Nishimura Toshihiko
| Faculty of Information Science and Technology Media and Network Technologies Information Communication Systems | Professor |
| Institute for the Promotion of Business-Regional Collaboration | Professor |
| Institute for the Advancement of Higher Education | Professor |
Last Updated :2025/11/11
■Researcher basic information
Degree
Researchmap personal page
Home Page URL
J-Global ID
Research Keyword
Research Field
Educational Organization
- Bachelor's degree program, School of Engineering
- Master's degree program, Graduate School of Information Science and Technology
- Doctoral (PhD) degree program, Graduate School of Information Science and Technology
■Career
Career
- Sep. 2021 - Present
Hokkaido University, Faculty of Information Science and Technology, Proffesor, Japan - Apr. 2017 - Aug. 2021
Hokkaido University, Graduate School of Information Science and Technology, 准教授 - 2007 - Mar. 2017
Hokkaido University, Graduate School of Information Science and Technology, 助教 - 1998 - 2007
Hokkaido University, Graduate School of Engineering, 助手
Committee Memberships
■Research activity information
Awards
Papers
- Strategies for DOA-DNN Estimation Accuracy Improvement at Low and High SNRs
Daniel Akira Ando, Toshihiko Nishimura, Takanori Sato, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
IEICE Transactions on Communications, 1, 17, Institute of Electrical and Electronics Engineers (IEEE), 2024, [Peer-reviewed]
English, Scientific journal - Deep Neural Networks Based End-to-End DOA Estimation System
Daniel Akira ANDO, Yuya KASE, Toshihiko NISHIMURA, Takanori SATO, Takeo OHGANE, Yasutaka OGAWA, Junichiro HAGIWARA
IEICE Transactions on Communications, E106.B, 12, 1350, 1362, Institute of Electronics, Information and Communications Engineers (IEICE), 01 Dec. 2023, [Peer-reviewed]
English, Scientific journal - Study on Subarray Beam Allocation for Sub-Terahertz-Band MIMO Spatial Multiplexing in Indoor Office Environments
TOSHIHIKO NISHIMURA
IEICE Proceeding Series, 29 Nov. 2023, [Domestic magazines]
English, Scientific journal - Performance Analysis of DNN-PCA for DOA Estimation with Three Radio Wave Sources
Daniel Akira Ando, Toshihiko Nishimura, Takanori Sato, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
2023 22nd International Symposium on Communications and Information Technologies (ISCIT), IEEE, 16 Oct. 2023
English, International conference proceedings - Smart Radio Environments with Intelligent Reflecting Surfaces for 6G Sub-Terahertz-Band Communications
Yasutaka OGAWA, Shuto TADOKORO, Satoshi SUYAMA, Masashi IWABUCHI, Toshihiko NISHIMURA, Takanori SATO, Junichiro HAGIWARA, Takeo OHGANE
IEICE Transactions on Communications, E106.B, 9, 735, 747, Institute of Electronics, Information and Communications Engineers (IEICE), 01 Sep. 2023, [Peer-reviewed], [Invited]
Scientific journal - Channel Prediction Based on Multipath Delay Estimation for Sub-Terahertz-Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄
電子情報通信学会論文誌 B(Web), J106-B, 6, 361, 372, 電子情報通信学会, 01 Jun. 2023, [Peer-reviewed]
Japanese, A sub-Terahertz band above 100 GHz will be used in 6G for extremely high-speed communication. In such a high frequency band, channels change rapidly in time-varying environments. The channel information obtained using pilot symbols may deviate from the actual channel information over time, resulting in degradation of channel characteristics. Thus, it is expected to be effective to predict channels at a future time. Since the number of multipaths in sub-THz bands is extremely small, we can resolve them and predict the channel. In this paper, we assume a MIMO system with a hybrid beamforming architecture, and resolve multipaths incident on a subarray in the delay domain with FISTA, one of the compressed sensing algorithms. Using the resolved multipaths, we predict the future channels. It is shown that the prediction technique works well, and that we can achieve the normalized mean square error from -30 dB to -20 dB. - Near-Optimal Stochastic MIMO Signal Detection with a Mixture of T-Distributions Prior
Junichiro Hagiwara, Kazushi Matsumura, Hiroki Asumi, Yukiko Kasuga, Toshihiko Nishimura, Takanori Sato, Yasutaka Ogawa, Takeo Ohgane
GLOBECOM 2023 - 2023 IEEE Global Communications Conference, 6627, 6633, 2023, [Peer-reviewed]
English, International conference proceedings - Sub-Terahertz MIMO Spatial Multiplexing in Indoor Propagation Environments
OGAWA Yasutaka, UTSUNO Taichi, NISHIMURA Toshihiko, OHGANE Takeo, SATO Takanori
IEICE Transactions on Communications, E105.B, 10, 1130, 1138, The Institute of Electronics, Information and Communication Engineers, 01 Oct. 2022, [Peer-reviewed], [Invited]
English, A sub-Terahertz band is envisioned to play a great role in 6G to achieve extreme high data-rate communication. In addition to very wide band transmission, we need spatial multiplexing using a hybrid MIMO system. A recently presented paper, however, reveals that the number of observed multipath components in a sub-Terahertz band is very few in indoor environments. A channel with few multipath components is called sparse. The number of layers (streams), i.e. multiplexing gain in a MIMO system does not exceed the number of multipaths. The sparsity may restrict the spatial multiplexing gain of sub-Terahertz systems, and the poor multiplexing gain may limit the data rate of communication systems. This paper describes fundamental considerations on sub-Terahertz MIMO spatial multiplexing in indoor environments. We examined how we should steer analog beams to multipath components to achieve higher channel capacity. Furthermore, for different beam allocation schemes, we investigated eigenvalue distributions of a channel Gram matrix, power allocation to each layer, and correlations between analog beams. Through simulation results, we have revealed that the analog beams should be steered to all the multipath components to lower correlations and to achieve higher channel capacity. - Parameter-Learned AMP for MIMO Signal Detection
Mari Miyoshi, Wakaba Tsujimoto, Toshihiko Nishimura, Takanori Sato, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
2022 IEEE VTS Asia Pacific Wireless Communications Symposium (APWCS), IEEE, 24 Aug. 2022
International conference proceedings - Accuracy Improvement in DOA Estimation with Deep Learning
KASE Yuya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, SATO Takanori, KISHIYAMA Yoshihisa
IEICE Transactions on Communications, E105.B, 5, 588, 599, The Institute of Electronics, Information and Communication Engineers, 01 May 2022, [Peer-reviewed]
English, Direction of arrival (DOA) estimation of wireless signals is demanded in many applications. In addition to classical methods such as MUSIC and ESPRIT, non-linear algorithms such as compressed sensing have become common subjects of study recently. Deep learning or machine learning is also known as a non-linear algorithm and has been applied in various fields. Generally, DOA estimation using deep learning is classified as on-grid estimation. A major problem of on-grid estimation is that the accuracy may be degraded when the DOA is near the boundary. To reduce such estimation errors, we propose a method of combining two DNNs whose grids are offset by one half of the grid size. Simulation results show that our proposal outperforms MUSIC which is a typical off-grid estimation method. Furthermore, it is shown that the DNN specially trained for a close DOA case achieves very high accuracy for that case compared with MUSIC. - A Proposal of an End-to-End DoA Estimation System Aided by Deep Learning
Daniel Akira Ando, Toshihiko Nishimura, Takanori Sato, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
International Symposium on Wireless Personal Multimedia Communications, WPMC, 2022-October, 98, 103, 2022
International conference proceedings - Shared Dataset Initiative toward Applications of Machine Learning and Mathematical Optimization for Wireless Communications
丸田一輝, 井田悠太, 實松豊, 牟田修, 岡田啓, 西村寿彦, 岡本英二, 眞田幸俊, 村田英一, 田野哲
電子情報通信学会誌, 105, 6, 2022 - A Novel MIMO Signal Detection Method Using Hamiltonian Monte Carlo Approach
Kazushi Matsumura, Junichiro Hagiwara, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Takanori Sato
2021 24th International Symposium on Wireless Personal Multimedia Communications (WPMC), IEEE, 14 Dec. 2021
International conference proceedings - Wireless Communications Merging with Photonics
西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄
電子情報通信学会誌, 104, 5, 485, 489, 電子情報通信学会, May 2021, [Invited], [Lead author]
Japanese - Fundamental Trial on DOA Estimation with Deep Learning
Yuya KASE, Toshihiko NISHIMURA, Takeo OHGANE, Yasutaka OGAWA, Daisuke KITAYAMA, Yoshihisa KISHIYAMA
IEICE Transactions on Communications, E103.B, 10, 1127, 1135, Institute of Electronics, Information and Communications Engineers (IEICE), 01 Oct. 2020, [Peer-reviewed], [Domestic magazines]
English, Scientific journal - Performance Evaluation of Beam Shapes in a Two-Step-Precoded Massive MIMO System
Jumpei Yamamoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Daiki Takeda, Yoshihisa Kishiyama
IEICE TRANSACTIONS ON COMMUNICATIONS, E103B, 6, 703, 711, 01 Jun. 2020, [Peer-reviewed], [Domestic magazines]
English, Scientific journal - Maximum Ratio Transmission for OAM Mode Multiplexing Using Multiple UCAs
Ayano Yamamoto, Toshihiko Nishimura, Takeo Ohgane, Tomoya Tandai, Daisuke Uchida
2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020), Mar. 2020, [Peer-reviewed]
English, International conference proceedings - Channel Prediction of Wideband OFDM Systems in a Millimeter-Wave Band Using Delay-Domain Multipath Detection
Yuta Takano, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, Junichiro Hagiwara
2020 International Workshop on Antenna Technology (iWAT), IEEE, Feb. 2020, [Peer-reviewed]
International conference proceedings - 包絡線変動量を抑圧する位相回転送信ダイバーシチを適用した狭帯域パイロットレス同期検波FSK方式
TOSHIHIKO NISHIMURA
電子情報通信学会論文誌 B, J103-B, 2, 100, 109, 01 Feb. 2020, [Peer-reviewed], [Last author], [Domestic magazines]
Japanese, Scientific journal - Radio Techniques Incorporating Sparse Modeling
Toshihiko NISHIMURA, Yasutaka OGAWA, Takeo OHGANE, Junichiro HAGIWARA
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Institute of Electronics, Information and Communications Engineers (IEICE), 2020, [Peer-reviewed], [Invited], [Lead author], [Domestic magazines]
English, Scientific journal - A Study on Iterative Equalization with GaBP and Soft Successive Cancellation List Decoding in a Polar-Coded System
Kentaro Fukuda, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
2019 22nd International Symposium on Wireless Personal Multimedia Communications (WPMC), IEEE, Nov. 2019, [Peer-reviewed]
International conference proceedings - A Study on Large-Scale Signal Detection Using Gaussian Belief Propagation in Overloaded Interleave Division Multiple Access
Wataru Kawabata, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2019 22nd International Symposium on Wireless Personal Multimedia Communications (WPMC), IEEE, Nov. 2019, [Peer-reviewed]
English, International conference proceedings - Performance Analysis of DOA Estimation of Two Targets Using Deep Learning
Yuya Kase, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Daisuke Kitayama, Yoshihisa Kishiyama
2019 22nd International Symposium on Wireless Personal Multimedia Communications (WPMC), IEEE, Nov. 2019, [Peer-reviewed]
International conference proceedings - A Study on Performance Improvement by CRC-Aided GaBP for Large-Scale SCMA Detection
Renjie Li, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
2019 22nd International Symposium on Wireless Personal Multimedia Communications (WPMC), IEEE, Nov. 2019, [Peer-reviewed]
International conference proceedings - A Narrow-Band Coherent FSK Transmission System Using Phase Rotated Transmit Diversity with Suppression of Envelope Fluctuation
Kanako Yamaguchi, Masatsugu Higashinaka, Hiroyasu Sano, Atsushi Okamura, Takeo Ohgane, Toshihiko Nishimura
2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall), IEEE, Sep. 2019, [Peer-reviewed]
International conference proceedings - Computational Complexity Reduction of Receive Weight Matrices in Massive MIMO SC-FDF†
Kensei Saito, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, Junichiro Hagiwara
2019 International Conference on Computing, Networking and Communications (ICNC), IEEE, Feb. 2019
International conference proceedings - A Study on Layouts of Distributed Antenna Arrays in an Indoor Multi-User Massive MIMO System.
Yuya Suzuki, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
International Conference on Computing, Networking and Communications(ICNC), 29, 33, IEEE, 2019
International conference proceedings - Prediction of Time-Varying Multi-User MIMO Channels Based on DOA Estimation Using Compressed Sensing
Uehashi, Shunsuke, Ogawa, Yasutaka, Nishimura, Toshihiko, Ohgane, Takeo
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, 68, 1, 565, 577, Jan. 2019, [Peer-reviewed]
English, Scientific journal - Evaluation of OAM Mode Multiplexing Considering Ground Reflection
Yamamoto, Ayano, Nishimura, Toshihiko, Ohgane, Takeo, Tandai, Tomoya, Uchida, Daisuke
2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), 2019, [Peer-reviewed]
English, International conference proceedings - Performance Comparison of Compressed Sensing Algorithms for DOA Estimation of Multi-band Signals
Toyoki Hoshikawa, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Junichiro Hagiwara
2018 15th Workshop on Positioning, Navigation and Communications (WPNC), IEEE, Oct. 2018, [Peer-reviewed]
International conference proceedings - DOA Estimation of Two Targets with Deep Learning
Yuya Kase, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Daisuke Kitayama, Yoshihisa Kishiyama
2018 15th Workshop on Positioning, Navigation and Communications (WPNC), IEEE, Oct. 2018, [Peer-reviewed]
International conference proceedings - MIMO SC-FDEにおける受信ウェイトの補間精度の劣化とその軽減法
TOSHIHIKO NISHIMURA
電子情報通信学会論文誌B, J101.B, 7, 01 Jul. 2018, [Peer-reviewed], [Domestic magazines]
Japanese, Scientific journal - A Basic Study on Antenna Selection for Loose Beamforming in a Massive MIMO System
Koichi Inoue, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2018 IEEE INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY (IWAT), Mar. 2018, [Peer-reviewed] - Performance Evaluation on Beam Shapes of a Large MIMO System
Jumpei Yamamoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Daiki Takeda, Yoshihisa Kishiyama
2018 IEEE INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY (IWAT), 2018, [Peer-reviewed]
English, International conference proceedings - Superposed 16-QAM Signal Detection Using GaBP in a Massive MIMO System
Watabe, Taisei, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, Hagiwara, Junichiro
2018 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA ASC), 1416, 1420, 2018, [Peer-reviewed]
English, International conference proceedings - Signal Detection with Belief Propagation in Faster-than-Nyquist Signaling
K. Kihara, T. Nishimura, T. Ohgane, Y. Ogawa
2017 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA ASC 2017), 1790, 1794, Dec. 2017, [Peer-reviewed] - 移動通信における信号処理アンテナの進展
TOSHIHIKO NISHIMURA
電子情報通信学会論文誌B, J100.B, 9, 658, 672, 01 Sep. 2017, [Peer-reviewed], [Domestic magazines]
Japanese, Scientific journal - Node Selection for Belief Propagation Based Channel Equalization
Mitsuyoshi Hagiwara, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E100B, 8, 1285, 1292, Aug. 2017, [Peer-reviewed]
English, Scientific journal - Serial and Parallel LLR Updates Using Damped LLR for LDPC Coded Massive MIMO Detection with Belief Propagation
Shuhei Tanno, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E100B, 8, 1277, 1284, Aug. 2017, [Peer-reviewed]
English, Scientific journal - Performance Comparison of Full-Dimension MIMO Systems with Different Base Station Places
Shun Nishizaki, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2017 INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY: SMALL ANTENNAS, INNOVATIVE STRUCTURES, AND APPLICATIONS (IWAT), 335, 338, 2017, [Peer-reviewed]
English, International conference proceedings - A Performance Comparison of Compressed Sensing Algorithms for Scatterer Detection
Daisuke Abe, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
2017 INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY: SMALL ANTENNAS, INNOVATIVE STRUCTURES, AND APPLICATIONS (IWAT), 74, 77, 2017, [Peer-reviewed]
English, International conference proceedings - Suppression of Scattering Waves from the Outside of a Search Area Using a Gating Technique in Compressed Sensing Based Scatterer Detection
Daisuke Abe, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
2016 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), 1008, 1009, 2016, [Peer-reviewed]
English, International conference proceedings - BP-based Detection of Spatially Multiplexed 16-QAM Signals in a Fully Massive MIMO System
Usami, Tomoya, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka
2016 INTERNATIONAL CONFERENCE ON COMPUTING, NETWORKING AND COMMUNICATIONS (ICNC), 2016, [Peer-reviewed]
English, International conference proceedings - A Comparison of Serial and Parallel LLR Updates for LDPC Coded Massive MIMO Detection with Belief Propagation
Shuhei Tanno, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
PROCEEDINGS OF 2016 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS (ISITA 2016), 473, 477, 2016, [Peer-reviewed]
English, International conference proceedings - Parameter Settings on DOA Estimation of Multi-band Signals Using a Compressed Sensing Technique
Toshihiko Nishimura, Taiki Endo, Takeo Ohgane, Yasutaka Ogawa
2016 ASIA-PACIFIC SIGNAL AND INFORMATION PROCESSING ASSOCIATION ANNUAL SUMMIT AND CONFERENCE (APSIPA), 2016, [Peer-reviewed]
English, International conference proceedings - Node Selection and LLR Damping for Channel Equalization with Belief Propagation
Mitsuyoshi Hagiwara, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
PROCEEDINGS OF 2016 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS (ISITA 2016), 483, 487, 2016, [Peer-reviewed]
English, International conference proceedings - DOA Estimation of Signals with Frequency Characteristics and Different Powers using a Compressed Sensing Technique
Taiki Endo, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
2016 IEEE INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY (IWAT), 192, 195, 2016, [Peer-reviewed]
English, International conference proceedings - Performance Evaluation of Alternative Routing in a Wireless Mesh Network with an Adaptive Array
Kosuke Suzuki, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2016 INTERNATIONAL CONFERENCE ON COMPUTING, NETWORKING AND COMMUNICATIONS (ICNC), 2016, [Peer-reviewed]
English, International conference proceedings - Channel Prediction Using Compressed Sensing in Multi-User MIMO Systems
Uehashi, Shunsuke, Ogawa, Yasutaka, Nishimura, Toshihiko, Ohgane, Takeo
2016 INTERNATIONAL CONFERENCE ON COMPUTING, NETWORKING AND COMMUNICATIONS (ICNC), 2016, [Peer-reviewed]
English, International conference proceedings - A Throughput Evaluation of an Over-Distributed Antenna System with Limited Pilot Resources
Yuki Nakanishi, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yusuke Ohwatari, Yoshihisa Kishiyama
IEICE TRANSACTIONS ON COMMUNICATIONS, E98B, 8, 1465, 1473, Aug. 2015, [Peer-reviewed]
English, Scientific journal - Iterative angle-and-time-domain gating technique for time-reversal MUSIC imaging
Heedong Choi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
SIGNAL PROCESSING, 111, 39, 49, Jun. 2015, [Peer-reviewed]
English, Scientific journal - Performance Evaluation of Full-Dimension MIMO in Indoor Line-of-Sight Environments
Hayato Fukuda, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
2015 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), 159, 164, 2015, [Peer-reviewed]
English, International conference proceedings - Comparison of Kalman Smoother to Wiener Smoother in Practical OFDM Channel Estimation
Junichiro Hagiwara, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2015 21ST ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC), 454, 459, 2015, [Peer-reviewed]
English, International conference proceedings - Channel Prediction Techniques for a Multi-User MIMO System in Time-Varying Environments
Yamaguchi, Kanako, Huu Phu Bui, Ogawa, Yasutaka, Nishimura, Toshihiko, Ohgane, Takeo
IEICE TRANSACTIONS ON COMMUNICATIONS, E97B, 12, 2747, 2755, Dec. 2014, [Peer-reviewed]
English, Scientific journal - Channel prediction techniques for a multi-user MIMO system in time-varying environments
Kanako Yamaguchi, Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEICE Transactions on Communications, E97B, 12, 2747, 2755, 01 Dec. 2014, [Peer-reviewed]
English, Scientific journal - DOA Estimation for Multi-Band Signal Sources Using Compressed Sensing Techniques with Khatri-Rao Processing
Terada, Tsubasa, Nishimura, Toshihiko, Ogawa, Yasutaka, Ohgane, Takeo, Yamada, Hiroyoshi
IEICE TRANSACTIONS ON COMMUNICATIONS, E97B, 10, 2110, 2117, Oct. 2014, [Peer-reviewed]
English, Scientific journal - マルチユーザMIMO―マルチアンテナとマルチユーザの相乗効果による通信速度向上―3.時変動環境におけるマルチユーザMIMOシステム
小川恭孝, 西村寿彦, 大鐘武雄
電子情報通信学会誌, 97, 4, 285, 289, 01 Apr. 2014
Japanese - Performance Investigation of Reduced Complexity Bit-Flipping using Variable Thresholds and Noise Perturbation
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka
2014 16TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY (ICACT), 206, +, 2014, [Peer-reviewed]
English, International conference proceedings - DOA Estimation by Applying Compressed Sensing Techniques
Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
2014 IEEE INTERNATIONAL WORKSHOP ON ELECTROMAGNETICS (IEEE IWEM): APPLICATIONS AND STUDENT INNOVATION COMPETITION, 121, 122, 2014, [Peer-reviewed]
English, International conference proceedings - Antenna splitting in a distributed antenna system for a multiuser MIMO transmission
Yuki Nakanishi, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yusuke Ohwatari, Yoshihisa Kishiyama
2014 IEEE 25TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATION (PIMRC), 193, 197, 2014, [Peer-reviewed]
English, International conference proceedings - DOA Estimation of Multi-band Signals Using a Compressed Sensing Technique
Terada, Tsubasa, Nishimura, Toshihiko, Ogawa, Yasutaka, Ohgane, Takeo, Yamada, Hiroyoshi
2014 INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY: "SMALL ANTENNAS, NOVEL EM STRUCTURES AND MATERIALS, AND APPLICATIONS" (IWAT), 359, 362, 2014, [Peer-reviewed]
English, International conference proceedings - DOA Estimation of Correlated Wideband Signals by using Multi-band EM Algorithm
Yamada, Hiroyoshi, Shirai, Satoshi, Nishimura, Toshihiko, Ogawa, Yasutaka, Ohgane, Takeo, Yamaguchi, Yoshio
2014 USNC-URSI RADIO SCIENCE MEETING (JOINT WITH AP-S SYMPOSIUM), 205, 205, 2014, [Peer-reviewed]
English - Behavior of a Multi-User MIMO System in Time-Varying Environments
Yasutaka Ogawa, Kanako Yamaguchi, Huu Phu Bui, Toshihiko Nishimura, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E96B, 10, 2364, 2371, Oct. 2013, [Peer-reviewed]
English, Scientific journal - Performance Evaluation of a Multi-User MIMO System With Prediction of Time-Varying Indoor Channels
Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 61, 1, 371, 379, Jan. 2013, [Peer-reviewed]
English, Scientific journal - Complexity Reduction for Signal Detection Based on Belief Propagation in a Massive MIMO System
Wataru Fukuda, Takashi Abiko, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yusuke Ohwatari, Yoshihisa Kishiyama
2013 INTERNATIONAL SYMPOSIUM ON INTELLIGENT SIGNAL PROCESSING AND COMMUNICATIONS SYSTEMS (ISPACS), 245, 250, 2013, [Peer-reviewed]
English, International conference proceedings - A Study on a Multi-User Single-Carrier E-SDM Scheme in Wideband Transmissions
Keita Harada, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
2013 INTERNATIONAL SYMPOSIUM ON INTELLIGENT SIGNAL PROCESSING AND COMMUNICATIONS SYSTEMS (ISPACS), 240, 244, 2013, [Peer-reviewed]
English, International conference proceedings - DOA Estimation of Multi-band Signals Using a Sparse Signal Reconstruction Method
Terada, Tsubasa, Nishimura, Toshihiko, Ogawa, Yasutaka, Ohgane, Takeo
2013 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM (APSURSI), 866, 867, 2013, [Peer-reviewed]
English, International conference proceedings - Considerations on a Multi-User MIMO System Using Channel Prediction Based on an AR Model
Yamaguchi, Kanako, Huu Phu Bui, Ogawa, Yasutaka, Nishimura, Toshihiko, Ohgane, Takeo
2013 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM (APSURSI), 550, +, 2013, [Peer-reviewed]
English, International conference proceedings - Impact on Inter-Cell Interference of Reference Signal for Interference Rejection Combining Receiver in LTE-Advanced Downlink
Yousuke Sano, Yusuke Ohwatari, Nobuhiko Miki, Yuta Sagae, Yukihiko Okumura, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura
IEICE TRANSACTIONS ON COMMUNICATIONS, E95B, 12, 3728, 3738, Dec. 2012, [Peer-reviewed]
English, Scientific journal - Time-Reversal MUSIC Imaging with Time-Domain Gating Technique
Heedong Choi, Yasutaka Ogawa, Toshihiko Nishmura, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E95B, 7, 2377, 2385, Jul. 2012
English, Scientific journal - A DSP and FPGA testbed for teaching and research of wireless communications
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka
INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING EDUCATION, 49, 3, 232, 242, Jul. 2012, [Peer-reviewed]
English, Scientific journal - Considerations on a Frequency Correlation for Distributed Antenna Systems
Kanako Yamaguchi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), 1128, 1131, 2012
English, International conference proceedings - Angle-and-time-domain Gating Technique for Time-reversal MUSIC Imaging
Heedong Choi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), 86, 89, 2012
English, International conference proceedings - A study on adaptive thresholds for reduced complexity bit-flip decoding
Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
International Conference on Advanced Communication Technology, ICACT, 497, 501, 2012
International conference proceedings - A Study on Transmit Beamforming at Source Node in MISO-SISO/MIMO-MIMO AF Relays
Naohito Kiyomi, Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2012 IEEE 75TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), 2012, [Peer-reviewed]
English, International conference proceedings - Reduced-Complexity Single-Carrier E-SDM for Wideband Transmissions
Cristian Davidescu, Yasutaka Ogawa, Julian Webber, Toshihiko Nishimura, Takeo Ohgane
2012 IEEE 75TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), 2012, [Peer-reviewed]
English, International conference proceedings - Selective Ultrawideband Time-Reversal MUSIC using a Time-Domain Gating Technique
Heedong Choi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
2012 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM (APSURSI), 2012, [Peer-reviewed]
English, International conference proceedings - Formulation of a Frequency Correlation for a Multiple-Antenna System
TOSHIHIKO NISHIMURA
IEICE Proceeding Series, 25 Oct. 2011, [Domestic magazines]
English, Scientific journal - Challenge of Time-Reversal MUSIC Imaging with a Limited Array
TOSHIHIKO NISHIMURA
IEICE Proceeding Series, 25 Oct. 2011, [Domestic magazines]
English, Scientific journal - An Overview of Actual SU- and MU-MIMO Performances in a Measured Indoor Channel
TOSHIHIKO NISHIMURA
IEICE Proceeding Series, 25 Oct. 2011, [Domestic magazines]
English, Scientific journal - Development of a channel emulator for evaluation of MIMO-OFDM and SC-FDMA systems
Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
APSIPA ASC 2011 - Asia-Pacific Signal and Information Processing Association Annual Summit and Conference 2011, 492, 495, 2011
International conference proceedings - Noise reduction method based on the gating technique for time-reversal MUSIC imaging
Heedong Choi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
iWEM2011 - IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition, 140, 144, 2011, [Peer-reviewed]
English, International conference proceedings - Accuracy Evaluation of DOA Estimation with Multi-band Signals
Kyouhei Maeda, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
2011 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (APSURSI), 835, 838, 2011, [Peer-reviewed]
English, International conference proceedings - Multi-User MIMO System with Channel Prediction for Time-Varying Environments
Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
2011 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (APSURSI), 59, 62, 2011, [Peer-reviewed]
English, International conference proceedings - Channel Characteristics and Performance of MIMO E-SDM Systems in an Indoor Time-Varying Fading Environment
Huu Phu Bui, Hiroshi Nishimoto, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING, 2010, [Peer-reviewed]
English, Scientific journal - Performance of a MIMO-OFDM eigenbeamforming system in a correlated channel
Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
APSIPA ASC 2010 - Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, 757, 760, 2010
International conference proceedings - Performance Evaluation of MIMO-UWB Systems Using Measured Propagation Data and Proposal of Timing Control Scheme in LOS Environments
Masaki Takanashi, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E92B, 8, 2698, 2707, Aug. 2009, [Peer-reviewed]
English, Scientific journal - Performance Evaluation of Multiuser MIMO E-SDM Systems in Time-Varying Fading Environments
Hun Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E92B, 7, 2374, 2388, Jul. 2009, [Peer-reviewed]
English, Scientific journal - MIMO Channel Technologies for Mobile Radio(
Simulation Methods in Mobile Communication Networks)
Ohgane Takeo, Ogawa Yasutaka, Nishimura Toshihiko
Journal of the Japan Society for Simulation Technology, 28, 2, 86, 90, Japan Society for Simmulation Technology, 15 Jun. 2009
Japanese - Subblock Processing for Frequency-Domain Turbo Equalization under Fast Fading Environments
Keiichi Kambara, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E92B, 5, 1466, 1474, May 2009, [Peer-reviewed]
English, Scientific journal - MIMO Technologies for Ultra High-Speed Wireless Transmission
Ogawa Yasutaka, Ohgane Takeo, Nishimura Toshihiko
B-Plus, 2009, 11, 11_32, 11_38, The Institute of Electronics, Information and Communication Engineers, 2009
Japanese, 数十Gbit/s以上の超高速通信が必要になった場合，MIMO伝送が必須技術となることは容易に想像できる．しかし，実際に超高速伝送を実現できるかどうかは，アンテナ本数のみならず，周波数帯，伝搬環境，実装技術に大きく依存する．特に超高速伝送が使用されると考えられる見通しのある解放空間では，空間相関が高くなるため，MIMO伝送の効果が減少する．したがって，アンテナ配置や伝搬構造の能動的最適化など，改善手法について述べる． - A Study on Decision-Feedback Assisted Channel Tracking and Channel Prediction for IEEE802.16e Based OFDM System
KIM Sang-Woo, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka
The IEICE transactions on communications B, 92, 1, 185, 195, The Institute of Electronics, Information and Communication Engineers, 01 Jan. 2009
Japanese, 周波数有効利用やマルチパス対策においてOFDMは有効な伝送方式である.しかし,高速移動によるマルチパスフェージング環境下では,プリアンブルで推定したチャネルが時間とともに変動するため,それに続くデータ区間においてその変動を補償する必要がある.本論文では,その補償法として判定帰還を用いたチャネル更新法を検討し,帰還系列の精度を向上させる手法を新たに提案した.また,追従特性をより改善するため線形予測を導入し,予測係数を少ないデータから決定する二つの手法について検討した.シミュレーションによる特性評価から,これらの提案手法が有効であることが確認できた. - Hardware development of a MIMO pseudo E-SDM system and real-time channel emulator
Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
APSIPA ASC 2009 - Asia-Pacific Signal and Information Processing Association 2009 Annual Summit and Conference, 684, 687, 2009
International conference proceedings - Tri-diagonalizing Approach on Frequency Domain Equalization in a Doubly-selective Channel
Keisuke Saito, Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
GLOBECOM 2009 - 2009 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-8, 2688, 2692, 2009, [Peer-reviewed]
English, International conference proceedings - A Study on Separation of Two Close DOAs by Using Wide-band Signals
Toshihiko Nishimura, Ysutaka Ogawa, Takeo Ohgane
2009 INTERNATIONAL SYMPOSIUM ON INTELLIGENT SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ISPACS 2009), 240, 243, 2009, [Peer-reviewed]
English, International conference proceedings - Precise DOA Estimation Using SAGE Algorithm with a Cylindrical Array
Masaki Takanashi, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E91B, 11, 3784, 3787, Nov. 2008, [Peer-reviewed]
English, Scientific journal - Soft Decision Directed Channel Estimation with Interference Cancellation for a MIMO System Using Iterative Equalization and Decoding
Masatsugu Higashinaka, Hiroshi Kubo, Akihiro Okazaki, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, E91A, 10, 2787, 2797, Oct. 2008, [Peer-reviewed]
English, Scientific journal - Frequency Offset Estimation and Transmit/Receive Weight Control in an Uplink Channel Using a Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko
The IEICE transactions on communications B, 91, 9, 940, 947, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2008
Japanese, 将来の高速移動通信は現在よりも高い周波数帯を使用することが考えられる.この場合,端末の電源がバッテリーであるため,上り回線の送信電力が制限され,通信品質は劣化する.そこで,近傍の複数端末が送信データを共有して互いに協力し合う協調無線が注目されている.しかし,仮想的なアレーアンテナを形成してビームフォーミングを行う場合,各端末は異なる発振器で動作しているため,キャリヤ周波数のずれによる端末周波数オフセットの存在が通信特性に大きな影響を与えてしまう.そこで,本論文では過去のチャネル情報を用いた端末周波数オフセット推定法とそれを用いた送信側での補償法,及び,RLSアルゴリズムを用いた受信ウェイト制御との組合せについて検討し,計算機シミュレーションによりその特性について評価する.その結果,これらの制御を組み合わせることで,特性を大きく改善できることが確認された. - Performance of MIMO E-SDM systems using channel prediction in actual time-varying indoor fading environments
Huu Phu Bui, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E91B, 6, 1713, 1723, Jun. 2008, [Peer-reviewed]
English, Scientific journal - Measurement-based performance evaluation of coded MIMO-OFDM spatial multiplexing with MMSE spatial filtering in an indoor line-of-sight environment
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E91B, 5, 1648, 1652, May 2008, [Peer-reviewed]
English, Scientific journal - Studies on an iterative frequency domain channel estimation technique for MIMO-UWB communications
Masaki Takanashi, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E91B, 4, 1084, 1094, Apr. 2008, [Peer-reviewed]
English, Scientific journal - Subblock processing in MMSE-FDE under fast fading environments
Keiichi Kambara, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 26, 2, 359, 365, Feb. 2008, [Peer-reviewed]
English, Scientific journal - Subblock processing for frequency-domain turbo equalization under fast fading environments
K. Kambara, H. Nishimoto, T. Nishimura, T. Ohgane, Y. Ogawa
IEEE Vehicular Technology Conference, 2008, [Peer-reviewed]
English, International conference proceedings - Subblock Processing for Frequency-domain Turbo Equalization Under Fast Fading Environments
K. Kambara, H. Nishimoto, T. Nishimura, T. Ohgane, Y. Ogawa
68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008, 839, 843, 2008, [Peer-reviewed]
English, International conference proceedings - Channel characteristics in actual SISO and MIMO propagation environments
Bui Huu Phu, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
2008 SECOND INTERNATIONAL CONFERENCE ON COMMUNICATIONS AND ELECTRONICS, 356, 361, 2008, [Peer-reviewed]
English, International conference proceedings - Measurement-based performance evaluation of MIMO spatial multiplexing in a multipath-rich indoor environment
Hiroshi Nishimoto, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 55, 12, 3677, 3689, Dec. 2007, [Peer-reviewed]
English, Scientific journal - Arrangement of scattering points in Jakes' model for i.i.d. time-varying MIMO fading
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E90B, 11, 3311, 3314, Nov. 2007, [Peer-reviewed]
English, Scientific journal - Pseudo eigenbeam-space division multiplexing (PE-SDM) in frequency-selective MIMO channels
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEICE TRANSACTIONS ON COMMUNICATIONS, E90B, 11, 3197, 3207, Nov. 2007, [Peer-reviewed]
English, Scientific journal - Comparison of Reduction Schemes of Feedback Amount in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo
The IEICE transactions on communications B, 90, 9, 885, 895, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2007
Japanese, MIMO-OFDM空間分割多重において,送信側でチャネル情報(CSI)が既知,若しくは,受信側から用いるべき送信ウェートが報知される場合,固有ビーム空間分割多重(E-SDM)方式を用いることができ,MIMOチャネル最大の容量が得られる.筆者らはこれまで時間領域で最小二乗法を適用し,推定したCSIのうち,主要な成分のみをフィードバックすることにより,情報量が削減できることを報告してきた.本論文では,筆者らが提案しているCSIフィードバック手法及びコードブックを用いた送信ウェートフィードバック手法について比較検討を行った.その結果,各手法におけるフィードバック情報量をほぼ等しくした場合,情報量が少ない4×2MIMOにおいては送信ウェート行列をフィードバックする手法の特性が,情報量が多い4×2MIMO,及び4×4MIMOにおいてはCSIフィードバック手法の特性が良好であることが確認された. - MIMO E-SDM transmission performance in an actual indoor environment
Hiroshi Nishimoto, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E90B, 6, 1474, 1486, Jun. 2007, [Peer-reviewed]
English, Scientific journal - Performance considerations on MIMO spatial multiplexing from the viewpoint of antennas and propagation
Y. Ogawa, H. P. Bui, H. Nishimoto, T. Nishimura, T. Ohgane
IET Seminar Digest, 2007, 11961, 2007, [Peer-reviewed]
English, International conference proceedings - Practical performance of coded MIMO-OFDM spatial multiplexing in an actual indoor environment
Hiroshi Nishimoto, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), 3876, 3879, 2007, [Peer-reviewed]
English, International conference proceedings - Robust MIMO-OFDM E-SDM systems with low complexity in time-varying indoor fading environments
Bui Huu Phu, Toshihiko Nishimura, Hiroshi Nishimoto, Takeo Ohgane, Yasutaka Ogawa
IEEE Vehicular Technology Conference, 1322, 1326, 2007, [Peer-reviewed]
English, International conference proceedings - Channel estimation with space-time windowing in MIMO PE-SDM transmission
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa
IEEE Vehicular Technology Conference, 541, 545, 2007, [Peer-reviewed]
English, International conference proceedings - On the performance of MIMO E-SDM systems with channel prediction in indoor time-varying fading environments
Huu Phu Bui, Toshihiko Nishimura, Hiroshi Nishimoto, Yasutaka Ogawa, Takeo Ohgane
2007 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, VOLS 1-12, 209, 212, 2007, [Peer-reviewed]
English, International conference proceedings - Doppler spectrum and performance of E-SDM systems in indoor time-varying MIMO channels
Huu Phu Bui, Hiroshi Nishimoto, Toshihiko Nishimura, Yasutaka Ogmata, Takeo Ohgane
2007 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, VOLS 1-12, 1245, 1248, 2007, [Peer-reviewed]
English, International conference proceedings - Channel extrapolation techniques for E-SDM system in time-varying fading environments
Hun Phu Bui, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura
IEICE TRANSACTIONS ON COMMUNICATIONS, E89B, 11, 3083, 3092, Nov. 2006, [Peer-reviewed]
English, Scientific journal - Reduction of the Amount of CSI Feedback in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo
The IEICE transactions on communications B, 89, 9, 1765, 1775, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2006
Japanese, 送受信側に複数のアンテナを設置し,各送信アンテナごとに独立したOFDM信号を送信するMIMO-OFDM空間分割多重では,マルチパス環境においても符号問干渉なしに伝送速度の向上が期待できる.更に,送信側でチャネル情報(CSI)が既知の場合,MIMOチャネルにおける最大スループットを得る固有ビーム空間分割多重(E-SDM)方式を用いることができる.しかしながら,OFDMでは各サブキャリヤごとにCSIをフィードバックする必要があり,通信容量を圧迫してしまう.本論文では,筆者らが以前より提案している時間領域で最小二乗法を適用し,推定したCSIをフィードバックすることで情報量を削減でき,更に良好な特性が得られることを示している. - A Study of MIMO Transmission for W-CDMA Uplink Channels
TANAKA Toyohisa, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka
The IEICE transactions on communications B, 89, 2, 264, 277, The Institute of Electronics, Information and Communication Engineers, 01 Feb. 2006
Japanese, 第3世代の移動通信方式として既にサービスが提供されているW-CDMAは,3rd Generation Partnership Project (3GPP)で引き続き性能向上のため仕様策定が行われている.下り回線に関しては最高データレート14.0Mbit/sのHigh Speed Downlink Packet Access (HSDPA)が規定され,更にMIMOの適用が検討されている.本論文では,W-CDMA方式の上り回線にMIMO伝送を適用した場合について,シングルユーザでの通信を対象として計算機シミュレーションにより検討した.3GPPのRelease99規格で仕様化されているチャネルコーディング,拡散方法を用いて,12.2kbit/s,384kbit/s,更に2,048kbit/sのデータレートについて評価した.特に遅延波の存在する周波数選択性フェージング環境下で,チャネルの状態に応じて送信電力を制御できるE-SDM (Eigen Space Division Multiplexing)アルゴリズムが有効であることが分かった. - Transmit and Receive Timing Control in LOS MIMO-UWB Environments
Masaki Takanashi, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane
Progress in Electromagnetics Research Symposium, 605, 609, Electromagnetics Academy, 2006
English, International conference proceedings - Reduction of the amount of channel state information feedback in MIMO-OFDM eigenbeam-space division multiplexing systems
Yusuke Ohwatari, Bui Huu Phu, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane
IEEE Vehicular Technology Conference, 401, 405, 2006, [Peer-reviewed]
English, International conference proceedings - Estimation of Channel and Frequency Offset in a MIMO-OFDM Space Division Multiplexing System
NAKAMURA Yuichiro, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo
The IEICE transactions on communications B, 88, 9, 1813, 1820, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2005
Japanese, マルチパス環境下で, 周波数選択性フェージングを受けにくいOFDM方式は, 無線LANに利用されている.また, 送受信側の双方に複数のアンテナを設置し, 各送信アンテナから独立なOFDM信号を送ることによって, 100Mbit/sを超える高速伝送を実現するMIMO-OFDM空間分割多重方式の研究が行われている.本論文では, MIMO-OFDM空間分割多重について, 筆者らが以前より提案している時間領域で最小二乗法を適用しチャネル推定を行う方法を, チャネルと送受信機間の周波数オフセット推定法に拡張し, IEEE802.11aと同じプリアンブルの長さで両者の推定が可能であることを示している. - Direction-of-arrival estimation of coherent signals using a cylindrical array
M Takanashi, T Nishimura, Y Ogawa, T Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E88B, 6, 2588, 2596, Jun. 2005, [Peer-reviewed]
English, Scientific journal - Applications of space division multiplexing and those performance in a MIMO channel
Takeo Ohgane, Toshihiko Nishimura, Yasutaka Ogawa
IEICE Transactions on Communications, E88-B, 5, 1843, 1851, Institute of Electronics, Information and Communication, Engineers, IEICE, 2005, [Peer-reviewed]
English, Scientific journal - Channel estimation and signal detection for space division multiplexing in a MIMO-OFDM system
Y Ogawa, K Nishio, T Nishimura, T Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E88B, 1, 10, 18, Jan. 2005, [Peer-reviewed]
English, Scientific journal - Performance of MIMO spatial multiplexing in indoor line-of-sight environments
Yasutaka Ogawa, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane
IEEE Vehicular Technology Conference, 4, 2398, 2402, Institute of Electrical and Electronics Engineers Inc., 2005, [Peer-reviewed]
English, International conference proceedings - Compensation of channel information error using first order extrapolation in eigenbeam space division multiplexing (E-SDM)
T Nishimura, T Tsutsumi, T Ohgane, Y Ogawa
2005 IEEE/ACES INTERNATIONAL CONFERENCE ON WIRELESS COMMUNICATIONS AND APPLIED COMPUTATIONAL ELECTROMAGNETICS, 44, 47, 2005, [Peer-reviewed]
English, International conference proceedings - Performance of 2x2 MIMO spatial multiplexing in indoor environments
Y Ogawa, H Nishimoto, T Nishimura, T Ohgane
2005 IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, 486, 489, 2005, [Peer-reviewed]
English, International conference proceedings - Performance of MIMO spatial multiplexing in indoor line-of-sight environments
Y Ogawa, H Nishimoto, T Nishimura, T Ohgane
VTC2005-FALL: 2005 IEEE 62ND VEHICULAR TECHNOLOGY CONFERENCE, 1-4, PROCEEDINGS, 2398, 2402, 2005, [Peer-reviewed]
English, International conference proceedings - A simplified iterative processing of soft MIMO detector and turbo decoder in a spatially multiplexed system
K Sumii, T Nishimura, T Ohgane, Y Ogawa
VTC2005-SPRING: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, PROCEEDINGS, 882, 886, 2005, [Peer-reviewed]
English, International conference proceedings - Applications of Space Division Multiplexing and Those Performance in a MIMO Channel
OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka
The Transactions of the Institute of Electronics, Information and Communication Engineers B, 87, 9, 1162, 1173, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2004
Japanese, MIMO(Multiple-Input Multiple-Output)チャネル伝送において,複数のアンテナから同時に異なる信号系列を伝送する空間分割多重方式は,限られた周波数帯域で高速伝送を可能とする手法として注目されている.本論文では,各種空間分割多重方式の送受信方式について解説するとともに,送受信アンテナ本数の増加による特性改善効果について計算機シミュレーションにより明らかにする.また,誤り訂正符号化時における特性評価も併せて行う. - Performance Evaluation of 2×2 MIMO Space Division Multiplexing Based on Indoor Propagation Measurement
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo
The Transactions of the Institute of Electronics, Information and Communication Engineers B, 87, 9, 1442, 1453, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2004
Japanese, 従来,MIMOシステムに空間分割多重方式を適用させるMIMO-SDMの研究では,送受信アンテナ間のチャネルは独立なレイリーフェージング環境と仮定されることが多く,この仮定のもとでは,受信側での処理により信号ストリームの分離検出が可能となる.本論文では,チャネル間の独立性が崩れる可能性のある,見通し内伝搬路で行った5.2GHz帯での伝搬実験結果から,そのような環境における2×2MIMO-SDMの有効性を検証し,見通しとならない環境における特性との比較を行っている.また,同様の実験を電波暗室でも行い,極めてマルチパス波の少ない環境でのMIMO-SDMの挙動を紹介する.これらの実験の結果,見通し内伝搬環境においても散乱波が存在する場合にはSDM方式が有効であること,見通し外伝搬環境に比べてアンテナ素子の配置等により,特性が大きく変動する傾向にあることが分かった. - An Impact of Channel State Information Error on SDM Applications
TSUTSUMI Takahiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka
The Transactions of the Institute of Electronics, Information and Communication Engineers B, 87, 9, 1496, 1504, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2004
Japanese, 各種空間分割多重方式について,チャネル情報に誤差がある場合の誤り率特性を比較検討した.また,固有ビーム空間分割多重(E-SDM)方式と重み付きSDM (W-SDM)においては,一次外挿法を用いることにより,特性の改善を図った.その結果,チャネルの時間変動が大きい場合には,送信側で処理を行わない結合推定を用いたSDM (JD)の特性より劣化することが明らかとなった.しかし,送信側で一次外挿法を用いることで,大きな改善効果が得られることが確認できた. - Quasi-Optical Antenna-Mixer Array Composed of a Magnetic Loop Antenna Operated at 10-GHz Band
Hiroyuki Saito, Toshihiko Nishimura, Manabu Yamamoto, Kiyohiko Itoh
Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi), 87, 4, 45, 53, Apr. 2004, [Peer-reviewed]
English, Scientific journal - A study on an antenna selection scheme for space-time turbo code for OFDM systems
M Hoshino, M Uesugi, T Ohgane, Y Ogawa, T Nishimura
IEICE TRANSACTIONS ON COMMUNICATIONS, E86B, 12, 3476, 3482, Dec. 2003, [Peer-reviewed]
English, Scientific journal - A MIMO-OFDM System for High-speed Transmission
Yasutaka Ogawa, Keisuke Nishio, Toshihiko Nishimura, Takeo Ohgane
IEEE Vehicular Technology Conference, 58, 1, 493, 497, Institute of Electrical and Electronics Engineers Inc., 2003
English, International conference proceedings - A MIMO-OFDM system for high-speed transmission
Y Ogawa, K Nishio, T Nishimura, T Ohgane
2003 IEEE 58TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS1-5, PROCEEDINGS, 493, 497, 2003, [Peer-reviewed]
English, International conference proceedings - Performance enhancement and compensation of carrier frequency offset using CRA-AA for uplink in SDMA system
Y Kishiyama, T Nishimura, T Ohgane, Y Ogawa, Y Doi
ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS, 86, 5, 81, 91, 2003, [Peer-reviewed]
English, Scientific journal - Quasi-Optical Antenna-Mixer Array Composed of a Magnetic Loop Antenna Operated at 10 GHz Band
SAITO Hiroyuki, NISHIMURA Toshihiko, YAMAMOTO Manabu, ITOH Kiyohiko
The Transactions of the Institute of Electronics,Information and Communication Engineers B, 85, 9, 1493, 1500, The Institute of Electronics, Information and Communication Engineers, 01 Sep. 2002
Japanese, 準光学アンテナ・ミキサは,高周波信号(RF)と局部発振周波(LO)の信号を空間的に受信すると同時に中間周波数(IF)信号へ変換する受信システムであり,ミリ波帯で問題となる線路の伝送損失をおさえることができる.本論文では,RFとLOを磁流ループアンテナで受信する準光学アンテナ・ミキサアレーの10GHz帯における試作測定を行い,準光学的ミキシングが可能であることを示す.また,この素子を用いた2次元アレーアンテナを提案し,理論的にその受信特性を明らかにする.LOの照射角または周波数を変えることでRFの受信方向が走査できることに加えて,出力端にろうえいするRF・LO信号の抑制が可能であることを示す.8素子の準光学アンテナ・ミキサで構成される2次元アレーの実験を行い,提案の妥当性を確認する. - High Data-rate Transmission with Eigenbeam-space Division Multiplexing (E-SDM) in a MIMO Channel
Kazumi Miyashita, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yasushi Takatori, Keizo Cho
IEEE Vehicular Technology Conference, 56, 3, 1302, 1306, 2002
English, International conference proceedings - Transmit nullforming for a MIMO/SDMA downlink with receive antenna selection
T Nishimura, Y Takatori, T Ohgane, Y Ogawa, KZ Cho
IEEE 56TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2002, VOLS 1-4, PROCEEDINGS, 190, 194, 2002, [Peer-reviewed]
English, International conference proceedings - High data-rate transmission with eigenbeam-space division multiplexing (E-SDM) in a MIMO channel
K Miyashita, T Nishimura, T Ohgane, Y Ogawa, Y Takatori, K Cho
IEEE 56TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2002, VOLS 1-4, PROCEEDINGS, 1302, 1306, 2002, [Peer-reviewed]
English, International conference proceedings - A spatial domain interference canceller using a multistage adaptive array with precise timing estimation
T Nishimura, Y Tanabe, T Ohgane, Y Ogawa, Y Doi, J Kitakado
IEICE TRANSACTIONS ON COMMUNICATIONS, E84B, 7, 1735, 1742, Jul. 2001, [Peer-reviewed]
English, Scientific journal - Space domain multistage interference canceller for SDMA
T Nishimura, T Ohgane, Y Ogawa, Y Doi, J Kitakado
IEICE TRANSACTIONS ON COMMUNICATIONS, E84B, 3, 377, 382, Mar. 2001, [Peer-reviewed]
English, Scientific journal - Performance Enhancement and Compensation of Carrier Frequency Offset Using CRA-AA for Uplink in SDMA System
KISHIYAMA Yoshihisa, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, DOI Yoshiharu
The Transactions of the Institute of Electronics,Information and Communication Engineers B, 84, 2, 178, 187, The Institute of Electronics, Information and Communication Engineers, 01 Feb. 2001
Japanese, 近年, チャネルの利用効率を向上させるためSDMA(Space Division Multiple Access)方式が提案されている.SDMA方式では, 同一チャネルに収容されたすべてのユーザ間で深刻な干渉が生じるため, 基地局でこれらを分離・検出する手法が必要となる.そこで, 本論文では, 上り回線においてチャネル応答推定を行い, その結果を用いて間接的に指向性制御を行うCRA-AA(Channel Response Assisted Adaptive Array)を提案し, MMSE基準のアダプティブアレー, 及び結合推定との特性比較を行った.また, 各ユーザにおいてそれぞれ発生するキャリヤ周波数オフセットを補償する手法についても検討を行った.その結果, CRA-AAが高速フェージングに対する特性, 及びキャリヤ周波数オフセットに対する特性がともに優れていることがわかった. - Downlink beamforming performance for an SDMA terminal with joint detection
Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yoshiharu Doi, Jun Kitakado
IEEE Vehicular Technology Conference, 3, 54, 1538, 1542, 2001, [Peer-reviewed]
English, Scientific journal - Analysis of dual-frequency operating microstrip antenna fed by coplanar waveguide using method of moments in spectral domain
Tsuyoshi Kaichida, Nozomu Ishii, Manabu Yamamoto, Toshihiko Nishimura, Kiyohiko Itoh
Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi), 84, 3, 21, 28, Scripta Technica Inc, 2001, [Peer-reviewed]
English, Scientific journal - Basestation adaptive antennas for a high-speed FDD/TDMA system
Y Ogawa, Y Tanabe, T Nishimura, T Ohgane
2001 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-10, CONFERENCE RECORD, 2558, 2562, 2001, [Peer-reviewed]
English, International conference proceedings - Downlink beamforming performance for an SDMA terminal with joint detection
T Nishimura, T Ohgane, Y Ogawa, Y Doi, J Kitakado
IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001, VOLS 1-4, PROCEEDINGS, 1538, 1542, 2001, [Peer-reviewed]
English, International conference proceedings - Combining techniques for spatial-domain path-diversity using an adaptive array
K Fujishima, Y Tanabe, T Nishimura, Y Ogawa, T Ohgane
IEICE TRANSACTIONS ON COMMUNICATIONS, E83B, 12, 2593, 2599, Dec. 2000, [Peer-reviewed]
English, Scientific journal - DOWNLINK NULL STEERING USING CHANNEL ESTIMATION IN A TDD/SDMA SYSTEM
Takeo Ohgane, Yasutaka Ogawa, Yoshihisa Kishiyama, Toshihiko Nishimura
IEICE Proceeding Series, 9, 4A3-2, The Institute of Electronics, Information and Communication Engineers, 22 Aug. 2000
English - Spatial Domain Interference Canceler Using Multistage Adaptive Array with Precise Timing Estimation
T. Nishimura, Y. Tanabe, T. Ohgane, Y. Ogawa, Y. Doi, J. Kitakado
IEEE Vehicular Technology Conference, 2, 52, 719, 724, 2000
English, International conference proceedings - Spatial domain interference canceler using multistage adaptive array with precise timing estimation
T Nishimura, Y Tanabe, T Ohgane, Y Ogawa, Y Doi, J Kitakado
IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2000, VOLS 1-6, PROCEEDINGS, 719, 724, 2000, [Peer-reviewed]
English, International conference proceedings - Space domain multistage interference canceler for SDMA
T Nishimura, T Ohgane, Y Ogawa, Y Doi, J Kitakado
2000 IEEE 51ST VEHICULAR TECHNOLOGY CONFERENCE, PROCEEDINGS, VOLS 1-3, 655, 659, 2000, [Peer-reviewed]
English, International conference proceedings - Weight estimation for downlink null steering in a TDD/SDMA system
Y Kishiyama, T Nishimura, T Ohgane, Y Ogawa, Y Doi
2000 IEEE 51ST VEHICULAR TECHNOLOGY CONFERENCE, PROCEEDINGS, VOLS 1-3, 346, 350, 2000, [Peer-reviewed]
English, International conference proceedings - An adaptive antenna for spatial-domain path-diversity using a super-resolution technique
Y Tanabe, K Fujishima, T Nishimura, Y Ogawa, T Ohgane
2000 IEEE 51ST VEHICULAR TECHNOLOGY CONFERENCE, PROCEEDINGS, VOLS 1-3, 1, 5, 2000, [Peer-reviewed]
English, International conference proceedings - Beam scan using the quasi-optical antenna mixer array
Nishimura Toshihiko, Ishii Nozomu, Itoh Kiyohiko
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 47, 7, 1160, 1166, IEEE, Jul. 1999, [Peer-reviewed]
English, The quasi-optical antenna mixer system transformsan RF signal into an intermediate frequency signal just after itspatially receives the RF signal and the local oscillator's (LO)signal. In this paper, we present a novel beam-scanning systemusing the quasi-optical antenna mixer array and describe its principleof operation and the experimental results in the microwaveband. The arrival direction of RF signals can be controlled byadjusting the LO incident angle and/or the LO frequency withoutimplementing RF circuits such as phase shifters. Therefore, thenovel beam-scanning system has no loss due to RF circuits andcan be easily designed because of its simple composition. - Quasi-optical antenna mixer system fed by a coplanar waveguide
Toshihiko Nishimura, Katsumi Tsuchida, Nozomu Ishii, Kiyohiko Itoh
Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi), 82, 1, 22, 30, John Wiley and Sons Inc., 1999, [Peer-reviewed]
English, Scientific journal - Beam scan using the quasi-optical antenna mixer array
Toshihiko Nishimura, Nozomu Ishii, Kiyohiko Itoh
IEEE Transactions on Antennas and Propagation, 47, 7, 1160, 1166, IEEE, 1999, [Peer-reviewed]
English, Scientific journal - Reception Properties of a Multielement Quasi-optical Antenna-mixer System
Toshihiko Nishimura, Katsumi Tsuchida, Nozomu Ishii, Kiyohiko Itoh
Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi), 81, 12, 1, 8, Scripta Technica Inc, Dec. 1998
English, Scientific journal - Beam scanning by the quasi-optical antenna mixer array
Toshihiko Nishimura, Katsumi Tsuchida, Nozomu Ishii, Kiyohiko Itoh, Yasutaka Ogawa
1998 28th European Microwave Conference, EuMC 1998, 1, 415, 420, IEEE Computer Society, 1998, [Peer-reviewed]
English, International conference proceedings - Accommodation of the K, Nh4 Ions in Rs-ars Mixed Crystal System
Y. Shiozaki, T. Nishimura, A. Amano, E. Suzuki, R. Nozaki
Ferroelectrics, 158, 1, 151, 156, 01 Aug. 1994, [Peer-reviewed]
English, Scientific journal
Other Activities and Achievements
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篭橋みのり, 日景隆, 西村寿彦, 柏達也, 山崎圭子, 田村菜穂美, 岸玲子, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2024, 2024 - Considerations on Computational Complexity Reduction in Channel Prediction Based on Multipath Separation for Sub-THz-Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 123, 434(RCS2023 250-294), 2024 - Study on IRS Control Using Vision-Assisted Beam Management in Sub-Terahertz-Band Communications
小林龍平, 西村寿彦, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 124, 84(RCS2024 28-83), 2024 - Characterization of Sub-THz-Band MIMO Spatial Multiplexing With Channel Estimation Errors
濱田直輝, 西村寿彦, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 124, 84(RCS2024 28-83), 2024 - Study on OAM Mode Multiplexing Transmission Using Uniform Square Array
西村寿彦, 大鐘武雄, 旦代智哉, 内田大輔, 電子情報通信学会大会講演論文集(CD-ROM), 2024, 2024 - Performance Evaluation of Loose Beamforming in the Presence of NLOS Areas
林優太, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会大会講演論文集(CD-ROM), 2024, 2024 - A Study on Nonlinear Precoding Methods in Massive MIMO~Improvement of VP method using MCMC and comparison with THP method~
角田俊介, 萩原淳一郎, 西村寿彦, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 124, 166(RCS2024 116-132), 2024 - Study on Initial Solutions of Direct-Binary Search for Loose Beam Forming
谷部遼馬, 西村寿彦, 小川恭孝, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2024, 2024 - DOA Estimation Improvement Through Angle-Range-Reduced DNNs Specialized in Narrow DOA Range
安藤ダニエル明, 西村寿彦, 佐藤孝憲, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告(Web), 123, 434(RCS2023 250-294), 2024 - Study on Weight Generation for Loose Beamforming with Quantum-inspired Tabu Search
林優太, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2023, 2023 - A Study on Performance Improvement of Stochastic MIMO Signal Detection Using Variational Bayesian Methods
阿隅大輝, 角田俊介, 萩原淳一郎, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 355(IT2022 29-67), 2023 - Study on IRS Control Based on Beamforming for Sub-Terahertz Band Communications
田所柊人, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 355(IT2022 29-67), 2023 - Study on Computational Complexity Reduction in Channel Prediction for Sub-THz Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 355(IT2022 29-67), 2023 - Characteristics Analysis of Direction of Arrival Estimation with Compressed Sensing Using Grid Shifts
國本周大, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 355(IT2022 29-67), 2023 - Impact of Channel Estimation Error on Antenna Selection Using Simulated Annealing for Distributed MIMO Systems
西村健斗, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 355(IT2022 29-67), 2023 - Direct-Binary Search Leveraged Loose Beam Forming in Massive MIMO Systems
林優太, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会大会講演論文集(CD-ROM), 2023, 2023 - Considerations on Subarray Beam Control for Sub-Terahertz MIMO Spatial Multiplexing
濱田直輝, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会大会講演論文集(CD-ROM), 2023, 2023 - Characteristic Comparison of UCA and Square Array on OAM Mode Multiplexing
釜谷俊輝, 西村寿彦, 大鐘武雄, 旦代智哉, 内田大輔, 電子情報通信学会大会講演論文集(CD-ROM), 2023, 2023 - A Study on Vector Perturbation Method using MCMC in Massive MIMO
角田俊介, 萩原淳一郎, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 123, 76(RCS2023 28-78), 2023 - Study on Characteristic Improvement of Direct-Binary Search Leveraged Loose Beam Forming in Massive MIMO Systems
林優太, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 123, 76(RCS2023 28-78), 2023 - Study on Subarray Beam Control for Sub-Terahertz-Band MIMO Spatial Multiplexing
濱田直輝, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 123, 76(RCS2023 28-78), 2023 - Fundamental Study of OAM Mode Multiplexing with Square Array
釡谷俊輝, 西村寿彦, 大鐘武雄, 旦代智哉, 内田大輔, 電子情報通信学会大会講演論文集(CD-ROM), 2022, 2022 - Spatial Signal Processing in Sub-Terahertz-Band Indoor Radio Communications
小川恭孝, 西村寿彦, 佐藤孝憲, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 235(RCS2022 128-154), 2022 - A Study on Channel Prediction Based on Multipath Separation for Sub-Terahertz-Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 235(RCS2022 128-154), 2022 - Fundamentals of Orbital Angular Momentum (OAM) Mode Multiplexing
西村寿彦, 電子情報通信学会技術研究報告(Web), 122, 251(AP2022 147-172), 2022 - Study on Transmit Weight Generation for Loose Beam Forming
林優太, 西村寿彦, 佐藤孝憲, 萩原淳一郎, 小川恭孝, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2022, 2022 - Study on Delay-Domain Multipath Separation in Sub-Terahertz-Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2022, 2022 - Novel Wireless Communication System Realized by Mobile Terminal Collaboration-Recent Results and Application to Uplink Transmission-
村田英一, 井田悠太, 丸田一輝, 實松豊, 牟田修, 岡田啓, 岡本英二, 眞田幸俊, 西村寿彦, 田野哲, 電子情報通信学会技術研究報告(Web), 122, 235(RCS2022 128-154), 2022 - A Study on Signal Detection Using L-BFGS Method in Massive MIMO
春日由紀子, 萩原淳一郎, 西村寿彦, 佐藤孝憲, 大鐘武雄, 小川恭孝, 電子情報通信学会大会講演論文集(CD-ROM), 2022, 2022 - Quantum Annealing Leveraged Loose Beamforming in Massive MU-MIMO Systems
大塚達樹, 西村寿彦, 大鐘武雄, 佐藤孝憲, 萩原淳一郎, 小川恭孝, 電子情報通信学会大会講演論文集(CD-ROM), 2022, 2022 - Fundamental Considerations on Channel Prediction Based on Multipath Delay and Angle-of-Arrival Estimation for Sub-Terahertz Band Communications
望月大瑚, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 73(RCS2022 24-67), 2022 - Comparison of Performance and Complexity for different Search Methods in Stochastic MIMO Signal Detection
阿隅大輝, 春日由紀子, 松村和士, 萩原淳一郎, 西村寿彦, 佐藤孝憲, 小川恭孝, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 73(RCS2022 24-67), 2022 - Direction of Arrival Estimation with Compressed Sensing Using Grid Shifts
國本周大, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 73(RCS2022 24-67), 2022 - Considerations on IRS Control based on Beamforming for Sub-Terahertz Band Communications
田所柊人, 西村寿彦, 佐藤孝憲, 小川恭孝, 萩原淳一郎, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 73(RCS2022 24-67), 2022 - A Study on Model Parameters for MIMO Signal Detection Using Learned AMP
三好茉莉, 西村寿彦, 佐藤孝憲, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告(Web), 122, 73(RCS2022 24-67), 2022 - Spatial-Domain Signal Processing in Sub-Terahertz Communications
小川恭孝, 西村寿彦, 大鐘武雄, 電子情報通信学会技術研究報告(Web), 122, 117(EMT2022 7-43), 2022 - Studies on Channel Prediction in a Millimeter-Wave Band Based on Multipath Delay and Angle-of-Arrival Estimation
望月大瑚, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 327(IT2021 28-82), 2022 - Studies on Sub-Terahertz MIMO Spatial Multiplexing in an Indoor Propagation Environment
宇津野太一, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 327(IT2021 28-82), 2022 - Study on Compensation for Axis Misalignment of UCA with Multiple UCAs
櫻谷信彦, 西村寿彦, 大鐘武雄, 旦代智哉, 内田大輔, 電子情報通信学会技術研究報告(Web), 121, 327(IT2021 28-82), 2022 - A Study of Antenna and UE Selection for Distributed Massive MIMO Systems
西村健斗, 大鐘武雄, 西村寿彦, 萩原淳一郎, 佐藤孝憲, 小川恭孝, 電子情報通信学会大会講演論文集(CD-ROM), 2021, 2021 - Performance Evaluation of Loose Beamforming for Different Receiver Numbers
大塚達樹, 西村寿彦, 大鐘武雄, 佐藤孝憲, 萩原淳一郎, 小川恭孝, 電子情報通信学会技術研究報告(Web), 120, 320(IT2020 63-111), 2021 - A Study on Small Scale Signal Detection Using Learned Approximate Message Passing
辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会大会講演論文集(CD-ROM), 2021, 2021 - A Study on Downlink Channel Estimation Based on Multipath Separation in a Wideband FDD System
登坂紫織, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 404(RCS2020 203-261), 2021 - Fundamental Studies on Beam Search of a 2-Dimensional Array in the Terahertz Band
宇津野太一, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会大会講演論文集(CD-ROM), 2021, 2021 - Compensation for Axis Misalignment of UCA with OAM Beam Control
