada, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal Indoor and Mobile Radio Communications Vol. PIMRC96 page： 492-496 1996

マルチパスフェージング環境下におけるCDMA ALOHA方式のスループット特性の改善

浅井裕介, 西田邦生, 山里敬也, 片山正昭, 小川明

1996年電気関係学会東海支部連合大会 page： 511 1996

A New M-ary/SSMA Scheme Applicable in LEO Satellite Systems Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

IEEE Global Telecommunications Conference, Westminster Vol. Globecom96 ( 1 ) page： 384-389 1996

Performance Evaluation of CDMA ALOHA Systems with Modified Channel Load Sensing Protocol Reviewed

H. Okada, M. Saito, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

IEEE Global Telecommunications Conference, Westminster Vol. Globecom96 ( 1.2 ) page： 1291-1295 1996

A Modified Power Control Scheme for Remedying the Effects of Traffic Nonuniformity in LEO Satellite Communications Systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato, A. Ogawa

International Journal of Wireless Information Networks Vol. 3 ( 1 ) page： 29-39 1996

Adaptive Transmit Permission Control on Spread-Slotted Aloha Packets Applicable in LEO systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E79-B ( 3 ) page： 257-265 1996

A new M-ary/SSMA scheme applicable in LEO satellite communication systems Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEEE GLOBECOM 1996 - CONFERENCE RECORD, VOLS 1-3 page： 384 - 389 1996

A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

Niwa H, Katayama M, Yamazato T, Ogawa A, Isaka N

IEEE ISSSTA '96 - IEEE FOURTH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES & APPLICATIONS, PROCEEDINGS, VOLS 1-3 page： 816 - 820 1996

DS/SS/GMSK with differential detection over multipath Rayleigh fading channels Reviewed

Wakaki I, Ishiguro T, Yamazato T, Katayama M, Ogawa A

IEEE ISSSTA '96 - IEEE FOURTH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES & APPLICATIONS, PROCEEDINGS, VOLS 1-3 page： 399 - 403 1996

Performance degradation due to the access timing delay on CDMA unslotted ALOHA with channel load sensing Reviewed

T Sato, H Okada, T Yamazato, M Katayama, A Ogawa

ICUPC '96 - 1996 5TH IEEE INTERNATIONAL CONFERENCE ON UNIVERSAL PERSONAL COMMUNICATIONS RECORD, VOLS 1 AND 2 page： 111 - 114 1996

Performance evaluation of CDMA ALOHA systems with modified channel load sensing protocol Reviewed

H Okada, M Saito, T Sato, T Yamazato, M Katayama, A Ogawa

IEEE GLOBECOM 1996 - CONFERENCE RECORD, VOLS 1-3 page： 1291 - 1295 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

The one of the problems that arise in the satellite packet communication system is the existence of a long access timing delay. In this paper, we clarify the effect of this access timing delay on the performance of CDMA ALOHA systems and then propose a new access control protocol, called Modified Channel Load Sensing Protocol (MCLSP), for the CDMA ALOHA systems. As a result, we found that by employing MCLSP, a significant improvement in the throughput performance was obtained even in the presence of a long access timing delay.

Performance of bit-by-bit interleaved trellis coded 16DAPSK on Rayleigh fading channel Reviewed

T Yamazato, H Nakagawa, M Katayama, A Ogawa

ICUPC '96 - 1996 5TH IEEE INTERNATIONAL CONFERENCE ON UNIVERSAL PERSONAL COMMUNICATIONS RECORD, VOLS 1 AND 2 page： 543 - 547 1996

Throughput improvement of CDMA slotted aloha system by modified channel load sensing protocol Reviewed

M Saito, H Okada, T Sato, T Yamazato, R Katayama, A Ogawa

PIMRC'96 - THE SEVENTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, PROCEEDINGS, VOLS 1-3 page： 103 - 107 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we present throughput performance of CDMA Slotted ALOHA system with Modified Channel Load Sensing Protocol (MCLSP). In MCLSP, hub station continuously senses channel load for a certain number of slot, and computes the probability with which each user station should transmit its packet, then broadcasts the computed value. As the access control is based on this probability, we can apply it to slotted system. We show that MCLSP can achieve significant improvement in throughput performance of CDMA Slotted ALOHA system even in large offered load.
One of the issues in such protocol is the access timing delay, which is the sum of process time and propagation time for the packet access control. We also show the effect of the access timing delay on the throughput performance.

The receiver with an adaptive array antenna and satellite diversity for low earth-orbital multiple satellite communication systems Reviewed

H Sumino, M Katayama, T Yamazato, A Ogawa

MOBILE AND PERSONAL SATELLITE COMMUNICATIONS 2 page： 180 - 194 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG, LONDON LTD

In a user terminal of low earth orbit (LEO) satellite communication systems, there are some technical issues, such as tracking of the connecting satellite, reduction of the interference from other satellites, and hand-off between satellites. As an answer to these issues, this paper proposes a new receiver structure using a set of adaptive array antennas. Combining the outputs of these adaptive array antennas, the receiver realizes satellite diversity. We also show a down-link signal design which employs Code Division Multiplex scheme for this proposed receiver structure. The performance of the system with the receiver and the down-link signals is evaluated by computational simulation.

