Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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A New Code Acquisition Scheme Using Divided Matched Filters for DS/SS Signal with Frequency Offset Reviewed

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

International Conference on Communication Systems page： 379-383 1994

A Study on Quasi-Synchronous CDMA Based on Selected PN Signature Sequences Reviewed

S. Kuno, T. Yamazato, M. Katayama and A. Ogawa

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. ISSSTA94 page： 479-483 1994

Differential Positioning with a Single Satellite Reviewed

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

International Conference on Vehicle Navigation & Information Systems Vol. D2-3 page： 579-584 1994

Performance of CDMA with DS/SS/GMSK Reviewed

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

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. ISSSTA94 page： 564-568 1994

GMSKを用いたSSシステムのサンプリング誤差の影響のシミュレーション

若木勇, 石黒隆之, 片山正昭, 山里敬也, 小川明

1994年電気学会東海支部連合大会 page： 517 1994

Simultaneous Transmission of Spread-Spectrum Signals of Different Process Gains Reviewed

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

International Conference on Communication Systems page： 607-611 1994

DIFFERENTIAL POSITIONING WITH A SINGLE SATELLITE Reviewed

YABUMOTO Y, KATAYAMA M, YAMAZATO T, OGAWA A

1994 VEHICLE NAVIGATION & INFORMATION SYSTEMS CONFERENCE PROCEEDINGS page： A579 - A584 1994

NEAR-FAR PROBLEM ON HYBRID DIRECT-SEQUENCE SLOW-FREQUENCY-HOPPING SPREAD-SPECTRUM MULTIPLE-ACCESS Reviewed

T YAMAZATO, Y SHINKAJI, M KATAYAMA, A OGAWA

WIRELESS NETWORKS - CATCHING THE MOBILE FUTURE, PROCEEDINGS, VOLS I - IV page： 319 - 323 1994

SIGNAL-TO-INTERFERENCE RATIO OF CDMA IN LOW EARTH-ORBITAL SATELLITE COMMUNICATION SYSTEMS WITH NONUNIFORM TRAFFIC DISTRIBUTION Reviewed

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

1994 IEEE GLOBECOM - CONFERENCE RECORD, VOLS 1-3, AND COMMUNICATIONS THEORY MINI-CONFERENCE RECORD page： 1748 - 1752 1994

Study on quasi-synchronous CDMA based on selected PN signature sequences Reviewed

Seiji Kuno, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. 2 page： 479 - 483 1994

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

In this paper, the performance of quasi-synchronous CDMA (QS-CDMA) system, which can allow an increased timing error in synchronized access, is discussed. QS-sequences are selected from M-sequence set or Gold-sequence set in consideration of cross-correlation property, and average BER is calculated for the system with QS-sequences. As a result, average BER of the system with QS-sequences improves considerably compared with asynchronous CDMA when access timing error is within a few chip durations.

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Performance of CDMA with DS/SS/GMSK Reviewed

Akira Ogawa, Masaaki Katayama, Takaya Yamazato, Tsuneo Maebara

IEEE International Symposium on Spread Spectrum Techniques & Applications Vol. 2 page： 564 - 568 1994

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

This paper is concerned with a study result on the performance of an asynchronous CDMA system in which information data are spectrum-spread with PN sequences, and the chip signals are modulated with GMSK. The GMSK signaling has remarkable features such as limited bandwidth and constant envelope, which are attractive for mobile communications. In this paper, the bit error rate performance and the spectral efficiency of the CDMA system are evaluated. As a result of the study, it is indicated that the spectral efficiency of CDMA with DS/SS/GMSK is better than that of CDMA with DS/SS/offset-QPSK in the presence of severe nonlinearity in the mobile transmitter.

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Spread Aloha system which controls the packet transmission by the channel load

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 49 ) page： 31-36 1993.10

A Performance Analysis on the Effects of Traffic Non-Uniformity in Low Earth-Orbit Satellite Communication System

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

Symposium on Information Theory and Its Applications (SITA) Vol. W33-3 page： 203-206 1993.10

Differential Positioning with a Single Satellite

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

Technical Report of IEICE Vol. SAT93 ( 59 ) page： 23-30 1993.10

Spread Aloha system which controls the packet transmission by the channel load

K. Toshimitsu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST93 ( 49 ) page： 31-36 1993.10

Differential Positioning with a Single Satellite

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

Technical Report of IEICE Vol. SST93 ( 59 ) page： 23-30 1993.10

An Experiment of Superposed Transmission on Satellite Communication Channel using Spread Spectrum

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

1993 IEICE Fall Conference Vol. SB-2-5 page： - 1993.9

The Spread ALOHA System with Modified Channel Load Sensing Protocol

K. Toshimitsu, K. Yonekura, T. Yamazato, M. Katayama and A. Ogawa

1993 IEICE Fall Conference Vol. A-124 page： - 1993.9

A NEW VITERBI ALGORITHM WITH ADAPTIVE PATH REDUCTION METHOD Reviewed

YAMAZATO T, SASASE I, MORI S

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E76A ( 9 ) page： 1422 - 1429 1993.9

A NEW VITERBI ALGORITHM WITH ADAPTIVE PATH REDUCTION METHOD Reviewed

T YAMAZATO, SASASE, I, S MORI

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E76A ( 9 ) page： 1422 - 1429 1993.9

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

A new Viterbi algorithm with adaptive path reduction method is presented. The proposed system consists of the pre-decoder and reduced path Viterbi decoder. The pre-decoder separates the mixed channel noise from the received sequence [6]-[9]. The number of errors in the pre-decoded error sequence is counted and the path reduction is implemented by the number of errors in pre-decoded error sequence. The path reduction is implemented as a function of channel condition because the errors in the pre-decoded error sequence can be considered as the channel error sequence. Due to the reduction of the path, the number of ACS (add compare select) operations can be reduced, which occupies the dominant part in Viterbi decoding. The ACS reduction ratio for the proposed system achieves up to 30% for the case of (2, 1, 2) Ungerboeck code without degradation of the error performance.

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Papers - YAMAZATO Takaya