研究者詳細 - 田野　哲

論文 - 田野　哲

分割表示 199 件中 161 - 180 件目／全件表示 >>

Coded Packet Immediate Access for Contention-Based Wireless Relay Networks 査読

Daisuke Umehara, Satoshi Denno, Masahiro Morikura, Takatoshi Sugiyama

2010 4TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS) 2010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

This paper proposes a medium access control (MAC) protocol with network coding on relay nodes for contention-based multihop wireless relay networks. The proposed protocol is called coded packet priority access (CPPA) protocol in which coded packets have higher transmission opportunity than non-coded native packets at relay nodes. In this paper, the performance of coded packet immediate access (CPIA) protocols, which are a subclass of CPPA protocols, is evaluated for single-relay bidirectional symmetric traffic and upper and lower bounds of analytical throughput are derived for any given node traffic. It is shown that the lower bound approximates to the throughput obtained from computer simulations with high accuracy. The conventional slotted ALOHA protocol with network coding (SALOHA/NC) is required to adapt the transmission probability of relay node to a rational function of node traffic so as to maximize the throughput whereas the CPIA protocol achieves the maximal throughput only if the relay node transmits no native packets. Furthermore it is clarified that the CPIA protocol is superior to the S-ALOHA/NC protocol in delay for given retransmission probabilities of user nodes.

Achievable Region in Slotted ALOHA Throughput for One-Relay Two-Hop Wireless Network Coding 査読

Daisuke Umehara, Satoshi Denno, Masahiro Morikura, Takatoshi Sugiyama

AD HOC NETWORKS 28 376 - + 2010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：SPRINGER-VERLAG BERLIN

This paper presents achievable regions in slotted ALOHA throughput both without and with network coding for one-relay two-hop wireless networks between two end node groups. In this paper, there are no restrictions on the total traffic and the number of end nodes per group. It follows that the relay node will be generally involved with asymmetric bidirectional traffic. This paper derives closed-form expressions of the throughput and packet delay per group both without and with network coding from a theoretical perspective regardless of whether the buffer on the relay node is saturated or not. Furthermore, we show that the maximum throughput per group with network coding can be achieved at the boundary of the relay buffer saturation and unsaturation which is expressed as the solution of a polynomial equation in two group node traffics. As a result, we clarify the enhancement of the achievable region in slotted ALOHA throughput by applying network coding.

An Iterative Parallel OFDM Demodulation for Fast Time-Varying Fading Channels 査読

田野哲

Proceedings of 4th international conference on signal processing and communication systems 1 2010年

Throughput analysis of two-hop wireless CSMA network coding 査読

Daisuke Umehara, Satoshi Denno, Masahiro Morikura, Takatoshi Sugiyama

IEEE International Conference on Communications 2010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）

This paper considers two-hop wireless systems employing network coding and a carrier sense multiple access (CSMA) protocol. Network coding is a recent and highly regarded technology for the capacity enhancement of multiple unicast and multisource multicast networks. The two-hop wireless CSMA systems are often involved with the hidden node problem, but the impact of the hidden nodes on network coding has not been analyzed in theory. This paper provides explicit expressions of the throughput for single-relay two-hop wireless CSMA systems both without and with network coding. The throughput can be obtained from these expressions for given system parameters even when end nodes via the relay node are hidden each other. Furthermore it is shown that the transmit probability of the relay node is a design parameter that is crucial for maximizing the achievable throughput for CSMA systems with network coding. It is clarified that the throughput for CSMA systems can be enhanced as compared with that for slotted ALOHA systems in case of non-hidden end nodes whereas it deteriorates considerably in case of hidden end nodes. ©2010 IEEE.

