研究者詳細 - 山里　敬也

論文 - 山里　敬也

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Performance Analysis of UWB Impulse Radar Using Parallel IPCP Receiver 査読有り

H. Hatano, H. Okada, T. Yamazato, M. Katayama

1st International Symposium on Wireless Communication Systems 頁： 115-119 2004年9月

記述言語：英語

UWB impulse radar has high accuracy of measurement because it uses a transmitted signal whose pulse length is below some nanosecond. In this paper, we propose two novel inter-period correlation processing (IPCP) receivers for UWB impulse radar. The conventional IPCP receiver uses the signal periodicity of signals, so it avoids estimation of unknown parameters determined by the targets and propagation. However, its accuracy of measurement is poor because the time resolution is restricted to a signal periodicity. We propose a parallel IPCP receiver to improve accuracy. When there are multiple targets, the conventional IPCP receiver needs multiple thresholds to detect. This results in complexity of the receiver. So, we propose a parallel differential IPCP receiver. We present the analysis of the outputs, and the performance of proposed receivers.

A Study on Error Correcting and Diversity Combiner Scheme on Multiple Routes in Wireless Multi-hop Networks 査読有り

H. Okada, N. Koie, N. Nakagawa, T. Yamazato, M. Katayama

1st International Symposium on Wireless Communication Systems 頁： 183-187 2004年9月

記述言語：英語

Wireless multi-hop networks have been much attention for the possibility of flexible construction of the network topology. One of the important and interesting techniques for multi-hop networks is a multi-path routing. By using the multi-path routing, multiple routes from a source node to a destination node can be established. In this paper, we propose the error correcting and diversity combiner scheme on multiple routes in wireless multi-hop networks to reduce bit errors. The diversity combiner outputs the likelihood information from the packets transmitted via multiple routes. By feeding the likelihood information into the Viterbi decoder, the diversity gain can be obtained. We evaluate the packet error rate and the total traffic. As a result, the packet error rate can be improved. Furthermore, the total traffic can be reduced in the low Eb/N0 in spite of the traffic increase due to transmission via redundant routes.

A Simple Data Relay Process and Turbo Code Application to Wireless Sensor Networks 査読有り

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

1st International Symposium on Wireless Communication Systems 頁： 398-402 2004年9月

記述言語：英語

In this study, we focus on relay process of intermediate node of wireless sensor networks. In conventional wireless sensor networks, the intermediate node performs the regenerative repeating process such that error correction, detection and re-encoding are processed. This is reliable, but it requires a lot of processing effort and may take much energy. To reduce a burden of relay process, we propose to omit error decoding and/or re-encoding process at the intermediate nodes. Further, we propose a method that realizes soft-decision decoding for hard-detected signals. With this method, we can employ Turbo code to wireless sensor networks. As results, we show that though omitting the decoding and re-encoding process at the intermediate node may not affect much to the performance.

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks 査読有り

Y. Hirayama, N. Nakagawa, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) PIMRC2004 巻頁： - 2004年9月

記述言語：英語

In real-time packet communications, packet retransmission is generally not used because it may produce undesired delays. In this case, however, packet errors caused by a channel may lead to a loss of transmitted information directly. Then, it is necessary to employ a technique which can reduce the influence of packet errors. We propose to employ a multiple-route packet combining scheme in real-time communications on wireless multihop networks. The scheme can achieve a diversity gain by combining multiple copies of the same packet that are transmitted along different routes. We analyze two characteristics of the proposed system. One is the average packet error probability, which is obtained as a function of elapsed time after transmission requests for copied packets are generated. The other is the required time for achieving a required packet error probability. The results are evaluated from a quality of service (QoS) point of view. From numerical results, it is shown that for a given tolerable delay, there exists a number of multiple routes that minimizes the achievable average packet error probability. Moreover, if the number of multiple routes is selected appropriately, the required time for achieving a required packet error probability can be minimized.

