Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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An analytically estimation of GMSK spread spectrum communication system

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

Technical Report of IEICE Vol. SST95 ( 49 ) page： 21-26 1995.9

A Doppler Frequency Estimation Scheme for Block Demodulators in LEO Satellite Communication Systems

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

Technical Report of IEICE Vol. SST95 ( 60 ) page： - 1995.9

NONCOHERENT RECEPTION OF M-ARY SPREAD-SPECTRUM SIGNALS IN THE PRESENCE OF CARRIER FREQUENCY OFFSET Reviewed

T WADA, T YAMAZATO, M KATAYAMA, A OGAWA

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E78A ( 9 ) page： 1102 - 1108 1995.9

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

This paper discusses the performance of noncoherent reception for M-ary spread-spectrum (M-ary/SS) signals in the presence of carrier frequency offset. In general, the M-ary/SS scheme is expected to be of higher spectral efficiency than the conventional DS/SS schemes, but its performance may be degraded by the carrier frequency offset. We: therefore, analyze the effect of carrier frequency offset on the performance of the non-coherent M-ary/SS system with orthogonal modulation using a set of sequences generated by the Hadamard matrix. As a result of the analysis, it has been found that the carrier frequency offset may cause a great deal of degradation in the performance, and that its effect has a distinctive property which is due to the characteristic of Hadamard matrix, at the same time. Making use of this property, we propose two schemes that can mitigate the effect of carrier frequency offset: one is based on choice of the code sequences, the other is on the error correcting code. The effectiveness of the schemes is evaluated in the terms of symbol-error-rates through analysis and computer simulation.

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PERFORMANCE OF BIT-INTERLEAVED TRELLIS-CODED 16-QAM WITH MAXIMIZED CODE DIVERSITY Reviewed

AOYAMA A, NAKAGAWA H, YAMAZATO T, KATAYAMA M, OGAWA A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E78A ( 9 ) page： 1215 - 1219 1995.9

A Receiver Structure with Adaptive Array Antennas for LEO Satellite Communication Systems

H. Sumino, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SAT95 ( 18 ) page： 67-72 1995.7

A Study on Improvement of Performance of GMSK with DS/SS/CDMA

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

Technical Report of IEICE Vol. SST95 ( 41 ) page： 43-48 1995.7

PERFORMANCE OF DS/FH-CDMA OVER FADING CHANNELS WITH NEAR-FAR PROBLEM Reviewed

Y SHINKAJI, T YAMAZATO, M KATAYAMA, A OGAWA

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS Vol. 78 ( 7 ) page： 97 - 107 1995.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA PUBL

The performance of a hybrid direct-sequence/frequency-hopping code-division multiple-access (DS/FHMA) system is investigated in the presence of both the near-far problem and multipath fading. It is confirmed that the error-correcting technique is essential lessening the effect of the near-far problem and that the coded DS/FH system employing the Reed-Solomon forward error-correcting code preforms better than the coded DS system. It is shown also that the path-diversity technique is effective in reducing the degradation caused by multipath fading.
As a result of this study, it is concluded that the DS/FH-CDMA with the error-control code and the path-diversity technique is better suited to solve both near-far problem and multipath fading than DS-CDMA in which an accurate power control is difficult to achieve in such an environment.

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

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

Technical Report of IEICE Vol. SST95-3 page： 13-18 1995.5

Performance Analysis of Spread Unslotted Aloha System Considering Packet Retransmission

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

Technical Report of IEICE Vol. SST95 ( 4 ) page： 19-24 1995.5

A Differential Positioning Scheme witn a Single Satellite to be incorporated into Mobile Communications Reviewed

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

IEICE Transaction on Communications Vol. 78-BII ( 5 ) page： 297-305 1995.5

Throughput of Spread Unslotted Aloha System with Fixed Packet Lengths

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

Technical Report of IEICE Vol. SST94 ( 98 ) page： 31-36 1995.3

A Study on Bit-Interleaved Coded Modulation for a Rayleigh Fading Channel

H. Nakagawa, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS95 ( 47 ) page： 25-30 1995.3

Throughput and Delay of Spread Unslotted Aloha System

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

1995 IEICE General Conference Vol. A-233 page： - 1995.3

Diversity Effect on Coded Modulation System with Bit Interleaver

T. Yamazato, M. Katayama and A. Ogawa

1995 IEICE General Conference Vol. B-396 page： - 1995.3

PERFORMANCE OF AN INTEGRATED VOICE DATA SYSTEM IN NONUNIFORM TRAFFIC LOW-EARTH-ORBIT SATELLITE COMMUNICATION-SYSTEMS Reviewed

A JAMALIPOUR, M KATAYAMA, T YAMAZATO, A OGAWA

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS Vol. 13 ( 2 ) page： 465 - 473 1995.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In some recent studies, the use of low earth-orbit satellites in various applications is considered, In all of these studies, uniform distribution of traffic load is assumed, In this paper, the performance of a low earth-orbit satellite communication system which is designed to service to two kinds of users; i.e., voice users and data users is estimated. The distribution of population of these users is assumed to be nonuniform, According to the simulation results, it is shown that the nonuniformity in traffic affects the performance of the system by decreasing the signal quality at the satellite which has to service to populated areas and increasing it superfluously at the satellite with not so populated service area, in a given period of time, By modeling the satellites during their movements, the change in signal quality while experiencing a peak of traffic load in their route is also determined, A modified power control method based on the amount of traffic load of each satellite is also examined and is shown that this method can make some performance improvements in signal quality, which is limited by special features of low earth-orbit satellite systems.

DOI： 10.1109/49.345892

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A Spread-Spectrum System with Dual Processing Gains Designed for Cyclic Noise in Power Line Communications

H. Niwa, M. Katayama, T. Yamazato, A. Ogawa and N. Isaka

Technical Report of IEICE Vol. SST95-95 page： 31-36 1995

Mon-coherent Reception of M-ary Spread-Spectrum Signals in the Presence of Carrier Frequency Offset Reviewed

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

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E78-A ( 9 ) page： 1102-1108 1995

Performance of Bit-Interleaved Trellis Coded 16-QAM with Maximized Code Diversity Reviewed

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

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E78-A ( 9 ) page： 1215-1219 1995

A Study on Improvement of Performance of CDMA with DS/SS/GMSK Reviewed

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

International Symposium on Communications page： 605-612 1995

Throughput of DS/SSMA Unslotted Aloha System with Channel Load Sensing Reviewed

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

IEEE Global Communications Conference (GLOBECOM'95) Vol. Globecom95 ( 2 ) page： 1492-1496 1995

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Papers - YAMAZATO Takaya