Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Performance of an Integrated Voice/Data System in Nonuniform Traffic Low Earth-Orbit Satellite Communication System Reviewed

A. Jamalipou, T. Yamazato, M. Katayama and A.Ogawa

IEEE Journal on Selected Areas in Communications Vol. 13 ( 2 ) page： 465-473 1995

A New Access Control Method for Spread Unslotted ALOHA Systems

H. Okada, T. Sato, T. Yamazato, M, Katayama and A. Ogawa

Technical Report of IEICE Vol. SST95-101 page： 67-72 1995

Performance Analysis of CDMA ALOHA Reviewed

T. Yamazato, T. Sato, H. Okada, K. Nishida, M. Katayama and A. Ogawa

International Symposium on Communications page： 434-441 1995

スペクトル拡散信号を用いた時間差送信ダイバシティ方式

坂耕一郎, 片山正昭, 山里敬也, 小川明

1995年電気関係学会東海支部連合大会 page： 536 1995

Bit-by-bit interleaved trellis coded MPSK with differential detection on Rayleigh fading channels Reviewed

NAKAGAWA H, YAMAZATO T, KATAYAMA M, OGAWA A

1995 IEEE 45TH VEHICULAR TECHNOLOGY CONFERENCE - COUNTDOWN TO THE WIRELESS TWENTY-FIRST CENTURY, VOLS 1-2 page： 659 - 663 1995

On remedying the traffic nonuniformity effects in LEO satellite communication systems Reviewed

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

1995 IEEE 45TH VEHICULAR TECHNOLOGY CONFERENCE - COUNTDOWN TO THE WIRELESS TWENTY-FIRST CENTURY, VOLS 1-2 page： 986 - 990 1995

Performance analysis of DS/SSMA with error correcting code in Rayleigh fading channel Reviewed

T Yamazato, M Katayama, A Ogawa

GLOBECOM '95 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-3 page： 1121 - 1125 1995

Throughput analysis of DS/SS unslotted Aloha system with channel load sensing Reviewed

T Sato, H Okada, T Yamazato, M Katayama, A Ogawa

GLOBECOM '95 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-3 page： 1492 - 1496 1995

Study on non-coherent reception of M-ary spread-spectrum signals in the presence of carrier frequency offset Reviewed

Tadahiro Wada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

Annual International Conference on Universal Personal Communications - Record page： 412 - 416 1995

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

In this paper, we deal with the reception of M-ary Spread-Spectrum(M-ary/SS) signals in the presence of the carrier frequency-offset. The influence of frequency-offset on reception of M-ary/SS signals is investigated and it is shown that frequency-offset may degrade the symbol-error-rate performance remarkably, yet, the influence has a distinctive property. Making use of this property, we propose a new scheme that can mitigate the influence of the frequency-offset. The scheme is based on the assignment of the two distinctive Hadamard code to in-phase and quadrature component of the transmitted signal. The selection of the set of Hadamard codes and the power ratio of the in-phase and quadrature component of the transmitted signal is evaluated in terms of symbol-error-rate and carrier frequency offset. As a result, we found that the scheme shows the satisfactory symbol-error-rate in the presence of carrier frequency offset up to a half of symbol rate.

DOI： 10.1109/ICUPC.1995.496932

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Coordinate-by-coordinate interleaved trellis coded QPSK with T-algorithm on Rayleigh fading channels Reviewed

Hiroki Nakamura, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC Vol. 2 page： 497 - 501 1995

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

In this paper, we propose a coordinate-by-coordinate interleaved trellis coded QPSK with T-algorithm. A rate 1/2 convolutional code of the constraint length of 7 and 15 are evaluated on Rayleigh fading channels in terms of bit error rate (BER) by an analysis and a computer simulation. As the effective code length (ECL) equals to the constraint length of the code for the case of QPSK system, the proposed system achieves satisfactory BER performance even in the situation that no channel state information (CSI) is available at the decoder. Further, in order to reduce the decoding complexity, we employ T-algorithm. It is shown that as the T-algorithm can track the fluctuating gains introduced by the fading channel, we can achieve satisfactory BER performance with 0.01% of the decoding complexity of Viterbi algorithm.

DOI： 10.1109/PIMRC.1995.480918

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New block demodulator for DS/SS signal with carrier frequency offset Reviewed

Shinji Okuda, Masaaki Katayama, Takaya Yamazato, Akira Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC Vol. 1 page： 203 - 207 1995

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

In this paper, we present a new Direct-Sequence Spread-Spectrum demodulator using the block signal processing in the presence of large carrier frequency offset such as Doppler shift in low earth-orbital satellites systems. The proposed demodulator employs the initial acquisition scheme which can roughly estimate both the timing and the carrier frequency offset. This scheme realizes the maximum likelihood estimation with the help of the FFT. As the result of the analytical discussion, it is shown that the proposed scheme makes the initial acquisition possible even in the presence of large frequency offset where the conventional demodulator cannot achieve the acquisition.

DOI： 10.1109/PIMRC.1995.476884

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Preliminary study of a multimedia SSMA system considering the interactions between the signals Reviewed

Motohiro Ichiba, Masaaki Katayama, Takaya Yamazato, Akira Ogawa

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC Vol. 1 page： 31 - 35 1995

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

In this study, we analyze the system which simultaneously transmits spread-spectrum signals with different processing gains. The main purpose of this study is to give an analytical framework that describes the influence of the interfering signals with different processing gains. As the results, we show that the power of the interference component after despreading procedure, the power ratio of the desired to undesired component, and thus the bit error rate are not constant but vary symbol by symbol. We also show that the processing gain of the interfering signal affects the performance.

DOI： 10.1109/PIMRC.1995.476274

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Influence of Crosscorrelation Properties on Simultaneous Transmission of Spread-Spectrum with Different Process Gains

M. Ichiba, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 64 ) page： 27-32 1994.12

A Study on Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Symposium on Information Theory and Its Applications (SITA) Vol. SITA94 ( W44-5 ) page： 417-420 1994.11

Performance of DS/FH-CDMA Over Fading Channels with Near-Far Problem Reviewed Open Access

Y. Shinkaji, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Communications Vol. 77-BII ( 11 ) page： 681-690 1994.11

Effect of Nonlinear Amplification on a Spread Spectrum Signal and Receiver Configurations Reviewed

M. Sawada, T. Yamazato, M. Katayama and A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. 77-A ( 11 ) page： 1855-1862 1994.11

A New Acquisition Scheme for a DS/SS Signal with Frequency Offset

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST94 ( 50 ) page： 19-24 1994.10

LEO Satellite Communication Systems under Nonuniform Traffic Distribution with Spread-Slotted ALOHA

A. Jamalipour, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT94 ( 57 ) page： 15-21 1994.10

A-146 Spectral Efficiency of DS/SS/GMSK System with RAKE Reviewed

ISHIGURO Takayuki, KATAYAMA Masaaki, YAMAZATO Takaya, OGAWA Akira, MAEBARA Tsuneo

Vol. 1994 page： 146 1994.9

A Study on Reception of M-ary/Spread-Spectrum Signals with Carrier Frequency Offset

1994 IEICE Fall Conference Vol. A-145 1994.9

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Papers - YAMAZATO Takaya