Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Detection and Tracking of LED Array Transmitter for Visible Light Communications on Driving Situation Reviewed

NAGURA Toru, OZAWA Toshiyuki, YAMAZATO Takaya, KATAYAMA Masaaki, YENDO Tomohiro, FUJII Toshiaki, OKADA Hiraku

ITE Technical Report Vol. 34 ( 0 ) page： 59 - 64 2010

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Image Information and Television Engineers

In this paper, we discuss on a decoding algorithm for visible light communication systems on driving situation using a LED array transmitter and a high-speed camera receiver. We propose a LED array detection method using M-sequence and a LED array tracking method using inversion signals. We demonstrate that we can distinguish LED array candidates correctly with M-sequence. We also demonstrate that we can suppress the flicker of LED and improve the data rate compared with the conventional method.

DOI： 10.11485/itetr.34.6.0_59

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TOA UWB position estimation with two receivers and a set of known reflectors Reviewed

Kietlinski-Zaleski J.

Proceedings - 2009 IEEE International Conference on Ultra-Wideband, ICUWB 2009 page： 376 - 380 2009.12

Traffic prediction scheme for resource assignment of satellite/terrestrial frequency sharing mobile communication system Reviewed

Aman T.

IWSSC'09 - 2009 International Workshop on Satellite and Space Communications - Conference Proceedings page： 40 - 44 2009.12

On-Vehicle Receiver for Road-to-Vehicle Communication System Reviewed

OKADA Satoshi, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 323 ) page： 77 - 82 2009.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We consider an on-vehicle receiving system for long-distance and high-speed visible light communication. There are several problems associated with applying visible light communication to the field of ITS. It is necessary to receive information from long distance. And tracking the transmitter for a certain moving distance of the vehicle is also important. We applied an imaging optics to receive information over long distance, and two cameras are used to solve the relationship between the transmitter and the receiver position changes with time, and vibrational correction technique is also fixed to the system to minimize vibrational affections.

On-Vehicle Receiver for Road-to-Vehicle Communication System Reviewed

OKADA Satoshi, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, PANAHPOUR TEHRANI Mehrdad, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 322 ) page： 77 - 81 2009.11

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

On-vehicle receiver for distant visible light road-to-vehicle communication Reviewed

Okada S.

IEEE Intelligent Vehicles Symposium, Proceedings page： 1033 - 1038 2009.11

Channel estimation and tracking schemes for the pulse-shaping OFDM systems Reviewed

Mongol B.

IEEE International Conference on Communications 2009.11

Encoding system based on spatial frequency characteristics of road-vehicle communication Reviewed

MASUDA Takato, YENDO Tomohiro, YAMAZATO Takaya, OKADA Hiraku, TEHRANI Mehrdad Panahpour, FUJII Toshiaki, TANIMOTO Masayuki

IEICE technical report Vol. 109 ( 266 ) page： 71 - 76 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper we propose a method for analyzing spatial frequency characteristics of road-vehicle communication. In the proposed communication, we use LED traffic lights as transmitter and high-speed camera on car as receiver. So the distance between LED traffic lights and high-speed camera change from far to near, and as the distance is farther, received pictures are smaller. Therefore it is thought that high frequencies of sending data deteriorate, and Moire occurs in received pictures. In this paper, we analyze the deterioration and confirm improvement of communication using simulation.

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes : Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 248 ) page： 95 - 100 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

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. In this paper, we focus on joint channel decoding utilizing the spatial correlation of multiple sensor observations. Our proposed scheme makes use of an estimation of the correlation according to ADC bit levels of the sensor observations. The performance of our approach is examined by simulations using sensing data from experiments in a real indoor environment.

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes : Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data Reviewed

KOBAYASHI Kentaro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 246 ) page： 121 - 126 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

An access control scheme for passengers wireless communication systems considering the passing of an opposite train Reviewed

YAMAMOTO Masahiro, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 229 ) page： 89 - 93 2009.10

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

This manuscript discusses on a wireless cellular communication system for railroad passengers, in which base stations are placed along the railroad. In this system, all users or passengers are on trains. Thus there is high concentration in user distribution, and a group of the users on a train move to the same direction with the same speed. In such a system, when two opposite trains enter in the same cell before they pass each other, the number of users in the cell abruptly increases, and forced terminations of communication, i.e. call dropping, may occur due to the concentration of traffic. This paper proposes access control methods that mitigate the probability of the dropping, by limiting the number of channels allowed to use on each train dynamically or statically before the two trains enter the same cell. As a result, it is shown that the probability of the forced termination of an existing call can be decreased with the cost of increase in blocking probability. It is also confirmed that the dynamic access control method can inhibit increasing of the rejection of newly arrived calls compared to the static access control method when the control duration is enough large. In conclusion, the proposed methods provide lower dropping probability than the conventional (no-control) system, under the same blocking probability.

M-ary Modulation Scheme Using Separation of Chaotic Dynamics for Noncoherent Chaos-Based Communications Reviewed

S. ARAI, Y. NISHIO, T. YAMAZATO, S. OZAWA

2009 International Symposium on Nonlinear Theory and its Applications page： - 2009.10

Language：English

This paper proposes a new M-ary modulation scheme for noncoherent chaos-based communications. A chaotic sequence is successive based on the chaotic dynamics. Without the successive sequence based on the chaotic dynamics, general noncoherent systems are very difficult to demodulate the data. However, we consider that the systematic separation and the reconstruction of the chaotic dynamics can be applied as additional information. Namely, M-ary data symbols can be expressed by separating the chaotic dynamics purposely. We carry out computer simulations of the proposed scheme and confirm that a saving of over 3-4 dB is realized in transmitter energy by increasing M.