櫻谷信彦, 西村寿彦, 大鐘武雄, 旦代智哉, 内田大輔, 電子情報通信学会技術研究報告(Web), 120, 404(RCS2020 203-261), 2021 - Considerations on Accuracy Improvement in Close DOA Estimation with Deep Learning
加瀬裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 佐藤孝憲, 岸山祥久, 電子情報通信学会技術研究報告(Web), 121, 101(RCC2021 22-40), 2021 - Considerations on Computational Complexity Reduction in Channel Prediction Based on Multipath Separation
望月大瑚, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 72(RCS2021 29-76), 2021 - A Comparison of Variational Bayesian and Expectation Propagation Methods for Massive MIMO Signal Detection
阿隅大輝, 萩原淳一郎, 西村寿彦, 大鐘武雄, 小川恭孝, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 72(RCS2021 29-76), 2021 - A Basic Study on Signal Detection Using Learned Approximate Message Passing
三好茉莉, 辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 72(RCS2021 29-76), 2021 - A Study on the Behavior of LLR Messages in Damped GaBP for Large-scale Signal Detection under a Correlated Channel
安藤ダニエル明, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 121, 72(RCS2021 29-76), 2021 - A Preliminary Study on Behavior of GaBP Messages in Massive MIMO Signal Detection
Daniel Akira ANDO, Toshihiko NISHIMURA, Takeo OHGANE, Yasutaka OGAWA, Junichiro HAGIWARA, Takanori SATO, IEICE Proceeding Series, 63, K1-2, 02 Dec. 2020, [Peer-reviewed]
Gaussian belief propagation (GaBP) is one of the light-weight signal detectors. Basically, it is expected that reliability information exchanged in the network gradually converges to the correct one. However, it has been confirmed that error-free detection can be achieved even if incorrect beliefs still exist in the network., The Institute of Electronics, Information and Communication Engineers, English - Channel Prediction of Wideband OFDM Systems in a Millimeter-wave Band Based on Multipath Delay Estimation
Takano Yuta, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Hagiwara Junichiro, IEICE Communications Express, 9, 12, 561, 566, 01 Dec. 2020
Multi-user MIMO systems enable high capacity transmission. A base station, however, needs accurate channel state information (CSI). In time-varying environments, the CSI may be outdated at the actual transmission time. One of the solutions to this issue is channel prediction. The authors have proposed the prediction method using FISTA, a compressive sensing technique, for OFDM systems in a millimeter-wave band. Unfortunately, in realistic multipath environments, the prediction performance of the proposed technique degrades. In this letter, we examine the prediction performance in wider OFDM systems. It will be shown that FISTA reveals excellent performance in a sufficiently wide band case., The Institute of Electronics, Information and Communication Engineers, English - A Study on Small Scale Signal Detection Using Approximate Message Passing
辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2020, 2020 - A Study on Wideband FDD Downlink Channel Estimation Using Compressed Sensing
登坂紫織, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2020, 2020 - Path Loss Measurements Tests at 900MHz Band Using LoRaWAN Terminals
DONG Bowen, 辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 74(RCS2020 23-57), 2020 - A Study on the Behavior of Each LLR in Gaussian Belief Propagation
安藤ダニエル明, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 74(RCS2020 23-57), 2020 - A Study on Signal Detection in Massive MIMO Using MCMC
松村和士, 萩原淳一郎, 西村寿彦, 大鐘武雄, 小川恭孝, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 74(RCS2020 23-57), 2020 - A Study on Massive MIMO Signal Detection Using Approximate Message Passing
辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 74(RCS2020 23-57), 2020 - A Study on Loose Beamforming Using Differential Evolution
大塚達樹, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 74(RCS2020 23-57), 2020 - Performance Evaluation of Beam Shapes in a Two-Step-Precoded Massive MIMO System
YAMAMOTO Jumpei, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, TAKEDA Daiki, KISHIYAMA Yoshihisa, IEICE Transactions on Communications (Web), E103.B, 6, 2020 - Fundamental Trial on DOA Estimation with Deep Learning
KASE Yuya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, KITAYAMA Daisuke, KISHIYAMA Yoshihisa, IEICE Transactions on Communications (Web), E103.B, 10, 2020 - Testing Different DNN Configurations in DOA Estimation Using Deep Learning
加瀬裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 来山大祐, 岸山祥久, 電子情報通信学会大会講演論文集(CD-ROM), 2020, 2020 - Considerations on Accuracy Improvement in DOA Estimation Using Deep Learning
加瀬裕也, 佐藤孝憲, 西村寿彦, 大鐘武雄, 小川恭孝, 来山大祐, 岸山祥久, 電子情報通信学会技術研究報告(Web), 120, 87(RCC2020 2-10), 2020 - Improvement on Signal Detection Performance with HMC in Massive MIMO
松村和士, 萩原淳一郎, 西村寿彦, 大鐘武雄, 小川恭孝, 佐藤孝憲, 電子情報通信学会技術研究報告(Web), 120, 298(RCS2020 134-153), 2020 - Fundamental Studies on Phased Array Beam Control in the Terahertz Band
宇津野太一, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 佐藤孝憲, 電子情報通信学会大会講演論文集(CD-ROM), 2020, 2020 - 深層学習を用いた近接波の到来方向推定の検討—A Study on Close DOA Estimation with Deep Learning—高信頼制御通信
加瀬 裕也, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 来山 大祐, 岸山 祥久, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 119, 106, 133, 138, Jul. 2019
電子情報通信学会, Japanese - Studies on Channel Prediction with Multipath Separation Based on Delay Estimation
高野裕太, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会技術研究報告, 118, 433(IT2018 35-74), 2019 - Indoor Path Loss Measurements at 900 MHz Band Using LoRaWAN Terminals
辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 90(RCS2019 37-100)(Web), 2019 - A Fundamental Study on Downlink Channel Estimation in an FDD System Based on Impulse Response Estimation
登坂紫織, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 90(RCS2019 37-100)(Web), 2019 - Throughput Evaluation of Antenna Selection in Indoor Massive MIMO Distributed Antenna Systems
島屋早希, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 90(RCS2019 37-100)(Web), 2019 - A Fundamental Study on Channel Estimation Using Deep Learning
中島亮太, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 90(RCS2019 37-100)(Web), 2019 - A Study on a Performance Improvement by Cyclic Redundancy Check for Large-Scale SCMA Detection
LI Renjie, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 176(RCS2019 146-177)(Web), 2019 - Signal Detection Using Approximate Message Passing with Node Selection in a Massive MIMO System
辻本若葉, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 119, 296(RCS2019 203-236)(Web), 2019 - 圧縮センシングを用いた2波の到来方向推定の基礎的検討
中都正義, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2019, 2019 - 雑音を考慮したマルチパスの遅延推定に基づくチャネル予測
高野裕太, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 遅延推定に基づくマルチパス分離によるチャネル予測に関する考察
高野裕太, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 敵対的生成ネットワークを用いたチャネル推定に関する基礎的研究
中島亮太, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - MIMO SC-FDEにおける受信ウェイト行列の演算量削減手法の評価
齋藤剣聖, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 重畳型16QAMを用いた大規模MIMOのDAMPによる信号検出
渡部泰成, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 16点SCMA大規模システムのガウス確率伝搬法による信号検出特性の評価
LI Renjie, 大鐘武雄, 西村寿彦, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - マルチパス通信路のインパルス応答を用いたFDDシステムの下り回線チャネル推定に関する基礎的検討
登坂紫織, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 基地局アンテナアレーの分散化とプリコーディングの関係について
鈴木裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - 屋内環境における大規模MIMO分散アンテナシステムのアンテナ選択に関する検討
島屋早希, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - Polar符号化伝送におけるSSCL復号とGaBPを用いた繰り返し適応等化に関する検討
福田健太郎, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - A Study on DOA Estimation Using Deep Learning
加瀬裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 来山大祐, 岸山祥久, 電子情報通信学会技術研究報告, 119, 8(RCS2019 1-19)(Web), 2019 - A Study on Close DOA Estimation with Deep Learning
加瀬裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 来山大祐, 岸山祥久, 電子情報通信学会技術研究報告, 119, 106(RCC2019 11-52), 2019 - 深層学習を用いた到来方向推定の検討
加瀬裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 来山大祐, 岸山祥久, 電子情報通信学会大会講演論文集(CD-ROM), 2019, 2019 - A Fundamental Study on Direction of Arrival Estimation with Deep Learning
加瀬 裕也, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 118, 123, 51, 55, 11 Jul. 2018
電子情報通信学会, Japanese - A Study on Channel Equalization with Belief Propagation in Polar-Coded Single Carrier Transmission
木原 光太郎, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 456, 25, 29, 28 Feb. 2018
電子情報通信学会, Japanese - Considerations on a MIMO Channel Prediction Scheme Using Multipath Separation in Delay, Departure Angle, and Arrival Angle Domains
奥村 香菜子, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 456, 179, 184, 28 Feb. 2018
電子情報通信学会, Japanese - Performance evaluation on beam shapes and number of selected beams in a massive MIMO system
山本 順平, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 岸山 祥久, 武田 大樹, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 394, 125, 130, 22 Jan. 2018
電子情報通信学会, Japanese - 圧縮センシングを用いたマルチバンド信号の到来方向推定におけるバンド数に関する検討
星川豊希, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - MIMO SC-FDEにおける受信ウェイト補間法の評価
齋藤剣聖, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - 遮蔽物のある屋内環境のマルチユーザ大規模MIMOシステムにおける基地局アンテナサブアレーの配置に関する検討
鈴木裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - Evaluation of Loose Beamforming with a Genetic Algorithm in a Multiuser Massive MIMO System
中村駿太, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 118, 101(RCS2018 35-79)(Web), 2018 - A Fundamental Study on Superposition Modulated Signal Detection Using Belief Propagation
福田健太郎, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 118, 101(RCS2018 35-79)(Web), 2018 - 大規模MU-MIMOシステムにおける簡易ビーム形成の特性改善に関する検討
中村駿太, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - マルチパスの遅延時間推定に基づくチャネル予測に関する検討
高野裕太, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - 異なる振幅を有するマルチバンド信号に対する圧縮センシングを用いた到来方向推定に関する検討
星川豊希, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - 大規模MIMO SC-FDEにおける受信ウェイト行列の演算量削減手法の比較
齋藤剣聖, 小川恭孝, 西村寿彦, 大鐘武雄, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - 屋内環境のマルチユーザ大規模MIMOシステムにおける基地局アンテナサブアレーの配置および素子配列に関する検討
鈴木裕也, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - LLR上限設定を行ったGaBP検出における重畳型16QAM不均一配置の最適化に関する検討
渡部泰成, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - 重畳変調信号の重畳数とGaBP検出特性に関する評価
福田健太郎, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - A Fundamental Study on Large-Scale SCMA Signal Detection Using GaBP
LI Renjie, 西村寿彦, 大鐘武雄, 小川恭孝, 萩原淳一郎, 電子情報通信学会技術研究報告, 118, 125(RCS2018 80-130)(Web), 2018 - 大規模MIMOにおけるビーム選択法とビーム選択数に関する特性評価
山本順平, 西村寿彦, 大鐘武雄, 小川恭孝, 武田大樹, 岸山祥久, 電子情報通信学会大会講演論文集(CD-ROM), 2018, 2018 - Considerations on Computational Complexity Reduction Using Receive Matrix Interpolation in a MIMO SC-FDE System
齋藤 剣聖, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 352, 101, 106, 14 Dec. 2017
電子情報通信学会, Japanese - Accuracy Evaluation of Compressed Sensing Algorithms for DOA Estimation of Multiband Signals
星川 豊希, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 283, 161, 165, 08 Nov. 2017
電子情報通信学会, Japanese - Quasi-upper Bound Evaluation of Multiuser Massive MIMO System by Loose Beam Forming
井上 航一, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 284, 117, 122, 08 Nov. 2017
電子情報通信学会, Japanese - A Study on m-QAM Signal Detection Using Belief Propagation in a Massive MIMO System
渡部 泰成, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 246, 19, 24, 19 Oct. 2017
電子情報通信学会, Japanese - Considerations on a Channel Prediction Scheme Using Multipath Separation in the Delay and Angle Domains
奥村 香菜子, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 132, 61, 66, 19 Jul. 2017
電子情報通信学会, Japanese - Performance Evaluation on Beam Selection Rules and Beam Shapes of a Massive MIMO System in Time-varying Environments
山本 順平, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 武田 大樹, 岸山 祥久, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 103, 31, 36, 21 Jun. 2017
電子情報通信学会, Japanese - Fundamental Considerations on Computational Complexity Reduction Using Receive Matrix Interpolation in a MIMO-OFDM System
齋藤 剣聖, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 103, 121, 126, 21 Jun. 2017
電子情報通信学会, Japanese - A Study on Placements of Distributed Antenna Arrays in an Indoor Multi-User Massive MIMO System
鈴木 裕也, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 103, 127, 132, 21 Jun. 2017
電子情報通信学会, Japanese - Loose Beamforming by Antenna Selection in a Multi-User Massive MIMO System
井上 航一, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 117, 11, 155, 159, 24 Apr. 2017
電子情報通信学会, Japanese - 大規模MIMOシステムのビーム形状に関する特性評価
山本順平, 西村寿彦, 大鐘武雄, 小川恭孝, 武田大樹, 岸山祥久, 電子情報通信学会大会講演論文集(CD-ROM), 2017, 2017 - A Study on Beam Selection Rules and Beam Shapes for Hybrid Beamforming
山本 順平, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 武田 大樹, 岸山 祥久, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116, 383, 147, 152, 21 Dec. 2016
電子情報通信学会, Japanese - Performance Evaluation of a Full-Dimension MIMO Base Station Using a Ray-tracing Technique
西崎 隼, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116, 318, 79, 84, 24 Nov. 2016
電子情報通信学会, Japanese - R&D Activities for 5G in IEICE Technical Committee on Radio Communication Systems in FY2015 : Multi-Antenna Technologies and Advanced Modulation/Multiple Access Schemes (無線通信システム)
Sanada Yukitoshi, Denno Satoshi, Murata Hidekazu, Nishimura Toshihiko, Tandai Tomoya, Okazaki Akihiro, Suyama Satoshi, Mashino Jun, Yamamoto Tetsuya, Taromaru Makoto, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116, 147, 177, 182, 20 Jul. 2016
電子情報通信学会, English - Invited Talk : SINR Evaluation of a Rectangular FD-MIMO System in Various Indoor Environments
西村 寿彦, 西崎 隼, 小川 恭孝, 大鐘 武雄, 映像情報メディア学会技術報告 = ITE technical report, 40, 23, 51, 54, Jul. 2016
映像情報メディア学会, Japanese - A Study on Interference Cancellation Using Belief Propagation in Faster-than-Nyquist Signaling
木原 光太郎, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116, 110, 47, 52, 22 Jun. 2016
電子情報通信学会, Japanese - Considerations on a Channel Prediction Scheme Based on Impulse Response Estimation
奥村 香菜子, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116, 110, 81, 86, 22 Jun. 2016
電子情報通信学会, Japanese - Performance Evaluation of Suppression of Scattereing Waves Using a Gating Technique from Outside of a Search Area in Scatterer Detection Based on Compressed Sensing
阿部 大輔, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 506, 69, 74, 10 Mar. 2016
電子情報通信学会, Japanese - Channel Prediction Using 2-Step Compressed Sensing in a Time-Varying Multi-User MIMO Environment
上橋 俊介, 小川 恭孝, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 472, 357, 362, 02 Mar. 2016
電子情報通信学会, Japanese - B-1-194 DOA Estimation using Compressed Sensing Technique for Multi-band Signals with Frequency Characteristics
Endo Taiki, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 2016, 1, 194, 194, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-43 A Study on Analogue Beamformer with a Butler Matrix under Nakagami-Rice Fading Environments
Yuki Shuto, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2016, 1, 436, 436, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-102 Trajectory Evaluation in Belief Propagation for Channel Equalization
Hagiwara Mitsuyoshi, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2016, 1, 495, 495, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-103 Considerations on LLR Damping in a Massive MIMO System with Belief Propagation
Tanno Shuhei, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2016, 1, 496, 496, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-119 Improvement of Channel Prediction Using Compressed Sensing in a Multi-User MIMO Environment with Moving Scatterers
Uehashi Shunsuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2016, 1, 512, 512, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-153 Considerations on Alternative Routing in a Wireless Mesh Network with an Adaptive Array
Suzuki Kosuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2016, 1, 546, 546, 01 Mar. 2016
The Institute of Electronics, Information and Communication Engineers, Japanese - A Suppression Method of Scattering Waves from Outside of a Search Area in Scatterer Detection Using Compressed Sensing
阿部 大輔, 小川 恭孝, 西村 寿彦, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 390, 77, 82, 14 Jan. 2016
電子情報通信学会, Japanese - 4. Massive MIMO
Ohgane Takeo, Nishimura Toshihiko, Ogawa Yasutaka, The Journal of The Institute of Image Information and Television Engineers, 70, 1, 17, 22, 2016
The Institute of Image Information and Television Engineers, Japanese - Massive MIMO
大鐘 武雄, 西村 寿彦, 小川 恭孝, 映像情報メディア学会誌 = The journal of the Institute of Image Information and Television Engineers, 70, 1, 17, 22, Jan. 2016
映像情報メディア学会, Japanese - Channel Prediction Using Compressed Sensing in a Multi-User MIMO Environment with Moving Scatterers
上橋 俊介, 小川 恭孝, 西村 寿彦, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 288, 299, 304, 04 Nov. 2015
電子情報通信学会, Japanese - A Study on Suppression of Scattering Waves from Outside of a Search Area in Scatterer Detection Using Compressed Sensing
阿部 大輔, 小川 恭孝, 西村 寿彦, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 286, 99, 104, 04 Nov. 2015
電子情報通信学会, Japanese - An EXIT Analysis for Belief-Propagation Based Channel Equalization
萩原 光義, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 288, 7, 12, 04 Nov. 2015
電子情報通信学会, Japanese - A Study on LLR Updating in an LDPC Coded Massive MIMO System with Belief Propagation
丹野 柊平, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 288, 37, 42, 04 Nov. 2015
電子情報通信学会, Japanese - 16-QAM Signal Detection Using Belief Propagation in a Massive MIMO System
宇佐美 友也, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 288, 43, 48, 04 Nov. 2015
電子情報通信学会, Japanese - Performance Evaluation of Full-Dimension MIMO Systems with Consideration for User Density Using a Ray-tracing Technique
西崎 隼, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 288, 127, 132, 04 Nov. 2015
電子情報通信学会, Japanese - B-1-142 Considerations on Detection of the Number of Scatterers Using Compressed Sensing with Thresholding
Abe Daisuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2015, 1, 142, 142, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-10 Doppler Frequency Estimation and Channel Prediction Using Compressed Sensing
Uehashi Shunsuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2015, 1, 272, 272, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-26 A Study on a High Frequency Band Beamformer with a Butler Matrix
Yuki Shuto, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2015, 1, 288, 288, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-81 Performance Evaluation of Full-Dimension MIMO Systems with Increasing a Number of BS Antenna Elements
Nishizaki Shun, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2015, 1, 343, 343, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-82 A Study on LDPC Decoding in Massive MIMO Detection with Belief Propagation
Tanno Shuhei, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2015, 1, 344, 344, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-83 Weighted LLR Damping in Belief Propagation for Channel Equalization
Hagiwara Mitsuyoshi, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2015, 1, 345, 345, 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - BS-2-5 Indoor SINR Performance of a Rectangular Array type FD-MIMO
Nishimura Toshihiko, Nishizaki Shun, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2015, 1, "S, 39"-"S-40", 25 Aug. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - Evaluation of DOA Estimation Using a Compressed Sensing Technique for Arrival Signals with Different Amplitudes
遠藤 大樹, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 164, 107, 112, 30 Jul. 2015
電子情報通信学会, Japanese - A Study on Beam Selection in a High Frequency Band Analogue Beamformer
結城 嵩仁, 小川 恭孝, 西村 寿彦, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 113, 247, 252, 24 Jun. 2015
電子情報通信学会, Japanese - Performance Evaluation of Full-Dimension MIMO Systems with a Different Number of BS Antenna Elements Using a Ray-tracing Technique
西崎 隼, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 113, 241, 246, 24 Jun. 2015
電子情報通信学会, Japanese - A Study on Channel Decoding in Massive MIMO Detection with Belief Propagation
丹野 柊平, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 113, 257, 261, 24 Jun. 2015
電子情報通信学会, Japanese - A Study on LLR Damping in Belief Propagation for Channel Equalization
萩原 光義, 西村 寿彦, 大鐘 武雄, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 113, 263, 267, 24 Jun. 2015
電子情報通信学会, Japanese - B-1-193 Detection of Scatterers Using Compressed Sensing with a Time-Domain Gating Technique
Kusano Kaoru, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2015, 1, 193, 193, 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-19 Channel Prediction Using Compressed Sensing in TDD Multi-User MIMO Systems
Uehashi Shunsuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2015, 1, 374, 374, 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-53 Performance Evaluation for Alternative Routing in a Wireless Mesh Network with an Adaptive Array
Suzuki Kosuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2015, 1, 408, 408, 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-111 A Study on BP-based Approach in a 16 QAM Modulated Massive MIMO System
Usami Tomoya, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2015, 1, 466, 466, 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-167 Channel Equalization Using a Belief Propagation Algorithm with High Rate Codes
Sugita Masatomo, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2015, 1, 522, 522, 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - BS-1-1 Parameter Dependency on an Arrival Wave Number in DOA Estimation Using a Compressed Sencing Technique
Endo Taiki, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 2015, 1, "S, 1"-"S-2", 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - BP-1-4 MIMO and Beamforming Technologies for 5G
Ohgane Takeo, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the IEICE General Conference, 2015, 1, "SS, 9"-"SS-10", 24 Feb. 2015
The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Channel Prediction Scheme Using Compressed Sensing in Multi-User MIMO Systems
UEHASHI Shunsuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Signal processing, 114, 394, 55, 60, 22 Jan. 2015
In multi-user MIMO systems, a base station needs downlink channel state information (CSI) to each user to suppress inter-user interference and inter-stream interference. In wireless communication, however, signal propagation environments are time-varying, and CSI obtained at the base station is different from the channel at the actual transmission time because we have delay. This deteriorates communication quality. To solve this problem, some channel prediction schemes have been developed. So far, we have proposed a channel prediction scheme using a compressed sensing technique. This scheme can predict channel with high accuracy even when the number of arrival waves is large. In this paper, we evaluate the effect of the proposed method in multi-user MIMO systems., The Institute of Electronics, Information and Communication Engineers, Japanese - A throughput evaluation of an over-distributed antenna system with signal distributing or switching under control delay
NAKANISHI Yuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, IEICE technical report. Signal processing, 114, 394, 61, 66, 22 Jan. 2015
When a base station has many transmit antennas such as a massive MIMO system, we need as many pilot resources as the transmit antennas to estimate channel state information (CSI) and its feedback in an FDD system, and thus transmission efficiency degrades. In our previous study, we have proposed an over-distributed antenna system (O-DAS) with much more transmit antennas than limited pilot resources, and have shown an improvement of the peak throughput under a perfect CSI assumption. However, the CSI is outdated if control delay exists, and thus it may cause the inter-user-interference which seriously degrades the transmission performance. In this paper, we evaluate the throughput performance of the O-DAS for two transmission methods, namely, signal distributing and switching, in time-varying environments with a control delay. Compared with the case in non time-varying environments, it is shown that the performance degradation of signal switching is not serious and that the signal distributing still provides sufficient gain although the profitable range becomes narrow., The Institute of Electronics, Information and Communication Engineers, Japanese - A BP-based approach for M-QAM signal detection in a fully massive MIMO system
USAMI Tomoya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report. Signal processing, 114, 394, 163, 168, 22 Jan. 2015
With the rapid traffic growth, a massive multiple-input multiple-output (MIMO) system with an order of 100 elements has been discussed recently. Increasing the number of both transmit and receive antennas improves peak data rate and capacity, but requires the complexity proportional to at least the third power of the number of antenna elements to detect spatially-multiplexed signals in general. Thus, the implementation of a fully massive MIMO system becomes very difficult. To solve this problem, detection based on the belief propagation has been developed and studied. It has been shown that the belief propagation is implementable in the order of the second power of the number of elements and achieves very good BER performance in a QPSK modulated massive MIMO system. But it is essential to study a multi-level QAM modulated massive MIMO system in the viewpoint of peak throughput. In this paper, we apply the belief propagation to a 16-QAM modulated massive MIMO system and have shown that starting the process from error-tolerant bit nodes improves the BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Channel Prediction Scheme Using Compressed Sensing in Multi-User MIMO Systems
UEHASHI Shunsuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 114, 395, 55, 60, 22 Jan. 2015
In multi-user MIMO systems, a base station needs downlink channel state information (CSI) to each user to suppress inter-user interference and inter-stream interference. In wireless communication, however, signal propagation environments are time-varying, and CSI obtained at the base station is different from the channel at the actual transmission time because we have delay. This deteriorates communication quality. To solve this problem, some channel prediction schemes have been developed. So far, we have proposed a channel prediction scheme using a compressed sensing technique. This scheme can predict channel with high accuracy even when the number of arrival waves is large. In this paper, we evaluate the effect of the proposed method in multi-user MIMO systems., 一般社団法人電子情報通信学会, Japanese - A throughput evaluation of an over-distributed antenna system with signal distributing or switching under control delay
中西裕基, 西村寿彦, 大鐘武雄, 小川恭孝, 大渡裕介, 岸山祥久, 電子情報通信学会技術研究報告, 114, 395(RCS2014 269-300), 61, 66, 22 Jan. 2015
When a base station has many transmit antennas such as a massive MIMO system, we need as many pilot resources as the transmit antennas to estimate channel state information (CSI) and its feedback in an FDD system, and thus transmission efficiency degrades. In our previous study, we have proposed an over-distributed antenna system (O-DAS) with much more transmit antennas than limited pilot resources, and have shown an improvement of the peak throughput under a perfect CSI assumption. However, the CSI is outdated if control delay exists, and thus it may cause the inter-user-interference which seriously degrades the transmission performance. In this paper, we evaluate the throughput performance of the O-DAS for two transmission methods, namely, signal distributing and switching, in time-varying environments with a control delay. Compared with the case in non time-varying environments, it is shown that the performance degradation of signal switching is not serious and that the signal distributing still provides sufficient gain although the profitable range becomes narrow., 一般社団法人電子情報通信学会, Japanese - A BP-based approach for M-QAM signal detection in a fully massive MIMO system
USAMI Tomoya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 114, 395, 163, 168, 22 Jan. 2015
With the rapid traffic growth, a massive multiple-input multiple-output (MIMO) system with an order of 100 elements has been discussed recently. Increasing the number of both transmit and receive antennas improves peak data rate and capacity, but requires the complexity proportional to at least the third power of the number of antenna elements to detect spatially-multiplexed signals in general. Thus, the implementation of a fully massive MIMO system becomes very difficult. To solve this problem, detection based on the belief propagation has been developed and studied. It has been shown that the belief propagation is implementable in the order of the second power of the number of elements and achieves very good BER performance in a QPSK modulated massive MIMO system. But it is essential to study a multi-level QAM modulated massive MIMO system in the viewpoint of peak throughput. In this paper, we apply the belief propagation to a 16-QAM modulated massive MIMO system and have shown that starting the process from error-tolerant bit nodes improves the BER performance., 一般社団法人電子情報通信学会, Japanese - A Throughput Evaluation of an Over-Distributed Antenna System with Limited Pilot Resources
NAKANISHI Yuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, IEICE Transactions on Communications (Web), E98.B, 8, 2015 - An impact of alternative routing in a wireless mesh network with an adaptive array
SUZUKI Kosuke, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 114, 372, 135, 140, 18 Dec. 2014
In a wireless mesh network, the interference between nearby links is not negligible and thus degrades the area spectral efficiency. There have been many works on a use of directional antennas capable of forming a narrow beam to a destination node. An adaptive array capable of controlling not only beams but also nulls is more effective for reducing interference, and thereby the possibility to establish new links increases. Here, an alternative route enables avoiding resource competitions and improves the possibility of new link establishment. In the paper, we evaluate the system throughput performance in a wireless mesh network consisting of nodes having alternative routes and an adaptive array function., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study of Channel Equalization Using a Belief Propagation Algorithm
SUGITA Masatomo, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 114, 295, 37, 42, 12 Nov. 2014
Frequency-domain equalization is well known as a countermeasure for inter-symbol interference in a single carrier transmission system in terms of light weight and reasonably high performance. Frequency-domain turbo equalization with iterative processing has been developed as the extension to provide very high performance. In this paper, we consider a channel equalizer using a belief propagation (BP) algorithm in the time domain. In multiple-input multiple-output multi-path environments, it has been reported that this algorithm achieves a near-optimum BER performance. However, in single-input single-output (SISO) multi-path environments, the normal BP algorithm does not work. We show the problems and a solution against that. And we evaluate the BER performance with our proposal in a SISO multi-path environment., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on Channel Prediction Schemes Using Compressed Sensing