The performance of CDMA system using pi/4-shift QPSK and pi/2-shift BPSK with the nonlinearity of HPA Reviewed

K Kashyap, T Wada, M Katayama, T Yamazato, A Ogawa

PIMRC'96 - THE SEVENTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, PROCEEDINGS, VOLS 1-3 page： 492 - 496 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In this paper, we evaluate the bit-error rate performance of Direct-Sequence Spread Spectrum (DS/SS) system using pi/4-shift QPSK and pi/2-shift BPSK and observe the effect of the nonlinearity of High Power Amplifier (HPA) of transmitters which occurs when the HPA is operated near its saturation region. Hard limiter is chosen as the example of nonlinear amplifier and the numerical results are reported by using coherent as well as differential detection at the receiving end. With the employment of either pi/4-shift QPSK or pi/2-shift BPSK, the DS/SS signal is not much influenced by the nonlinearity of the HPA as the two modulation schemes have the advantage of nearly constant envelope.

The DS/CDMA system using transmission diversity for indoor wireless communications Reviewed

K Ban, M Katayama, T Yamazato, A Ogawa

PIMRC'96 - THE SEVENTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, PROCEEDINGS, VOLS 1-3 page： 808 - 812 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In multi-path fading channels, direct-sequence spread spectrum (DS/SS) technique is often employed because of the capability to resolve signals from different paths and realize path diversity at the receiver. This advantage of DS/SS, however, is only when the time difference of propagation delay between paths is greater than a chip duration. In indoor communications, the delay spread is often very small and the above condition on the delay and chip duration is no longer satisfied, and this performance improvement by the path diversity with conventional DS/SS systems cannot be expected. In this paper we propose a new diversity technique for indoor wireless communication systems where delay spread is smaller than a chip duration. In this system, the transmitter sends signals at the same time from multiple antennas with intentional time delays, which allow a receiver to distinguish and combine the signals from different antennas.

A modified power control scheme for remedying the effects of traffic nonuniformity in LEO satellite communications systems Reviewed

Throughput performance improvement of spread-slotted Aloha in mobile satellite communications Reviewed

A Jamalipour, M Katayama, T Yamazato, A Ogawa

1996 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS - CONVERGING TECHNOLOGIES FOR TOMORROW'S APPLICATIONS, VOLS. 1-3 page： 1740 - 1744 1996

Abbas Jamalipour, Masaaki Katayama, Takaya Yamazato, Akira Ogawa

International Journal of Wireless Information Networks Vol. 3 ( 1 ) page： 29 - 39 1996

Language：English Publishing type：Research paper (scientific journal) Publisher：Kluwer Academic/Plenum Publishers

It has been shown in our previous studies that the geographical traffic nonuniformity considerably affects the performance of the low earth orbit satellite communications systems. In this paper, a new scheme for improving the throughput characteristics of these systems at nonuniform traffic distribution is proposed. In this method, some parts of the users under the satellite which is flying over the area with high traffic load are assigned to its neighbor satellites with lower transmitting power levels. It is shown that the method equalizes the traffic loads of the satellites to some degree and, hence, can improve the throughput characteristics of the system. © 1996 Plenum Publishing Corporation.

DOI： 10.1007/BF02106660

A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

H Niwa, M Katayama, T Yamazato, A Ogawa, N Isaka

IEEE ISSSTA '96 - IEEE FOURTH INTERNATIONAL SYMPOSIUM ON SPREAD SPECTRUM TECHNIQUES & APPLICATIONS, PROCEEDINGS, VOLS 1-3 page： 816 - 820 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

Many electric appliances using power lines for their power supply often tend to emit larger noise to the lines when the absolute instantaneous voltage of the power-supplying AC is higher. Thus, total noise on the lines has positive relation to the AC voltage. In this paper, We first model the noise to be cyclic stationary Gaussian with the instantaneous power (variance) proportional to the n-th power of the absolute instantaneous voltage of the AC. Considering this statistical feature of the noise, we also propose a power-line communication system and show its performance. The proposed system employs two processing gains: the smaller ope for the period with lower AC voltage and the larger for the rest period.

A new M-ary/SSMA scheme applicable in LEO satellite communication systems Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEEE GLOBECOM 1996 - CONFERENCE RECORD, VOLS 1-3 page： 384 - 389 1996

Language：English Publishing type：Research paper (international conference proceedings) Publisher：I E E E

In this paper, we discuss a non-coherent reception of M-ary spread-spectrum multiple-access (M-ary/SSMA) signals in the presence of large Doppler frequency shift.
The Hadamard Codes (H-codes) is applied as orthogonal codes. The influence of Doppler frequency shift has a particular characteristic according to the property of H-codes. Making use of this property, we, first, propose an initial carrier frequency acquisition method which can estimate the value of large Doppler frequency shift. We, then, proposed a M-ary/SSMA scheme that is based on the simultaneous transmission of two distinctive H-codes.

Adaptive transmit permission control on spreadslotted aloha packets applicable in leos systems Reviewed

Jamalipouri A., Katayamat M., Yamazato T., Ogawai A.

IEICE Transactions on Communications Vol. E79-B ( 3 ) page： 257 - 264 1996

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Communications

Throughput performance of Spread Slotted ALOHA System with Modified Channel Load Sensing Protocol

M. Saito, H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SAT95 ( 83 ) page： 67-72 1995.12

Throughput analysis of spread-slotted ALOHA in LEO satellite communication systems with nonuniform traffic distribution Reviewed

A Jamalipour, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E78B ( 12 ) page： 1657 - 1665 1995.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

An analytical framework to study the nonuniformity in geographical distribution of the traffic load in low earth orbit satellite communication systems is presented. The model is then used to evaluate the throughput performance of the system with direct-sequence packet spread-slotted ALOHA multiple-access technique. As the result, it is shown that nonuniformity in traffic makes the characteristics of the system significantly different from the results of uniform traffic case and that the performance of each user varies according to its location. Moreover, the interference reached from users of adjacent satellites is shown to be one of the main factors that limit the performance of system.

