Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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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.

CiNii Research

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.

CiNii Research

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.

CiNii Research

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.

CiNii Research

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.

CiNii Research

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.

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Papers - YAMAZATO Takaya