研究者詳細 - 山里　敬也

論文 - 山里　敬也

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CDMA ALOHA方式におけるトラヒックの相関性に着目したアクセス制御方式

平山泰弘，岡田啓，山里敬也，片山正昭

電子情報通信学会技術研究報告頁： - 2001年

記述言語：日本語

本研究では, 音声, 動画像, データトラヒックが統合的に扱われるマルチメディア無線パケット通信を扱う. マルチメディアトラヒックは, パケットの発生状況が異なる複数のトラヒックが混在している. 本研究では, このようなマルチメディアトラヒックのためのアクセス制御方式を提案する. この方式は, 未来における音声パケットの発生数の推定値に基づいて, データパケットの送信制御を行う. この推定は音声パケットトラヒックの相関性に着目して行われる. 提案方式をCDMA ALOHA方式に適用した場合の性能を計算機シミュレーションによって評価した結果, オファードロードが増加した場合にデータスループットや音声パケット, 動画像パケットの損失率をある一定値に維持できることを示す.

A design of source matched MAP receiver for image transmission 査読有り

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

Materials Research Society Symposium - Proceedings 626 巻 2001年

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：Materials Research Society Symposium - Proceedings

In this paper we will discuss the MAP receiver design for the reception of the image signal. It is impractical to use the MAP algorithm for the source detection because of its huge calculation costs. To solve this problem we propose a novel MAP receiver structure, where the receiver contains a predictor within it. With an aid of the predictor we can reduce the calculation. Furthermore we can approximate the a priori probability by the prediction error distribution.

Scopus

A new packet detection scheme in CDMA unslotted ALOHA system with successive interference cancellation 査読有り

Tadokoro Y, Okada H, Yamazato T, Katayama A, Ogawa A

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 頁： 3173 - 3177 2001年

An adaptive antenna selection scheme for transmit diversity in OFDM systems 査読有り

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

IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001, VOLS 1-4, PROCEEDINGS 頁： 2168 - 2172 2001年

An adaptive antenna selection scheme for transmit diversity in OFDM systems 査読有り

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

IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001, VOLS 1-4, PROCEEDINGS 頁： 2168 - 2172 2001年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

In wireless communication systems, as one of effective techniques for combating fading, transmit diversity has attracted much attention, especially when receive diversity is expensive or impractical due to the constraint of terminal size. In this study we consider an adaptive carrier-by-carrier basis antenna selection scheme for transmit diversity, in OFDM systems under the assumption that a transmitter has priori knowledge of the Channel State Information(CSI). In the proposed schemes transmit antennas are selected adaptively for each subcarrier according to CSI.

DOI： 10.1109/VTC.2001.957128

Web of Science

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An adaptive antenna selection scheme for transmit diversity in OFDM systems 査読有り

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

IEEE Vehicular Technology Conference 4 巻 ( 54ND ) 頁： 2168 - 2172 2001年

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：IEEE Vehicular Technology Conference

In wireless communication systems, as one of effective techniques for combating fading, transmit diversity has attracted much attention, especially when receive diversity is expensive or impractical due to the constraint of terminal size. In this study we consider an adaptive carrier-by-carrier basis antenna selection scheme for transmit diversity in OFDM systems under the assumption that a transmitter has priori knowledge of the Channel State Information(CSI). In the proposed schemes transmit antennas are selected adaptively for each subcarrier according to CSI.

Scopus

Comparison of CDMA and FDMA/TDMA in non-GEO satellite systems 査読有り

Ichikawa N.

IEEE International Conference on Communications 10 巻頁： 3167 - 3172 2001年

Comparison of CDMA and FDMA/TDMA in non-GEO satellite systems 査読有り

N Ichikawa, M Katayama, H Okada

2001 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-10, CONFERENCE RECORD 頁： 3167 - 3171 2001年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

We compare CDMA and FDMA (or TDMA) schemes in multi-beam non-geostationary satellite systems, taking the effects of antenna patterns on inter-cell interference into consideration. The maximum acceptable number of users per cell in uplink is employed as a measure of the system capacity. We have found that in FDMA (or TDMA) systems the maximum acceptable number of users varies according to the altitude of the satellites, while the performance is insensitive to the altitude in CDMA systems. For this reason, the altitude of the satellites is found to be an important factor for selecting multiple access schemes in non-geostationary satellite systems.

DOI： 10.1109/ICC.2001.937256

Web of Science

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Hierarchical transmission of video signal using multi-code DS/SS modulation based on DCT coefficients 査読有り

Honjo M, Makido S, Yamazato T, Okada H, Katayama M, Ogawa A

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 頁： 3395 - 3399 2001年

New analytical model for the TCP throughput in wireless environment 査読有り

Naito K.