The Optimum Received Signal-Power Distribution for CDMA Packet Communication Systems Employing Successive Interference Cancellation 査読有り

Y. Tadokoro, H. Okada, T. Yamazato, M. Katayama

IEEE International Symposium on Spread Spectrum Techniques and Applications, pp.37-41 頁： 37-41 2004年9月

記述言語：英語

In CDMA packet communication systems employing Successive Interference Cancellation(SIC) scheme, the suppression of MAI depends on the received signal-power distribution, in addition to the cross-correlation characteristic of spreading sequences and the number of transmitted packets. Some works have been done about discovering the received signal-power distribution which makes MAI be suppressed effectively. This distribution minimizes the averaged Bit Error Rate(BER). However, in packet communication systems, it is dominant to the performance if packets can be transmitted successfully or not. Even if the averaged BER is high, many packets can be correctly transmitted. It implies that the optimum distribution on averaged BER does not give the best performance of packet transmission.In this paper, the received signal-power distribution which gives the best performance of packet transmission is derived. Such a distribution will make clear the limit of performance improvement using SIC.

Assisted Highway System Using Reference Course Information and Inter-Vehicle Communications 査読有り

D. Yamakage, T. Yamazato, H. Okada, M. Katayama

The 4th International Workshop on ITS Telecommunications 頁： 181-185 2004年7月

記述言語：英語

In this paper, we propose AHS system using DGPS, RVC and IVC. And, we evaluate the system performance in simulation. From simulation results, we find that if the RVC bit error rate is about 10^-5, it is possible to accomplish the same tracking performance as the case that RVC bit error does not occur. Moreover, we confirm that when IVC packet error rate is less than 10^-3, it can be enough to achieve ideal platooning performance.

基地局ダイバシチを利用したTCP無線接続に関する一検討査読有り

内藤克浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会論文誌 J87-B 巻 ( 4 ) 頁： 512-523 2004年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）

無線環境からのTCPを利用したインターネット接続では, TCPの特性が劣化し通信が殆ど行えなくなることが知られている. 本研究では, 無線端末が自らの無線環境とTCPの特性を評価することで, 複数の基地局に接続するセルラーシステムを提案する. また, 提案システムでのTCPの特性について検討を行う. 結果より, TCPの特性は基地局ダイバシチを利用することにより大幅に改善する. そして, 提案する接続基地局選択手法を利用することで, 無線資源を不必要に利用することも避けることができる. さらに, TCPの特性を改善するためには, 要求されるTCPの特性をもとに, 適切なセル半径を決定する必要があることを示す.

基地局ダイバシチを利用したTCP無線接続に関する一検討査読有り

内藤克浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会論文誌 B J87-B 巻 ( 4 ) 頁： 512 - 523 2004年4月

B-17-17 ソフトウェア受信機におけるサンプリングジッタの受信誤り率への影響(B-17.ソフトウェア無線) 査読有り

鈴木健介, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会総合大会講演論文集 2004 巻 ( 1 ) 頁： 852 2004年3月

An Adaptive PLC Receiver with the Estimation of Instantaneous Noise Power 査読有り

Y. Hirayama, H. Okada, T. Yamazato and M. Katayama

8th International Symposium on Power-Line Communications and Its Applications 頁： 116-121 2004年3月

記述言語：英語

The noise on power-lines is non-stationary, while the instantaneous noise power in different frequency bands are dependent. Under such noise environments, the instantaneous noise power in a frequency band can be estimated by observing the noise in other frequency bands. In this paper, we propose a receiver structure which uses the estimated instantaneous noise power in the decoding process and show its superiority in BER performance to conventional systems.

Performance evaluation for a diversity decoding scheme under multipath environment with OFDM 査読有り

H. Shibata, A. Ogawa, T. Yamazato

2004 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP04) 頁： 25-28 2004年3月

記述言語：英語

This paper is concerned with the performance evaluation for the diversity decoding scheme in which space diversity technique and iterative decoding for non systematic convolutional error-correcting code are effectively combined. The concept of the diversity decoding is applied to an OFDM system (e.g. the digital terrestrial TV broadcasting system). This paper shows the performance evaluation for the diversity decoding scheme under multipath environment with OFDM.