A Study on M-ary Spread-Spectrum Scheme Using Pseudo Noise Sequences in the Presence of Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA95 ( C-6-3 ) page： 597-600 1995.10

Adaptive Transmission Control Scheme for Spread-Slotted Aloha Mobile Satellite Communication Systems

Abbas Jamalipour, M. Katayama, T. Yamazato, A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA95 ( C-8-4 ) page： 777-780 1995.10

Performance of Bit Interleaved Trellis Coded 16DAPSK in Land Mobile Radio Communicatinon

H. Nakagawa, T. Yamazato, M. Katayama, A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA95 ( D-3-1 ) page： 297-300 1995.10

A Study of DS/SS/GMSK with Differential Detection

I. Wakaki, T. Ishiguro, T. Yamazato, M, Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 85 ) page： 25-30 1995.10

Throughput Analysis of Spread Unslotted Aloha System in Rayleigh Channel

T. Yamazato, T. Sato, H. Okada, M. Katayama and A. Ogawa

1995 Society Conference of IEICE Vol. SB-4-2 page： - 1995.9

An analytically estimation of GMSK spread spectrum communication system

T. Ishiguro, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 49 ) page： 21-26 1995.9

A Doppler Frequency Estimation Scheme for Block Demodulators in LEO Satellite Communication Systems

M. Ise, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 60 ) page： - 1995.9

NONCOHERENT RECEPTION OF M-ARY SPREAD-SPECTRUM SIGNALS IN THE PRESENCE OF CARRIER FREQUENCY OFFSET Reviewed

T WADA, T YAMAZATO, M KATAYAMA, A OGAWA

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E78A ( 9 ) page： 1102 - 1108 1995.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper discusses the performance of noncoherent reception for M-ary spread-spectrum (M-ary/SS) signals in the presence of carrier frequency offset. In general, the M-ary/SS scheme is expected to be of higher spectral efficiency than the conventional DS/SS schemes, but its performance may be degraded by the carrier frequency offset. We: therefore, analyze the effect of carrier frequency offset on the performance of the non-coherent M-ary/SS system with orthogonal modulation using a set of sequences generated by the Hadamard matrix. As a result of the analysis, it has been found that the carrier frequency offset may cause a great deal of degradation in the performance, and that its effect has a distinctive property which is due to the characteristic of Hadamard matrix, at the same time. Making use of this property, we propose two schemes that can mitigate the effect of carrier frequency offset: one is based on choice of the code sequences, the other is on the error correcting code. The effectiveness of the schemes is evaluated in the terms of symbol-error-rates through analysis and computer simulation.

PERFORMANCE OF BIT-INTERLEAVED TRELLIS-CODED 16-QAM WITH MAXIMIZED CODE DIVERSITY Reviewed

AOYAMA A, NAKAGAWA H, YAMAZATO T, KATAYAMA M, OGAWA A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E78A ( 9 ) page： 1215 - 1219 1995.9

A Receiver Structure with Adaptive Array Antennas for LEO Satellite Communication Systems

H. Sumino, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT95 ( 18 ) page： 67-72 1995.7

A Study on Improvement of Performance of GMSK with DS/SS/CDMA

T. Ishiguro, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 41 ) page： 43-48 1995.7

PERFORMANCE OF DS/FH-CDMA OVER FADING CHANNELS WITH NEAR-FAR PROBLEM Reviewed

Y SHINKAJI, T YAMAZATO, M KATAYAMA, A OGAWA

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 78 ( 7 ) page： 97 - 107 1995.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA PUBL

The performance of a hybrid direct-sequence/frequency-hopping code-division multiple-access (DS/FHMA) system is investigated in the presence of both the near-far problem and multipath fading. It is confirmed that the error-correcting technique is essential lessening the effect of the near-far problem and that the coded DS/FH system employing the Reed-Solomon forward error-correcting code preforms better than the coded DS system. It is shown also that the path-diversity technique is effective in reducing the degradation caused by multipath fading.
As a result of this study, it is concluded that the DS/FH-CDMA with the error-control code and the path-diversity technique is better suited to solve both near-far problem and multipath fading than DS-CDMA in which an accurate power control is difficult to achieve in such an environment.

