Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 415 ) page： 47 - 52 2010.2

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

In this paper, we propose a kalman channel estimator for MC-CDMA based Inter-Vehicle Communication (IVC). In IVC, the channel characteristic of each car is different among pilot signals because of a doppler shift, a multipath fading, and the difference of receiving power. Our proposed kalman channel estimator uses a kalman filter to track the channel fluctuation and implements a pilot-based channel estimation which interpolates among pilot signals by using an interpolation polynomial into our proposed channel estimator to suppress an estimation error. As results, we show that the kalman channel estimator shows better performance than a pilot-based channel estimation.

Kalman Channel Estimator for MC-CDMA based Inter-Vehicle Communication Reviewed

HIRAIWA Noriaki, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 414 ) page： 47 - 52 2010.2

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

In this paper, we propose a kalman channel estimator for MC-CDMA based Inter-Vehicle Communication(IVC). In IVC, the channel characteristic of each car is different among pilot signals because of a doppler shift, a multipath fading, and the difference of receiving power. Our proposed kalman channel estimator uses a kalman filter to track the channel fluctuation and implements a pilot-based channel estimation which interpolates among pilot signals by using an interpolation polynomial into our proposed channel estimator to suppress an estimation error. As results, we show that the kalman channel estimator shows better performance than a pilot-based channel estimation.

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera Reviewed

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

IEICE technical report Vol. 109 ( 414 ) page： 53 - 58 2010.2

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

We propose a successive interference cancellation scheme(SIC)for the hierarchical coding parallel optical communication system using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

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

IEICE technical report Vol. 109 ( 414 ) page： 59 - 64 2010.2

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

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

IEICE technical report Vol. 109 ( 415 ) page： 59 - 64 2010.2

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

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

T. Nagura, T. Ozawa, T. Yamazato, M. Katayama, T. Yendo, T. Fujii, H. Okada

Technical Report of IEICE page： - 2010.2

Language：Japanese

An application of regenerative relay to the cognitive piggyback overlay system

J.Naganawa, T.Yamazato, M.Katayama

Technical Report of IEICE, vol.109, no.383 (SR2009-75), pp.9-14 Vol. Vol.109 ( No.383 (SR2009-75) ) page： pp.9-14, 2010.2

Language：Japanese

This manuscript considers a secondary system sharing the spectrum with the primary system at the same time and same frequency. This manuscript proposes a cognitive overlay system, in which the secondary system relays the primary signal and piggybacks its own data on it. As the relay procedure, non-regenerative and regenerative repeaters are considered and performance with them are compared. The result of the analysis shows that the proposed scheme with regenerative relay allows the secondary signal to communicate at the same speed of the primary signal without any harm to it.

Successive Interference Cancellation for Hierarchical Coding in Optical Wireless Communication Systems using LED array and High speed camera

T.Ozawa, T.Nagura, T.Yamazato, M.Katayama, T.Yendo T.Fujii, H.Okada

Technical Report of IEICE page： - 2010.2

Language：Japanese

We propose a successive interference cancellation scheme (SIC) for the hierarchical coding parallel optical communicationsystem using LED array and high-speed camera. The high priority data is first demodulated and Turbo-decoded. The retrieved high priority data is then re-modulated and subtracted from the received signal. In this way, the reliability of the middle priority data can be improved as the interference caused by the high priority data can be reduced. By the way, the performance of SIC depends on the performance of Turbo code. In this paper, we apply LogMAP decoding to improve the performance instead of MaxLogMAP algorithm that we have used in the previous.

An Access Control Method for Multipoint Data Gathering with ACK/NACK Errors Reviewed

OHTOMO Yuzo, YAMAZATO Takaya, KATAYAMA Masaaki

Vol. 2010 ( 1 ) page： 21 - 26 2010.1

An application of regenerative relay to the cognitive piggyback overlay system Reviewed

NAGANAWA Jun, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 109 ( 383 ) page： 9 - 14 2010.1

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

An access control method for multipoint data gathering with ACK/NACK errors

Y. Ohtomo, T. Yamazato, M. Katayama

The Papers of Technical Meeting on Communications, IEE Japan, pp21-26 page： pp21-26 2010.1

Language：Japanese

This manuscript proposes a media access control method for a multipoint cyclic data gathering system, in witch a base-station collects data generated periodically at each node. In such condition, by broadcasting ACK/NACK signals form the base-station, the proposed method ensures assignment a time slot for each node once the node succeeds to transfer its data. It is confirmed that the proposed method outperforms conventional slotted-ALOHA in throughput of data even with ACK/NACK errors. Furthermore, the proposed method realizes adaptive slot assignment under cyclostationary channel environment.

Nagoya Univeristy OCW

Takaya YAMAZATO

Japanese Society for Engineering Education 57th Annual Conference page： - 2010.1

1-5 Study on parallel visible light communication using visually non-lighting LED Reviewed

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

PROCEEDINGS OF THE ITE ANNUAL CONVENTION Vol. 2010 ( 0 ) page： 1-5-1 - _1-5-2_ 2010

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

The proposed visible light communication method uses visually non-lighting LED, which enable us to communicate by using tail lamps of cars. In addition, this method can communicate with visually non-lighting traffic lights.