*Visible Light Communications using LED Array and High-Speed Camera for ITS Applications Invited

T. Yamazato

IEICE Fundamental Review, Vol.3, No.2, pp.45-53 Vol. Vol.3 ( No.2 ) page： pp.45-53 2009.10

A Note on Joint Decoding of Correlated Data Observed by Multiple Sensor Nodes - Correlation Estimation According to ADC Bit Levels of Experimentally Observed Data -

K. Kobayashi, T. Yamazato, M. Katayama

Technical Report of IEICE, vol.USN2009-42, pp.95-100 Vol. Vol.USN2009-42 page： pp.95-100 2009.10

Language：Japanese

Decoding of Separately Encoded Multiple Correlated Sources Transmitted over Noisy Channels Reviewed

K. Kobayashi, T. Yamazato, M. Katayama

IEICE Transactions on Fundamentals, vol.E92-A, no.10, pp.2402-2410 Vol. Vol.E92-A ( No.10 ) page： pp.2402-2410 2009.10

Language：English Publishing type：Research paper (scientific journal)

We propose an iterative channel decoding scheme for two or more multiple correlated sources. The correlated sources are separately turbo encoded without knowledge of the correlation and transmitted over noisy channels. The proposed decoder exploits the correlation of the multiple sources in an iterative soft decision decoding manner for joint detection of each of the transmitted data. Simulation results show that achieved performance for the more than two sources is also close to the Shannon and Slepian-Wolf limit and large additional SNR gain is obtained in comparison with the case of two sources. We also verify through simulation that no significant penalty results from the estimation of the source correlation in the decoding process and the code with a low error floor achieves good performance for a large number of the correlated sources.

Phase Compensation for Narrowband PLC Channels with Cyclic Time-Varying Features Reviewed

Y. Sugiura, T. Yamazto, M. Katayama

Third Workshop on Power Line Communications page： - 2009.10

Language：English

Phase transfer functions of power-line channels often show sharp and periodic variation synchronous to the (double of) mains frequency. This is a result of impedance change of nonlinear devices connected to the power-lines. This manuscript proposes a phase estimation strategy for phase compensation at a receiver under such environment. In the proposed method, phase estimates are calculated using cyclic observation (average) of the channel phase. The numerical examples under periodic phase variation of the channel and cyclostationary noise show that the receiver with the proposed phase estimation scheme outperforms that with the conventional phase estimation, which uses average over the whole observation period without considering the periodic feature of the channel.

The Receiver for visible Light Road-to-Vehicle Communication

S. Okada, T. Yendo, T. Yamazato, Hiraku Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

PCSJ/IMPS 2009 page： - 2009.10

Language：Japanese

In this paper, we propose a road-to-vehicle visible communication system for ITS. In this system, a LED traffic light is used as transmitter and a photodiode is used as receiver. There are several problems associated with applying visible light communication to the field of ITS. It is necessary to receive information from long distance. And tracking the transmitter for a certain moving distance of the vehicle is also important. We applied an imaging optics to receive information over long distance, and two cameras are used to solve the relationship between the transmitter and the receiver position changes with time, and vibrational correction technique is also fixed to the system to minimize vibrational corrections. We developed algorithms to track the transmitter. The experiments were conducted to confirm the proposals.

Traffic Light Detection for Visible Light Communication Image Sensor

D Takasao, T. Yendo, T. Yamazato, H. Okada, M. P. Tehrani, T. Fujii, M. Tanimoto

PCSJ/IMPS 2009 page： - 2009.10

Language：Japanese

The visible light communication used as telecommunications equipment by modulating LED at high speed is researched. And the road-to-vehicle visible light communication applied to the ITS field is researched. In this paper, the visible light communication is done by using a special image sensor. The pixel for the video that can capture video with 30fps and the pixel for the communication that can be communicated at high speed exist in the image sensor. We can detect the position of the traffic light in the image, and communicate by the pixel for the communication. We propose the detection method of the traffic light that makes the best use of the feature of the image sensor.

An access control scheme for passenger wireless communication systems considering the passing of an opposite train

M. Yamamoto, T. Yamazato, M. Katayama

Technical Report of IEICE Vol. Vol.RCS2009-125 page： pp.89-93 2009.10

Language：Japanese

This manuscript discusses on a wireless cellular communication system for railroad passengers, in which base stations are placed along the railroad. In this system, all users or passengers are on trains. Thus there is high concentration in user distribution, and a group of the users on a train move to the same direction with the same speed. In such a system, when two opposite trains enter in the same cell before they pass each other, the number of users in the cell abruptly increases, and forced terminations of communication, i.e. call dropping, may occur due to the concentration of traffic. This paper proposes access control methods that mitigate the probability of the dropping, by limiting the number of channels allowed to use on each train dynamically or statically before the two trains enter the same cell. As a result, it is shown that the probability of the forced termination of an existing call can be decreased with the cost of increase in blocking probability. It is also confirmed that the dynamic access control method can inhibit increase of the rejection of newly arrived calls compared to the static access control method when the control duration is enough large. In conclusion, the proposed methods provide lower dropping probability than the conventional(no-control) system, under the same blocking probability.

Decoding of Separately Encoded Multiple Correlated Sources Transmitted over Noisy Channels Reviewed

Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E92A ( 10 ) page： 2402 - 2410 2009.10

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

DOI： 10.1587/transfun.E92.A.2402

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Papers - YAMAZATO Takaya