UEHASHI Shunsuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 114, 245, 1, 6, 15 Oct. 2014
In wireless communication, channel estimation using pilot symbols is essential. If we need to transmit many pilot symbols in time-varying environments, the transmission efficiency is lowed. Also, channel state information (CSI) obtained by the pilot symbols is different from the channel at the actual transmission time because we have delay. This deteriorates communication quality. To solve this problem, some channel prediction schemes have been developed. In this paper, we propose a channel prediction scheme which combines a sum-of-sinusoids (SOS) method and direction-of-arrival (DOA) estimation using a compressed sensing technique. Using simulation, it is shown that the proposed method realizes highly precise channel prediction., The Institute of Electronics, Information and Communication Engineers, Japanese - Study on Parameter Dependence of DOA Estimation of Multi-band Signals using a Compressed Sensing Technique
ENDO Taiki, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report. Antennas and propagation, 114, 245, 7, 12, 15 Oct. 2014
In recent years, much attention has been paid to DOA estimation using a compressed sensing technique. We have studied a DOA estimation method of multi-band signals with frequency characteristics. Using multi-band signals, we can achieve higher probability of correct estimation that using single-band signals and estimate more waves than the number of antenna elements. The half-quadratic regularization (HQR) method is a technique to solve a linear programming problem of the compressed sensing technique. In this paper, we study dependence property of three parameters in the HQR method for probability of correct estimation and obtaine adequate values of the parameters., The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-172 Dependency of Parameters for DOA Estimation of Multiband Signals using a Compressed Sensing Technique
Endo Taiki, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2014, 1, 172, 172, 09 Sep. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-50 Considerations on Channel Prediction Using Compressed Sensing
Uehashi Shunsuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2014, 1, 321, 321, 09 Sep. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-51 SINK Performance Comparison for Different Areas of User Distribution in Indoor Full-Dimension MIMO Systems Using a Ray-tracing Technique
Fukuda Hayato, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2014, 1, 322, 322, 09 Sep. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - DOA Estimation Applying Compressed Sensing Techniques
NISHIMURA T., ENDO T., OGAWA Y., OHGANE T., Technical report of IEICE. SANE, 114, 194, 65, 70, 28 Aug. 2014
It has been proposed to apply compressed sensing methods to problems estimating the direction of arrival angles of radio waves. Using the proposed method, angular resolution can be more precise than the traditional methods such as the MUSIC. If the arrival waves are multiband signal spread over a wide-frequency-band, the performance can be improved. Furthermore, the performance enhancement can be expected by using the Khatri-Rao product and normalization of power even when the arrival waves have frequency dependency. We show how the compressed sensing method is applied, and then we explain how the method using the Khatri-Rao product and normalization of power is applied. The effectiveness of our proposal is confirmed by some simulation results., The Institute of Electronics, Information and Communication Engineers, Japanese - DOA Estimation Applying Compressed Sensing Techniques
NISHIMURA T., ENDO T., OGAWA Y., OHGANE T., IEICE technical report. Antennas and propagation, 114, 193, 79, 84, 28 Aug. 2014
It has been proposed to apply compressed sensing methods to problems estimating the direction of arrival angles of radio waves. Using the proposed method, angular resolution can be more precise than the traditional methods such as the MUSIC. If the arrival waves are multiband signal spread over a wide-frequency-band, the performance can be improved. Furthermore, the performance enhancement can be expected by using the Khatri-Rao product and normalization of power even when the arrival waves have frequency dependency. We show how the compressed sensing method is applied, and then we explain how the method using the Khatri-Rao product and normalization of power is applied. The effectiveness of our proposal is confirmed by some simulation results., The Institute of Electronics, Information and Communication Engineers, Japanese - SINR Performance Comparison of Full-Dimension MIMO Systems in Indoor Environments Using a Ray-tracing Technique
FUKUDA Hayato, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, Technical report of IEICE. RCS, 114, 180, 1, 6, 19 Aug. 2014
In order to realize high capacity communication, massive multiple-input multiple-output (MIMO) systems which have a very large number of antenna elements at a base station (BS) or an access point (AP) have been studied for future cellular systems. It is, however, difficult to build the massive MIMO system because the installation space is limited. To cope with this limitation, a full-dimension MIMO (FD-MIMO) system where antenna elements are placed on a 2D grid at the BS or AP for MIMO transmission is proposed. The 2D antenna array saves the space and allows elevation beamforming as well as azimuth beamforming. In this paper, we evaluate performance of the FD-MIMO in indoor Line-of-Sight environments compared with that of a ID antenna arrangement using a ray tracing technique which enables to obtain channel matrices between BS and user terminals. It has been shown that FD-MIMO with a small rectangular antenna array performs better than ID antenna array when users are located near the BS., The Institute of Electronics, Information and Communication Engineers, Japanese - An evaluation of multiuser MIMO throughput in a distributed antenna system with signal distribution
NAKANISHI Yuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 114, 180, 7, 12, 19 Aug. 2014
A distributed antenna system, where antennas of a base station are spatially distributed over the cell, can improve throughput at the cell edge compared to a centralized antenna system but reduces peak throughput. Therefore, it is expected that we can obtain higher throughput by increasing the number of antennas per remote antenna unit. In general, we need to send as many pilot sequences as transmit antennas to estimate channel state information and thus transmission efficiency degrades. In this paper, we present a novel system where we distribute the same signal to several antennas to increase the number of antennas without increasing the number of pilot sequences. We show the throughput improvement with signal distribution and evaluate the effect of weighted signal distribution., The Institute of Electronics, Information and Communication Engineers, Japanese - A Multi-user MIMO System in Time-varying Environments
OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, The Journal of the Institute of Electronics, Information, and Communication Engineers, 97, 4, 285, 289, Apr. 2014
マルチユーザMIMOシステムの下り回線においては,通常,ユーザ間の干渉,及び,同一ユーザの複数ストリーム間の干渉がなくなるように基地局は送信ウェイトを決定し,それを信号に乗算して伝送が行われる.一方,ユーザ端末や周囲の散乱体の移動により,一般に,チャネルは時間変動する.このような環境では,送信ウェイトを決定したときのチャネルと実際に送信を行うときのチャネルに変動があるため干渉が発生し,特性が劣化する.この問題はチャネルを予測することにより軽減が可能である.本稿では,時変動チャネルがマルチユーザMIMOシステムに与える影響とチャネル予測の効果を明らかにする., 一般社団法人電子情報通信学会, Japanese - ABS-1-1 A Basic Concept of Massive MIMO and Its Enhancement to Fully-Massive MIMO
Ohgane Takeo, Usami Tomoya, Fukuda Wataru, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the IEICE General Conference, 2014, "S, 54"-"S-55", 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-216 Considerations on a Multi-User MIMO System Using Channel Prediction in the Presence of Channel Estimation Error
Yamaguchi Kanako, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 216, 216, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-228 Error Reduction of Wideband DOA Estimation Using Khatri-Rao Processing
SHIRAI Satoshi, YAMADA Hiroyoshi, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, YAMAGUCHI Yoshio, Proceedings of the IEICE General Conference, 2014, 1, 228, 228, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-231 A Compressed Sensing DOA Estimation Method of Multi-band Signals with Frequency Characteristics
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Yamada Hiroyoshi, Proceedings of the IEICE General Conference, 2014, 1, 231, 231, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-21 PAPR Reduction in a Single-Carrier E-SDM System
Tanaka Tomoki, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 416, 416, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-33 Signal Detection Based on Belief Propagation for a Massive MIMO System in Spatially Correlated Channels
Fukuda Wataru, Abiko Takashi, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Ohwatari Yusuke, Kawamura Teruo, Kishiyama Yoshihisa, Proceedings of the IEICE General Conference, 2014, 1, 428, 428, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-35 A Fundamental Study on an EXIT Chart Analysis for Belief-Propagation Based Signal Detection in Spatially Correlated MIMO Channels
Abiko Takashi, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Ohwatari Yusuke, Kawamura Teruo, Kishiyama Yoshihisa, Proceedings of the IEICE General Conference, 2014, 1, 430, 430, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-78 A Study on a Single-Carrier Multi-User E-SDM Scheme with Resource Allocation in Wideband Transmissions
Harada Keita, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 473, 473, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-80 An impact of reduced pilot signals in a multi-cell distributed antenna system using antenna selection
Nakanishi Yuki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 475, 475, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-100 Channel Equalization Using Belief Propagation Algorithm
Sugita Masatomo, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 495, 495, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-158 Fundamental study on antenna pattern control using LabVIEW and USRP for wireless mesh networks
Izumo Kyousuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 553, 553, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - ABS-1-1 A Basic Concept of Massive MIMO and Its Enhancement to Fully-Massive MIMO
Ohgane Takeo, Usami Tomoya, Fukuda Wataru, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the IEICE General Conference, 2014, 1, "S, 54"-"S-55", 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - ABS-1-1 A Basic Concept of Massive MIMO and Its Enhancement to Fully-Massive MIMO
Ohgane Takeo, Usami Tomoya, Fukuda Wataru, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the IEICE General Conference, 2014, "S, 54"-"S-55", 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-21 PAPR Reduction in a Single-Carrier E-SDM System
Tanaka Tomoki, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 416, 416, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-216 Considerations on a Multi-User MIMO System Using Channel Prediction in the Presence of Channel Estimation Error
Yamaguchi Kanako, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 216, 216, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-80 An impact of reduced pilot signals in a multi-cell distributed antenna system using antenna selection
Nakanishi Yuki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 475, 475, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-33 Signal Detection Based on Belief Propagation for a Massive MIMO System in Spatially Correlated Channels
Fukuda Wataru, Abiko Takashi, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Ohwatari Yusuke, Kawamura Teruo, Kishiyama Yoshihisa, Proceedings of the IEICE General Conference, 2014, 1, 428, 428, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-228 Error Reduction of Wideband DOA Estimation Using Khatri-Rao Processing
SHIRAI Satoshi, YAMADA Hiroyoshi, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, YAMAGUCHI Yoshio, Proceedings of the IEICE General Conference, 2014, 1, 228, 228, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-231 A Compressed Sensing DOA Estimation Method of Multi-band Signals with Frequency Characteristics
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Yamada Hiroyoshi, Proceedings of the IEICE General Conference, 2014, 1, 231, 231, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-35 A Fundamental Study on an EXIT Chart Analysis for Belief-Propagation Based Signal Detection in Spatially Correlated MIMO Channels
Abiko Takashi, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Ohwatari Yusuke, Kawamura Teruo, Kishiyama Yoshihisa, Proceedings of the IEICE General Conference, 2014, 1, 430, 430, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-158 Fundamental study on antenna pattern control using LabVIEW and USRP for wireless mesh networks
Izumo Kyousuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 553, 553, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-100 Channel Equalization Using Belief Propagation Algorithm
Sugita Masatomo, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2014, 1, 495, 495, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-78 A Study on a Single-Carrier Multi-User E-SDM Scheme with Resource Allocation in Wideband Transmissions
Harada Keita, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2014, 1, 473, 473, 04 Mar. 2014
The Institute of Electronics, Information and Communication Engineers, Japanese - High Reliability Vehicle-to-vehicle Communication System
SAI Seii, DOI Yoshiharu, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 113, 456, 169, 174, 03 Mar. 2014
In Japan, 700MHz-band ITS has been promoted to improve not only the "environment", "comfort and convenient", but also the "road safety" over recent years. The idea is to exchange safety-related information between neighboring vehicles to extend the driver's view and provide more information to drivers by using the wireless communication. In the near future, it is expected that neighboring vehicles may even directly exchange critical control-relevant information without driver involved to realize safer road environments. Therefore, it is necessary to improve the reliability of vehicle-to-vehicle commutation. In the paper, we propose a new communication method for high reliability vehicle-to-vehicle communication and show the initial performance evaluation results through computer simulations., The Institute of Electronics, Information and Communication Engineers, Japanese - High Reliability Vehicle-to-vehicle Communication System
SAI SEII, DOI YOSHIHARU, NISHIMURA TOSHIHIKO, OGANE TAKEO, OGAWA YASUTAKA, 電子情報通信学会技術研究報告, 113, 456(RCS2013 306-396), 169, 174, 24 Feb. 2014
Japanese - Study on Wideband DOA Estimation Using Khatri-Rao Processing
SHIRAI Satoshi, YAMADA Hiroyoshi, NISHIMURA Toshihiko, OGAWA Yasutaka, YAMAGUCHI Yoshio, IEICE technical report. Antennas and propagation, 113, 344, 35, 40, 12 Dec. 2013
Recently, research and communication using wideband signal have been investigated intensively. With the progress of wideband communications, wideband DOA estimation technique has been also required. The history of wideband DOA estimation has several decades, but standard approach does not still exist. In this report, we have proposed a new wideband DOA estimation method using the Khatri-Rao matrix product. This method enables a wideband DOA estimation using a simple conversion of sub-frequency band signals. Furthermore, it has the advantage of enhance the degrees-of-freedom of the array. In this paper, we evaluate the performance of the proposed method through simulations and experiments., The Institute of Electronics, Information and Communication Engineers, Japanese - Study on Wideband DOA Estimation Using Khatri-Rao Processing
SHIRAI SATOSHI, YAMADA HIROYOSHI, NISHIMURA TOSHIHIKO, OGAWA YASUTAKA, YAMAGUCHI YOSHIO, 電子情報通信学会技術研究報告, 113, 344(AP2013 124-133), 35, 40, 05 Dec. 2013
Japanese - A Study on BP-based Signal Detection for a Massive MIMO system in Spatially Correlated Channels
FUKUDA Wataru, ABIKO Takashi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KAWAMURA Teruo, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 113, 301, 55, 60, 20 Nov. 2013
The easiest way to improve the throughput performance of multiple-input multiple-output (MIMO) systems is increasing the number of both transmit and receive antennas. In general, however, algorithms detecting spatially-multiplexed signals require the complexity to be proportional to the third power of the number of antenna elements at least. Thus, the implementation of an antenna array with an order of 100 elements becomes very difficult. Several studies have shown that a detection based on the belief propagation with a parallel interference canceller is implementable in the order of the second power of the number of elements and achieves very good BER performance in uncorrelated MIMO channels. However, it is expected that the detection performance degrades in spatially correlated MIMO channels. In this paper, we propose applying node selection, and show the BER performance in correlated channels., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on Prediction Effects of Multi-User MIMO Channels in Time-Varying Environments
YAMAGUCHI Kanako, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 113, 300, 43, 48, 20 Nov. 2013
A multi-user MIMO system uses block diagonalization and eigenbeam-space division multiplexing to suppress inter-user interference and inter-stream interference. In order to use these techniques, the transmitter needs to determine beamforming weights from channel state information (CSI). In time-varyinig environments, however, MIMO channels change during the time interval between transmission parameter determination and actual MIMO transmission. Therefore, the outdated CSI causes the interfernces and seriously affects the transmission performance. Channel prediction schemes have been developed to mitigate the effect of the outdated CSI. In this paper, we evaluate the prediction effects based on the autoregressive (AR) model and the Lagrange extrapolation such as linear extrapolation in time-varying environments., The Institute of Electronics, Information and Communication Engineers, Japanese - DOA Estimation of Multi-band Signals with Frequency Characteristics
TERADA Tsubasa, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, YAMADA Hiroyoshi, IEICE technical report. Antennas and propagation, 113, 300, 93, 98, 20 Nov. 2013
Much attention has been paid to direction of arrival (DOA) estimation using a compressed sensing technique. In our previous study, we have proposed a method to estimate DOAs of multi-band signals using an array antenna at a receiver. As a result, we have produced an improvement of the probability of correct estimation. Moreover, the method can deal with waves exceeding the degrees of freedom of the array. However, we have assumed that incident waves have multi-bands where complex amplitudes are the same. First, in this paper, we propose a method that allows the estimation of DOAs when only the phases at the bands are different using not the complex amplitudes but powers of the signals. Second, we extend the technique in such a way that it can estimate DOAs of the signals having different amplitudes among bands., The Institute of Electronics, Information and Communication Engineers, Japanese - DOA Estimation of Multi-band Signals with Frequency Characteristics
TERADA TSUBASA, NISHIMURA TOSHIHIKO, OGAWA YASUTAKA, OGANE TAKEO, YAMADA HIROYOSHI, 電子情報通信学会技術研究報告, 113, 300(AP2013 100-123), 93, 98, 13 Nov. 2013
Japanese - Considerations on Prediction Effects of Multi-User MIMO Channels in Time-Varying Environments
YAMAGUCHI KANAKO, OGAWA YASUTAKA, NISHIMURA TOSHIHIKO, OGANE TAKEO, 電子情報通信学会技術研究報告, 113, 300(AP2013 100-123), 43, 48, 13 Nov. 2013
Japanese - A Study on BP-based Signal Detection for a Massive MIMO system in Spatially Correlated Channels
福田航, 安孫子卓史, 西村寿彦, 大鐘武雄, 小川恭孝, 大渡裕介, 川村輝雄, 岸山祥久, 電子情報通信学会技術研究報告, 113, 301(RCS2013 174-205), 55, 60, 13 Nov. 2013
Japanese - Considerations on Detection of Scatterers Using Compressed Sensing
Kusano Kaoru, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2013, 1, 209, 209, 03 Sep. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation for a pilot"-"Signal"-"Shared capacity in a multiuser MIMO distributed antenna system
Nakanishi Yuki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2013, 1, 396, 396, 03 Sep. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on Detection of Scatterers Based on Compressed Sensing
KUSANO Kaoru, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 113, 151, 43, 48, 23 Jul. 2013
A radar is a device for detecting scatterers by observing scattered electromagnetic waves. To enhance the precision, we need a wide frequencyband and/or more antennas. The frequency band and the number of antennas are, howerver, limited, and a higly accurate method is needed when the samples are not sufficient. In this paper, we formulate a method based on compressed sensing. Then, we consider the performance of cases of using a single transmit antenna and all of the transmit ones in the array., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on Detection of Scatterers Based on Compressed Sensing
KUSANO KAORU, OGAWA YASUTAKA, NISHIMURA TOSHIHIKO, OGANE TAKEO, 電子情報通信学会技術研究報告, 113, 151(AP2013 46-61), 43, 48, 16 Jul. 2013
Japanese - Considerations on a Multi-User Single-Carrier E-SDM Scheme in Wideband Transmissions
HARADA Keita, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 113, 93, 49, 54, 20 Jun. 2013
Multi-user multiple-input multiple-output (MU-MIMO) systems in which signals are simultaneously transmitted from a base station to multiple users are well known as a method to improve the throughput performance. In MU-MIMO systems, the block diagonalization scheme is used to eliminate inter-user interference and the eigenbeam-space division multiplexing (E-SDM) technique is used for channel capacity maximization. In this paper, a multi-user single-carrier E-SDM scheme in wideband transmissions is formulated. The transmit and receive weights are obtained in the frequency domain. The receive weights are based on the zero-forcing method, which simultaneously operates the spatial domain processing and frequency domain equalization. Then, the bit error rate performance is evaluated using computer simulations., The Institute of Electronics, Information and Communication Engineers, Japanese - An impact of reduced pilot signals on capacity of a multiuser MIMO system with distributed antennas
NAKANISHI Yuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 113, 93, 55, 60, 20 Jun. 2013
A distributed antenna system, where antennas of a base station are spatially distributed over the cell, can improve throughput at the cell edge compared to a centralized antenna system. In a multiuser multiple-input multiple-output (MIMO) system, we can obtain higher sum capacity by increasing the number of antennas per distributed base station. However, the large number of total antenna elements requires the same or larger number of pilot sequences to estimate the channel gains. In this paper, we propose pilot signal sharing to reduce the number of pilot signals, and the impact of the pilot signal sharing on the sum capacity is evaluated. From computer simulations, it is shown that inter-user interference due to the wrong channel information can be suppressed at a certain sharing condition., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Evaluation of MIMO Single-carrier Block Transmission with 1024QAM Using FPGA-based Testbed
YAMAGUCHI Kanako, NISHIMOTO Hiroshi, OKAZAKI Akihiro, SANO Hiroyasu, ISHIZU Fumio, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 113, 93, 193, 198, 20 Jun. 2013
As a countermeasure for serious shortage of radio frequency resources, single-carrier block transmission (SCBT) techniques, which can achieve a low PAPR property and high spectral efficiency simultaneously, have attracted much attention. Further efficient spectral utilization can be yielded by incorporating multilevel modulation and MIMO spatial multiplexing into SCBT. In that case, however, the receiver requires accurate channel estimation in order to demultiplex and detect the spatially-multiplexed multilevel-modulated signal. So far, the authors have proposed core techniques for SCBT and verified their availability by computer simulations: (a) a frequency-domain scattered pilot multiplexing technique with maintenance of the low PAPR property of SCBT, and (b) a two-dimensional channel estimation technique using parameter table selection, which equivalently achieves an MMSE criterion with highly-reduced numerical complexity. Here, the authors construct a testbed of multilevelmodulated MIMO-SCBT using an FPGA-based prototype modem in order to demonstrate our techniques. This paper reports experimental performance evaluation of the 1024QAM-modulated 2 x 4 MIMO-SCBT., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Evaluation of MIMO Single-carrier Block Transmission with 1024QAM Using FPGA-based Testbed
YAMAGUCHI KANAKO, NISHIMOTO HIROSHI, OKAZAKI AKIHIRO, SANO HIROYASU, ISHIZU FUMIO, NISHIMURA TOSHIHIKO, OGANE TAKEO, OGAWA YASUTAKA, 電子情報通信学会技術研究報告, 113, 93(RCS2013 37-77), 193, 198, 13 Jun. 2013
Japanese - An impact of reduced pilot signals on capacity of a multiuser MIMO system with distributed antennas
NAKANISHI YUKI, NISHIMURA TOSHIHIKO, OGANE TAKEO, OGAWA YASUTAKA, 電子情報通信学会技術研究報告, 113, 93(RCS2013 37-77), 55, 60, 13 Jun. 2013
Japanese - Considerations on a Multi-User Single-Carrier E-SDM Scheme in Wideband Transmissions
HARADA KEITA, OGAWA YASUTAKA, NISHIMURA TOSHIHIKO, OGANE TAKEO, 電子情報通信学会技術研究報告, 113, 93(RCS2013 37-77), 49, 54, 13 Jun. 2013
Japanese - B-1-198 DOA Estimation of Multi--band Signals Using Compressed Sensing
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 2013, 1, 198, 198, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-217 Considerations on a Multi-User MIMO SystemUsing Channel Prediction Based on an AR Model in Time-Varying Environments
Yamaguchi Kanako, Bui Huu Phu, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2013, 1, 217, 217, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-10 A study on LLR generation of coded MIMO-OFDM using lattice reduction
MORITANI Kentaro, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 420, 420, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-11 Signal Detection Based on Belief Propagation in a Large Scale MIMO System
Fukuda Wataru, Abiko Takashi, Nishimura Toshihiko, Ohgane Takeo, Ohwatari Yusuke, Kishiyama Yoshihisa, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 421, 421, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-12 An EXIT Chart Analysis of lterative Processing in Belief-Propagation Based Signal Detection in a Large Scale MIMO System
Abiko Takashi, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ohwatari Yusuke, Kishiyama Yoshihisa, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 422, 422, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-30 A Study on the Effect of Terminal Velocity in an OFDM Uplink Virtual MIMO System
KOBAYASHI Takuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2013, 1, 440, 440, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-170 Full-Duplex AFリレ-におけるMMSE-FDEに関する検討
KIYOMI Naohito, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 580, 580, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-198 DOA Estimation of Multi--band Signals Using Compressed Sensing
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 2013, 1, 198, 198, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-217 Considerations on a Multi-User MIMO SystemUsing Channel Prediction Based on an AR Model in Time-Varying Environments
Yamaguchi Kanako, Bui Huu Phu, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2013, 1, 217, 217, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-30 A Study on the Effect of Terminal Velocity in an OFDM Uplink Virtual MIMO System
KOBAYASHI Takuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2013, 1, 440, 440, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-4 A Study on a Multi-User E-SDM Scheme in Wideband Transmissions
Harada Keita, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2013, 1, 414, 414, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-170 Full-Duplex AFリレ-におけるMMSE-FDEに関する検討
KIYOMI Naohito, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 580, 580, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-12 An EXIT Chart Analysis of lterative Processing in Belief-Propagation Based Signal Detection in a Large Scale MIMO System
Abiko Takashi, Fukuda Wataru, Nishimura Toshihiko, Ohgane Takeo, Ohwatari Yusuke, Kishiyama Yoshihisa, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 422, 422, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-10 A study on LLR generation of coded MIMO-OFDM using lattice reduction
MORITANI Kentaro, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 420, 420, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-11 Signal Detection Based on Belief Propagation in a Large Scale MIMO System
Fukuda Wataru, Abiko Takashi, Nishimura Toshihiko, Ohgane Takeo, Ohwatari Yusuke, Kishiyama Yoshihisa, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2013, 1, 421, 421, 05 Mar. 2013
The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity Reduction Approaches for Signal Detection Based on Belief Propagation in a Large Scale MIMO System
FUKUDA Wataru, ABIKO Takashi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 424, 225, 230, 31 Jan. 2013
The easiest way to improve the throughput performance of multiple-input multiple-output (MIMO) systems is to increase the number of both transmit and receive antennas. In general, however, algorithms detecting spatially-multiplexed signals require the complexity proportional to the third power of the number of antenna elements in the least case. Thus, the implementation of an antenna array with an order of 100 elements becomes very difficult. Several studies have shown that a detection based on the belief propagation with a parallel interference canceller is implementable in the order of the second power of the number of elements and achieves very good BER performance. In this paper, we apply three methods for the complexity reduction into the belief propagation with focus on the Tanner graph, and evaluate those BER performances., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of Belief-Propagation Algorithm with MRC for Signal Detection in a Large Scale MIMO System
ABIKO Takashi, FUKUDA Wataru, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 424, 231, 236, 31 Jan. 2013