DOI： 10.1109/ICC.2010.5502114

Iterative Decoding on Soft Information for Virtual Layered Space-Frequency Receivers 査読

Jun Imamura, Satoshi Denno, Daisuke Umehara, Masahiro Morikura

2010 4TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS) 2010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 this paper, we propose an iteration scheme for the virtual layered space frequency communication architecture. The architecture enables the decoding of the transmitted orthogonal frequency division multiplexing (OFDM)-QPSK signals even if the number of spatial multiplexed layers is twice that of receiving antennas over multipath fading channels. In the proposed iteration scheme, the MAP decoder and detector exchange soft information on the virtual channel. Using the soft informations, the architecture achieves much higher performance with lower computational complexity compared to maximum likelihood detection (MLD) even when the punctured code is used. Consequently, a gain of 4.5 dB can be achieved at a BER of 10-3 compared to that achieved with the MLD in the 4 x 2 MIMO-OFDM system when the rate 3/4 punctured code is used. The performance of the proposed architecture is verified by carrying out computer simulations.

MIMO空間多重伝送における仮想伝搬路判定を適用した逐次復号法

丸山浩史, 田野哲, 梅原大祐, 守倉正博

電子情報通信学会論文誌. B, 通信 = The transactions of the Institute of Electronics, Information and Communication Engineers. B 92 ( 10 ) 1677 - 1686 2009年10月

記述言語：日本語出版者・発行元：一般社団法人電子情報通信学会

MIMO空間多重伝送を用いた無線通信の復号方法の一つに,逐次復号法がある.逐次復号法を利用する場合,送信アンテナ数は受信アンテナ数の同等以下である必要がある.この条件が空間多重伝送の伝送容量を制限していた.本論文では,この条件を緩和し伝送容量を拡大できる新しい直列型逐次復号器の構成を提案する.提案する直列型逐次復号器では,"仮想伝搬路"という概念を導入することで,仮想的に受信アンテナ数を2倍たする.これにより,送信アンテナ数が受信アンテナ数よりも多い場合にも復号を可能にする.このことを計算機シミュレーションにより確認する.

Blind Image-Band Interference Canceller Based on CM (Constant Modulus) Criteria for Multimode Receivers

DENNO Satoshi, FURUNO Tatsuo, MORIKURA Masahiro

IEICE transactions on communications 92 ( 9 ) 2903 - 2914 2009年9月

担当区分：筆頭著者,　責任著者記述言語：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

This paper proposes a blind image-band interference canceller that enables heterodyne receivers with only a single receiver chain to demodulate signals in any frequency band. In this paper, such a receiver is called "multimode/multiband heterodyne receiver." If multimode/multiband receivers are desired to receive signals with carrier frequency ranging from several MHz to GHz, then, such receivers are not allowed to have a narrow band RF-BPF (Radio Frequency Band Pass Filter) at the RF front end. However, although heterodyne receivers have been applied to wireless systems due to their high performance, it is known that without an RF-BPF heterodyne receivers suffer from severe image-band interference. Therefore, a blind image-band interference canceller is proposed in this paper to mitigate the image-band interference. Moreover, a novel algorithm based on the CM (Constant Modulus) criterion is proposed to carry out the cancellation. Performance of the blind image-band interference canceller is theoretically analyzed and the performance of the proposed canceller is verified by computer simulation. As a result, it is shown that the blind image-band interference canceller achieves superior performance even in the presence of strong image-band interference, for example, CIR=-40dB. In summary, the proposed canceller makes it possible for the receiver with the single receiver chain to achieve multimode/multiband communications with high quality.

DOI： 10.1587/transcom.E92.B.2903

高速フェージング伝送路のための並列FFT等化

橋本幸一郎, 田野哲, 梅原大祐, 守倉正博

電子情報通信学会論文誌. B, 通信 = The transactions of the Institute of Electronics, Information and Communication Engineers. B 92 ( 7 ) 1174 - 1184 2009年7月

記述言語：日本語出版者・発行元：一般社団法人電子情報通信学会

FFT等化は簡易なハードウェア構成で優れたマルチパスフェージング耐性を有するが,高速フェージング環境下では等化器出力にひずみが発生し,著しく伝送特性が劣化する.本論文では,この特性劣化を抑圧する並列FFT等化器を提案する.並列FFT等化器では,異なる時刻におけるチャネルインパルス応答を用いて並列にFFT等化を行い,その出力を合成する.更に,フェージングひずみによる特性劣化を抑圧するため,ひずみ補償法も並列化し各等化器に備える.加えて,高速に変動する伝送路を高精度に推定するため,等化復号後の信号を利用した繰返し伝送路推定を適用する.提案する等化器の伝送特性を計算機シミュレーションにより評価し,従来のFFT等化器に比べ大幅に誤り率が改善できることを示す.

