Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Performance Evaluation of Range Estimation for Image Sensor Communication Using Phase-only Correlation Reviewed

Ruiyi Huang, Masayuki Kinoshita, Takaya Yamazato, Hiraku Okada, Koji Kamakura, Shintaro Arai, Tomohiro Yendo, Toshiaki Fujii

2020 IEEE Globecom Workshops, GC Wkshps 2020 - Proceedings 2020.12

Publishing type：Research paper (international conference proceedings)

Stereo cameras, serving as the 'eyes' of automotive vehicles, can determine the distance between objects and the vehicles. In this paper, stereo cameras are introduced into image-sensor-based visible light communication (IS-VLC) systems, in which the combination of VLC and stereo ranging shows promising prospects for intelligent transport systems. However, one of the problems of IS-VLC stereo ranging is that the luminance level of LEDs in the captured images would greatly affect disparity estimation, which would result in inaccurate range estimation. This paper gives the performance evaluation of this problem using phase-only correlation algorithm with luminance selection. The proposed scheme using stereo cameras exhibited a ranging accuracy of 60± 0.15m in static conditions.

DOI： 10.1109/GCWkshps50303.2020.9367540

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Estimation for direction of signal arrival based on area density of estimated lines for ultrasonic sensor array Reviewed

Morita E.

2020 IEEE 9th Global Conference on Consumer Electronics, GCCE 2020 page： 333 - 335 2020.10

Sequential maximum likelihood decoding incorporating reliability determination for image sensor communication Reviewed

Zhengqiang Tang, Shintaro Arai, Tomohiro Yendo, Di He, Takaya Yamazato

IEICE Communications Express Vol. 9 ( 8 ) page： 365 - 370 2020.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this study, the sequential maximum likelihood decoding (S-MLD) for image sensor based visible light communication, referred to as image sensor communication, is proposed. The conventional system cannot correctly decode degraded captured images. To overcome this problem, S-MLD partitions the LED area on the image into two segments and sequentially creates pseudo-captured images, which imitate all possible LED blinking patterns. This approach is based on MLD for each segment. Moreover, reliability determination is incorporated to improve communication quality. We performed computer simulations and confirmed that S-MLD exhibits superior decoding performance and approximately 90% computational cost reduction compared to the previous MLD.

DOI： 10.1587/comex.2020XBL0058

Web of Science

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Nonlinear Transform for Parallel Transmission for Image-Sensor-based Visible Light Communication Reviewed

Takahashi K.

IEEE International Conference on Communications Vol. 2020-June 2020.6

Visible Light Communications for Automotive Intelligence Reviewed

Yamazato T.

2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings 2020.3

BER Measurement for Transmission Pattern Design of ITS Image Sensor Communication Using DMD Projector Reviewed

Arisue T.

2020 IEEE 17th Annual Consumer Communications and Networking Conference, CCNC 2020 2020.1

Nonlinear Transform for Parallel Transmission for Image-Sensor-based Visible Light Communication Reviewed

Takahashi Kotomi, Kamakura Koji, Kinoshita Masayuki, Yamazato Takaya

ICC 2020 - 2020 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) 2020

Visible light communications for automotive intelligence Reviewed

Yamazato T.

Optics InfoBase Conference Papers Vol. Part F174-OFC 2020 2020

Stereo ranging method using led transmitter for visible light communication Reviewed

Masayuki Kinoshita, Koji Kamakura, Takaya Yamazato, Hiraku Okada, Toshiaki Fujii, Shitaro Arai, Tomohiro Yendo

2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings 2019.12

Publishing type：Research paper (international conference proceedings)

This paper focuses on high-speed stereo cameraã receivers for visible light communication (VLC) in intelligent transport systems (ITSs), contrary to conventional studies where a single (high-speed) camera is used. An advantage of high-speed stereo cameras as VLC receivers is that both front-facing ranging and wireless communication can be achieved in one device. In this paper, utilizing features of VLC, we consider stereo ranging with high accuracy. Moreover, it is known that an LED transmitter for VLC has specific features, high-luminance and high- speed blinking. This paper proposes stereo ranging by applying LED transmitter detection (utilizing these features) to disparity estimation. Additionally, we introduce subpixel estimation using equiangular line fitting to obtain more accurate disparity. Finally, we experimentally demonstrate that the proposed stereo ranging achieves an accuracy of 60 m Â± 0.1 m.

DOI： 10.1109/GLOBECOM38437.2019.9013641

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Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time Reviewed

Takuya Mitani, Takaya Yamazato, Katsuhiro Naito, Yuki Mori

IEEE International Conference on Connected Vehicles and Expo:ICCVE 2019 2019.11

Analysis of Data Collected by the 700 MHz Band Intelligent Transport Systems for Reducing Ambulance Transportation Time Reviewed

Mitani T., Yamazato T., Naito K., Mori Y.

