研究者詳細 - 山里　敬也

論文 - 山里　敬也

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BER analysis for multi-carrier DS CDMA with multi-rate traffic 査読有り

Sandouk A, Harada M, Okada H, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E84A 巻 ( 7 ) 頁： 1723 - 1731 2001年7月

BER analysis for multi-carrier DS CDMA with multi-rate traffic 査読有り

Sandouk A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E84-A 巻 ( 7 ) 頁： 1723 - 1731 2001年7月

BER Analysis for Multi-carrier DS CDMA with Multi-rate Traffic 査読有り

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

IEICE Transactions on Fundamentals E84-A 巻 ( 7 ) 頁： 1723-1731 - 1731 2001年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電子情報通信学会

In this letter, we present bit error analysis(BER) of orthogonal multi-carrier direct sequence code division multiple access(DS-CDMA) system with multi-rate (multimedia) traffic. Analysis is carried out with random signature codes for an AWGN channel. Interference in such a system is severe because all users of all media transmit over the same assigned sub-carriers. This makes the analysis difficult. In our analysis, we divide this interference into different types and carry out our analysis to obtain the BER taking into account all these types. We show that the performance of the system is improved as the number of assigned sub-carriers M increases until a limit where the improvement does not continue even when M increases more. This is because of, as we show, the interference due to other sub-carriers becomes constant even in the case of M → ∞, and the interference in a multi-rate multi-carrier system is bigger than that in a single-carrier (M = 1) by a factor of π^2/3.

CiNii Books

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QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks 査読有り

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

電子情報通信学会英文論文誌 E84-B 巻 ( 6 ) 頁： 1588-1595 2001年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this letter, performance evaluation of a system that combines between Code-Division Multiple Access (CDMA) and ALOHA protocol in multimedia networks is presented. In our analysis, we compare the performance between the two basic techniques of ALOHA protocol, i.e., Slotted-ALOHA (S-ALOHA) and Unslotted-ALOHA (U-ALOHA), when combined with CDMA scheme to support voice and data users operating in same CDMA channel. The quality of service (QoS) required for voice and data media is completely taken care of. We obtain the throughput of data media, and the outage probability for voice considering both voice and data offered loads. Throughput performance of S-ALOHA technique is almost twice of that of U-ALOHA. However, we show in this letter that when we combine CDMA with the two basic techniques of ALOHA to accomplish multimedia transmission, both techniques have almost same performance. And, thus, CDMA U-ALOHA can be a good candidate for multimedia networks.

QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks 査読有り

Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS E84B 巻 ( 6 ) 頁： 1588 - 1595 2001年6月

QoS and capacity comparison of CDMA ALOHA protocols in multimedia networks 査読有り

Sandouk A.

IEICE Transactions on Communications E84-B 巻 ( 6 ) 頁： 1588 - 1595 2001年6月

予測誤差に基づいたMAP受信機に関する検討査読有り

牧戸知史, 山里敬也, 岡田啓, 片山正昭, 小川明

映像情報メディア学会誌 55 巻 ( 6 ) 頁： 886-893 - 893 2001年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人映像情報メディア学会

A MAP (Maximum A posteriori Probability) receiver is described that is designed for Markovian sources in a wireless environment. A MAP receiver, a well-known efficient receiver, uses the stochastic characteristics of the source in the decision procedure. However, it is very difficult to implement a MAP algorithm at the front of the receiver because of its calculation costs. To reduce these costs we introduce a source predictor in the receiver. With the aid of the predictor, the MAP detector can be operated with a small calculation cost. Experimental PCM (Pulse Coded Modulation) image transmission demonstrated the feasibility of the proposed receiver. Simulation of the receiver's performance showed it had better MSE (Mean Squared Error) performance in spite of its implementation simplicity.