DOI： 10.11485/iteac.2010.0_1-5-1

CiNii Research

A study on joint channel decoding using spatial correlation of sensor observations according to ADC bit levels Reviewed

Kentaro Kobayashi, Takaya Yamazato, Masaaki Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC page： 485 - 490 2010

Language：English Publishing type：Research paper (international conference proceedings)

In densely deployed wireless sensor networks, observations of the sensor nodes are spatially correlated. In this paper, we study a joint channel decoding scheme utilizing bit correlation of the sensor observations according to bit levels of analog-digital converter (ADC). If sensor ADC output is interpreted as natural binary numeral, carry propagation may occur between adjacent ADC output values. Such carry propagation leads to the degradation of joint decoding gain. We focus on the use of Gray code for avoiding the carry propagation. The performance of our approach is demonstrated by simulations using sensor data from experiments in a real indoor environment. ©2010 IEEE.

DOI： 10.1109/PIMRCW.2010.5670522

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An access control method for multipoint cyclic data gathering over a PLC network Reviewed

Yuzo Ohtomo, Takaya Yamazato, Masaaki Katayama

IEEE ISPLC 2010 - International Symposium on Power Line Communications and its Applications page： 285 - 290 2010

Language：English Publishing type：Research paper (international conference proceedings)

This paper proposes a media access control method for a multipoint cyclic data gathering system, in which each node transmits its data to the base-station periodically. In such condition, by broadcasting ACK/NACK signals from the basestation, the proposed method ensures assignment of a time slot for each node once the node succeeds to transfer its data. It is confirmed that the proposed scheme reduces packet collisions and outperforms conventional slotted-ALOHA scheme in throughput of data even with ACK/NACK errors. Furthermore the proposed scheme realizes adaptive slot assignment under cyclostationary channel environment. ©2010 IEEE.

DOI： 10.1109/ISPLC.2010.5479914

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Dynamic Bandwidth Allocation of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

Yamazato Takaya, Aman Tomohiro, Katayama Masaaki

2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010 2010

Error-correcting scheme based on chaotic dynamics and its performance for noncoherent chaos communications Reviewed

Arai Shintaro, Nishio Yoshifumi, Yamazato Takaya

Nonlinear Theory and Its Applications, IEICE Vol. 1 ( 1 ) page： 196 - 206 2010

Publishing type：Research paper (scientific journal) Publisher：一般社団法人電子情報通信学会

This paper proposes a novel error-correcting scheme using chaotic dynamics for noncoherent chaos communications. In our proposed system, two successive chaotic sequences are generated from the same chaotic map; the second sequence is generated with an initial value which is the last value of the first sequence. In this case, successive chaotic sequences having the same chaotic dynamics are created. This feature gives the receiver additional information to correctly recover the information data and thus improves the bit error performance of the receiver. As results of the computer simulation, we confirm that the advantage gained in BER performance of the proposed error-correcting method is about 1-1.5 dB compared to conventional method. In addition, we achieve that the proposed error-correcting scheme is performed without the new additional redundancy code by using the chaotic dynamics.<br/>

DOI： 10.1587/nolta.1.196

Dynamic Bandwidth Allocation of Satellite/Terrestrial Integrated Mobile Communication System Reviewed

Takaya Yamazato, Tomohiro Aman, Masaaki Katayama

2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010 page： 1 - 5 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, we propose two dynamic bandwidth allocation (DBA) schemes, a game theory based DBA and a successive DBA, for satellite/terrestrial integrated mobile communication system (STICS). The game theory based DBA allocate the bandwidth according to a utility function based on a weighted demand bandwidth of both satellite and terrestrial system. The successive DBA recursively allocates an unit of bandwidth according to a weighted number of bandwidth unfilled cells of both satellite and terrestrial systems, until the total bandwidth is fulfilled. As results, both DBA outperform the conventional fixed bandwidth allocation scheme. Between two proposed DBA, the successive DBA shows better spectral improvement ratio than the game theory based DBA.

DOI： 10.1109/GLOCOM.2010.5683362

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Experimental Validation of TOA UWB Positioning with Two Receivers Using Known Indoor Features Reviewed

Kietlinski-Zaleski Jan, Yamazato Takaya, Katayama Masaaki

2010 IEEE-ION POSITION LOCATION AND NAVIGATION SYMPOSIUM PLANS page： 748 - 752 2010

Inband and outband spectrum analysis of the BFDM and BFDM/OQAM signals with truncated Gaussian pulses Reviewed

Bayarpurev Mongol, Takaya Yamazato, Masaaki Katayama

ISITA/ISSSTA 2010 - 2010 International Symposium on Information Theory and Its Applications page： 743 - 746 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Pulse-shaping OFDM, or more generally BFDM and BFDM/OQAM, systems are originally proposed to combat inter-carrier interference (ICI) caused by time-variance of the channel. The main property that makes these signals robust against ICI is that they allow to employ time-frequency well localized pulses, particularly Gaussian pulse which has the best time-frequency localization. However, this property also suppresses the outband or inband spectral leakage of the BFDM and BFDM/OQAM signal, making them attractive physical layer modulation scheme for cognitive radio. In this paper we analyze the power density spectra of the BFDM and BFDM/OQAM signals and numerically evaluate the inband and outband spectra for truncated Gaussian pulses. © 2010 IEEE.

DOI： 10.1109/ISITA.2010.5649641

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Papers - YAMAZATO Takaya