A study of adaptive MMSE receiver operating in thefrequency domain for CDMA system 査読有り

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

2004 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP04) 頁： 57-60 2004年3月

A study on error correcting and diversity combiner scheme on multiple routes in wireless multi-hop networks 査読有り

Okada H, Koie N, Nakagawa N, Yamazato T, Katayama M

1ST INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS 2004, PROCEEDINGS 頁： 183 - 187 2004年

Performance analysis of CDMA Unslotted ALOHA system employing successive interference cancellation 査読有り

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

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE 87 巻 ( 6 ) 頁： 32 - 43 2004年

Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks 査読有り

Y Hirayama, N Nakagawa, H Okada, T Yamazato, M Katayama

2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS 頁： 140 - 144 2004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 real-time packet communications, packet retransmission is generally not used because it may produce undesired delays. In this case, however, packet errors caused by a channel may lead to a loss of transmitted information directly. Then, it is necessary to employ a technique which can reduce the influence of packet errors. We propose to employ a multiple-route packet combining scheme in real-time communications on wireless multihop networks. The scheme, which is proposed in [1], can achieve a diversity gain by combining multiple copies of the same packet that are transmitted along different routes. We analyze two characteristics of the proposed system. One is the average packet error probability, which is obtained as a function of elapsed time after transmission requests for copied packets are generated. The other is the required time for achieving a required packet error probability. The results are evaluated from a quality of service (QoS) point of view. From numerical results, it is shown that for a given tolerable delay, there exists a number of multiple routes that minimizes the achievable average packet error probability. Moreover, if the number of multiple routes is selected appropriately, the required time for achieving a required packet error probability can be minimized.

DOI： 10.1109/PIMRC.2004.1370852

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Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks 査読有り

Hirayama Y, Nakagawa N, Okada H, Yamazato T, Katayama M

2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS 頁： 140 - 144 2004年

Performance analysis of UWB impulse radar using parallel IPCP receiver 査読有り

Hatano H, Okada H, Yamazato T, Katayama M

1ST INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS 2004, PROCEEDINGS 頁： 115 - 119 2004年

周波数選択性フェージング環境下における非同期MC-CDMA方式のSNIR解析査読有り

竹内裕志, 山里敬也, 岡田啓, 片山正昭

電子情報通信学会論文誌 J86-A 巻 ( 12 ) 頁： 1426-1430 2003年12月

周波数選択性フェージング環境下における非同期MC-CDMA方式のSNIR解析査読有り

竹内裕志, 山里敬也, 岡田啓, 片山正昭

電子情報通信学会論文誌 J86-A 巻 ( 12 ) 頁： 1426-1430 2003年10月

符号化OFDM通信方式における複数シンボルマッピングによる最大瞬時電力抑圧手法査読有り

原田政明, 山里敬也, 岡田啓, 片山正昭, 小川明

電子情報通信学会論文誌 J86-A 巻 ( 10 ) 頁： 1058-1067 2003年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本論文では, 畳込み符号を適用したときのOFDM信号の最大瞬時電力抑圧手法を示す. まず, 畳込み符号化されたビット列をピーク電力を低く抑える複数のシンボルへマッピングすることを考える. 通常の方式では, 符号化されたビットは 1つづつ順次マッピングされていく. このような方法では, 各サブキャリヤへ割り当てるシンボルは互いに無相関の関係にあり, 最大瞬時電力を低くおさえるように相関をもたせるのは困難である. 提案する方式では, 符号化されたビット列を最大瞬時電力を低くおさえるように相関をもたせた複数のシンボルへマッピングするため, OFDM信号のピーク電力を通常の方式より低くおさえることが可能である. また, この複数シンボル全体の集合を集合分割することによって, 複数シンボル間のユークリッド距離を大きくすることを考え, 特性の改善を図る. この手法は, 複数のシンボルへ集合分割を行うMTCM (Multiple Trellis Coded Modulation)によって可能になる. 提案方式の有効性を評価するため, 非直線増幅器の影響が存在する環境下において, シミュレーションを行い, その有効性を示す.

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