Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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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

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.

DOI： 10.1587/transcom.E97.B.1759

Web of Science

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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

Web of Science

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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

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

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.

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Papers - YAMAZATO Takaya