Papers - YAMAZATO Takaya

Throughput Analysis for CDMA Unslotted ALOHA Systems with Finite Population Assumption Reviewed Open Access

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

IEICE Transaction on Fundamentals   Vol. J81-A ( 7 ) page： 1089-1092   1998.7

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

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An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

Ishiguro T, Yamazato T, Katayama M, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS   Vol. 81 ( 6 ) page： 51 - 60   1998.6

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An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

T Ishiguro, T Yamazato, M Katayama, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS   Vol. 81 ( 6 ) page： 51 - 60   1998.6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

The CDMA system using DS/SS/GMSK modulation can realize a high spectral efficiency by using the constant-envelope property of GMSK modulation, even if the signal is band-limited and the transmitter is nonlinear. This paper discusses the optimization of a receiver in order to further improve spectral efficiency. The idea is to apply optimal weights to the despreading matrix. Using the signal-to-noise power ratio based on a linear approximation to the DS/SS/GMSK waveform, the weights that minimize the signal-to-noise power ratio are determined. The performance is compared to that of the conventional receiver, in terms of the signal-to-noise power ratio after despreading, the bit error rate, and the spectral efficiency. As a result, we show that performance is improved by applying optimal weights to the despreading matrix. (C) 1998 Scripta Technica.

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An improvement in the performance of DS/SS/CDMA with GMSK Reviewed

Ishiguro T., Yamazato T., Katayama M., Ogawa A.

Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)   Vol. 81 ( 6 ) page： 51 - 60   1998.6

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)  

The CDMA system using DS/SS/GMSK modulation can realize a high spectral efficiency by using the constant-envelope property of GMSK modulation, even if the signal is band-limited and the transmitter is nonlinear. This paper discusses the optimization of a receiver in order to further improve spectral efficiency. The idea is to apply optimal weights to the despreading matrix. Using the signal-to-noise power ratio based on a linear approximation to the DS/SS/GMSK waveform, the weights that minimize the signal-to-noise power ratio are determined. The performance is compared to that of the conventional receiver, in terms of the signal-to-noise power ratio after despreading, the bit error rate, and the spectral efficiency. As a result, we show that performance is improved by applying optimal weights to the despreading matrix. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(6): 51-60, 1998.

DOI： 10.1002/(sici)1520-6424(199806)81:6<51::aid-ecja6>3.3.co;2-h

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The Effect of Channel Error on H.263 Image Transmission

M. Honjo, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

1998 IEICE General Conference, vol.B-5-234, p.598 (1998-3)   Vol. B-5 ( 234 ) page： 598   1998.3

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A Channel Control Scheme using Channel State Information in Multi-Carrier Transmission

T. Shibata, M. Fujimoto, N. Suzuki, K. Nishikawa, T. Yamazato and A. Ogawa

1998 IEICE General Conference   Vol. B-5 ( 23 ) page： 387   1998.3

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Performance Analysis of a Multi Processing-Gain CDMA System with Adaptive Array Antenna at Base Station

L. Zhang, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE   Vol. A・P97 ( 215 ) page： 101-108   1998.2

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A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed Open Access

Okuda S, Katayama M, Yamazato T, Ogawa A

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE   Vol. 81 ( 2 ) page： 24 - 33   1998.2

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A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed Open Access

S Okuda, M Katayama, T Yamazato, A Ogawa

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE   Vol. 81 ( 2 ) page： 24 - 33   1998.2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

This paper considers the direct-sequence spread-spectrum (DS/SS) communication system, and proposes an initial acquisition scheme for the spread signal in an environment where a large frequency offset is included in the carrier. By the proposed scheme, not only is the initial acquisition of the spread signal realized, but also the carrier frequency offset can be estimated to some extent. The proposed configuration assumes acquisition by digital signal processing, using the fast Fourier transform (FFT). Numerical examples are shown for the mean acquisition time and the frequency synchronization characteristics by the proposed scheme, and it is shown that the proposed scheme can realize excellent acquisition performance even if there exists a large frequency offset in the carrier. (C) 1998 Scripta Technica.

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A new acquisition scheme for the DS/SS signal with large carrier frequency offset Reviewed Open Access

Okuda S., Katayama M., Yamazato T., Ogawa A.

Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)   Vol. 81 ( 2 ) page： 24 - 33   1998.2

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)  

This paper considers the direct-sequence spread-spectrum (DS/SS) communication system, and proposes an initial acquisition scheme for the spread signal in an environment where a large frequency offset is included in the carrier. By the proposed scheme, not only is the initial acquisition of the spread signal realized, but also the carrier frequency offset can be estimated to some extent. The proposed configuration assumes acquisition by digital signal processing, using the fast Fourier transform (FFT). Numerical examples are shown for the mean acquisition time and the frequency synchronization characteristics by the proposed scheme, and it is shown that the proposed scheme can realize excellent acquisition performance even if there exists a large frequency offset in the carrier. © 1998 Scripta Technica.

DOI： 10.1002/(sici)1520-6440(199802)81:2<24::aid-ecjc3>3.0.co;2-5

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CDMA slotted ALOHA system with finite buffers Reviewed

Okada H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences   Vol. E81-A ( 7 ) page： 1473 - 1478   1998.1

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Publishing type：Research paper (scientific journal)   Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  

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Queueing analysis of CDMA unslotted aloha systems with finite buffers Reviewed

Okada H.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences   Vol. E81-A ( 10 ) page： 2083 - 2091   1998.1

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Publishing type：Research paper (scientific journal)   Publisher：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  

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Performance Analysis of a Multi Processing-Gain CDMA System with Adaptive Array Antenna at Base Station

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

Technical Report of IEICE   Vol. A・P97-215   page： 101-108   1998

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An Integrated Voice and Multi-Code CDMA Data System for CDMA Slotted-ALOHA with Modified Channel Load Sensing Protocol

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

Symposium on Information Theory and Its Applications (SITA)   Vol. 2   page： 523-526   1998

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Application of TURBO Code to Band-limited VIDEO Signal Transmission

M. Honjo, M. Matsui, T. Yamazato, M. Katayama, and A. Ogawa

Symposium on Information Theory and Its Applications (SITA)   Vol. 26.7,2   page： 619-622   1998

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A Study on Parallel Decording of Turbo-Codes Using Soft-output Viterbi Decorder

M. Matsui, S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE   Vol. IT98 ( 21 ) page： 17-22   1998

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A Study on Cross-Correlation Property in Orthogonal Multi-Code SYstems

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

Technical Report of IEICE   Vol. SST98-13   page： 19-24   1998

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Weight Control Scheme of Adaptive Array Antennas in CDMA Systems

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

Technical Report of IEICE   Vol. CS98-56   page： 39277   1998

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A New Acquisition Scheme of DS/SS Signals using Space Diversity Techniques

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

Technical Report of IEICE   Vol. SST98-24   page： 53-60   1998

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A Channel Control Method for Multi-Carrier Transmission Considering Channel Response Reviewed

T. Shibata, N. Suzuki, M. Fujimoto, K. Nishikawa, T. Yamazato and A. Ogawa

APMC'98   Vol. 3   page： 853-856   1998

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Language：English