PERFORMANCE OF AN INTEGRATED VOICE DATA SYSTEM IN NONUNIFORM TRAFFIC LOW-EARTH-ORBIT SATELLITE COMMUNICATION-SYSTEMS Reviewed

A Study on Non-Coherent Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95-3 page： 13-18 1995.5

Performance Analysis of Spread Unslotted Aloha System Considering Packet Retransmission

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95 ( 4 ) page： 19-24 1995.5

A Differential Positioning Scheme witn a Single Satellite to be incorporated into Mobile Communications Reviewed

Y. Yabumoto, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Communications Vol. 78-BII ( 5 ) page： 297-305 1995.5

Throughput of Spread Unslotted Aloha System with Fixed Packet Lengths

T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 98 ) page： 31-36 1995.3

A Study on Bit-Interleaved Coded Modulation for a Rayleigh Fading Channel

H. Nakagawa, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS95 ( 47 ) page： 25-30 1995.3

Throughput and Delay of Spread Unslotted Aloha System

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

1995 IEICE General Conference Vol. A-233 page： - 1995.3

Diversity Effect on Coded Modulation System with Bit Interleaver

T. Yamazato, M. Katayama and A. Ogawa

1995 IEICE General Conference Vol. B-396 page： - 1995.3

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 13 ( 2 ) page： 465 - 473 1995.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In some recent studies, the use of low earth-orbit satellites in various applications is considered, In all of these studies, uniform distribution of traffic load is assumed, In this paper, the performance of a low earth-orbit satellite communication system which is designed to service to two kinds of users; i.e., voice users and data users is estimated. The distribution of population of these users is assumed to be nonuniform, According to the simulation results, it is shown that the nonuniformity in traffic affects the performance of the system by decreasing the signal quality at the satellite which has to service to populated areas and increasing it superfluously at the satellite with not so populated service area, in a given period of time, By modeling the satellites during their movements, the change in signal quality while experiencing a peak of traffic load in their route is also determined, A modified power control method based on the amount of traffic load of each satellite is also examined and is shown that this method can make some performance improvements in signal quality, which is limited by special features of low earth-orbit satellite systems.

DOI： 10.1109/49.345892

A Spread-Spectrum System with Dual Processing Gains Designed for Cyclic Noise in Power Line Communications

H. Niwa, M. Katayama, T. Yamazato, A. Ogawa and N. Isaka

Technical Report of IEICE Vol. SST95-95 page： 31-36 1995

Mon-coherent Reception of M-ary Spread-Spectrum Signals in the Presence of Carrier Frequency Offset Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E78-A ( 9 ) page： 1102-1108 1995

Performance of Bit-Interleaved Trellis Coded 16-QAM with Maximized Code Diversity Reviewed

A. Aoyama, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E78-A ( 9 ) page： 1215-1219 1995

A Study on Improvement of Performance of CDMA with DS/SS/GMSK Reviewed

T. Ishiguro, T. Yamazato, M. Katayama and A. Ogawa

International Symposium on Communications page： 605-612 1995

Throughput of DS/SSMA Unslotted Aloha System with Channel Load Sensing Reviewed

T. Sato, T. Yamazato, M. Katayama and A. Ogawa

IEEE Global Communications Conference (GLOBECOM'95) Vol. Globecom95 ( 2 ) page： 1492-1496 1995

Performance Analysis of DS/SSMA with Error Correcting Code in Rayleigh Fading Channel Reviewed

T. Yamazato, M. Katayama and A. Ogawa

IEEE Global Communications Conference (GLOBECOM'95) Vol. Globecom95 page： 1121-1125 1995

Throughput and Delay analysis of DS/SSMA unslotted Aloha by non-perfect capture Reviewed

T. Sato, T. Yamazato, M. Katayama and A. Ogawa

4th IEEE International Conference on Universal Personal Cmmunications Vol. ICUPC95 ( C8.3 ) page： 738-742 1995

A Study on Non-Coherent Reception of M-ary Spread-Spectrum Signals in the Presence of Carrier Frequency Offset Reviewed

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

4th IEEE International Conference on Universal Personal Cmmunications Vol. ICUPC95 ( B5.5 ) page： 412-416 1995

A New Block Demodulator for DS/SS Signal with Carrier Frequncy Offset Reviewed

S. Okuda, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC95 page： 203-207 1995

A Preliminaly Study of a Multimedia SSMA System Considering the Interactions between the Signals Reviewed

M. Ichiba, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC95 page： 31-35 1995

On Remedying the Traffic Nonuniformity Effects in LEO Satellite Communication Systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

IEEE Vehicular Technology Conference (VTC) Vol. VTC95 page： 986-990 1995

Coordinate-by-coordinate Interleaved Trellis Coded QPSK with T-algorithm on Rayleigh Fading Channels Reviewed

H. Nakamura, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC95 page： 497-501 1995

Transmit Permission Control Scheme for Spread-Slotted ALOHA in LEO Satellite Communication Systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

2nd Asia-Pacific Conference on Communications Vol. APCC95 page： 848-852 1995

Bit-by-bit Interleaved Trellis Coded MPSK with Differential Detection on Rayleigh Fading Channels Reviewed

H. Nakagawa, T. Yamazato, M. Katayama and A. Ogawa

IEEE Vehicular Technology Conference (VTC) Vol. VTC95 page： 659-663 1995

Performance Analysis of Spread Unslotted Aloha System Considering Packet Retransmission

H. Okada, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE, vol.SST95-4, pp.19-24 (1995-5) Vol. SST95 ( 4 ) page： 19-24 1995

チップ同期が不完全な場合における分割MFを用いた拡散信号の初期同期捕捉特性

石津美帆子, 奥田慎治, 片山正昭, 山里敬也, 小川明

1995年電気関係学会東海支部連合大会 page： 538 1995

ALOHA方式と拡散ALOHA方式の比較

西田邦生, 岡田啓, 佐藤毅, 山里敬也, 片山正昭, 小川明

1995年電気関係学会東海支部連合大会 page： 537 1995

Throughput Analysis of Spread-Slotted ALOHA in LEO Satellite Communication Systems with Nonuniform Traffic Distribution Reviewed