Multiple-input multiple-output (MIMO) systems are well known as a method to improve the throughput performance Recently, a concept of massive (or very large) MIMO using an antenna array with an order of 100 elements has been proposed. In general, the complexity order of signal detection in such a MIMO system becomes the third power of the number of antenna elements in the least case. The authors have evaluated the belief propagation based algorithm with parallel interference cancellers and shown that it is implementable in the order of the second power of the number of elements Here, we describe a method to use maximum ratio combining (MRC) for message fusion and evaluate BER performance. In addition, the convergence behavior is discussed by applying the extrinsic information transfer analysis., The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity Reduction Approaches for Signal Detection Based on Belief Propagation in a Large Scale MIMO System
FUKUDA Wataru, ABIKO Takashi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 424, 225, 230, 31 Jan. 2013
The easiest way to improve the throughput performance of multiple-input multiple-output (MIMO) systems is to increase the number of both transmit and receive antennas. In general, however, algorithms detecting spatially-multiplexed signals require the complexity proportional to the third power of the number of antenna elements in the least case. Thus, the implementation of an antenna array with an order of 100 elements becomes very difficult. Several studies have shown that a detection based on the belief propagation with a parallel interference canceller is implementable in the order of the second power of the number of elements and achieves very good BER performance. In this paper, we apply three methods for the complexity reduction into the belief propagation with focus on the Tanner graph, and evaluate those BER performances., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of Belief-Propagation Algorithm with MRC for Signal Detection in a Large Scale MIMO System
ABIKO Takashi, FUKUDA Wataru, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATARI Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 424, 231, 236, 31 Jan. 2013
Multiple-input multiple-output (MIMO) systems are well known as a method to improve the throughput performance Recently, a concept of massive (or very large) MIMO using an antenna array with an order of 100 elements has been proposed. In general, the complexity order of signal detection in such a MIMO system becomes the third power of the number of antenna elements in the least case. The authors have evaluated the belief propagation based algorithm with parallel interference cancellers and shown that it is implementable in the order of the second power of the number of elements Here, we describe a method to use maximum ratio combining (MRC) for message fusion and evaluate BER performance. In addition, the convergence behavior is discussed by applying the extrinsic information transfer analysis., The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity Reduction Approaches for Signal Detection Based on Belief Propagation in a Large Scale MIMO System
福田航, 安孫子卓史, 西村寿彦, 大鐘武雄, 小川恭孝, 大渡裕介, 岸山祥久, 電子情報通信学会技術研究報告, 112, 424(RCS2012 238-283), 225, 230, 24 Jan. 2013
Japanese - Performance Evaluation of Belief-Propagation Algorithm with MRC for Signal Detection in a Large Scale MIMO System
安孫子卓史, 福田航, 西村寿彦, 大鐘武雄, 小川恭孝, 大渡裕介, 岸山祥久, 電子情報通信学会技術研究報告, 112, 424(RCS2012 238-283), 231, 236, 24 Jan. 2013
Japanese - A Study on a Multi-User Single-Carrier E-SDM Scheme in Wideband Transmissions
Keita Harada, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, 2013 INTERNATIONAL SYMPOSIUM ON INTELLIGENT SIGNAL PROCESSING AND COMMUNICATIONS SYSTEMS (ISPACS), 2013, 1, 240, 244, 2013
English - Low-complexity Detection Based on Belief Propagation in a Massive MIMO System
Wataru Fukuda, Takashi Abiko, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yusuke Ohwatari, Yoshihisa Kishiyama, 2013 IEEE 77TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), 1, 5, 2013, [Peer-reviewed]
English - An EXIT chart analysis for belief-propagation based detection in a large-scale MIMO system
Takashi Abiko, Wataru Fukuda, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, Yusuke Ohwatari, Yoshihisa Kishiyama, IEEE Vehicular Technology Conference, 1, 5, 2013, [Peer-reviewed]
IEEE, English - Performance Evaluations of an Uplink Virtual MIMO-OFDM System in Dynamic Channels
Kobayashi Takuya, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Technical report of IEICE. RCS, 112, 351, 197, 202, 13 Dec. 2012
In future mobile communications, a higher frequency band will be used because we need a wider frequency bandwidth for high-speed transmission. However, the propagation loss increases in a higher frequency band.It causes the communication quality degradation. The power of terminals is supplied by the battery. Thus, this problem is serious in an uplink channel. The virtual MIMO system that a communication terminal cooperates with nearby terminals has been proposed to solve this problem. We evaluated the performance of the virtual MIMO-OFDM system in static channels in previous works. In this paper, we investigate the performance of the virtual MIMO-OFDM system in dynamic channels., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Full-Duplex AF Relay using FDE at Destination Node with Multiple Antenna Elements
Kiyomi Naohito, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Technical report of IEICE. RCS, 112, 351, 203, 208, 13 Dec. 2012
A cooperative relay has been studied as a method to improve transmission quality. A half-duplex (HD) relay uses 2 time-intervals to avoid interference between the signals from source and relay nodes. In contrast, a full-duplex (FD) relay consumes less time resources than the HD relay because the source and relay nodes transmit each packet at the same time-interval. However, the destination node requires to suppress the inter-symbol interference caused by the signal via relay. In this paper, we evaluate the FD-AF relay performance using frequency domain equalization with multiple antennas at the destination node under the condition of perfectly-known channel information and no self-interference at the relay., The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity reduction and performance evaluation of coded MIMO-OFDM using lattice reduction
Moritani Kentaro, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Technical report of IEICE. RCS, 112, 351, 257, 262, 13 Dec. 2012
Lattice reduction is known as a method improving detection performance for multiple-input multiple-output (MIMO) systems. The Lenstra, Lenstra, and Lovasz (LLL) algorithm, which is most-typically used for lattice reduction, has a problem that the maximum computational load is not a constant due to existence of exchanged steps. On the other hand, in coded MIMO systems, lattice reduction based detection requires reproduction of log-likelihood ratio (LLR) values for missing bits. In the paper, we discuss the computational complexity reduction and LLR estimation methods and evaluate the detection performance for various parameters for those methods., The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity reduction and performance evaluation of coded MIMO-OFDM using lattice reduction
MORITANI KENTARO, NISHIMURA TOSHIHIKO, OGANE TAKEO, OGAWA YASUTAKA, 電子情報通信学会技術研究報告, 112, 351(RCS2012 184-237), 257, 262, 06 Dec. 2012
Japanese - A Study on Full-Duplex AF Relay using FDE at Destination Node with Multiple Antenna Elements
KIYOMI NAOHITO, NISHIMURA TOSHIHIKO, OGANE TAKEO, OGAWA YASUTAKA, 電子情報通信学会技術研究報告, 112, 351(RCS2012 184-237), 203, 208, 06 Dec. 2012
Japanese - Performance Evaluations of an Uplink Virtual MIMO-OFDM System in Dynamic Channels
KOBAYASHI TAKUYA, OGAWA YASUTAKA, NISHIMURA TOSHIHIKO, OGANE TAKEO, 電子情報通信学会技術研究報告, 112, 351(RCS2012 184-237), 197, 202, 06 Dec. 2012
Japanese - USRPを用いたマルチホップネットワークの実装
出雲恭輔, 西村寿彦, 大鐘武雄, 小川恭孝, 電気・情報関係学会北海道支部連合大会講演論文集(CD−ROM), 2012, ROMBUNNO.118, 20 Oct. 2012
Japanese - シングルキャリアE‐SDM方式におけるPAPRの評価
田中友基, 小川恭孝, 西村寿彦, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD−ROM), 2012, ROMBUNNO.119, 20 Oct. 2012
Japanese - Time‐Reversal法を用いた多元接続方式に関する検討
原田佳太, 小川恭孝, 西村寿彦, 大鐘武雄, 電気・情報関係学会北海道支部連合大会講演論文集(CD−ROM), 2012, ROMBUNNO.117, 20 Oct. 2012
Japanese - A study on Signal Detection in a Large Scale MIMO System : Concept and BER Performance
FUKUDA Wataru, ABIKO Takashi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATAR Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 239, 7, 12, 10 Oct. 2012
The easiest way to improve the throughput performance of multiple-input multiple-output (MIMO) systems is increasing the number of both transmit and receive antennas. In general, however, algorithms detecting spatially-multiplexed signals require the complexity proportional to the third power of the number of antenna elements in the least case. Thus, the implementation of an antenna array with an order of 100 elements becomes very difficult. In this paper, we evaluate the algorithm based on belief propagation with parallel interference cancellers. This algorithm is implementable in the order of the second power of the number of elements, and it has been shown that the array with the order of 100 elements reveals very good BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Signal Detection in a Large Scale MIMO System : An EXIT Chart Analysis of Iterative Processing
ABIKO Takashi, FUKUDA Wataru, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, OHWATAR Yusuke, KISHIYAMA Yoshihisa, Technical report of IEICE. RCS, 112, 239, 13, 18, 10 Oct. 2012
Multiple-input multiple-output (MIMO) systems are well known as a method to improve the throughput performance. Recently, a concept of massive (or very large) MIMO using an antenna array with an order of 100 elements has been proposed. In general, the complexity order of signal detection in such a MIMO system becomes the third power of the number of antenna elements in the least case. The authors have evaluated the belief propagation based algorithm with parallel interference cancellers and shown that it is implementable in the order of the second power of the number of elements. Here, the extrinsic information transfer analysis is applied to evaluate the convergence performance., The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-203 Accuracy Evaluation for DOA Estimation of Wide-band Signals Using Spatial Smoothing Preprocessing at Transmitter
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2012, 1, 203, 203, 28 Aug. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-203 Accuracy Evaluation for DOA Estimation of Wide-band Signals Using Spatial Smoothing Preprocessing at Transmitter
Terada Tsubasa, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2012, 1, 203, 203, 28 Aug. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - Sequential Gating Processing for Time-Reversal MUSIC
CHOI Heedong, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 112, 149, 17, 22, 18 Jul. 2012
Time-reversal (TR) approach with multiple signal classification (MUSIC) has been developed for a remote sensing system due to super-resolution and statistical stability. Especially, TR-MUSIC imaging using the angle- and/or time-domain gating (filtering) technique in early papers provides a tremendous enhancement for the imaging results by reducing noise components and relaxing the antenna restriction. In this paper, we address the formulation of our approach, and discuss its performance in more detail., The Institute of Electronics, Information and Communication Engineers, English - Sequential Gating Processing for Time-Reversal MUSIC
CHOI Heedong, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 112, 149, 17, 22, 18 Jul. 2012
Time-reversal (TR) approach with multiple signal classification (MUSIC) has been developed for a remote sensing system due to super-resolution and statistical stability. Especially, TR-MUSIC imaging using the angle- and/or time-domain gating (filtering) technique in early papers provides a tremendous enhancement for the imaging results by reducing noise components and relaxing the antenna restriction. In this paper, we address the formulation of our approach, and discuss its performance in more detail., The Institute of Electronics, Information and Communication Engineers, English - Correlation Suppression Performance of Spatial Smoothing Preprocessing at a Transmitter for DOA Estimation of Wide-band Signals
MAEDA Kyouhei, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report. Antennas and propagation, 111, 487, 25, 30, 08 Mar. 2012
Recently, due to the wide spread of wireless communications, importance of a precise direction-of-arrival (DOA) estimation technology has become greater in order to investigate propagation environments or determine terminal's positions. The authors have proposed the precise DOA estimation method of wide-band signals. First, coarse DOAs are estimated at the lowest frequency band where grating lobes do not appear. Next, precise DOA estimation is done at a higher frequency band in a narrower search range to prevent grating lobes. In this paper, to estimate DOA accurately under multipath environments, we use multiple antenna elements at a transmitter and apply spatial smoothing preprocessing (Transmit-SSP). The multiple signals transmitted from different positions cause correlation reduction effect. From computer simulations, we show the correlation suppression effect and high accuracy of the proposed method., The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-186 A Study on DOA Estimation of Wide-band Signals Using Spatial Smoothing Preprocessings at Transmitter
Maeda Kyouhei, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 2012, 1, 186, 186, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-224 Considerations on a Frequency Correlation for a Distributed Antenna System
YAMAGUCHI Kanako, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2012, 1, 224, 224, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-54 Performance Evaluations of an OFDM Uplink Virtual MIMO System Compensating for Frequency Offsets
KOBAYASHI Takuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2012, 1, 453, 453, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-80 A study on complexity reduction of a MIMO detection algorithm with lattice reduction
MORITANI Kentaro, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2012, 1, 479, 479, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-166 A Study on Multi-Hop Networks Using an Adaptive Array Under a Bursty Traffic Model
Takeda Daiki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2012, 1, 565, 565, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - BP-2-3 MIMO Technologies for Ultra-high-speed Broadband Access
Ohgane Takeo, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the IEICE General Conference, 2012, 1, "SS, 7"-"SS-8", 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese - 超高速ブロードバンドアクセスにおけるMIMOチャネル伝送技術
大鐘武雄, 小川恭孝, 西村寿彦, 電子情報通信学会大会講演論文集, 2012, SS.7-SS.8, 06 Mar. 2012
Japanese - Considerations on Reduced-Complexity Single-Carrier E-SDM for Wideband Transmissions
DAVIDESCU Cristian, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proc. IEEE VTC2612-Spring, May, 111, 451, 55, 60, 29 Feb. 2012
Single-carrier modulation combined with frequency-domain equalization (FDE) at the receiver has been proposed as an alternative to the OFDM system for the uplink transmission, in the case of severe frequency-selective fading channels. Furthermore, an eigenbeam-space division multiplexing (E-SDM) technique can be used to improve the spectrum efficiency. In order to reduce computational complexity at the transmitter, some techniques decreasing the number of singular value decompositions have been proposed. In this paper, we propose some reduced-complexity techniques that can improve the bit error rate (BER) performance. The evaluations of these techniques and the trade-off between complexity and BER are analyzed by computer simulations., The Institute of Electronics, Information and Communication Engineers, English - Frequency Offset Estimation and its Compensation in an Uplink Virtual MIMO System Using OFDM
KOBAYASHI Takuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 111, 451, 61, 66, 29 Feb. 2012
We need a wider frequency bandwidth for high-speed transmission, and thus a higher frequency band will be used in future mobile communications. However, the propagation loss increases in a higher frequency band. It causes degradation of communication quality especially for an uplink channel because the power is supplied by the terminal battery. Then, it has been proposed that a communication terminal cooperates with nearby terminals to solve this problem. However, different frequency offsets of the terminals cause different phase rotations. In this paper, we propose a frequency offset estimation and compensation scheme of them. We evaluate the performance of the virtual MIMO-based OFDM communications using the compensation scheme., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Frequency Correlation for a Multiple-Antenna System
YAMAGUCHI Kanako, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 111, 451, 67, 72, 29 Feb. 2012
In wireless communication channels, we have multipath propagation due to a large number of reflected and diffracted waves. When the delay difference between multipath waves is not negligible, we encounter frequency selective fading. Thus far, a frequency correlation defined for a single receive antenna has been used for evaluating the frequency selectivity. Recently, multiple antennas have been introduced to realize space diversity and/or spatial filtering. Then, the conventional frequency correlation defined for a single antenna cannot be used for a multiple-antenna system. In this paper, we extend the frequency correlation to a multiple-antenna system. Moreover, we compare the newly-introduced correlation with the conventional one and the error for signal detection under several propagation environments., The Institute of Electronics, Information and Communication Engineers, Japanese - A study on adaptive thresholds for reduced complexity bit-flip decoding
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, International Conference on Advanced Communication Technology, ICACT, 2012 - Investigation of Dual Threshold Scaling Factors for Bit Flip Decoding
WEBBER Julian, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, 電子情報通信学会技術研究報告, 111, 345(RCS2011 232-266), 1, 6, 08 Dec. 2011
Very low error rates can be obtained using low-density parity-check (LDPC) codes and their use is now common in new communications standards such as the Long Term Evolution (LTE) Advanced. The decoders based on belief propagation offer excellent performance but have high complexity. Therefore simpler architectures based on the bit flipping algorithm have been researched. Over the last two years a few adaptive threshold algorithms have been proposed in which a bit is either inverted if it is below a threshold, or the threshold itself is lowered using a scaling factor. This work looks at how the scaling factor influences the iteration count and error performance. We propose an algorithm that switches between two scaling factors based on the syndrome sum on each branch. Using this technique we show that the error performance is comparable with that of a single scaling factor but the iteration count is significantly reduced. Further, if a non-transmitted codeword is detected, which corresponds to a trapped search point, an addition of a small noise perturbation can potentially provide an escape opportunity and this is experimentally investigated., 一般社団法人電子情報通信学会, Japanese - Optimazation of High Accuracy DOA Estimation Using Wide-band Signals
MAEDA Kyouhei, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report. Antennas and propagation, 111, 288, 1, 6, 16 Nov. 2011
Recently, with the spreading of wireless communication technology, importance of a precise direction of arrival (DOA) estimation technology becomes larger in order to investigate propagation environments or determine terminal's positions. An array antenna is used in general DOA estimation algorithms. In a case where antenna element positions of the array are fixed, the higher frequency signal is used, the higher resolution DOA estimation is obtained. However, calculation load increases because we must calculate MUSIC spectra with a narrow angle step. Also, grating lobes occur when using high frequency signals for a fixed element interval. The authors have proposed the DOA estimation method based on the MUSIC algorithm using wide-band signals to solve these problems. First, coarse DOA is estimated at the lowest frequency band where grating lobes do not appear. Next, precise DOA estimation is done at a higher frequency band in a narrower search range to prevent grating lobes and increase of calculation load. In this paper, to estimate DOA using higher frequency signals while avoiding grating lobes, we optimize the frequency, search range, step width., 一般社団法人電子情報通信学会, Japanese - Optimazation of High Accuracy DOA Estimation Using Wide-band Signals
MAEDA Kyouhei, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, 電子情報通信学会技術研究報告. A・P, アンテナ・伝播, 111, 288, 1, 6, 09 Nov. 2011
Japanese - Performance Evaluation of an Uplink Virtual MIMO System Using OFDM
KOBAYASHI Takuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 111, 289, 185, 190, 09 Nov. 2011
In future mobile communication, we need wider frequency bandwidth transmission in a higher frequency band. However, the propagation loss increases in a high frequency band. It causes a degradation of communication quality. Especially for an uplink channel, the transmission power is limited because the power is supplied by the battery. Then, it has been proposed that a communication terminal cooperates with nearby terminals to solve this problem. The virtual MIMO-based cooperative communication using a single carrier in a narrow bandwidth has been examined in detail. In this paper, we evaluate the characteristics of the virtual MIMO-based cooperative communication using OFDM., The Institute of Electronics, Information and Communication Engineers, Japanese - Transmit Beamforming at Source Node in MISO/MIMO AF Relay
KIYOMI Naohito, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 111, 289, 203, 208, 09 Nov. 2011
Data transmission through relay nodes has been studied as a method to improve transmission quality in wireless mesh networks and cellular systems. Multiple antenna elements at a source node enable adaptive beamforming and thus improve total performance of the relay transmission. In this paper, we propose simple transmit beamforming at a source node when the source node has two or more antenna elements and knows all channel information in MISO/MIMO amplify-and-forward relay with direct link and evaluate the packet error rate., The Institute of Electronics, Information and Communication Engineers, Japanese - Low-Complexity Threshold Updating for LDPC Bit-Flip Decoders
WEBBER Julian, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, 電子情報通信学会大会講演論文集, 2011, 1, 30 Aug. 2011
一般社団法人電子情報通信学会, English - B-5-43 Reduced-Complexity Single-Carrier E-SDM for Wide Band Transmissions
Davidescu Cristian, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2011, 1, 30 Aug. 2011
一般社団法人電子情報通信学会, English - B-5-129 Transmit Beamforming at Source Node in AF Relay
KIYOMI Naohito, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 2011, 1, 508, 508, 30 Aug. 2011
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-130 A Study on Routing for Multi-Hop Wireless Networks Using Adaptive Arrays
Takeda Daiki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2011, 1, 509, 509, 30 Aug. 2011
The Institute of Electronics, Information and Communication Engineers, Japanese - BS-2-11 Considerations on TR-MUSIC Imaging using the Time-Domain Gating
CHOI Heedong, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the Society Conference of IEICE, 2011, 1, "S, 27"-"S-28", 30 Aug. 2011
The Institute of Electronics, Information and Communication Engineers, English - A Fundamental Study on Routing for Multi-Hop Wireless Networks Using Adaptive Array
TAKEDA Daiki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 111, 68, 1, 6, 19 May 2011
The interference between nearby links in a wireless multihop network degrades the area spectral efficiency. Thus there have been many works on a use of narrow beam antenna or adaptive array capable of forming nulls. In specific, the adaptive array allows the multiple links within a limited area by suppressing the interference among those. However, efficient routing is required to exploit the benefit. In the paper, the system throughput performance is evaluated under a partially-ideal routing, and the potential ability of the adaptive array is indicated., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on High Accuracy DOA Estimation Using Wide-band Signals
MAEDA Kyouhei, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report, 111, 29, 65, 70, 05 May 2011
Recently, according to rapid spreading of cellular phones and wireless LAN equipment, importance of a precise direction of arrival (DOA) estimation technology becomes larger in order to investigate propagation environments or determine terminal's position. Generally, an array antenna with an estimation is used for the DOA estimation algorithm. In a case where the element position of array antenna is fixed, the higher frequency signal is used, the higher resolution DOA estimation is. However, calculation load increases because we must treat MUSIC spectra which have a narrow angle step and grating lobes occur by using high frequency signals for a fixed element interval. The authers have proposed the precise DOA estimation method using wide-band signals. In the beginning, coarse DOA is estimated at the lowest frequency band that grating lobes do not appear. Next, precise DOA estimation is done at higher frequency band in a narrower angle range in order to prevent grating lobes and calculation load. In this paper, we propose a method that can prevent grating lobes much effectively by changing adaptively the band in higher frequencies. We evaluated the performance of the technique using computer simulations. From the computer simulations, we show the highly accuracy of the proposed method., 一般社団法人電子情報通信学会, Japanese - B-5-91 An Evaluation of Transmit Diversity Gain in Generalized Block Diagonalization for Multiuser MIMO Downlink
Sada Tomoki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2011, 1, 477, 477, 28 Feb. 2011
The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Precoding Prediction in LTE Downlink
SHIMODA Yusuke, KISHIYAMA Yoshihisa, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 110, 433, 319, 323, 23 Feb. 2011
In the downlink of Long Term Evolution (LTE), it is planned to apply multiuser MIMO (MU-MIMO) systems for system capacity improvement. MU-MIMO transmission requires pre-coding at the transmitter side to decrease interference between users. In LTE, a code-book describing pre-coding matrices is defined. Thus, the user equipment is allowed to feed back the pre-coding matrix indicator only. In this paper, we consider a time-variant fading channel and evaluate the performance of pre-coding prediction to reduce degradation due to processing delay., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of GBD under Channel Estimation Errors for MU-MIMO Downlink
SADA Tomoki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 110, 368, 7, 12, 13 Jan. 2011
In a downlink (broadcast channel) of multiuser MIMO systems, we need to suppress the inter-user interference (IUI). It is known that block diagonalization and MMSE precoding are typical schemes for IUI suppression. In addition, we have proposed generalized block diagonalization (GBD) to achieve both high transmit diversity gain and IUI space limiting with a partial nulling concept. In this paper, we evaluate the impact of channel estimation error on the these precoding methods by computer simulations for BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Transmit Beamforming in an Interactive MIMO Wireless Relay
MATSUYA Sakiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 110, 368, 173, 178, 13 Jan. 2011
Recently, wireless relay systems have been discussed to achieve a flexible network for connecting ubiquitous communication terminals. Network coding that encodes the packets using XOR in the relay node reduces the number of transmission packets and thus improves throughput performance in the network. In our previous papers, we investigated beamforming techniques at the relay node for multicasting the network-coded data and proposed the capacity-maximizing criterion. In this paper, we expand the system model to a MIMO relay and propose a simple beamforming criterion. The high performance has been numerically confirmed., The Institute of Electronics, Information and Communication Engineers, Japanese - Development of a channel emulator for evaluation of MIMO-OFDM and SC-FDMA systems
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, APSIPA ASC 2011 - Asia-Pacific Signal and Information Processing Association Annual Summit and Conference 2011, 2011 - Accuracy evaluation of DOA estimation with multi-band signals
Kyouhei Maeda, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane, IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), 835, 838, 2011
一般社団法人電子情報通信学会, English - Investigation of simple threshold shifting for bit-flip decoding
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, 2011 the 14th International Symposium on Wireless Personal Multimedia Communications: Communications, Networking and Applications for the Internet of Things, WPMC'11, 1, 5, 2011, [Peer-reviewed]
IEEE - A fundamental study on routing and scheduling for multi-hop wireless networks with adaptive array
Takeda, Daiki, Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, 2011 the 14th International Symposium on Wireless Personal Multimedia Communications: Communications, Networking and Applications for the Internet of Things, WPMC'11, 1, 5, 2011, [Peer-reviewed]
IEEE - Performance Evaluation of a Virtual MIMO System in an Uplink Channel
ITO Tatsuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 110, 339, 43, 48, 09 Dec. 2010
In future cellular radio, we need to transmit signals in a higher frequency band to accommodate a wider frequency bandwidth. The higher a frequency band is, the larger the propagation loss is. Also, a wider frequency bandwidth requires higher transmission power. For an uplink channel, however, the transmission power is limited because the power is supplied by the terminal battery. Thus, we will encounter a difficulty in sending uplink signals. The authors have proposed virtual MIMO-based cooperative communication to solve this problem. In this paper, we clarify bit error rate and packet error rate performances for various conditions. We evaluate the required transmission power. It has been shown that the virtual MIMO system requires lower transmission power than the conventional SIMO scheme., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Multi-User MIMO System Using Channel Prediction
BUI Huu Phu, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 110, 267, 47, 52, 03 Nov. 2010