Wireless Network Coding in Slotted ALOHA with Two-Hop Unbalanced Traffic 査読

Daisuke Umehara, Tomoya Hirano, Satoshi Denno, Masahiro Morikura, Takatoshi Sugiyama

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 27 ( 5 ) 647 - 661 2009年6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：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper deals with two representative unbalanced traffic cases for two-hop wireless relay access systems employing network coding and a slotted ALOHA protocol. Network coding is a recent and highly regarded technology for capacity enhancement with multiple unicast and multisource multicast networks. We have analyzed the performance of network coding on a two-hop wireless relay access system employing the slotted ALOHA under a balanced bidirectional traffic. The relay nodes will generally undergo this unbalanced multidirectional traffic but the impact of this unbalanced traffic on network coding has not been analyzed. This paper provides closed-form expressions for the throughput and packet delay for two-hop unbalanced bidirectional traffic cases both with and without network coding even if the buffers on nodes are unsaturated. The analytical results are mainly derived by solving queueing systems for the buffer behavior at the relay node. The results show that the transmission probability of the relay node is a design parameter that is crucial to maximizing the achievable throughput of wireless network coding in slotted ALOHA on two-hop unbalanced traffic cases. Furthermore, we show that the throughput is enhanced even if the traffic at the relay node is unbalanced.

DOI： 10.1109/JSAC.2009.090607

A Virtual Layered Space-Frequency Communication Architecture with Iterative Decoding 査読

Jun Imamura, Satoshi Denno, Daisuke Umehara, Masahiro Morikura

GLOBECOM 2009 - 2009 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-8 6339 - 6344 2009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 this study, we develop a virtual layered space-frequency communication architecture. This architecture enables the decoding of transmitted OFDM (Orthogonal Frequency Division Multiplexing)-QPSK signals even if the number of antennas at the transmitter is twice the number of antennas at the receiver over multipath fading channels. Furthermore, we propose two detection schemes called "hard replica" and "soft replica." In addition, in order to improve the performance of this architecture, we propose an iteration in which the receiver decodes the detected signals; through such iterations, this architecture can obtain path diversity and achieve high performance. When the transmitter has four antennas and receiver has two antennas, the proposed architecture achieves HER of 8 x 10(-4) using the soft replica at E-b/N-0 = 15 dB. Furthermore, by performing more iterations, it provides additional gains of 3 dB. The performance of the proposed architecture is verified using computer simulations.

Influences of periodically switching channels synchronized with power frequency on PLC equipment 査読

Daisuke Umehara, Taro Hayasaki, Satoshi Denno, Morikura Masahiro

Journal of Communications 4 ( 2 ) 108 - 118 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Academy Publisher

The regulation on power line communication (PLC) has been eased in Japan, and the frequency band between 2 and 30 MHz can be used for in-home PLC. Several different types of commercial PLC equipment are available in the market. Almost all of them include PLC adapters that interconvert Ethernet signals and power line signals. An in-home network can easily be constructed by using these PLC adapters because there are many power outlets in every room. However, there are various factors that tend to destabilize the communication among PLC adapters. These factors involve time-varying channel response and noise characteristics, which are both synchronized with the power frequency. In particular, it has been observed that the noise in a power line varies more significantly than the channel response. Therefore, many PLC adapters contain certain features to mitigate the time-varying noise in a power line. We show a number of examples of more significant variations in the channel response synchronized with the power frequency due to the switching regulators used. This paper deals with such a time-varying channel response synchronized with the power frequency. We show that the performance of the PLC adapters suffers due the time-varying channel response and analyze its influences on the PLC adapters. © 2009 Academy Publisher.