A. Jamalipour, M. Katayama, T. Yamazato, A. Ogawa

IEICE Transaction on Communications Vol. E78-B ( 12 ) page： 1657-1665 1995

Performance of an Integrated Voice/Data System in Nonuniform Traffic Low Earth-Orbit Satellite Communication System Reviewed

A. Jamalipou, T. Yamazato, M. Katayama and A.Ogawa

IEEE Journal on Selected Areas in Communications Vol. 13 ( 2 ) page： 465-473 1995

A Differential Positioning Scheme witn a Single Satellite to be incorporated into Mobile Communications

Y. Yabumoto, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Communications, vol.78-B, no.5, pp.297-305 (1995-5) Vol. 78-BII ( 5 ) page： 297-305 1995

A New Access Control Method for Spread Unslotted ALOHA Systems

H. Okada, T. Sato, T. Yamazato, M, Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95-101 page： 67-72 1995

Performance Analysis of CDMA ALOHA Reviewed

T. Yamazato, T. Sato, H. Okada, K. Nishida, M. Katayama and A. Ogawa

International Symposium on Communications page： 434-441 1995

スペクトル拡散信号を用いた時間差送信ダイバシティ方式

坂耕一郎, 片山正昭, 山里敬也, 小川明

1995年電気関係学会東海支部連合大会 page： 536 1995

Bit-by-bit interleaved trellis coded MPSK with differential detection on Rayleigh fading channels Reviewed

NAKAGAWA H, YAMAZATO T, KATAYAMA M, OGAWA A

1995 IEEE 45TH VEHICULAR TECHNOLOGY CONFERENCE - COUNTDOWN TO THE WIRELESS TWENTY-FIRST CENTURY, VOLS 1-2 page： 659 - 663 1995

On remedying the traffic nonuniformity effects in LEO satellite communication systems Reviewed

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

1995 IEEE 45TH VEHICULAR TECHNOLOGY CONFERENCE - COUNTDOWN TO THE WIRELESS TWENTY-FIRST CENTURY, VOLS 1-2 page： 986 - 990 1995

Performance analysis of DS/SSMA with error correcting code in Rayleigh fading channel Reviewed

T Yamazato, M Katayama, A Ogawa

GLOBECOM '95 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-3 page： 1121 - 1125 1995

Throughput analysis of DS/SS unslotted Aloha system with channel load sensing Reviewed

T Sato, H Okada, T Yamazato, M Katayama, A Ogawa

GLOBECOM '95 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-3 page： 1492 - 1496 1995

Influence of Crosscorrelation Properties on Simultaneous Transmission of Spread-Spectrum with Different Process Gains

M. Ichiba, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 64 ) page： 27-32 1994.12

A Study on Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA94 ( W44-5 ) page： 417-420 1994.11

Performance of DS/FH-CDMA Over Fading Channels with Near-Far Problem Reviewed

Y. Shinkaji, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Communications Vol. 77-BII ( 11 ) page： 681-690 1994.11

Effect of Nonlinear Amplification on a Spread Spectrum Signal and Receiver Configurations Reviewed

M. Sawada, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. 77-A ( 11 ) page： 1855-1862 1994.11

A New Acquisition Scheme for a DS/SS Signal with Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 50 ) page： 19-24 1994.10

LEO Satellite Communication Systems under Nonuniform Traffic Distribution with Spread-Slotted ALOHA

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT94 ( 57 ) page： 15-21 1994.10

A-146 Spectral Efficiency of DS/SS/GMSK System with RAKE Reviewed

ISHIGURO Takayuki, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira, MAEBARA Tsuneo

Vol. 1994 page： 146 1994.9

A Study on Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

1994 IEICE Fall Conference Vol. A-145 1994.9

Spectral Efficiency of DS/SS/GMSK System with RAKE

T. Ishiguro, M. Katayama, T. Yamazato, A. Ogawa and T. Maebara

1994 IEICE Fall Conference Vol. A-146 page： - 1994.9

A Study on Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST94-41 page： 51-56 1994.8

Multiple-Symbol Differential Detection on 16 Circular Shaped Signal Constellation Reviewed

Nakagawa Hitoshi, Yamazato Takaya, Katayama Masaaki, Ogawa Akira

IEICE technical report. Communication systems Vol. 94 ( 108 ) page： 55 - 60 1994.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Multiple-symbol differential detection of 16DAPSK is attractive in the field of mobile communication because of its good error rate performance.In this paper,we study multiple-symbol differential detection on 16 circular shaped signal constellation(CSSS)whose minimum distance is larger than that of 16DAPSK signal constellation.Their error rate performances over an AWGN channel are compared by computer simulation.As a result,we show that error rate is affected by both Euclid distance and phase difference on signal constellation,and comparatively good error rate performance is obtained on(7,9)CSSS.

