Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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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

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.

[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

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.

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

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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

B-20-15 A note on turbo compression and joint error correction of temporally and spatially correlated sources Reviewed

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

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Papers - YAMAZATO Takaya