DOI： 10.4304/jcm.4.2.108-118

A Simulator of Periodically Switching Channels for Power Line Communications 査読

Taro Hayasaki, Daisuke Umehara, Satoshi Denno, Masahiro Morikura

ACCESS NETS 6 162 - 175 2009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：SPRINGER-VERLAG BERLIN

An indoor power line is one of the most attractive media for in-home networks. However, there are many technical problems for achieving in-home power line communication (PLC) with high rate and high reliability. One of such problem is the degradation in the performance of the in-home PLC caused by periodically time-varying channel responses, particularly when connecting the switching power supply equipment. We present a measurement method for power line channel responses and reveal the switching of the channel responses synchronized with power-frequency voltage when connecting switching power supply equipment in sending or receiving outlets. In this paper, we term them periodically switching channel responses. The performance of PLC adapters is seriously affected by the periodically switching channel responses. Therefore, we provide a modeling of the periodically switching channel responses by using finite impulse response (FIR) filters with a shared channel memory and construct a simulator for in-home power line channels including the periodically switching channel responses in order to evaluate the various communication systems through the power line. We present the validity of the proposed simulator through the performance evaluation of OFDM/64QAM over periodically switching channels with additive white Gaussian noise. Furthermore, we evaluate the influence of the periodically switching channel responses on the communication quality of a time-invariant modulation scheme by using the proposed simulator.

A Virtual Layered Space Time Receiver with Maximum Likelihood Channel Detection

DENNO S.

Proc. IEEE VTC' 09 Spring, Barcelona, April 2009年

Throughput Analysis of Wireless Relay Slotted ALOHA Systems with Network Coding 査読

Daisuke Umehara, Tomoya Hirano, Satoshi Denno, Masahiro Morikura

GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE 2008年12月

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

This paper deals with a simple but essential two-hop wireless relay network employing network coding and a slotted ALOHA protocol. Network coding is a recent and highly regarded technology for capacity enhancement on multiple unicast and multisource multicast networks. However, the performance of network coding on wireless relay networks employing random access protocols has not been analyzed. This paper provides closed-form expressions for the throughput and delay on two-hop wireless relay networks both with and without network coding from a theoretical perspective of the slotted ALOHA protocol. The analytical results are derived by solving queueing systems for the buffer activity at the relay node. The results show that the transmission probability of the relay node is a design parameter that is crucial to maximizing the achievable throughput of slotted ALOHA with network coding on a twohop wireless relay network. Furthermore, this paper clarifies that the throughput is enhanced by controlling the transmission probability of the relay node such that it has considerable opportunity for network coding.

DOI： 10.1109/GLOCOM.2008.ECP.953

ヘテロダインマルチモード受信における決定論的補償行列推定

林大祐, 田野哲, 古野辰男, 守倉正博

電子情報通信学会論文誌. B, 通信 = The transactions of the Institute of Electronics, Information and Communication Engineers. B 91 ( 11 ) 1440 - 1449 2008年11月

記述言語：日本語出版者・発行元：一般社団法人電子情報通信学会

マルチモードバンド受信を単一のRF回路により実現するために,ヘテロダイン受信機においてRFフィルタを取り除き,RF帯にアナログヒルベルト変換器を用いる構成が知られている.ところが,マルチモードバンド受信が扱う広範囲な周波数帯においてアナログヒルべルト変換器の特性を理想的に保つことは困難であり,その結果,イメージ干渉が発生し,伝送特性が劣化する問題があった.本論文ではヒルべルト変換器の不完全性をブラインド処理により高速に推定する決定論的手法を提案する.そして,提案手法がOFDMやCDMA方式において,10サンプル程度で所望の推定精度を達成することを示す.また,提案手法に基づく干渉抑圧法が強力なイメージ干渉下でも,所望信号を必要とせずとも高速にイメージ干渉を抑圧できることを示す.

デュアル周波数変換型ヘテロダインマルチモード・マルチバンド受信機

林大祐, 古野辰男, 田野哲

電子情報通信学会論文誌. B, 通信 = The transactions of the Institute of Electronics, Information and Communication Engineers. B 91 ( 5 ) 566 - 574 2008年5月

記述言語：日本語出版者・発行元：一般社団法人電子情報通信学会

ヘテロダイン受信機では,マルチモード化するためにRFフィルタを除去すると,イメージ干渉が発生し,伝送特性を劣化させる.そのため,従来この干渉を適応的に抑圧する技術が提案されている.ただし従来技術では,収束に時間がかかるという問題があった.そこで,本論文では,所望信号とイメージ信号の両方をベースバンド帯に変換し,その後にMMSE規範に基づいて重み付け加算することで,イメージ干渉を除去する方式を提案する.計算機シミュレーションにより,提案手法が高速な収束特性と優れた耐干渉性能を有することを示す.