Inter-chip interference rejection in DS/SS/GMSK applied RAKE

T. Ishiguro, M. Katayama, T. Yamazato, A. Ogawa and T. Maebara

Technical Report of IEICE Vol. SST94 ( 10 ) page： 31-36 1994.6

Throughput of Spread Unslotted Aloha in an Additive White Gaussian Noise Channel

T. Sato, K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 9 ) page： 25-30 1994.6

A Study of M-algorithm combined with Pre-Decoding

H. Nakamura, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. CS94 ( 37 ) page： 39275 1994.6

Multiple-Symbol Differential Detection on 16 Circular Shaped Signal Constellation

H. Nakagawa, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS94 ( 36 ) page： 55-60 1994.6

A NOVEL SPREAD SLOTTED ALOHA SYSTEM WITH CHANNEL LOAD SENSING PROTOCOL Reviewed

TOSHIMITSU K, YAMAZATO T, KATAYAMA M, OGAWA A

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 12 ( 4 ) page： 665 - 672 1994.5

A NOVEL SPREAD SLOTTED ALOHA SYSTEM WITH CHANNEL LOAD SENSING PROTOCOL Reviewed

K TOSHIMITSU, T YAMAZATO, M KATAYAMA, A OGAWA

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 12 ( 4 ) page： 665 - 672 1994.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper presents a noval spread slotted Aloha system with channel load sensing protocol (CLSP). CLSP is an effective scheme to improve the throughput performance in spread unslotted Aloha systems. In spread slotted Aloha systems, however, it does not make sense to utilize CLSP because the slot size is usually the same as the packet size. The slot size of the proposed system is set less than the packet size, thereby enabling us to apply CLSP and improving the throughput performance. Another feature of the proposed system is that the system is not likely affected by the time difference between channel load sensing and timing of packet access, which we call the access timing delay. Throughput performance of the proposed system is evaluated in the presence of the access timing delay and a significant increase of the throughput is shown compared with that of spread unslotted Aloha with CLSP.

DOI： 10.1109/49.286673

Acquisition of DS/SS Signal with Frequency Offset using Matched Filters

M. Mizutani, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST93-109 page： 55-60 1994.3

A Study on Bit-Interleaved Coded Modulation for a Rayleigh Fading Channel

A. Aoyama, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. IT93-116 page： 61-66 1994.3

A Novel Variable Source Coding Algorithm Based on LZW Adopting Move to Front Method

S. Hayashi, J. Kubo, T. Yamazato and I. Sasase

1994 IEICE Spring Conference Vol. A-370 page： - 1994.3

Diversity Effect on Coded Modulation System in Rayleigh Channel

T. Yamazato, M. Katayama and A. Ogawa

1994 IEICE Spring Conference Vol. A-364 page： - 1994.3

Throuput of Spread Unslotted Aloha System

T. Sato, K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

1994 IEICE Spring Conference Vol. A-278 page： - 1994.3

Performance of Bit-by-Bit Interleaved Trellis-Coded 16QAM in Land Mobile Communications

A. Aoyama, T. Yamazato, M. Katayama and A. Ogawa

1994 IEICE Spring Conference Vol. B-358 page： - 1994.3

Simultaneous Transmission of two Spread Spectrum Signals of Different Process Gains

M. Ichiba, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT93 ( 90 ) page： 17-24 1994.2

Spread Unskotted Aloha 方式のスループット特性

岡田啓, 佐藤毅, 山里敬也, 片山正昭, 小川明

1994年電気学会東海支部連合大会 page： 516 1994

Signal-to-Interference Ratio of CDMA in Low Earth-Orbital Satellite Communication Systems with Non-uniform Traffic Distribution Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

IEEE Global Communications Conference (GLOBECOM'94) Vol. Globecom94 ( 18019 ) page： 1748-1752 1994

A Novel Spread Slotted Aloha System with Channel Load Sensing Protocol Reviewed

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

IEEE Journal on Selected Areas in Communications Vol. 12 ( 4 ) page： 665-672 1994

Near-Far Problem of Hybrid DS/SFH-SSMA with Multi-Level Power Control. Reviewed

T. Yamazato, Y. Shinkaji, M. Katayama and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA94 page： 109-113 1994

A New Access Protocol for Asynchronous Packet CDMA Systems Reviewed

A. Ogawa, T. Yamazato, M. Katayama and K. Toshimitsu

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA94 page： 917-920 1994

Spread-Slotted ALOHA Throughput in Nonuniform Traffic Situation for LEO Satellite Communication Systems Reviewed

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

International Conference on Communication Systems page： 554-558 1994

Performance of 16-QAM with Increased Diversity on Raleigh Fading Channels Reviewed

A. Aoyama, T. Yamazato, M. Katayama and A. Ogawa

International Symposium on Information Theory and Its Applications (ISITA) Vol. ISITA94 page： 1133-1137 1994

Near-Far Problem on Hybrid Direct-Sequence/Slow-Frequency-Hopping Spread-Spectrum Multiple-Access. Reviewed

T. Yamazato, Y. Shinkaji, M. Katayama and A. Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Vol. PIMRC94 ( C3-2 ) page： 319-323 1994

A New Code Acquisition Scheme Using Divided Matched Filters for DS/SS Signal with Frequency Offset Reviewed

M. Mizutani, M. Katayama, T. Yamazato and A. Ogawa

International Conference on Communication Systems page： 379-383 1994

A Study on Quasi-Synchronous CDMA Based on Selected PN Signature Sequences Reviewed

S. Kuno, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. ISSSTA94 page： 479-483 1994

Differential Positioning with a Single Satellite Reviewed

Y. Yabumoto, M. Katayama, T. Yamazato and A. Ogawa

International Conference on Vehicle Navigation & Information Systems Vol. D2-3 page： 579-584 1994

Performance of CDMA with DS/SS/GMSK Reviewed

A. Ogawa, M. Katayama, T. Yamazato and T. Maebara

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. ISSSTA94 page： 564-568 1994