A downlink multi-user MIMO system uses a block diagonalization scheme to suppress inter-user interference. Furthermore, the system can realize efficient transmission using eigenbeam-space division multiplexing. In time-varying environments, however, bit error rate (BER) performance seriously degrades because MIMO channels change during the time interval between transmission parameter determination and actual MIMO transmission. Channel prediction techniques have been proposed to improve the BER performance in dynamic environments. In this paper, based on indoor measurement data, we evaluate the BER performance of the downlink multiuser MIMO system with linear extrapolation and second order extrapolation., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-13 An Impact of Channel Estimation Error on GBD for MU-MIMO Downlink
Sada Tomoki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2010, 1, 367, 367, 31 Aug. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-17 A Study on Precoding Prediction in MU-MIMO Downlink
Shimoda Yusuke, Nishimura Yoshihisa, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2010, 1, 371, 371, 31 Aug. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - BS-2-2 Evaluation of Transmission Power in an Uplink Virtual MIMO System in Dynamic Fading Environments
Ito Tatsuya, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2010, 1, "S, 9"-"S-10", 31 Aug. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - A Multi-User MIMO System in Time-Varying Environments
BUI Huu Phu, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 110, 135, 7, 12, 14 Jul. 2010
A multi-user MIMO system which simultaneously accommodates multiple users uses a block diagonalization scheme to suppress inter-user interference. Also, it can use an eigenbeam-space division multiplexing technique for efficient transmission. However, in time-varying environments, we may have performance degradation because of a channel change during the time interval between multi-user MIMO parameter determination and actual transmission. In this paper, on the basis of time-varying indoor measurements, we show Doppler spectra and average bit error rates (BERs). We also show that time-varying channels seriously degrade the BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Evaluation of Transmission Power in an Uplink Virtual MIMO System
ITO Tatsuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 110, 127, 125, 130, 08 Jul. 2010
In future cellular radio, we need to transmit signals in a higher frequency band to accommodate a wider frequency bandwidth. The higher a frequency band is, the larger the propagation loss is. Also, a wider frequency bandwidth requires higher transmission power. For an uplink channel, however, the transmission power is limited because the power is supplied by the terminal battery. Thus, we will encounter a difficulty in sending uplink signals. Virtual MIMO-based cooperative communication is expected to be a key technology to solve this problem. In this paper, we clarify bit error rate and packet error rate performances on the basis of a realistic propagation channel model. We evaluate the required transmission power. It has been shown that the virtual MIMO system requires lower transmission power than the conventional SIMO scheme., The Institute of Electronics, Information and Communication Engineers, Japanese - Generalized Block Diagonalization for Multiuser MIMO Downlink
SADA Tomoki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 110, 127, 161, 166, 08 Jul. 2010
In the downlink(broadcast channel)of multiuser MIMO systems, we need to suppress the inter-user interference(IUI). Block diagonalization(BD)which achieves perfect nulling is noted as an effective solution. In addition, imperfect block diagonalization(IBD)has been proposed previously as one of the solutions. The IBD can obtain transmit diversity gain by partial nulling. In this paper, we unify approaches of BD and IBD into generalized BD(GBD). In the paper, the BER performance of the GBD is evaluated by computer simulations., 一般社団法人電子情報通信学会, Japanese - Prevention of False Detection due to Grating Lobes in Estimating Pedestrian Direction Using a Vehicle-Mounted Array Antenna
NOBA Toshihiro, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 110, 1, 47, 51, 02 Apr. 2010
Some techniques using intelligent transport systems have been studied to prevent traffic accidents whose victims are a pedestrian. We have studied a scheme that informs a driver of a pedestrian's position using an electromagnetic wave radiated from the pedestrian's RFID tag. Although the direction-of-arrival (DOA) of a direct wave indicates the direction of the pedestrian, it is, however, difficult to estimate the DOA under multipath fading environments. Therefore, we have used a simple technique we proposed for DOA estimation. Using multiple antennas with the spacing of 1.5 wavelengths, we receive signals that experience different fading due to vehicle motion. If we beamform towards the direction of the direct wave, we can expect to compute the maximum average power because its signal is the largest and the multipath components are reduced by the array. Using received horizontally-polarized signals, we then beamform towards multiple directions, and the direction that gives the maximum average power indicates the direction of the pedestrian. Since the antenna spacing is larger than a half wavelength, we have grating lobes and may have false detections. In this paper, we propose a scheme to cope with the grating lobe problem., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-34 An Approximation to Optimum Trasmit Beamforming in an Interactive Wireless Relay
MATSUYA Sakiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2010, 1, 466, 466, 02 Mar. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-59 Imperfect Block Diagonalization with Eigenvector Selection for Multiuser MIMO Downlink
Sada Tomoki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2010, 1, 491, 491, 02 Mar. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-69 Spectrum Reduction Scheme for Multi-carrier Transmission under EMI Environments
Nishimoto H., Hirai H., Taira A., Kubo H., Nishimura T., Ohgane T., Ogawa Y., Proceedings of the IEICE General Conference, 2010, 1, 501, 501, 02 Mar. 2010
The Institute of Electronics, Information and Communication Engineers, Japanese - Interference Reduction Using Smart Antennas under OFDM Wireless LAN Environments
NOBA Toshihiro, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 109, 440, 29, 34, 24 Feb. 2010
Information transmission between a controller and a machine is essential for reliable factory automation. To help facilitate this, wireless communication is useful in the building of flexible factory environments because it does not need cables. The wireless system can employ an OFDM LAN technique. However, in a case where a plurality of communication systems are used in a neighborhood, we may have mutual interference among them. This paper describes a smart antenna for the interference reduction. We examine two weight control schemes: one is based on channel estimation, and the other is the SMI algorithm. We show cumulative distributions of SINR and average BERs of the smart antenna., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of Blind Detection in PTS-OFDM
SHIBATA Koji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 440, 427, 432, 24 Feb. 2010
OFDM has a problem of high peak to average power ratio (PAPR) whereas it is tolerant to the frequency selective fading. As a countermeasure for the high PAPR problem, partial transmit sequence (PTS) giving different phase rotation to segmented blocks has been proposed. However, PTS requires side information on the phase rotation. Previously, we proposed a simple blind detection based on the M-algorithm with very low complexity. The blind detection performance is highly affected by phase rotation candidates. In this paper, we propose the search technique of the proper phase rotation for blind detection. Also, we examine the impact of channel estimation error and signal distortion on the blind detection performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of FDE using a Tri-diagonalizing Approach
SAITO Keisuke, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 440, 443, 448, 24 Feb. 2010
Frequency-domain equalization (FDE) and frequency-domain turbo equalization (FDTE) based on iterative decoding have been studied for suppressing inter-symbol interference (ISI) due to frequency selective fading in single carrier systems. When a high-mobility terminal is assumed in the system, ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. To solve this problem, we have proposed a channel approximation and tri-diagonalizing approach to FDE and FDTE without strict calculation and ascertained the validity of our proposal by computer simulations. As a realistic scenario, in this paper, we introduce channel estimation and evaluate the impact of the channel estimation error on the equalizing performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of a MIMO-OFDM eigenbeamforming system in a correlated channel
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, APSIPA ASC 2010 - Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, 2010 - Measurement-Based Evaluation of a Multiuser MIMO System in an Indoor Time-Varying Environment
Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, 2010 IEEE 72ND VEHICULAR TECHNOLOGY CONFERENCE FALL, 1, 5, 2010, [Peer-reviewed]
English - Optimum Transmit Beamforming in an Interactive Wireless Relay System with Network Coding
Sakiko Matsuya, Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, 2010 IEEE 21ST INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), 2093, 2098, 2010, [Peer-reviewed]
English - A Generalized Approach to Block Diagonalization for Multiuser MIMO Downlink
Tomoki Sada, Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, 2010 IEEE 21ST INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), 504, 509, 2010, [Peer-reviewed]
English - Characteristic Evaluation of a Virtual MIMO System in an Uplink Channel in Dynamic Fading Environments
ITO Tatsuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 109, 305, 73, 78, 19 Nov. 2009
A higher frequency band is considered to be used for future mobile communications for broadband transmission. However, propagation loss increases at a higher frequency band. The transmission will be difficult in an uplink channel because of limited transmit power of terminals. To solve the problem, cooperative communication has drawn attention. We have proposed a virtual MIMO system where neighboring terminals cooperate each other and form transmit beams as a distributed antenna system. In this paper, we examine frequency offset estimation performance and BER versus transmit power in dynamic fading environments. It has been clarified that the advantage of the virtual MIMO system decreases in dynamic fading environments. The reason for this is considered to be that transmit parameters cannot be determined properly because the channel at transmission time is not obtained exactly., The Institute of Electronics, Information and Communication Engineers, Japanese - Transmit Beamforming in an Interactive Wireless Relay System
MATSUYA Sakiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 305, 25, 30, 19 Nov. 2009
Recently, wireless relay systems have been investigated to achieve a flexible network for ubiquitous communication. Network coding that encodes the packets using XOR in the relay node is expected to reduce the number of transmission packets and to improve throughput performance in the network. In this paper, we propose the transmit beamforming technique when the relay node has two or more antenna elements in the interactive wireless relay system and evaluate the packet error rate and throughput performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Characteristic Evaluation of a Virtual MIMO System in an Uplink Channel in Dynamic Fading Environments
ITO Tatsuya, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 109, 305, 73, 78, 19 Nov. 2009
A higher frequency band is considered to be used for future mobile communications for broadband transmission. However, propagation loss increases at a higher frequency band. The transmission will be difficult in an uplink channel because of limited transmit power of terminals. To solve the problem, cooperative communication has drawn attention. We have proposed a virtual MIMO system where neighboring terminals cooperate each other and form transmit beams as a distributed antenna system. In this paper, we examine frequency offset estimation performance and BER versus transmit power in dynamic fading environments. It has been clarified that the advantage of the virtual MIMO system decreases in dynamic fading environments. The reason for this is considered to be that transmit parameters cannot be determined properly because the channel at transmission time is not obtained exactly., The Institute of Electronics, Information and Communication Engineers, Japanese - Multi-stream Transmission with Imperfect Block Diagonalization for Multiuser MIMO Downlink
SADA Tomoki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 229, 37, 42, 08 Oct. 2009
In the downlink (broadcast channel) of the multiuser MIMO system, suppression of inter-user interference (IUI) is an important issue to be solved. Due to the limitated antenna resources, it is difficult to implement the IUI cancellation at the terminal side. Thus, reduction of undesired radiation by a certain beam-control is preferable. The imperfect block diagonalization (IBD) has been proposed previously as one of the solutions. In the paper, we extend the IBD to be capable of multi-stream transmission per user and evaluate the BER performance using computer simulations., The Institute of Electronics, Information and Communication Engineers, Japanese - Hardware Development of a MIMO Pseudo E-SDM System and Real-time Channel Emulator
Webber Julian, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings : APSIPA ASC 2009 : Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference, 684, 687, 04 Oct. 2009
APSIPA ASC 2009: Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference. 4-7 October 2009. Sapporo, Japan. Poster session: Signal Processing and Implementations in Communications (6 October 2009)., Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference, International Organizing Committee, English - B-5-49 Multi-stream Transmission in IBD Scheme for Multiuser MIMO Downlink
Sada Tomoki, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2009, 1, 398, 398, 01 Sep. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-50 Virtual MIMO System in Dynamic Fading Environments
Ito Tatsuya, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2009, 1, 399, 399, 01 Sep. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-55 A Study on Trasmit Beamforming in an Interactive Wireless Relay
MATSUYA Sakiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 2009, 1, 404, 404, 01 Sep. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-62 A Blind Detection of Side Information in PTS OFDM with a Simplified Search Algorithm
Shibata Koji, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2009, 1, 411, 411, 01 Sep. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-88 Improving of Tri-diagonal Matrix Approximation for FDTE in Fast Fading Environment
Saito Keisuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2009, 1, 437, 437, 01 Sep. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - An improved blind detection of side information in PTS OFDM
SHIBATA Koji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 130, 125, 130, 09 Jul. 2009
OFDM has a problem of high peak to average power ratio (PAPR) whereas it is tolerant to the frequency selective fading. As a countermeasure for the high PAPR problem, partial transmit sequence (PTS) giving different phase rotation to segmented blocks has been proposed. However, PTS requires side information on the phase rotation. Previously, we proposed a simple blind detection based on the M-algorithm with very low complexity. However, some degradation has been observed when the constraint length of the convolutional code is long. In the paper, as the countermeasure we evaluate the case with two survivor paths in M-algorithm in addition to the bi-directional search., The Institute of Electronics, Information and Communication Engineers, Japanese - Tri-diagonalizing Approach on FDE in a Fast Fading Environment
SAITO Keisuke, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 109, 130, 119, 124, 09 Jul. 2009
Frequency-domain equalization (FDE) and frequency-domain turbo equalization (FDTE) based on iterative decoding have been studied for suppressing inter-symbol interference (ISI) due to frequency selective fading in single carrier systems. When a high-mobility terminal is assumed in the system, ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. To solve this problem, we propose a tri-diagonalizing approach to FDE and FDTE without strict calculation and evaluate our proposal by computer simulations., The Institute of Electronics, Information and Communication Engineers, Japanese - A Basic Study on Pedestrian Direction Estimation Using a Vehicle-Mounted Array Antenna
NOBA Toshihiro, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, TANAKA Makoto, SASAKI Kunihiko, IEICE technical report, 109, 117, 177, 182, 01 Jul. 2009
Some techniques using intelligent transport systems have been studied to prevent traffic accidents whose victims are a pedestrian. We have studied a scheme that informs a driver of a pedestrian's position using an electromagnetic wave radiated from the pedestrian's RFID tag. Although the direction-of-arrival (DOA) of a direct wave indicates the direction of the pedestrian, it is, however, difficult to estimate the DOA under multipath fading environments. This paper proposes a simple technique for DOA estimation. Using multiple antennas, we receive signals that experience different fading due to vehicle motion. If we beamform towards the direction of the direct wave, we can expect to compute the maximum average power because its signal is the largest and the multipath components are reduced by the array. Using the received data, we then beamform towards multiple directions, and the direction that gives the maximum average power indicates the direction of the pedestrian. Conducting computer simulations, we show the performance of the proposed scheme., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-70 A Study on Blind Estimation of Side Information in PTS OFDM
Shibata Koji, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2009, 1, 503, 503, 04 Mar. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-56 Amplitude Correction for MMSE Receiver Outputs
Nishimoto Hiroshi, Sogabe Yasushi, Shibuya Akihiro, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2009, 1, 489, 489, 04 Mar. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-51 Tri-diagonal Matrix Approximation for Frequency Domain Turbo Equalization in Fast Fading Environment
Saito Keisuke, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2009, 1, 484, 484, 04 Mar. 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Transmit Power in an Uplink Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, IEICE technical report, 108, 445, 65, 70, 25 Feb. 2009
A higher frequency band is considered to be used for future mobile communications. However, reliable transmission may not be possible in an uplink channel because of limited transmit power of terminals. We can improve uplink transmission performance using a virtual antenna array which is formed by multiple terminals cooperating with each other. However, because we have neglected the power for sharing data among the terminals in our previous studies, a fair comparison with a non-cooperating system has not been done. In this paper, we consider total transmit power required for a virtual MIMO system and compare the characteristic with that of non-cooperating system in variety of propagation environments., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Complexity Reduction of HARQ with Frequency Domain Turbo Equalization using Chase Combining
QIN Fei, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 108, 390, 201, 205, 15 Jan. 2009
Frequency domain turbo equalization with soft canceller is a powerful way to reduce the inter-symbol interference in a frequency selective fading channel for single-carrier systems. When applying the frequency domain turbo equalization to a Type-I HARQ system, chase combining with parallel turbo-equalizers using multiple received packets achieves a significant improvement of throughput performance at a cost of heavy load. In the paper, the performance of the complexity reduction method previously proposed by the authors is analyzed. And, improved methods for complexity reduction is proposed., The Institute of Electronics, Information and Communication Engineers, Japanese - Hardware development of a MIMO pseudo E-SDM system and real-time channel emulator
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, APSIPA ASC 2009 - Asia-Pacific Signal and Information Processing Association 2009 Annual Summit and Conference, 2009 - B-1-228 A Basic Study on Pedestrian Location Detection Using a Vehicle-Mounted Array Antenna
Noba Toshihiro, Ogawa Yasutaka, Nishimura Toshiihko, Ohgane Takeo, Tanaka Makoto, Sasaki Kunihiko, Proceedings of the IEICE General Conference, 228, 228, 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-209 A Study on DOA Estimation by Using a UWB Signal
Morikawa Hiroaki, Nishimura Toshihiko, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 209, 209, 2009
The Institute of Electronics, Information and Communication Engineers, Japanese - MIMO technologies for ultra high-speed wireless transmission
小川 恭孝, 大鐘 武雄, 西村 寿彦, B-plus, 11, 12, 49,1, 2009
電子情報通信学会通信ソサイエティ, Japanese - Blind Detection of Partial Transmit Sequence in a Coded OFDM System
Koji Shibata, Julian Webber, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, GLOBECOM 2009 - 2009 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-8, 2705, 2710, 2009, [Peer-reviewed]
English - Experimental MIMO Pseudo E-SDM and Channel Emulation System
Webber, Julian, Nishimura, Toshihiko, Ohgane, Takeo, Ogawa, Yasutaka, 2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, 1039, 1043, 2009, [Peer-reviewed]
English - Performance of MIMO-OFDM E-SDM Systems Using Circular Arrays
Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, 2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, 2459, 2463, 2009, [Peer-reviewed]
English - Cooperative Communication Using a Virtual MIMO System with a Feedback Channel for Uplink Transmission in Cellular Radio
Yuta Saito, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura, 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, 1084, 1088, 2009, [Peer-reviewed]
English - A study on blind esimation of side information in PTS OFDM
SHIBATA Koji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 108, 249, 7, 12, 15 Oct. 2008
OFDM has a problem of high peak to average power ratio (PAPR) whereas it is tolerant to the frequency selective fading. As a countermeasure for high PAPR problem, partial transmit sequence (PTS) giving different phase rotation to segmented blocks has been proposed. However, PTS requires inverse phase rotation at the receiver side for corrent detection. Thus, an extra subchannel for side information transmission is needed. in the paper, a blind detection based on the parallel trellis decoding under the use of a convolutional code is proposed. And, its high performance has been confirmed by computer simulations., The Institute of Electronics, Information and Communication Engineers, Japanese - BS-1-2 A Study on the Feedback of Transmit Weights Using a Codebook in a Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the Society Conference of IEICE, 2008, 1, "S, 3"-"S-4", 02 Sep. 2008
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-58 Performance Evaluation of HARQ with Frequency Domain Turbo Equalization
QIN Fei, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 2008, 1, 371, 371, 02 Sep. 2008
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of Multiuser MIMO Systems Employing the Block-Diagonalization Scheme and the E-SDM Technique in Actual Time-Varying Fading Environments
BUI Huu Phu, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 108, 188, 19, 24, 27 Aug. 2008
In the paper, we present our measurement campaigns in a typical meeting room to get multiuser multiple-input multiple-output (MIMO) channels. Based on the data, the performance of multiuser MIMO systems employing the block-diagonalization (BD) scheme and the eigenbeam-space division multiplexing (E-SDM) technique for downlink transmission is evaluated in actual time-varying fading environments. Simulation results show that due to a channel change during the time interval between the transmit weight matrix determination and the actual downlink data transmission, the performance is much degraded because of inter-user and inter-substream interference. Here, we propose two methods of channel extrapolation, linear extrapolation and second-order extrapolation, to compensate for the channel change. Simulation results show that applying the proposed methods to the systems, much better performance can be obtained., The Institute of Electronics, Information and Communication Engineers, English - A Study on the Feedback Amount Reduction of Frequency Offset and Transmit Weight in a Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 108, 188, 25, 30, 27 Aug. 2008
A higher frequency band is considered to be used for future mobile communications. However, reliable transmission may not be possible in an uplink channel because of limited transmit power of terminals. We can improve uplink transmission performance using a virtual antenna array which is formed by multiple terminals cooperating with each other. However, in this system, the terminals need information about transmit weight, frequency offset, and transmit power ratio from a base station. The feedback of the information from a base station limits downlink transmission. In this paper, we propose a codebook for transmit weight, and quantization of frequency offset and transmit power ratio. We examine the impact of them on the bit error rate performance., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on HARQ with Frequency Domain Turbo Equalization
QIN Fei, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 108, 188, 151, 156, 27 Aug. 2008
Frequency domain turbo equalization with soft canceller is a powerful way to reduce the inter-symbol interference in a frequency selective fading channel for single-carrier systems. In the paper, the frequency domain turbo equalization is applied to an HARQ system and its throughput performance is confirmed. In addition, several simplified methods of chase combining for multiple received packets is proposed. The computer simulation results show that the performance degradation due to simplifying is not significant., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on MIMO Channel Characteristics and Performance of Spatial Multiplexing in Time-Varying Fading Environments
BUI Huu Phu, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 108, 148, 129, 134, 16 Jul. 2008
The main contribution of the paper is to investigate channel charateristics based on measured data in a typical meeting room and to evaluate the performance of MIMO systems using an eigenbeam-space division multiplexing (E-SDM) technique in actual time-varying fading environments. Results based on the measured channel data show that channel auto-correlation and Doppler spectrum are much dependent not only on the direction of terminal motion, but also on the antenna configuration. Even in the non-line-of-sight environment, observed Doppler spectrum is quite different from the theoretical U-shaped Jakes one. In addition, it has been also shown that a channel change during the time interval between the transmit weight matrix determination and the actual data transmission can degrade the performance of MIMO E-SDM systems., The Institute of Electronics, Information and Communication Engineers, English - Blind Iterative Decoding in Bit-Interleaved Coded DPSK
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 107, 518, 193, 198, 05 Mar. 2008
When the transmitter maps a bit-interleaved coded sequence into DPSK symbols, turbo (iterative) decoding is applicable at the receiver by regarding a differential encoder in DPSK as an inner encoder, i.e., serial concatenation of two encoders. In this paper, we examine blind iterative decoding in a bit-interleaved coded DPSK system. We also propose a blind channel estimation scheme based on decision feedback because coherent detection is required for the iterative decoding. The result obtained by computer simulations shows that performance of the iterative decoding significantly outperforms that of coherent PSK with perfect CSI. In addition, it is demonstrated that the proposed channel estimation scheme provides the performance approaching to that of the perfect CSI case by 0.1dB and 0.9dB in no fading and dynamic fading environments, respectively, at BLER of 10^<-2>., The Institute of Electronics, Information and Communication Engineers, Japanese - Imperfect Block Diagonalization for Downlink Multiuser MIMO Systems
KATO Shohei, NISHIMOTO Hiroshi, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, IEICE technical report, 107, 518, 329, 334, 05 Mar. 2008
Recently, a multiuser MIMO system has attracted much attention. In the downlink of the multiuser MIMO system, since the base station simultaneously transmits signals to terminals, there is inter-user interference (IUI) at each terminal. Block diagonalization, which can achieve perfect IUI supression, has been extensively studied to solve the issue. However, with the scheme we cannot obtain sufficient diversity gain due to the null steering at the base station. In this paper, we propose imperfect block diagonalization based on maximum eigenvectors of users and Gram-Schmidt orthonormalization, and its error rate performance is evaluated using computer simulation. The result shows that, despite its low complexity, the proposed scheme provides excellent performance, especially in many user environments., The Institute of Electronics, Information and Communication Engineers, Japanese - A study on channel prediction and decision-feedback assisted channel tracking for IEEE802.16e based OFDM system
KIM Sang-Woo, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 107, 438, 85, 90, 17 Jan. 2008
OFDM is an attractive system for high spectral efficiency and capability of multipath fading compensation. In high-speed fading environments, however, channel tracking during the data period becomes a substantial technique to maintain good BER performance since channel change from the initial estimate using preamble symbols cannot be ignored. In this paper, we focus on the decision feedback channel tracking and propose a way to generate more accurate replicas by switching the decoder output based on a property of concatenated codes. In addition, we introduce a linear prediction method with two different techniques for the estimate of prediction coefficients. The simulation results show the effectiveness of these proposed methods under an IEEE 802.16e-OFDM model with 250Hz and higher Doppler frequency., The Institute of Electronics, Information and Communication Engineers, Japanese - Design of a Real-time IEEE 802.11n MIMO-OFDM System with PE-SDM Beamforming