The influence of time-varying channels synchronized with commercial power supply on PLC equipments 査読

Daisuke Umehara, Taro Hayasaki, Satoshi Denno, Masahiro Morikura

IEEE ISPLC: 2008 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS 30 - 35 2008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

The regulation on power line communication (PLC) has been eased in Japan and the frequency band between 2 and 30 MHz can be exploited for in-home PLC. Several commercial PLC equipments are available in the market. Almost all PLC equipments take on a form of PLC adapters interconverting Ethernet signals and power line signals. We can construct in-home network by these PLC adapters easily because there are many power outlets in every room. However there are various factors destabilizing the communication among PLC adapters. These factors involve time-varying channel response and noise characteristics which are synchronized with commercial power supply. In particular, it has been seen that the noise on power line has significant variations rather than the channel response. Therefore, many PLC adapters are taking some measures to mitigate the time-varying noise on power line. On the other hand, we show a number of examples of more significant variations of the channel response synchronized with power supply due to some kinds of switching regulators. In this paper, we deal with such the time-varying channel response synchronized with commercial power supply. We show that the PLC adapters suffer from the time-varying channel response and analyze its influence on the PLC adapters.

An Initial Acquisition Method for Channel Synchronization on In-home Power Line Communications 査読

Keita Watanabe, Daisuke Umehara, Satoshi Denno, Masahiro Morikura

ISPLC: 2009 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS 137 - 142 2008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 this paper, we propose an initial acuisition method for channel synchronization on in-home broadband power line communication (PLC). It has been considered that the time fluctuation in the transfer function has been smaller than that in the noise on the in-home broadband PLC. However, we have observed that the extensively and rapidly time fluctuation across the whole frequency band appears in the in-home PLC at the half of power cycle intervals while connecting some switching power supply devices. Such largely and quickly, time fluctuation makes the extensive degradation in performance of in-home PLC devices. Therefore, we should estimate the timing of time fluctuation and synchronize the in-home PLC systems with the estimated time fluctuation. We evaluate the performance of the proposed initial acquisition method under impulsive noise environments and investigate its feasibility for the real in-home PLC.

Power Saving Effect of Sensor Collaborative Beam Forming for Wireless Ubiquitous Network Systems

Sousuke Tokunaga, Yoshihisa Kawakami, Kenichi Hashimoto,*Shigeru Tomisato, Satoshi Denno, and Masaharu Hata

Proc. CD of the 14th Asia-Pacific Conference on Communications (APCC2008) 301 - + 2008年

A Bit-Loaded OFDMA for In-home Power Line Communications 査読

Taro Hayasaki, Daisuke Umehara, Satoshi Denno, Masahiro Morikura

ISPLC: 2009 IEEE INTERNATIONAL SYMPOSIUM ON POWER LINE COMMUNICATIONS AND ITS APPLICATIONS 171 - 176 2008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

The in-home broadband power line communication (PLC) is drawing attention to us lately. The broadband PLC has regulation issues for the coexistence with shortwave wireless systems. Therefore, orthogonal frequency division multiplexing (OFDM) is adopted for the broadband PLC. On the other hand the power line channels suffer from frequency selective fading. It is effective to load appropriate bits on each subcarrier in the OFDM for PLC. In this paper, we propose a bit loading algorithm that maximizes the bit rate by optimizing not only the bit quantity on each subcarrier but also the whole code rate of the forward error correction (FEC) code subject to constraints on the total bit error rate (BER) and power on each subcarrier. Furthermore, we investigate orthogonal frequency division multiple access (OFDMA) as a multiple access scheme on the in-home power line networks. We show that the proposed OFDMA scheme is superior to a time division multiple access (TDMA) scheme from the viewpoint of throughput by computer simulations.

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10