GMSKを用いたSSシステムのサンプリング誤差の影響のシミュレーション

若木勇, 石黒隆之, 片山正昭, 山里敬也, 小川明

1994年電気学会東海支部連合大会 page： 517 1994

Simultaneous Transmission of Spread-Spectrum Signals of Different Process Gains Reviewed

M. Katayama, A. Kakami, T. Yamazato and A. Ogawa

International Conference on Communication Systems page： 607-611 1994

DIFFERENTIAL POSITIONING WITH A SINGLE SATELLITE Reviewed

YABUMOTO Y, KATAYAMA M, YAMAZATO T, OGAWA A

1994 VEHICLE NAVIGATION & INFORMATION SYSTEMS CONFERENCE PROCEEDINGS page： A579 - A584 1994

NEAR-FAR PROBLEM ON HYBRID DIRECT-SEQUENCE SLOW-FREQUENCY-HOPPING SPREAD-SPECTRUM MULTIPLE-ACCESS Reviewed

T YAMAZATO, Y SHINKAJI, M KATAYAMA, A OGAWA

WIRELESS NETWORKS - CATCHING THE MOBILE FUTURE, PROCEEDINGS, VOLS I - IV page： 319 - 323 1994

SIGNAL-TO-INTERFERENCE RATIO OF CDMA IN LOW EARTH-ORBITAL SATELLITE COMMUNICATION SYSTEMS WITH NONUNIFORM TRAFFIC DISTRIBUTION Reviewed

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

1994 IEEE GLOBECOM - CONFERENCE RECORD, VOLS 1-3, AND COMMUNICATIONS THEORY MINI-CONFERENCE RECORD page： 1748 - 1752 1994

Spread Aloha system which controls the packet transmission by the channel load

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 49 ) page： 31-36 1993.10

A Performance Analysis on the Effects of Traffic Non-Uniformity in Low Earth-Orbit Satellite Communication System

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. W33-3 page： 203-206 1993.10

Differential Positioning with a Single Satellite

Y. Yabumoto, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SAT93 ( 59 ) page： 23-30 1993.10

Spread Aloha system which controls the packet transmission by the channel load

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 49 ) page： 31-36 1993.10

Differential Positioning with a Single Satellite

Y. Yabumoto, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 59 ) page： 23-30 1993.10

An Experiment of Superposed Transmission on Satellite Communication Channel using Spread Spectrum

A. Kakami, M. Katayama, T. Yamazato and A. Ogawa

1993 IEICE Fall Conference Vol. SB-2-5 page： - 1993.9

The Spread ALOHA System with Modified Channel Load Sensing Protocol

K. Toshimitsu, K. Yonekura, T. Yamazato, M. Katayama and A. Ogawa

1993 IEICE Fall Conference Vol. A-124 page： - 1993.9

A NEW VITERBI ALGORITHM WITH ADAPTIVE PATH REDUCTION METHOD Reviewed

YAMAZATO T, SASASE I, MORI S

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E76A ( 9 ) page： 1422 - 1429 1993.9

A NEW VITERBI ALGORITHM WITH ADAPTIVE PATH REDUCTION METHOD Reviewed

T YAMAZATO, SASASE, I, S MORI

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E76A ( 9 ) page： 1422 - 1429 1993.9

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A new Viterbi algorithm with adaptive path reduction method is presented. The proposed system consists of the pre-decoder and reduced path Viterbi decoder. The pre-decoder separates the mixed channel noise from the received sequence [6]-[9]. The number of errors in the pre-decoded error sequence is counted and the path reduction is implemented by the number of errors in pre-decoded error sequence. The path reduction is implemented as a function of channel condition because the errors in the pre-decoded error sequence can be considered as the channel error sequence. Due to the reduction of the path, the number of ACS (add compare select) operations can be reduced, which occupies the dominant part in Viterbi decoding. The ACS reduction ratio for the proposed system achieves up to 30% for the case of (2, 1, 2) Ungerboeck code without degradation of the error performance.

Computational Carrier Regeneration for Low Earth-Orbital Satellite Communication Systems

Y. Uno, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT93 ( 21 ) page： 13-18 1993.8

Near-Far Effect on Coded DS/FH/SSMA

Y. Shinkaji, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SAT93 ( 33 ) page： 39275 1993.8

A Study on Quasi-Synchronous Spread Spectrum

S. Kuno, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 26 ) page： 43-48 1993.8

The Spread Slotted ALOHA System with Channel Load Sensing Protocol

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 4 ) page： 19-24 1993.6

干渉波除去を用いたQPSK信号とSS信号の重畳伝送システム

各務綾加, 片山正昭, 山里敬也, 小川明

電子情報通信学会技術研究報告 Vol. SST93-3 page： 13-18 1993

A Novel Detection Technique for CPM Using Variable Mapping Method Reviewed

K. Nemoto, T. Yamazato, I. Sasase and S. Mori

IEEE Pacific Rim Conference on Communication and Signal Processing (PACRIM) Vol. PACRIM93 page： 573-576 1993

Reduced Path Viterbi Decoder with Inverse Circuit of Encoder Reviewed

T. Yamazato, I. Sasase, S. Mori, M. Katayama and A. Ogawa

IEEE Pacific Rim Conference on Communication and Signal Processing (PACRIM) Vol. PACRIM93 page： 569-572 1993

Carrier Regeneration in a Block Demodulator for Low Earth-Orbital Satellite Communication Systems Reviewed