WEBBER Julian, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, 光電技報, 24, 2008 - Multiuser MIMO E-SDM Systems: Performance Evaluation and Improvement in Time-Varying Fading Environments
Huu Phu Bui, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, 3303, 3307, 2008, [Peer-reviewed]
English - Imperfect block diagonalization for multiuser MIMO downlink
Hiroshi Nishimoto, Shohei Kato, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 1, 5, 2008, [Peer-reviewed]
IEEE, English - A Received Block Division Technique with SC/MMSE Turbo Equalization under Fast Fading Environments
KAMBARA Keiichi, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 107, 402, 37, 42, 13 Dec. 2007
Frequency-domain equalization (FDE) has been studied as a very simple countermeasure against frequency selective fading in a single carrier transmission system. In a fast fading environment, however, the equalization performance degrades since periodicity of the channel within an FDE block is lost. Therefore, we have proposed a method dividing a received data block into multiple subblocks to decrease the channel transition within the block in such an environment. In this method, the performance is degraded by inaccuracies of pseudo CP processing, which is introduced to satisfy periodicity in each subblock. In this paper, we study the application of frequency-domain turbo equalization (FDTE) to subblock processing for improving the accuracy of pseudo CP. The simulation results show that FDTE with subblock processing yields remarkable performance improvements., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Uplink Weights Compensating Terminal Frequency Offsets in a Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, IEICE technical report, 107, 305, 31, 36, 01 Nov. 2007
Recently, a virtual antenna array, which is formed by multiple terminals cooperating each other, has attracted attention because it can potentially improve uplink capacity in high-frequency-band communications. However, since it is difficult in practice to accurately synchronize carrier frequencies at the terminals, performance is degraded due to frequency offsets. In this paper, we propose a method to estimate frequency offsets and to conpensate them at the terminals. Also, this paper describes a receive weight tracking scheme by the RLS algorithm at a basestation. Then, we evaluate the BER performance by computer simulations. The simulation results show performance improvements by applying these techniques., The Institute of Electronics, Information and Communication Engineers, Japanese - Channel Estimation with Ordered Interference Cancellation for a MIMO Receiver Using Iterative Equalization and Decoding
HIGASHINAKA Masatsugu, KUBO Hiroshi, SHIBUYA Akihiro, OKAZAKI Akihiro, OGAWA Yasutata, OHGANE Takeo, NISHIMURA Toshihiko, IEICE technical report, 107, 262, 1, 6, 11 Oct. 2007
This paper proposes a channel estimation method with ordered interference cancellation for a MIMO receiver using iterative equalization and decoding. In the iterative receiver, channel estimation can be performed in every iteration by using symbol estimates composed of extrinsic information from a soft-output decoder. In the MIMO case, however, data sequences transmitted from each transmit antenna are not always applicable to the iterative channel estimation because the transmitted data sequences may be not suitable for the channel estimation. The proposed channel estimation method performs ordered interference cancellation and then estimates the channel state information for a residual stream, reffering to a decoder output. Computer simulation confirms that the proposed method has excellent frame error rate performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Evaluations of E-SDM Transmission with Adaptive Modulation Using a Testbed
NAITO A., NISHIMURA T., OHGANE T., OGAWA Y., IEICE technical report, 107, 262, 19, 24, 11 Oct. 2007
We can realize high-speed communications with MIMO systems that have multiple antennas at both transmitter and receiver. For a downlink channel in a MIMO system, we apply E-SDM using adaptive modulation in which communication speed is changed according to the channel condition. In this case, assuming packet transmission, we apply a maximum throughput criterion for the adaptive modulation. In this paper, we evaluate the throughput performance of E-SDM transmission with adaptive modulation by using an indoor testbed. Because computation load with conventional adaptive modulation is heavy, it is reduced by simplification. Additionally, we show that linear extrapolation that compensates errors caused by channel fluctuation works in dynamic fading environments., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-25 An Effective Channel Estimation Scheme Using Space-Time Windowing in Pseudo Eigenbeam Transmission
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 2007, 1, 439, 439, 07 Mar. 2007
The Institute of Electronics, Information and Communication Engineers, Japanese - Fundamental Studies on Transmit Beamforming with Virtual Antenna Arrays
OGAWA Kenta, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, IEICE technical report, 106, 555, 65, 68, 28 Feb. 2007
Recently, the virtual antenna array, which is formed by multiple terminals cooperating each other, has attracted attention because it can potentially improve capacity in high-frequency-band communications. However, since it is difficult in practice to accurately synchronize the terminals, performance may be affected by phase and frequency offsets, which are caused by the imperfect synchronization. In this paper, we evaluate effects of the offsets and channel estimation errors on the system performance by computer simulations. The results show that degradation of performance can be reduced by using the equivalent channel, which includes both the actual channel and offsets, in processing at the receiver, and that performance in multi-beam transmission is more affected by the frequency offset compared with that in single-beam transmission., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Improvement of Channel Estimation Accuracy in Pseudo Eigenbeam Space Division Multiplexing
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, 電子情報通信学会技術研究報告. RCS, 無線通信システム, 106, 480, 67, 72, 26 Jan. 2007
Japanese - A Study on Reduction Schemes of Feedback Amount in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, 電子情報通信学会技術研究報告. RCS, 無線通信システム, 106, 480, 73, 78, 26 Jan. 2007
Japanese - Improvement of a Received Block Division Technique for MMSE-FDE under Fast Fading Environments
KAMBARA Keiichi, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report, 106, 480, 7, 12, 26 Jan. 2007
Frequency domain equalization (FDE) has been studied for preventing performance degradation due to frequency selective fading in single carrier transmission. In fast fading environments, however, another problem occurs since cyclicity in the FDE block is lost. Thus, we have proposed subblock processing at the receiver side with pseudo cyclic prefix (CP) generation. The performance highly depends on the CP accuracy. Therefore, here, we apply a higher order interpolation method for more accurate channel estimation. In addition, overlapped subblock processing is used to reduce an effect of degradation in pseudo CP accuracy. The simulation results show performance improvements by applying these techniques to the subblock processing., 一般社団法人電子情報通信学会, Japanese - A Study on Improvement of Channel Estimation Accuracy in Pseudo Eigenbeam Space Division Multiplexing
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 480, 67, 72, 26 Jan. 2007
In a MIMO system with space-frequency domain beamforming under frequency selective fading scenarios, a pseudo eigenvector decomposition has been proposed to reduce the calculation load at the transmitter and to maintain frequency continuity of the effective channel observed at the receiver. It has been reported that a pseudo eigenbeam space division multiplexing (PE-SDM) technique can provide almost the same or better performance compared with eigenbeam space division multiplexing when the receiver employs a simple channel estimator exploiting pseudo-eigenvector properties. In this paper, focusing on the calculating process of pseudo eigenvectors, we propose a new scheme improving the accuracy of the effective channel estimates. The simulation results show that the accuracy in the PE-SDM is improved by combining the proposed scheme with the conventional one., 一般社団法人電子情報通信学会, Japanese - A Study on Reduction Schemes of Feedback Amount in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 106, 480, 73, 78, 26 Jan. 2007
In a multiple-input multiple-output system for OFDM (MIMO-OFDM), eigenbeam-space division multiplexing (E-SDM) which is also called a singular value decomposition (SVD) algorithm can provide maximum throughput in MIMO channels when channel state information (CSI) or transmit weight matrix is available at the transmitter. We have proposed a technique that only dominant time-domain CSI is fed back in order to reduce the amount of feedback. In this paper, we compare the proposed method to the scheme which feeds back the transmit weight matrix with a codebook., 一般社団法人電子情報通信学会, Japanese - Subblock processing for MMSE-FDE under fast fading environments
K. Kambara, H. Nishimoto, T. Nishimura, Y. Ogawa, T. Ohgane, IEEE Vehicular Technology Conference, 2190, 2194, 2007
一般社団法人電子情報通信学会, English - B-1-201 Uplink Weight Determination Compensating Terminal Frequency Offsets in a Virtual MIMO System
SAITO Yuta, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, Proceedings of the Society Conference of IEICE, 201, 201, 2007
The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-202 Downlink Weights for Multiuser MIMO Systems Using the Gram-Schmidt Orthogonalization
Kato Shohei, Nishimoto Hiroshi, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 202, 202, 2007
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-15 A study on channel tracking with decision feedback in WiMAX-OFDM systems
Kim Sang-Woo, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 337, 337, 2007
The Institute of Electronics, Information and Communication Engineers, Japanese - Channel estimation with space-time windowing in MIMO PE-SDM transmission
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, 2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, 541, 545, 2007, [Peer-reviewed]
English - High throughput performance of PE-SDM in MIMO single-carrier systems with MMSE-FDE
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, 1852, 1856, 2007, [Peer-reviewed]
English - Robust performance of MIMO E-SDM systems in actual time-varying indoor fading environments
Bui Huu Phu, Toshihiko Nishimura, Hiroshi Nishimoto, Yasutaka Ogawa, Takeo Ohgane, 2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 1460, 1464, 2007, [Peer-reviewed]
English - Robust MIMO-OFDM E-SDM systems with low complexity in time-varying indoor fading environments
Bui Huu Phu, Toshihiko Nishimura, Hiroshi Nishimoto, Takeo Ohgane, Yasutaka Ogawa, 2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, 1322, 1326, 2007, [Peer-reviewed]
English - Subblock processing for MMSE-FDE under fast fading environments
K. Kambara, H. Nishimoto, T. Nishimura, Y. Ogawa, T. Ohgane, 2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 2190, 2194, 2007, [Peer-reviewed]
English - Pseudo eigenbeam transmission technique in frequency selective MIMO channels
Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane, Yasutaka Ogawa, 2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 2068, 2072, 2007, [Peer-reviewed]
English - MIMO-UWB systems with parallel interference canceller using timing control scheme in LOS environments
Masaki Takanashi, Toshihiko Nishimura, Yasutaka Ogawa, Takeo Ohgane, 2007 IEEE WIRELESS COMMUNICATIONS & NETWORKING CONFERENCE, VOLS 1-9, 1601, 1605, 2007, [Peer-reviewed]
English - Effects of Channel Prediction on MIMO E-SDM System Performance in Actual Time-Varying Fading Environments
BUI Huu Phu, NISHIMURA Toshihiko, NISHIMOTO Hiroshi, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report, 106, 395, 97, 104, 22 Nov. 2006
In time-varying fading environments, a channel prediction method should be used to reduce channel errors due to the channel changes between the transmit weight matrix determination time and the actual data transmission time, so that the performance of MIMO E-SDM (Eigenbeam-Space Division Multiplexing) system can be improved. Here, we present an experimental measurement setup to evaluate the performance in actual environments. Based on the measured data, simulation results show that by using our proposed prediction methods much better performance can be obtained in both actual line-of-sight (LOS) and non-LOS (NLOS) communications environments. We can also see that the performance in LOS environments is better than that in NLOS ones., The Institute of Electronics, Information and Communication Engineers, English - A Received Block Division Technique for MMSE-FDE under Fast Fading Environments
KAMBARA Keiichi, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report, 106, 305, 95, 100, 12 Oct. 2006
Frequency domain equalization (FDE) has been studied for suppressing inter-symbol interference (ISI) due to frequency selective fading in single carrier systems. When a high-mobility terminal is assumed in the system, channel transition within a FFT block can not be ignored. Then, ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. Here, we propose a method dividing a received data block into multiple subblocks to decrease the channel transition within the FFT block in fast fading environments. In addition, we propose a method generating pseudo cyclic prefix to satisfy periodicity of the received signal in each subblock., The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-217 Performance of MIMO-OFDM Pseudo Eigenbeam Transmission in an Indoor Propagation Environment
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 2006, 1, 217, 217, 07 Sep. 2006
周波数選択性フェージング環境下のMIMOシステムでは,各周波数において固有ビーム形成を行うことで最適伝送を実現できるが[1],周波数毎の固有ウェイトの算出は大きな計算負荷となり,周波数連続性のない送信ウェイトは受信側で観測される実効チャネルのインパルス応答に大きな遅延広がりを生じさせる.これらの問題を解決するため,筆者らは文献[2]において疑似固有ベクトル手法を提案し,これにより演算量削減,及び,実効チャネルの周波数連続性を実現できることを示した.本稿では.文献[3]の屋内伝搬実験に基づき,疑似固有ベクトルを用いるPE-SDM (Pseudo Eigenbeam-Space Division Multiplexing)について,実環境におけるMIMO-OFDM伝送特性を評価する., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-9 Performance of E-SDM Single Carrier Transmission with MMSE-FDE and a Parallel Interference Canceller
ISHIDA Takahiro, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 2006, 1, 368, 368, 07 Sep. 2006
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-40 A study on multicode transmission with frequency domain equalization
Iwazaki Kiyoto, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2006, 1, 400, 400, 07 Sep. 2006
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of MIMO-OFDM Pseudo Eigenbeam Space Division Multiplexing
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 223, 1, 6, 24 Aug. 2006
In a MIMO system with space-frequency domain beamforming under frequency selective fading scenarios, a pseudo eigenvector decomposition has been proposed to reduce the calculation load at the transmitter and to maintain frequency continuity of the effective channel observed at the receiver. It has been reported that pseudo eigenbeam space division multiplexing (PE-SDM) technique can provide almost the same or better performance compared with eigenbeam space division multiplexing (E-SDM) when the receiver employs a simple channel estimator exploiting pseudo-eigenvector properties. In this paper, under various multipath delay profiles, we evaluate performance of the PE-SDM in MIMO-OFDM with an interference canceller and compare it with E-SDM perfor-mance. The simulation results show that the accuracy of the estimated effective channel in the PE-SDM can be improved more under lower delay spread multipath environments, and that the receiver incorporating a parallel interference canceller can make the performance of the PE-SDM better than that of the E-SDM., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of Frequency-Flat E-SDM (FFE-SDM) Single Carrier Transmission with MMSE-FDE Incorporating an Interference Canceller
ISHIDA Takahiro, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 223, 7, 12, 24 Aug. 2006
In frequency selective MIMO channels, frequency-flat E-SDM (FFE-SDM) with MMSE-FDE suffers from co-channel interference (CCI). Thus it has been shown that resource adaptation based on both inter-symbol interference and CCI measures gives good performance. In this paper, we apply a parallel interference canceller (PIC) to this system for reducing CCI effectively and evaluate performance with resource adaptation based on three criteria. In comparison with the conventional SDM, the results show that the FFE-SDM technique is more robust to fading correlation and that an eigenvalue criterion which can be easily calculated is practical., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Reduction of the Amount of CSI Feedback with Time-domain Channel in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 106, 168, 31, 36, 12 Jul. 2006
In a multiple-input multiple-output system for OFDM (MIMO-OFDM), eigenbeam-space division multiplexing (E-SDM) which is also called a singular value decomposition (SVD) algorithm can provide maximum throughput in the MIMO channel when channel state information (CSI) is available at the transmitter. We have proposed reduction of the CSI feedback using the minimum mean square error method in the time domain, and clarified good bit error rate performance. In this paper, we propose a novel technique that only dominant time-domain CSI is fed back in order to reduce the amount of feedback compared to the conventional scheme., The Institute of Electronics, Information and Communication Engineers, Japanese - Pseudo Eigenbeam SDM with MMSE-FDE for Single Carrier Transmission
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 168, 61, 66, 12 Jul. 2006
In a MIMO system with space-frequency domain beamforming under frequency selective fading scenarios, a pseudo eigenvector decomposition has been proposed to reduce the calculation load at the transmitter and maintain frequency continuity of the effective channel observed at the receiver. In this paper, we evaluate the performance of the pseudo E-SDM (PE-SDM) transmission in MIMO single carrier systems with MMSE-FDE, and compare three substream quality measures for transmit resource control and two encoding schemes. The simulation results show that difference among the three criteria becomes smaller as the number of antennas increases. Moreover, the scheme, in which each data sequence is encoded and interleaved over all substreams, makes the difference smaller so that a simple resource control is practically applicable., The Institute of Electronics, Information and Communication Engineers, Japanese - A fundamental study on multicode transmission with frequency domain equalization
IWAZAKI Kiyoto, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 168, 73, 78, 12 Jul. 2006
In frequency-selective channels, the performance of a direct sequence code division multiplexing (DS-CDM) system is severely degraded by inter-code interference since code orthogonality is no longer satisfied. However, the inter-code interference can be suppressed by frequency domain equalization (FDE). On the other hand, multicode transmission in DS-CDM causes an increase of peak-to-average-power-ratio (PAPR). For PAPR reduction, it is known that selection or multiplexed symbol combination from a limited group is effective. Here, side information on the selection must be transmitted. In this paper, we propose to use the side information as a code redundancy and to apply turbo type decoding. As the first step, the performance of multicode transmission with a simple even parity is evaluated. The resutls show that, using turbo type decoding and MMSE-FDE in a frequency selective channel, the obtained gain at FER of 10^<-3> is about 3dB., The Institute of Electronics, Information and Communication Engineers, Japanese - Pseudo Eigenbeam-Space Division Multiplexing in Frequency Selective Fading Environments
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 119, 125, 130, 15 Jun. 2006
In frequency selective MIMO channels, the optimum transmission is achieved by beamforming based on eigenvectors (i.e., E-SDM) at each frequency point. However, the calculation load of eigenvalue decomposition at the transmitter increases in proportion to the number of frequency points. In addition, frequency-independent eigenvectors enlarge delay spread of the effective channel observed at the receiver. In this paper, we propose pseudo eigenvectors for the purpose of maintaining frequency continuity of the effective channel and reducing the calculation load at the transmitter. First, we demonstrate that pseudo eigenvectors decrease delay spread of effective channels. Next, the performance of the pseudo E-SDM (PE-SDM) transmission in MIMO-OFDM systems is evaluated. The simulation results show that PE-SDM provides almost the same or better performance compared with E-SDM when an estimated effective channel is used to detect the substreams at the receiver., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Reduction of the Amount of Channel State Information Feedback in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report, 106, 25, 37, 42, 14 Apr. 2006
MIMO space division multiplexing in an OFDM system (MIMO-OFDM) can achive high-data-rate transmission without additional frequency spectra. Furthermore, eigenbeam-space division multiplexing (E-SDM) which is also called the singular value decomposition (SVD) algorithm can provide maximum throughput in the MIMO channel when channel state information (CSI) is available at the transmitter. When the uplink and downlink channels are not reciprocal as in a FDD system, we need to feed back the CSI from the receiver to the transmitter. However, capacity is limited because CSI feedback is needed for each subcarrier in an OFDM system. This paper proposes the feedback of the time-domain channel estimated using the minimum mean square error method. The proposed method can reduce the amount of feedback information, and reveals better bit error rate performance than the other schemes., 一般社団法人電子情報通信学会, Japanese - A Study on Eigenbeam-Space Division Multiplexing with MMSE-FDE
ISHIDA Takahiro, NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 106, 25, 55, 60, 14 Apr. 2006
In frequency selective multiple-input multiple-output (MIMO) channels, equalization for suppressing inter-symbol interference is necessary as well as spatial-demultiplexing. When MMSE frequency domain equalization (MMSE-FDE) is applied to a single carrier system in eigenbeam-space division multiplexing with frequency-flat transmit weights, resource adaptation based on the extended MIMO channel does not give expected performance due to not considering less detection capability of MMSE-FDE. In this paper, we propose two criteria and evaluate their performance compared with the conventional space division multiplexing transmission. The results show that a new criterion incorporating the amount of interference in the MMSE-FDE output gives better performance than the others., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-76 Channel Prediction for an E-SDM System in Time-Varying Fading Environments
BUI Huu-Phu, OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko, Proceedings of the IEICE General Conference, 2006, 1, 428, 429, 08 Mar. 2006
The Institute of Electronics, Information and Communication Engineers, English - B-5-68 A Study on Reduction of the Amount of CSI Feedback in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
OHWATARI Yusuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2006, 1, 420, 420, 08 Mar. 2006
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-97 An Estimation Method of Multiple User Uplink OFDMA Channels
MIYAZAWA Makoto, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2006, 1, 450, 450, 08 Mar. 2006
The Institute of Electronics, Information and Communication Engineers, Japanese - A-5-27 Performance Evaluation of MIMO-UWB Systems in Actual Propagation Environments
Takanashi Masaki, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2006, 141, 141, 08 Mar. 2006
The Institute of Electronics, Information and Communication Engineers, Japanese - A study on transmit-antenna selection for multiuser-MIMO uplink
OHKAWARA Junya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 105, 559, 65, 70, 19 Jan. 2006
In this paper, we discuss methods of transmit-antenna selection for uplink multiuser MIMO-SDM systems. In multiuser MIMO-SDM systems, signal detection quality at a basestation is degraded by cochannel interference, and depends on the number of transmit antennas of each user. In this paper, we propose a novel method for antenna selection to increase diversity gain. The criterion of antenna selection is based on capacity using spatial filter output. Simulation results show that frame error rate performance in the multiuser MIMO-SDM systems is improved by the proposed method. In addition, we show the advantage of diversity gain to select the number of transmit antennas at each user., The Institute of Electronics, Information and Communication Engineers, Japanese - Simplification of transmit resource control in E-SDM with adaptive modulation
Toshihiko Nishimura, Yasuo Hata, Takeo Ohgane, Yasutaka Ogawa, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 105, 559, 89, 94, 2006, [Peer-reviewed]
IEEE, English - Extrapolation of Time-Varying MIMO Channels for an E-SDM System
Bui Huu Phu, Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura, 2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 1748, 1752, 2006, [Peer-reviewed]
English - Reduction of the Amount of Channel State Information Feedback in MIMO-OFDM Eigenbeam-Space Division Multiplexing Systems
Yusuke Ohwatari, Bui Huu Phu, Yasutaka Ogawa, Toshihiko Nishimura, Takeo Ohgane, 2006 IEEE 64TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 401, 405, 2006, [Peer-reviewed]
English - Indoor Experiments of an E-SDM Testbed with Channel Prediction
Toshihiko Nishimura, Yasuo Hata, Takeo Ohgane, Yasutaka Ogawa, 2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, 2285, 2289, 2006, [Peer-reviewed]
English - Performance Evaluation of MIMO E-SDM Based on Indoor Measurement
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 105, 355, 127, 132, 13 Oct. 2005
A multiple input multiple output (MIMO) system in which multiple antennas are placed at both the transmitter and receiver end can potentially meet the growing demand for higher capacity in wireless communications. When information on the channel state is available at the transmitter end, eigenbeam-space division multiplexing (E-SDM) which can provide maximum throughput in the MIMO channel is more efficient technique in order to achieve higher speed transmission compared with the conventional space division multiplexing (SDM). This paper shows MIMO channel measurement campaigns conducted in indoor line-of-sight (LOS) and non line-of-sight (NLOS) environments. Using the measured data, we present the bit error rate performance of 2×2 and 4×4 E-SDM. The results shows that, E-SDM generally gives better performance than SDM, and LOS environments provide more excellent performance of E-SDM compared with NLOS ones. However, we can see that the performance of E-SDM in LOS environments strongly depends on the array configuration., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Evaluations of a Coded MIMO-OFDM System
OHWATARI Yusuke, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, IEICE technical report, 105, 356, 61, 66, 13 Oct. 2005
MIMO space division multiplexing in an OFDM system (MIMO-OFDM) can achive high-data-rate transmission without inter-symbol interference in frequency selective fading channels. In a receiver, however, spatial filtering is needed to separate and detect transmitted signals because the signals sent from all the transmit antennas interfere each other. It has been reported that precise channel estimation is possible and the performance of MIMO-OFDM using MMSE-OSD is improved by an evaluation system experimentaly. In this paper, we introduce a coded MIMO-OFDM system in order to improve the performance. Also, we show the experimental results of performance of BER and FER., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-24 Compensation of Time-variant Fading Channel Error for E-SDM in a TDD System
Phu Bui Huu, Ogawa Yasutaka, Ohgane Takeo, Nishimura Toshihiko, Proceedings of the Society Conference of IEICE, 2005, 1, 424, 424, 07 Sep. 2005
The Institute of Electronics, Information and Communication Engineers, English - B-5-31 Multi-user MIMO Systems for W-CDMA Uplink
TANAKA Toyohisa, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2005, 1, 431, 431, 07 Sep. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - BS-1-4 Performance Evaluation of MIMO Eigen-beam Space Division Multiplexing in Actual Environments
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the Society Conference of IEICE, 2005, 1, "S, 7"-"S-8", 07 Sep. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - AS-1-10 Studies on MIMO-UWB-IR Systems using Frequency Domain Equalization
Takanashi Masaki, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the Society Conference of IEICE, 2005, "S, 19"-"S-20", 07 Sep. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - A study on transmit-antenna selection in Multiuser-MIMO systems
OHKAWARA Junya, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 105, 121, 53, 58, 10 Jun. 2005
In this paper, we discuss effects of transmit-antenna selection for uplink multiuser MIMO-SDM systems. In multiuser MIMO-SDM systems, signal detection quality at a basestation is degraded by cochannel interference and depends on the number of transmit antennas. To reduce cochannel interference, we consider limiting the number of transmit-antennas and antenna selection at each or target mobile station. Computer simulation results show that frame error rate performance in multiuser MIMO-SDM systems is improed by transmit-antena selection., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental evaluation on E-SDM with channel estimation error compensation
HATA Y., NISHIMURA T., OHGANE T., OGAWA Y., Technical report of IEICE. RCS, 105, 121, 65, 70, 10 Jun. 2005
Applying E-SDM system is evaluated for a TDD uplink in MIMO (Multiple-Input Multiple-Output) channels when a channel response matrix is known at a transmitter. If time difference between transmit weight calculation from channel information at a transmitter and actual transmission is large, performance of E-SDM degrades because channel orthogonality is not kept. In this study, indoor experiments of E-SDM are done using fading simulators to evaluate the channel estimation error compensation by the first order extrapolation, which has been proposed. Furthermore, simplification of transmission resource control and reduction of calculation load are proposed. Experimental results show that the channel estimation error compensation by the first order extrapolation is very effective and improves BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance evaluation of MIMO-SDM using a tripole antenna based on indoor channel measurements