IEEE Vehicular Technology Conference 3 巻 ( 53ND ) 頁： 2128 - 2132 2001年

New analytical model for the TCP throughput in wireless environment 査読有り

Naito K, Okada H, Yamazato T, Katayama M, Ogawa A

IEEE VTC 53RD VEHICULAR TECHNOLOGY CONFERENCE, SPRING 2001, VOLS 1-4, PROCEEDINGS 頁： 2128 - 2132 2001年

Throughput performance of CDMA Slotted ALOHA systems based on average packet success probability considering bit-to-bit dependence 査読有り

Saito M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E84-A 巻 ( 2 ) 頁： 653 - 659 2001年

A new packet detection scheme in CDMA unslotted ALOHA system with successive interference cancellation 査読有り

Y Tadokoro, H Okada, T Yamazato, A Katayama, A Ogawa

GLOBECOM '01: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-6 頁： 3173 - 3177 2001年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

A packet detection is one of the most important problems in packet communication systems. In a CDMA Unslotted ALOHA system, which is one of the wireless packet communication systems, Multiple Access Interference(MAI) makes the performance of the packet detection worse. To reduce the effect of MAI, we propose a new packet detection scheme in this paper. In this scheme, Successive Interference Cancellation(SIC) is applied. The packet's signal is detected after the cancellation of MAI using SIC. This proposed scheme gives good performance of the packet detection.

DOI： 10.1109/GLOCOM.2001.966012

Web of Science

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W-CDMAシステムにおける変形HPSK拡散変調方式招待有り査読有り

藤原昭博, 山里敬也, 片山正昭, 小川明

電子情報通信学会論文誌 J83-A 巻 ( 12 ) 頁： 1552-1557 2000年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）

次世代のW-CDMAでは，拡散変調方式としてHPSK（Hybrid Phase Shift Keying）拡散変調方式の採用が決まっている．しかしこのHPSK拡散変調方式には，帯域外輻射電力特性の改善の余地が残っている．そこで本論文では，HPSK拡散変調方式の帯域外輻射電力特性改善策としてm(modified)-HPSK拡散変調方式を提案し，ビット誤り率特性及び帯域外輻射電力特性においてHPSK拡散変調方式と比較する．

OFDM systems with multiple trellis coded modulation 査読有り

Harada M.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2 巻頁： 814 - 818 2000年12月

An Access Control Protocol for a Heterogeneous Traffic with a Multi-Code CDMA Scheme 査読有り

SANDOUK Abbas, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE Transactions on Fundamentals, A 83 巻 ( 11 ) 頁： 2085 - 2092 2000年11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：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss the access control in multimedia CDMA ALOHA protocol. We introduce a new algorithm for the access control based on Modified Channel Load Sensing Protocol (MCLSP) in an integrated voice and two different classes of data users, high bit rate and low bit rate, exist in a multi-code CDMA Slotted ALOHA system. With our new algorithm, we show that the throughput of high bit rate data users, as well as, the total throughput of the data medium can be optimized and take a maximum value even at high values of offered loads. We also investigate the performance when voice activity detection (VAD) is consideraed in voice transmission.

CiNii Research

An Initial Code Acqusition Scheme for Indoor Packet DS/SS Systems with Macro/Micro Antenna Diversity 査読有り

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

電子情報通信学会英文論文誌 E83-A 巻 ( 11 ) 頁： 2072-2077 2000年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this paper, we study macro/micro diversity techniques for code acquisition of a direct-sequence spread-spectrum signal in an indoor packet communication system. In the system discussed, the base station has several radio ports each with a cluster of antennas, and the terminal also has multiple antennas. The performance in the uplink of this system is analyzed under Lognormal shadowing and flat Rayleigh fading. The numerical results show great performance improvements by proposed diversity techniques. In addition, it is clarified that the mean acquisition time, which is often used as the measure of performance, is not suitable for packet radio systems as it underestimates the necessary preamble length for initial code acquisition.

Efficient Channel Parameter Estimators for DS-CDMA Systems in Slow Time-Varying Channels Using a Modified version of the SAGE Algorithm 査読有り

Y. R. Senhaji, T. Yamazato, M. Katayama, and A. Ogawa

IEEE Global Communications Conference (Globecom2000) 3 巻 ( 3 ) 頁： 1483-1487 2000年11月

記述言語：日本語

A modified version of the SAGE algorithm applied for joint estimation of delays, incidence azimuths and attenuation parameters characterizing the channel is presented. The modifications are based on using different observation intervals in optimizing the parameters and using time correlation in estimating delays, for the purpose of a further reduction in SAGE's computational weight, and improving its accuracy in delay estimation. We show analytically that short observation intervals are sufficient for optimizing the delays and the azimuths, and verify through simulation the reliability of using time correlation. Two other estimators are proposed combining the modified SAGE with a sequential estimation of the attenuation parameters suitable for slowly varying channels.

An Access Control Protocol for a Heterogenous Traffic with a Multi-Code CDMA Scheme 査読有り

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

電子情報通信学会英文論文誌 E83-A 巻 ( 11 ) 頁： 2085-2092 2000年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

An access control protocol for a heterogeneous traffic with a multi-code CDMA scheme 査読有り

Sandouk A, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E83A 巻 ( 11 ) 頁： 2085 - 2092 2000年11月

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