Papers - YAMAZATO Takaya

Performance evaluation of DS/CDMA communications systems modulated with pi/2-shift BPSK over multipath Rayleigh fading channels Reviewed

Galib MMA, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   Vol. E81A ( 11 ) page： 2304 - 2310   1998.11

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New quasi-synchronous sequences for CDMA slotted ALOHA systems Reviewed

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

IEICE Transactions on Fundamentals   Vol. E81-A ( 11 ) page： 2274 - 2280   1998.11

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

One of unique features of CDMA slotted ALOHA (CDMA S-ALOHA) is that user must synchronize his transmission to give slot. thus orthogonal sequence as spreading sequence would achieve ideal throughput if each of packets accomplish perfect synchronization. In ths presence of any ambiguity in synchronizations, however, quasi-synchronous (QS) sequences suit well with CDMA S-ALOHA system. In this paper, we introduce new QS-sequences obtained from the orthogonal Gold sequences and discuss their performance when applying to CDMA S-ALOHA systems. As a result, withstanding to access timing error, good performance is ensured with this sequence under the environment of AWGN, MAI (multiple access interference) and frequency non-selective fading, that is, micro or pico cellular systems and indoor wireless LANs.

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A Study on the Throughput of Multi-Code CDMA ALOHA System with Modified Channel Load Sensing Protocol

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

Technical Report of IEICE   Vol. SST98 ( 40 ) page： 61-68   1998.10

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Parallel Transmission of Huffman Code Under Fading Environment

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

Technical Report of IEICE   Vol. CS98 ( 117 ) page： IE98-96   1998.10

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Language：Japanese  

Performance of a LEOS Communication System with Overlaid and Overlapped Cell Arrangement

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

Technical Report of IEICE   Vol. SAT98 ( 42 ) page： 39090   1998.10

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Handoff Performance of LEO Satellite Communication Systems with Overlapped-Cell Arrangement

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

1998 IEICE General Conference   Vol. SB-3 ( 13 ) page： 556-557   1998.10

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Error correcting capability of constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   Vol. E81A ( 10 ) page： 2166 - 2169   1998.10

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Queueing analysis of CDMA unslotted ALOHA systems with finite buffers Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   Vol. E81A ( 10 ) page： 2083 - 2091   1998.10

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Queueing Analysis of CDMA Unslotted ALOHA Systems with Finite Buffers Reviewed

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

IEICE Transaction on Fundamentals   Vol. E81-A ( 10 ) page： 2083-2091 - 2091   1998.10

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE  

CDMA unslotted ALOHA system with finite size of quenueing buffers is discussed in this paper. We introduce an analytical model in which the system is divided into two Markov chains; one is in the user part, and the other is in the channel part. In the user part, we can model the queueing behavior of the user station as an M/G/1/B queue. In the channel part, we can consider the number of simulataneously transmitted packets as an M_1+M_2/D/∞//K queue. We analyze the queueing system by using this analytical model, and evaluate the effect of buffer capacity in terms of the throughput, the rejection probability and the average delay. As a result, increase in the buffer size brings about an improvement in the grade of service in terms of higher throughput and lower rejection probability.

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Throughput Performance of QS-CDMA Slotted ALOHA System on 2-path Rayleigh Fading Environment Reviewed

SAITO Masato, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

Proceedings of the Society Conference of IEICE   Vol. 1998   page： 99   1998.9

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

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Performance of Transmit/Receive Antenna Diversity with FEC Coding under Correlated Rician Fading Channels

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

1998 IEICE General Conference   Vol. A-5 ( 8 ) page： 98   1998.9

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Throughput Performance of QS-CDMA Slotted ALOHA System on 2-path Rayleigh Fading Environment

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

1998 Society Conference of IEICE   Vol. A-5-9   page： 99   1998.9

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A Study on Reducing the Nonlinear Distortion in OFDM Systems

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

Technical Report of IEICE   Vol. RCS98 ( 61 ) page： 25-30   1998.7

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

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

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences   Vol. J81-A ( 7 ) page： 1089-1092   1998.7

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CDMA slotted ALOHA system with finite buffers Reviewed

Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   Vol. E81A ( 7 ) page： 1473 - 1478   1998.7

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CDMA Slotted ALOHA System with Finite Buffers Reviewed

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

IEICE Transaction on Fundamentals   Vol. E81-A ( 7 ) page： 1473-1478 - 1478   1998.7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE  

In this paper, CDMA slotted ALOHA system with finite size of buffers is proposed. To analyze the system performance, we use the linear approximate solution based on restricted occupancy urn models. We evaluate the system performance in terms of throughput, average delay, and rejection probability and clarify the effect of buffer capacity.

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

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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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

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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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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