Y. Uno, M. Katayama, T. Yamazato and A. Ogawa

IEEE International Symposium on Personal Indoor and Mobile Radio Communications Vol. PIMRC93 ( C3-6 ) page： 458-462 1993

A New Source Coding Method Based on LZW Adopting the Least Recently Used Deletion Heuristic Reviewed

S. Hayasi, J. Kubo, T. Yamazato, I. Sasase and S. Mori

IEEE Pacific Rim Conference on Communication and Signal Processing (PACRIM) Vol. PACRIM93 page： 190-193 1993

三衛星を用いた移動体通信・測位統合システムの一方式

竹田真人, 片山正昭, 山里敬也, 小川明

1993年電気学会東海支部連合大会 page： 512 1993

Configuration of the Receiver for Nonlinearly Amplified Spread Spectrum Signals in CDMA Systems Reviewed

M. Sawada, M. Katayama, T. Yamazato and A. Ogawa

International Symposium on Nonlinear Theory and its Applications (NOLTA) Vol. 7 ( 39207 ) page： 875-878 1993

適応的にパス削減を行うビタビ復号法

山里敬也, 片山正昭, 小川明

1993年電気学会東海支部連合大会 page： 502 1993

A New Viterbi Algorithm with Adaptive Path Reduction Method Invited

Takaya Yamazato, Iwao Sasase, Shinsaku Mori

IEICE Transaction on Fundamental of Electronics, communications and computer science Vol. E76-A ( 9 ) page： 1422-1429 1993

Trellis Coded Modulation Using Totally Overlapped Signal Sets Invited

Masayuki Ariyoshi, Takaya Yamazato, Iwao Sasase , Shinsaku Mori

IEICE Transaction on Communications Vol. E76-B ( 3 ) page： 304-309 1993

A New Viterbi Algorithm with Adaptive Path Reduction Method Reviewed

YAMAZATO T., Sasase Iwao, Mori Shinsaku

IEICE Trans. Fundamentals Vol. 76 ( 9 ) page： 1422 - 1429 1993

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

A new Viterbi algorithm with adaptive path reduction method is presented. The proposed system consists of the pre-decoder and reduced path Viterbi decoder. The pre-decoder separates the mixed channel noise from the received sequence [6]-[9]. The number of errors in the pre-decoded error sequence is counted and the path reduction is implemented by the number of errors in pre-decoded error sequence. The path reduction is implemented as a function of channel condition because the errors in the pre-decoded error sequence can be considered as the channel error sequence. Due to the reduction of the path, the number of ACS (add compare select) operations can be reduced, which occupies the dominant part in Viterbi decoding. The ACS reduction ratio for the proposed system achieves up to 30 for the case of (2, 1, 2) Ungerboeck code without degradation of the error performance.

A novel trellis coded modulation system without signal point expansion Reviewed

Ariyoshi M., Yamazato T., Sasase I., Mori S.

Proceedings of 2nd IEEE International Conference on Universal Personal Communications: Gateway to the 21st Century, ICUPC 1993 Vol. 2 page： 653 - 657 1993

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Proceedings of 2nd IEEE International Conference on Universal Personal Communications: Gateway to the 21st Century, ICUPC 1993

In conventional trellis coded modulation (TCM), the number of signal points in the constellation is doubled by additional redundant bits. This paper proposes a novel TCM system without signal point expansion which employs 2m kinds of trellis paths depending upon m encoder input bits, instead of 2/sup m+1/ kinds of paths of conventional TCM. The number of cosets assigned to trellis paths and total number of signal points can be reduced to half of those in conventional TCM. Therefore, it is possible to implement a coded modulation systems without signal point expansion by additional redundant bits, and the effective bit rate becomes unity. This scheme achieves a considerable coding gain in comparison to the traditional uncoded systems, and to the conventional TCM system. Furthermore, as the proposed scheme needs only half the signal points of conventional TCM, the average power is lower and it is less sensitive to the carrier phase offset.

DOI： 10.1109/ICUPC.1993.528462

REDUCED PATH VITERBI DECODER WITH INVERSE CIRCUIT OF THE ENCODER Reviewed

T YAMAZATO, SASASE, I, S MORI, M KATAYAMA, A OGAWA

IEEE PACIFIC RIM CONFERENCE ON COMMUNICATIONS, COMPUTERS AND SIGNAL PROCESSING : PROCEEDINGS, VOLS 1 AND 2 page： 569 - 572 1993

INTERLACE CODING SYSTEM INVOLVING DATA-COMPRESSION CODE, DATA ENCRYPTION CODE AND ERROR CORRECTING CODE Reviewed

T YAMAZATO, SASASE, I, S MORI

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E75B ( 6 ) page： 458 - 465 1992.6

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

An Interlace Coding System (ICS) involving data compression code, data encryption code and error correcting code is proposed and its error performance on additive white Gaussian noise (AWGN) channel with quadrature phase shift keying (QPSK) is analyzed. The proposed system handles data compression, data encryption and error correcting processes together, i.e. adds error correcting redundancy to the block lists of the dictionary in which compression system constructs to reduce source redundancy. Each block list is encoded by Ziv-Lempel code and Data Encryption Standard (DES). As the catastrophic condition determined by the data compression procedure is not negligible, error correcting redundancy should be added so as to avoid catastrophic condition. We found that the catastrophic condition depends only on the size of the dictionary for our proposed system. Thus, by employing a large dictionary, good error performance can be applied by the proposed system and the catastrophic condition can be avoided.