2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings 2019.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings

Emergency services around the world face the problem of increasing patient transportation times. The operation of emergency vehicles is fundamentally different from that of general vehicles; hence, algorithms recommending optimal routes in a conventional way are not always applicable to emergency vehicles. In this study, we analyzed data of inter-vehicle and road-vehicle communication collected at 700 MHz band intelligent transport systems and demonstrated that the overall travel time of emergency vehicles can be reduced by decreasing their travel time at intersections.

DOI： 10.1109/ICCVE45908.2019.8965232

Scopus

Direct wireless link to out-of-range node with assistance of surrounding nodes Reviewed

Hiroya Tanaka, Shintaro Hiraoka, Shintaro Arai, Takaya Yamazato, Yukihiro Tadokoro

IEEE Transactions on Vehicular Technology Vol. 68 ( 11 ) page： 10703 - 10712 2019.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We propose a method that establishes a direct wireless link from a transmission source to an out-of-range destination with the assistance of the surrounding communication nodes. In this method, a weak (subthreshold) signal is amplified by utilizing the interference signals transmitted from the surrounding communication nodes. To evaluate the amplification gain, we study the mutual information in a multipath fading channel. As a result, we reveal that the mutual information is enhanced owing to the interference signals, and the proposed method enlarges the radio coverage area of the source node. To understand the enhancement mechanism, we introduce a toy model of the propagation channel and discuss the role of the interference signals. We find that the interference signals allow the subthreshold signals into the detectable region in the signal space. Moreover, the mutual information is maximized at the optimal power of the interference signals. In addition, a detailed discussion of the channel capacity shows that there exists an optimal a priori probability of symbol transmission.

DOI： 10.1109/TVT.2019.2934502

Web of Science

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Proposal for Identification Scheme of Driver and Impostor based on Acceleration Data Reviewed

Yuki Mori, Ryota Ono, Takuya Mitani, Katsuhiro Naito, Takaya Yamazato

IEEE International Conference on Connected Vehicles and Expo:ICCVE 2019 2019.11

Proposal for identification scheme of driver and impostor based on acceleration data Reviewed

Mori Y.

2019 8th IEEE International Conference on Connected Vehicles and Expo, ICCVE 2019 - Proceedings 2019.11

Noise-aided demodulation of direct spread-code division multiple access signals with a 1bit analog-to-digital converter Reviewed

Yasuo NAKASHIMA, Takaya YAMAZATO, Shintaro ARAI, Hiroya TANAKA, Yukihiro TADOKORO

IEICE TRANSACTIONS on Communications Vol. J102-B ( 8 ) 2019.8

High performance demodulation method with less complexity for image-sensor communication Reviewed

Ohira Yuki, Yendo Tomohiro, Arai Shintaro, Yamazato Takaya

OPTICS EXPRESS Vol. 27 ( 15 ) page： 21565 - 21578 2019.7

MD2.3-visible light communication and ranging system using high-speed stereo cameras (Invited) Reviewed

Kinoshita M.

IEEE Photonics Society Summer Topical Meeting Series 2019, SUM 2019 2019.7

{For the applications of Stochastic resonance in the telecommunications Reviewed

IEICE TRANSACTIONS on Communications Vol. J102-B ( 6 ) page： 445 - 458 2019.6

Maximum Likelihood Decoding Based on Pseudo-Captured Image Templates for Image Sensor Communication Reviewed

Shintaro ARAI, Haruna MATSUSHITA, Yuki OHIRA, Tomohiro YENDO, Di HE, Takaya YAMAZATO

Nonlinear Theory and Its Applications, IEICE Vol. 10 ( 2 ) page： 173 - 189 2019.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper focuses on an image sensor communication system that uses an LED as the transmitter and a high-speed image sensor (camera) as the receiver. Communication in this scheme depends on the quality of images transmitted from the LED to the sensor. If the image becomes unfocused on the way to the receiver, the LED luminance that make up the signal cannot be detected, so the receiver cannot demodulate the signal data. To overcome this problem, this study proposes a novel demodulation scheme to recover data from a degraded image, based on a maximum likelihood decoding (MLD) algorithm. The proposed method creates template images that imitate all possible blinking patterns produced by the LED transmitter, and then calculates the Euclidean distances between pixels in the captured image and the pseudo images for all possible blinking patterns. Finally, the algorithm chooses the image template with the smallest Euclidian distance from the received signal as the recovered data. Though an exhaustive set of image templates must be prepared for the proposed MLD, the number of templates depends on the number of LEDs on the transmitter. Thus, the computational complexity of this method increases as the number of transmitter LEDs increases. To reduce the computational complexity of the proposed MLD algorithm, the binary differential evolution (BDE) algorithm is used, which is a swarm intelligence technique. Computer simulations are used to evaluate the BDE algorithm's usefulness for reducing computational complexity and improving the BER of the communication system.

DOI： 10.1587/nolta.10.173

Web of Science

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Parallel Transmission Using M-Point DFT for Image-Sensor-Based Visible Light Communication Reviewed

Kibe S.

2018 IEEE Globecom Workshops, GC Wkshps 2018 - Proceedings 2019.2

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Papers - YAMAZATO Takaya