Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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

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.

Open Access

CiNii Research

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

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

Open Access

CiNii Research

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

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.

Open Access

CiNii Research

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

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

Open Access

CiNii Research

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 Open Access

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 Open Access

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

Web of Science

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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

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Papers - YAMAZATO Takaya