論文 - 山里　敬也

A study of wireless TCP access with base station diversity 査読有り

Naito K, Okada H, Yamazato T, Katayama M

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS   88 巻 ( 9 ) 頁： 49 - 61   2005年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)  

It is known that performance is degraded in Internet access using TCP in a wireless environment, making communications almost impossible. This study proposes a cellular system in which a wireless terminal evaluates its own wireless environment and TCP performance and connects to multiple base stations. The TCP performance in the proposed system is evaluated and it is found to be greatly improved by applying base station diversity. By applying the proposed procedure for selecting the base station to which it will connect, the unnecessary use of wireless resources can be avoided. It is shown that in order to improve TCP performance, the cell radius should be set appropriately for the required TCP performance. © 2005 Wiley Periodicals, Inc.

DOI： 10.1002/ecja.20169

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On the second-order statistics of the channel parameters for BFDM/OQAM systems 査読有り

Mongol B, Yamazato T, Okada H, Katayama M

2ND INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS 2005 (ISWCS 2005)     頁： 534 - 538   2005年

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掲載種別：研究論文（学術雑誌）  

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Performance evaluation of route coding scheme in wireless multi-hop networks 査読有り

Okada H, Wada T, Ohuchi K, Saito M, Yamazato T, Katayama M

VTC2005-SPRING: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, PROCEEDINGS     頁： 3092 - 3096   2005年

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掲載種別：研究論文（学術雑誌）  

Web of Science

Successive interference cancellation for hierarchical parallel optical wireless communication systems 査読有り

Okada H, Masuda K, Yamazato T, Katayama M

2005 ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC), VOLS 1& 2     頁： 788 - 792   2005年

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掲載種別：研究論文（学術雑誌）  

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A simple data relay process and turbo code application to wireless sensor networks 査読有り

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

1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04     頁： 398 - 402   2004年12月

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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：1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04  

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 reencoding process at the intermediate nodes. Farther, 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. © 2004 IEEE.

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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 ISWCS '04     頁： 183 - 187   2004年12月

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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：1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04  

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. © 2004 IEEE.

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Performance analysis of MC-CDMA system with and without guard interval in two-path channel 査読有り

Yamamoto H.

IEEE International Symposium on Spread Spectrum Techniques and Applications     頁： 67 - 71   2004年12月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE International Symposium on Spread Spectrum Techniques and Applications  

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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.

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC   1 巻   頁： 140 - 144   2004年12月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC  

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

Hatano H.

1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04     頁： 115 - 119   2004年12月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：1st International Symposium on Wireless Communication Systems 2004, Proceedings ISWCS '04  

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The optimum received signal-power distribution for CDMA packet communication systems employing successive interference cancellation 査読有り

Tadokoro Y.

IEEE International Symposium on Spread Spectrum Techniques and Applications     頁： 37 - 41   2004年12月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE International Symposium on Spread Spectrum Techniques and Applications  

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

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

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E87A 巻 ( 11 ) 頁： 3001 - 3007   2004年11月

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掲載種別：研究論文（学術雑誌）  

Web of Science

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

Honjo M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences   E87-A 巻 ( 11 ) 頁： 3001 - 3007   2004年11月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  

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

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

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E87A 巻 ( 11 ) 頁： 3001 - 3007   2004年11月

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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  

We propose a novel hierarchical transmission method of DCT coefficients using multi-code DS/SS modulation. For low resolution image transmission over noisy channel, an error resilient and graceful degradation technique is necessary. Here, the DCT coefficients are divided into each stratum (a branch of multi-code DS/SS) and transmitted simultaneously through a noisy channel. By assigning an appropriate transmission energy that corresponds to their source energy variances, energy assignment, it is possible to maintain picture quality effectively even in a noisy channel. Analysis of this method was performed using an image data model, 2-D Gauss-Markov random field, which showed that picture quality is maintained even in the noisy channel condition.

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[招待論文] Information and Signal Processing for Sensor Networks 招待有り 査読有り

A. Ogawa, T. Yamazato, T. Ohtsuki

電子情報通信学会英文論文誌   E87-A 巻 ( 10 ) 頁： 2599-2606   2004年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Sensor networks, in which a large number of sensor nodes are connected with each other through communication networks, are potential to provide extensive new applications with various research and technical challenges and attracting much attention all over the world. In this paper we describe information and signal processing for sensor networks with emphasis on the concepts of collaboration and fusion as one of the most important issues for the sensor networks. We also review some basic aspects of sensor networks in terms of their features and the network architecture.

A Macro and Micro MIMO Diversity Scheme for a Shadowing Environment 査読有り

R. Uchida, H. Okada, T. Yamazato, M. Katayama

International Symposium on Information Theory and Its Applications (ISITA2004)     頁： 1535-1539   2004年10月

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記述言語：英語  

In this paper, we propose a 2-layer spatial diversity scheme to guarantee the reliability of indoor wireless communication/control systems. The performance in uplink is numerically evaluated with the outage probability of a required bit-error rate (BER). As a result, the superiority of the proposed system to conventional ones is clarified.

Performance Evaluation for Error Correcting Scheme on Multiple Routes in Wireless Multi-hop Networks 査読有り

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

International Symposium on Information Theory and Its Applications (ISITA2004)     頁： 1535-1539   2004年10月

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記述言語：英語  

In this paper, we consider the improvement of packet error rate on wireless multi-hop networks. One of the important and interesting techniques for wireless multi-hop networks is multi-path routing. By using multi-path routing, multiple routes can be established from a source node to a destination node. In this paper, we propose the error correcting scheme in which the coded different packets are transmitted using multiple routes on wireless multi-hop networks. Hence, we can achieve a coding gain for multiple routes and expect the improvement of performance. In wireless multi-hop networks, the route loss due to topological change or recognizing failure may be happened. From the above discussion, we evaluate the proposed scheme by packet error rate in consideration of the influence of the route loss.

Information and signal processing for sensor networks 査読有り

Ogawa A, Yamazato T, Ohtsuki T

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E87A 巻 ( 10 ) 頁： 2599 - 2606   2004年10月

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掲載種別：研究論文（学術雑誌）  

Web of Science

Information and signal processing for sensor networks 査読有り

Ogawa A.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences   E87-A 巻 ( 10 ) 頁： 2599 - 2606   2004年10月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  

Scopus

Information and signal processing for sensor networks 査読有り

A Ogawa, T Yamazato, T Ohtsuki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E87A 巻 ( 10 ) 頁： 2599 - 2606   2004年10月

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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  

Sensor networks, in which a large number of sensor nodes are connected with each other through communication networks, are potential to provide extensive new applications with various research and technical challenges and attracting much attention all over the world. In this paper we describe information and signal processing for sensor networks with emphasis on the concepts of collaboration and fusion as one of the most important issues for the sensor networks. We also review some basic aspects of sensor networks in terms of their features and the network architecture.

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Performance Analysis of MC-CDMA System with and without Guard Interval in Two-Path Channel 査読有り

H. Yamamoto, T. Yamazato, H. Okada, and M. Katayama

IEEE International Symposium on Spread Spectrum Techniques and Applications, pp.67-71     頁： 67-71   2004年9月

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記述言語：英語  

In this paper, we analyze the performance of multi-carrier CDMA (MC-CDMA) system with and without guard interval (GI) in two-path channel. As results, we show that the BER performance of two cases are almost the same. This implies the removal of GI for the MC-CDMA system.