Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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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

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.

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

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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

A Study on Cluster Partitioning with Cooperative MISO Scheme in Wireless Sensor Networks Reviewed

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

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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

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Papers - YAMAZATO Takaya