DOI： 10.3169/itej.55.886

Scopus

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00075825751?from=CiNii

New Analytical Model for the TCP Throughput in Wireless Environment 査読有り

Katsuhiro Naito, Hiraku Okada, Takaya Yamazato, Masaaki Katayama, Akira Ogawa

IEEE Vehicular Technology Conference (VTC-Spring 2001) 3 巻 2001年5月

A-5-22 非同期マルチキャリアCDMA方式のSNIR解析査読有り

村松宏基, 山里敬也, 岡田啓, 片山正昭

電子情報通信学会総合大会講演論文集 2001 巻頁： 181 2001年3月

A-6-4 画像通信に適したMAP受信機の構成に関する検討査読有り

牧戸知史, 本庄勝, 山里敬也, 岡田啓, 片山正昭, 小川明

電子情報通信学会総合大会講演論文集 2001 巻頁： 186 2001年3月

Joint Multi-dimensional Channel Parameter Estimation Schemes for DS-CDMA Systems Using a Modified version of the SAGE Algorithm 査読有り

Youssef R. Senhaji, T. Yamazato, M. Katayama, A. Ogawa

電子情報通信学会英文論文誌 E84-B 巻 ( 3 ) 頁： 511-519 2001年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths when calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

画像通信に適したMAP受信機の構成に関する検討

牧戸知史，本庄勝，山里敬也，岡田啓，片山正昭，小川明

電子情報通信学会総合大会 A-6 巻 ( 4 ) 頁： 186 2001年3月

Adaptive Subcarrier Assignment Schemes for OFDM Systems with Transmit Diversity

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

電子情報通信学会総合大会 SB-139 巻頁： 17-18 2001年3月

非同期マルチキャリアCDMA方式のSNIR解析

村松宏基，山里敬也，岡田啓，片山正昭

電子情報通信学会総合大会 A-5 巻 ( 22 ) 頁： 181 2001年3月

記述言語：日本語

本研究では, 各ユーザがマルチキャリアCDMA方式を用いて非同期に通信を行っている場合を想定し, 信号対雑音干渉電力比(SNIR)の解析を行った. 数値例ではマルチキャリアCDMA方式と従来のDS-CDMA方式のビット誤り率特性を比較し, その結果, 必要とされる帯域幅を考えた場合には, マルチキャリアCDMA方式のほうがビット誤り率特性が良くなることを示した.

Generation of Sets of Sequences Suitable for MulticodeTransmission in Quasi-Synchronous CDMA Systems 査読有り

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

電子情報通信学会英文論文誌 EB-84 巻 ( 3 ) 頁： 576-580 2001年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this letter, we present a method to generate sets of sequences suitable for multicode transmission in quasi-synchronous (QS) CDMA systems. We focus on Gold code but extension to orthogonal Gold code is straightforward. We show that by appropriate classification of sequences, it is possible to have sets whose cross correlation is small in QS situations.

Generation of sets of sequences suitable for multicode transmission in quasi-synchronous CDMA systems 査読有り

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

IEICE TRANSACTIONS ON COMMUNICATIONS E84B 巻 ( 3 ) 頁： 576 - 580 2001年3月

Joint multi-dimensional channel parameter estimation schemes for DS-CDMA systems using a modified version of the SAGE algorithm 査読有り

YR Senhaji, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS E84B 巻 ( 3 ) 頁： 511 - 519 2001年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths wizen calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

Web of Science

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Joint multi-dimensional channel parameter estimation schemes for DS-CDMA systems using a modified version of the SAGE algorithm 査読有り

Senhaji YR, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS E84B 巻 ( 3 ) 頁： 511 - 519 2001年3月

Generation of Sets of Sequences Suitable for MulticodeTransmission in Quasi-Synchronous CDMA Systems 査読有り

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

IEICE Transactions on Communications E84-B 巻 ( 3 ) 頁： 576-580 2001年3月

Generation of sets of sequences suitable for multicode transmission in quasi-synchronous CDMA systems 査読有り

Saito M.

IEICE Transactions on Communications E84-B 巻 ( 3 ) 頁： 576 - 580 2001年3月

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