NISHIMOTO H., IEICE Technical Report, 105, 121, RCS2005, 39, 10 Jun. 2005
Recently a MIMO system, which promises very high-speed data transmission, has attracted great attention to wireless communications. In multipath-rich environments, it is considered that strong cross-polarization components also arrive at a receiver. We measured 3×3 MIMO channels in a multipath-rich room using tripole antennas. The tripole antenna is composed of three orthogonal omni-directional antennas. It is shown that the tripole antennas give lower fading correlations. However, we cannot find clear differences of the performance in array configurations., 一般社団法人電子情報通信学会, Japanese - B-1-244 Performance Comparison of MIMO Spatial Multiplexing on Various Array Configurations in Actual Propagation Environments
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2005, 1, 244, 244, 07 Mar. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-84 A study on scaling of likelihood values on MIMO-OFDM systems
HOSHINO Masayuki, TAKAKUSAKI Keiji, OHGANE Takeo, OGAWA Yasutaka, NISHIMURA Toshihiko, Proceedings of the IEICE General Conference, 2005, 1, 533, 533, 07 Mar. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - A-5-5 Interference cancelation in UWB-IR Systems with a Filter Based on an MMSE Criterion
Takanashi Masaki, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2005, 121, 121, 07 Mar. 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Comparison of MIMO-SDM Depending on Array Configurations Based on Indoor Measurements
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 104, 679, 123, 128, 24 Feb. 2005
A MIMO measurement campaign was conducted in indoor multipath-rich line-of-sight (LOS) and non-LOS (NLOS) environments. In this paper, for various antenna array configurations, we examined the performance of bit error rate (BER) for 2×2 and 4×4 MIMO-SDM systems using the actual channel state data with mutual coupling of antennas, and considered the effects of channel correlations and eigenvalue distributions. Results showed that MIMO channels in LOS generally give better BER performance than those in NLOS. Meanwhile, we also found that the performance in LOS tends to change largely depending on an array configuration., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Evaluation of a MIMO-OFDM System with MMSE-Ordered Successive Detection
MATSUNOSHITA Masahiro, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 679, 81, 86, 24 Feb. 2005
MIMO space division multiplexing in an OFDM system (MIMO-OFDM) can achive high-data-rate transmission without inter-symbol interference in frequency selective fading channels. In a receiver, however, spatial filtering must be needed to separate and detect transmitted signal, because received signals include transmitted signals from all the transmit antennas. We constructed an evaluation system with fading simulators in order to verify the MIMO-OFDM spatial division multiplexing system experimentaly. In this paper, we show some improvements of the hardware and processing software., The Institute of Electronics, Information and Communication Engineers, Japanese - Interference Cancelation and Equalization in UWB-IR Systems with a Filter Based on an MMSE Criterion
TAKANASHI Masaki, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, 電子情報通信学会技術研究報告. A・P, アンテナ・伝播, 104, 675, 207, 212, 23 Feb. 2005
Japanese - A Study on Parallel Interference Canceller in a Coded MIMO-OFDM System
SHIBAHARA Koji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 678, 37, 42, 23 Feb. 2005
In this paper, it is considered to apply a parallel interference canceller (PIC) to a coded MIMO-OFDM system. In a hard canceller with a simple configuration, a cancelling factor is generally introduced to reduce the effect of error propagation due to low reliability replicas. Here, a novel hard canceller using a spatial filtering factor is proposed. In addition, a symbol-by-symbol PIC is also applied to reduce the packet processing delay. The simulation results show that it achieves low computational complexity and short packet processing delay, and that the performance degradation compared to soft PIC is reasonably small., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Computational Complexity Reduction of Iterative Decoding for Turbo-coded MIMO-SDM Using Sphere Decoding
SUMII Kenji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 678, 43, 48, 23 Feb. 2005
A turbo-coded MIMO-SDM system requires a soft-output MIMO detector. Although MAP-based soft-output detection is optimum, its hardware implementation is very difficult since its computational complexity increases exponentially with the antennas and constellations. Sphere decoding (SD) is one of promising ways to reduce the computational complexity effectively. In SD, however, it occasionally excludes signal points required for the likelihood estimation in turbo decoding. In this paper, we propose a method recovering the signal points outside the sphere, and its error performance is evaluated. The simulation results reveal its extremely low complexity., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on MIMO for W-CDMA Uplink Channel
TANAKA Toyohisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 599, 37, 42, 21 Jan. 2005
W-CDMA has already been operated as the 3rd generation mobile communication system. Continuously the 3rd Generation Partnership Project (3GPP) has been worked for enhancing the 3G systems. A specification of High Speed Downlink Packet Access (HSDPA), which enables up to 14.4Mbps data rate for downlink, was completed so far. In addition to the HSDPA, MIMO has been proposed to apply for further enhancement. We studied MIMO for W-CDMA uplink by using a computer simulation in this report., The Institute of Electronics, Information and Communication Engineers, Japanese - B-1-241 Evaluation of 3×3 MIMO-SDM Using a Tripole Antenna Based on Indoor Propagation Measurment
Nishimura Toshihiko, Nishimoto Hiroshi, Ogawa Yasutaka, Ohgane Takeo, Proceedings of the IEICE General Conference, 241, 241, 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-23 An adaptive modulation control with eigenvalues in E-SDM
HATA Yasuo, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 423, 423, 2005
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of MIMO-SDM Considering Mutual Coupling Based on Indoor Measurements
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 104, 399, 53, 58, 29 Oct. 2004
We measured MIMO channels with mutual coupling of antennas in indoor line-of-sight (LOS) and non-LOS (NLOS) environments where we have rich multipath signals. Using the measured data, we examined bit error rate performance, channel correlations, and eigenvalue distributions for 2x2 MIMO space division multiplexing (SDM) systems to evaluate effects of mutual coupling on the performance. We show that t,he MIMO-SDM is useful also in an indoor LOS environment, whereas the performance in the LOS environment tends to change significantly depending on an array configuration. Moreover, it is shown that the mutual coupling tends to effect on LOS channel data more largely than on NLOS ones., The Institute of Electronics, Information and Communication Engineers, Japanese - Estimation of Channel and Frequency Offset in a MIMO-OFDM System
NAMKAMURA Yuichiro, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 104, 258, 79, 84, 20 Aug. 2004
An OFDM system has been used also for wireless local area networks. MIMO space division multiplexing in an OFDM system has been studied to achive high-speed transmission over lOOMbps. In this paper, we compare three methods of channel estimation using a few training symbols. We show that the time-domain minimum square error method that the authors have proposed enables accurate channel estimation. Furthermore, we develop this scheme to estimation of channel and frequency offset between a transmitter and a receiver. We show that the proposed method can estimate them using a preamble that have the same duration as that of the IEEE802.11 a standard., The Institute of Electronics, Information and Communication Engineers, Japanese - Experimental Studies on a MIMO-OFDM System
MATSUNOSHITA Masahiro, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 258, 103, 107, 20 Aug. 2004
MIMO space division multiplexing in an OFDM system (MIMO-OFDM) can achive high-data-rate transmission without inter-symbol interference in frequency-selective fading channels. It has been reported that precise channel estimation is possible by using the training symbols with a low condition number even though the number of training symbols in an OFDM system (for example, IEEE802.ila) is small. In this paper, we evaluate sensitivity of channel estimation acculacy and BER performance to the condition number depending on the training symbols, experimentary, using a DSP-based MIMO-OFDM system., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Analysis of MIMO-SDM Based on 5.2GHz Band Measurements in Indoor Environments
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, IEICE technical report. Antennas and propagation, 104, 202, 25, 30, 15 Jul. 2004
We measured MIMO channels in a line-of-sight (LOS) environment where channels may be correlated, then examined bit error rate performance for 2 × 2 MIMO-SDM and eigenvalue distributions to compare with channels, in a non-LOS (NLOS) environment. Furthermore, we analyzed channel data with mutual coupling between antennas, and evaluated its effect on the performance. We show that the performance of MIMO-SDM is useful also in a LOS environment where there are rich multipath signals, and that the performance in the LOS environment changes significantly depending on antenna spacing and array configuration. Moreover, it is shown that the presence of mutual coupling tends to effect on LOS channel data more largely than NLOS ones., 一般社団法人電子情報通信学会, Japanese - Performance Evaluation of a Parallel Interference Canceller for FEC-Coded MIMO-OFDM
SHIBAHARA Koji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 123, 31, 35, 11 Jun. 2004
MIMO space division multiplexing in an OFDM system can achieve very high-speed transmission. In this paper, a parallel interference canceller (PIC) is considered for coded MIMO-OFDM based on the IEEE standard 802.11a, and its performance is evaluated. In addition, we propose PIC processing symbol by symbol to reduce a processing delay. Numerical analysis shows that PIC has better PER performance compared to spatial filtering, and that severe degradation is not observed in the symbol PIC., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Computational Complexity Reduction for Turbo-coded MIMO-SDM
SUMII Kenji, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 104, 123, 37, 42, 11 Jun. 2004
A soft output MIMO decoder is required for turbo-coded MIMO-SDM. Although soft output maximum likelihood detection (MLD) is optimal, its computational complexity prevents application to iterative decoding of turbo decoding and soft output MIMO decoding. We propose a complexity reduction method for soft output MLD in iterative decoding, and also consider the application to partial search MLD. Computer simulation results show that the proposed method reduces complexity effectively., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-32 Performance Evaluation of Parallel Interference Canceller for FEC-coded MIMO-SDM
Shibahara Koji, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2004, 1, 519, 519, 08 Mar. 2004
The Institute of Electronics, Information and Communication Engineers, Japanese - SB-1-2 Estimation of Frequency Offset and Channel in MIMO-OFDM Systems
Nishio Keisuke, Ogawa Yasutaka, Nishimura Toshihiko, Ohgane Takeo, Proceedings of the IEICE General Conference, 2004, 1, "S, 27"-"S-28", 08 Mar. 2004
The Institute of Electronics, Information and Communication Engineers, Japanese - SB-1-5 Effects on MIMO Space Division Multiplexing in Indoor LOS Environments
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Proceedings of the IEICE General Conference, 2004, 1, "S, 33"-"S-34", 08 Mar. 2004
The Institute of Electronics, Information and Communication Engineers, Japanese - Complexity reduction approaches for SDM systems in a frequency selective MIMO channel
FURUTA Takayuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 103, 680, 49, 54, 25 Feb. 2004
In a frequency selective MIMO channel, a maximum likelihood receiver performing both joint detection and sequence estimation is optimum. However, an increase of the number of delayed waves and substreams complicates the receiver process exponentially. We applied sphere decoding (SD) and M-algorithm (MA) for complexity reduction to the receiver in convolutional-coded SDM and E-SDM systems. In this paper, we evaluate effects of those algorithms in both complexity reduction and performance degradation., The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-29 A Study on Itertive Decoding in Turbo-Coded MIMO-SDM
SUMII Kenji, NISHIMURA Toshihiko, OHGANE Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 516, 516, 2004
The Institute of Electronics, Information and Communication Engineers, Japanese - Channel and frequency offset estimation for a MIMO-OFDM system
Y Ogawa, K Nishio, T Nishimura, T Ohgane, VTC2004-FALL: 2004 IEEE 60TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-7, 1523, 1527, 2004, [Peer-reviewed]
English - Performance Evaluation of MIMO Space Division Multiplexing in Actual Channels
NISHIMOTO Hiroshi, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 103, 460, 139, 144, 21 Nov. 2003
Independent and identically distributed (i. i. d.) Rayleigh channels between transmit and receive antennas have been assumed in many studies on MIMO space division multiplexing (MIMO-SDM). In this case, transmitted streams can be separated and detected by processing at a receiver end. However, channels may be correlated in a line-of-sight (LOS) environment. We measured MIMO channels in a very rich multipath environment, and showed that the performance of LOS channels is more excellent than that of NLOS (Non-LOS) ones. We also evaluated the performance of channels measured in an an-echoic chamber where we do not have rich multipath propagation., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance Evaluation of MIMO Space Division Multiplexing in Line-Of-Sight (LOS) Channels
NISHIMOTO Hiroshi, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, Proceedings of the Society Conference of IEICE, 2003, 1, 236, 236, 10 Sep. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - A study on OFDM-STTuC with feedback information
HOSHINO Masayuki, UESUGI Mitsuru, OHGANE Takeo, OGAWA Yasutaka, NISHIMURA Toshihiko, Proceedings of the Society Conference of IEICE, 2003, 1, 390, 390, 10 Sep. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of MIMO-SDM communications in Nakagami-Rician fading
Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Takatori Yasushi, Cho Keizo, Proceedings of the Society Conference of IEICE, 2003, 1, 408, 408, 10 Sep. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - Signal Processings in MIMO Sytems
Ohgane Takeo, Ogawa Yasutaka, Nishimura Toshihiko, Proceedings of the Society Conference of IEICE, 2003, 1, "SS, 34"-"SS-35", 10 Sep. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - Sphere decoding in a frequency selective MIMO channel
FURUTA Takayuki, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 103, 253, 7, 12, 21 Aug. 2003
In a frequency selective MIMO channel, the maximum likelihood receiver performing both joint detection and sequence estimation is optimum. However, an increase of the number of delayed waves and substreams complicates the receiver process, exponentially. In this paper, we apply Sphere Decoding (SD) to the receiver. SD limits the number of constellation points to be searched by setting a sphere around a received signal. Here, we evaluate effects of sequence estimation to SD and the performance., The Institute of Electronics, Information and Communication Engineers, Japanese - An impact of channel state information error on SDM applications
TSUTSUMI Takahiko, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 103, 204, 13, 18, 18 Jul. 2003
For some SDM applications, performance degradation due to error in channel state information is numerically analyzed. In addition, a channel prediction method using first order extrapolation is proposed. The computer simulation results show that SDM using a joint detector outperforms E-SDM and w-SDM which requires channel state information at the transmitter in fast fading condition. However, by using the channel prediction, the performance of E-SDM and w-SDM is improved., The Institute of Electronics, Information and Communication Engineers, Japanese - Studies on MIMO Space Division Multiplexing in an OFDM System
NISHIO Keisuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 103, 66, 83, 90, 23 May 2003
MIMO space division multiplexing in an OFDM system can achieve very high-speed transmission. This paper nresents signal separation techniques for spatially multiplexed signals. We consider a channel estimation scheme using a very few training symbols. Then, we investigate reasons for degradation of channel estimation accuracy, and propose training symbol selection for better channel estimation. Also, we examine several MIMO reception techniques., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on E-SDM in a Frequency Selective Channel
Furuta Takayuki, Ohgane Takeo, Nishimura Toshihiko, Ogawa Yasutaka, Tomisato Shigeru, Proceedings of the IEICE General Conference, 2003, 1, 775, 775, 03 Mar. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - A study on weight compensation for time-variant channel in E-SDM
Tsutsumi Takahiko, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2003, 1, 776, 776, 03 Mar. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - A study on antenna selection scheme for Space-Time Turbo code
HOSHINO Masayuki, EBIKO Keisuke, UESUGI Mitsuru, OHGANE Takeo, OGAWA Yasutaka, NISHIMURA Toshihiko, Proceedings of the IEICE General Conference, 2003, 1, "S, 49"-"S-50", 03 Mar. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - Throughput performance of weighted BLAST transmission in a MIMO channel
Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Takatori Yasushi, Cho Keizo, Proceedings of the IEICE General Conference, 2003, 1, "S, 55"-"S-56", 03 Mar. 2003
The Institute of Electronics, Information and Communication Engineers, Japanese - On performance of FEC in E-SDM
KIMURA Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 102, 675, 1, 5, 27 Feb. 2003
In multiple-input multiple-output channels, channel capacity is highly improved by eigenbeam space division multiplexing (E-SDM), when the channel response is known at a transmitter. In this paper, we introduce FEC (turbo codes, in specific) to the E-SDM and evaluate its performance. Computer simulations show the results on performance improvement due to coding gain. However, the improvement is larger in the SDM case. Thus, the performance of E-SDM and SDM becomes very close., The Institute of Electronics, Information and Communication Engineers, Japanese - Fundamental Studies on MIMO-OFDM Space Division Multiplexing
NISHIO Keisuke, OGAWA Yasutaka, NISHIMURA Toshihiko, OHGANE Takeo, Technical report of IEICE. RCS, 102, 551, 121, 126, 10 Jan. 2003
OFDM is useful for high-speed transmission in a multipath environment. Space division multiplexing in a MIMO system can increase a transmission rate because different transmit antennas radiate indivisual signals. This paper describes an adaptive antenna configuration and weight control method for the OFDM system. Then, the authors propose MIMO-OFDM space division multiplexing based on the adaptive antenna. It is shown from computer simulations that the proposed system reveals excellent performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Evaluation of weighted BLAST compared with E-SDM in MIMO Channel Systems
NISHIMURA T., OHGANE T., OGAWA Y., TAKATORI Y., CHO K., Technical report of IEICE. RCS, 102, 551, 127, 132, 10 Jan. 2003
In this paper, two schemes to improve channel capacity, weighted-BLAST and E-SDMA, are evaluated in multiple-input multiple-output (MIMO) channels, when the channel response matrix is known at a transmitter. In the paper, we describe transmitting power and bit rate controls for each scheme, and three receiving methods for weighted-BLAST is examined by numerical simulations. Also, bit error rates of weighted-BLAST and E-SDM are computed and compared. The results show that the weighted BLAST is a promising scheme for some applications because of less feedback data and less terminal load even though bit error rate is higher than E-SDM., The Institute of Electronics, Information and Communication Engineers, Japanese - Studies on 2-Dimensional DOA Estimation Using a Cylindrical Array
TAKANASHI Masaki, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report. Antennas and propagation, 102, 230, 77, 82, 17 Jul. 2002
A uniform linear array (ULA) has been mainly used for DOA estimation of coherent signals because we can apply the spatial smoothing preprocessing (SSP) technique. However, the ULA has ambiguity due to the symmetry, and the estimation accuracy depends on the DOA. Although these problems can be solved by using a uniform circular array (UCA), we cannot estimate the DOA of coherent signals because the SSP technique cannot be employed for the UCA. In this paper, we propose to estimate 2-dimensional DOA (polar angle and azimuth angle) of the coherent signals using a cylindrical array which is composed of stucked UCAs., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on SDM Turbo Codes in a MIMO Channel
KIMURA Hiroshi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 102, 204, 19, 24, 10 Jul. 2002
The performance of Turbo Codes in MIMO systems was evaluated. When the channel state information is not known at a transmitter, the BER performance of Turbo codes using space division multiplexing (SDM) was numerically analyzed in comparison to Turbo codes with space-time block codes (STBC). When the channel state information is known at a transmitter in a MIMO system, we evaluated the BER performance combining Turbo Codes and E-SDM/transmit MRC. The simulation results for an unknown channel assuming 4-tx and 2-rx antennas show that Turbo codes using SDM have better BER performance than Turbo codes with STBC. For a known channel, the performance of Turbo codes with MRC is better., The Institute of Electronics, Information and Communication Engineers, Japanese - Evaluation of E-SDM Performance in the Presence of Channel Estimation Error
NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, TAKATORI Yasushi, CHO Keizo, Technical report of IEICE. RCS, 102, 204, 25, 30, 10 Jul. 2002
Eignebeam-space division multiplexing (E-SDM) in the MIMO channel is effective when a receiver has less number of elements. In this paper, we evaluate E-SDM performance in the presence of chanel estimation error between channel response matrices used for determining transmit weights and actual channel responce ones. Average BER performance for maximal ratio combining has error floor because eigenbeams are not formed perefectly orthogonal. Therfore, zero-forcing method or joint detection are needed. The results of computer simulation show that the E-SDM method is superiour to normal SDM while channel correlation is over 0.8 with the joint detector., The Institute of Electronics, Information and Communication Engineers, Japanese - Eigenbeam-Space Division Multiplexing (E-SDM) in a MIMO Channel
MIYASHITA Kazumi, NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, TAKATORI Yasushi, CHO Keizo, Technical report of IEICE. RCS, 102, 86, 13, 18, 17 May 2002
In MIMO systems, when the channel state information is known at transmitter, the optimum capacity is given by eigenmode channel division with the water filling power control. In this paper, eigenbeam-space division multiplexing (E-SDM) is proposed based on that concept, and the BER performance is numerically analyzed in comparison to the conventional SDM. The simulation results assuming 5-tx and 2-rx antennas show that the E-SDM provides about 10 dB gain compared to the conventional SDM at average BER of 10^-3., The Institute of Electronics, Information and Communication Engineers, Japanese - Downlink Nullforming by a Receiving Antenna Selection for a MIMO/SDMA channel
NISHIMURA Toshihiko, TAKATORI Yasushi, OHGANE Takeo, OGAWA Yasutaka, CHO Keizo, Technical report of IEICE. SST, 101, 677, 17, 22, 07 Mar. 2002
In this paper, we propose a novel downlink nullforming technique for space division multiple access (SDMA) in a multi-input multi-output (MIMO) channel where a basestation and all terminal stations have multiple antennas. In the SDMA system, simple beamforming is not efficient to achieve a good performance due to cochannel interference (CCI). Proposed method is based on nullforming and characterized by an antenna element selection at each terminal where the selected antenna pair satisfies the lowest spatial correlation condition in all combinations. The results obtained by the computer simulations show the selective diversity gain of the proposed method and its performance improvement due to joint detection at each terminal., The Institute of Electronics, Information and Communication Engineers, Japanese - Studies on Tap Coefficients for a Cascaded Connect Space-Time Equalizer
TANABE Yasuhiko, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, ASAI Takahiro, TOMISATO Shigeru, Technical report of IEICE. SST, 101, 677, 23, 30, 07 Mar. 2002
In this paper, we discuss a cascaded connection of an adaptive array antenna, in which each antenna contains a feedforward filter, and the Viterbi equalizer. When using the feedforward filter, MMSE tap coefficients degrade the system performance because noise correlation in an array output becomes high. computer simulations show that proposed methods have better BER performance under a large delay spread condition and when the feedforward filters have few taps. In addition, we propose a method applying a multi-input Viterbi algorithm with a multi-beam adaptive array antenna. As a result, the proposed method improves BER performance significantly., The Institute of Electronics, Information and Communication Engineers, Japanese - Downlink Nullforming by a Receiving Antenna Selection for a MIMO/SDMA channel
NISHIMURA Toshihiko, TAKATORI Yasushi, OHGANE Takeo, OGAWA Yasutaka, CHO Keizo, Technical report of IEICE. RCS, 101, 683, 17, 22, 28 Feb. 2002
In this paper, we propose a novel downlink nullforming technique for space division multiple access (SDMA) in a multi-input multi-output (MIMO) channel where a basestation and all terminal stations have multiple antennas. In the SDMA system, simple beamforming is not efficient to achieve a good performance due to cochannel interference (CCI). Proposed method is based on nullforming and characterized by an antenna element selection at each terminal where the selected antenna pair satisfies the lowest spatial correlation condition in all combinations. The results obtained by the computer simulations show the selective diversity gain of the proposed method and its performance improvement due to joint detection at each terminal., The Institute of Electronics, Information and Communication Engineers, Japanese - Studies on Tap Coefficients for a Cascaded Connect Space-Time Equalizer
TANABE Yasuhiko, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, ASAI Takahiro, TOMISATO Shigeru, Technical report of IEICE. RCS, 101, 683, 23, 30, 28 Feb. 2002
In this paper, we discuss a cascaded connection of an adaptive array antenna, in which each antenna contains a feedforward filter, and the Viterbi equalizer. When using the feedforward filter, MMSE tap coefficients degrade the system performance because noise correlation in an array output becomes high. Computer simulations show that proposed methods have better BER performance under a large delay spread condition and when the feedforward filters have few taps. In addition, we propose a method applying a multi-input Viterbi algorithm with a multi-beam adaptive array antenna. As a result, the proposed method improves BER performance significantly., The Institute of Electronics, Information and Communication Engineers, Japanese - SDMA Downlink Beamforming for a MIMO channel
NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Technical report of IEICE. RCS, 101, 371, 23, 30, 13 Oct. 2001
SDMA 方式の下り回線ビーム形成において, MISO(Multi-Input-Single-Output)およびMIMO(Multi-Input Multi-Output)チャンネルを想定した場合に, 結合推定機能をもつ端末での受信特性について考察する.希望信号の電力がそれぞれの端末で最大となる送信最大比合成ダイバーシチと, 干渉信号電力を最小とするヌル制御の概念から導出した下り回線でのビーム形成法について評価する.計算機シミュレーションから, 結合推定機能を持つ端末を用いた場合, ヌル制御によるビーム形成法は送信最大比合成ダイバーシチとなるビーム形成法より特性が優れているという結果が得られた., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of The SDMA Base Station Employing Multistage Interference Canceller and Adaptive Array
Nakao Seigo, Kitakado Jun, Doi Yoshiharu, Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the Society Conference of IEICE, 2001, 1, 374, 374, 29 Aug. 2001
The Institute of Electronics, Information and Communication Engineers, Japanese - The Quasi-Optical Antenna-Mixer Array Using a Magnetic Loop Antenna in the 10GHz Band
SAITO Hiroyuki, NISHIMURA Toshihiko, YAMAMOTO Manabu, ITOH Kiyohiko, IEICE technical report. Antennas and propagation, 101, 231, 89, 96, 27 Jul. 2001
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. A simple Quasi-Optical Antenna-Mixer (QOAM) have been proposed using a magnetic loop antenna in our former study, and we have confirmed experimentally the performance of beam scanning with the arrayed QOAM in the 3GHz-band. In this report, we explore possibility for our proposal of application in the high-frequency band, verifying experimentally the behavior of the arrayed QOAM in the 10GHz band. Furthermore, we show that the RF signal the local oscillator's signal output are canceled out respectively by a symmetric arrangement of the QOAM., The Institute of Electronics, Information and Communication Engineers, Japanese - Downlink weight control using channel response estimation in TDD/SDMA
MIYASHITA Kazumi, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 101, 197, 31, 36, 12 Jul. 2001
Recently, with the demand on capacity increase, space division multiple access(SDMA) has been studied in order to improve channel efficiency. In TDD/SDMA using an adaptive array for a base station, weight control using a channel response estimated by first-order extrapolation is known as improving the BER performance in downlink. However, the performance degrades with increase of the fading speed. In this paper, we propose a channel response estimation method using exponential function approximation and evaluate its performance., 一般社団法人電子情報通信学会, Japanese - Quasi-Optical Antenna Mixer Array Using Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, The Transactions of the Institute of Electronics,Information and Communication Engineers B, 84, 5, 954, 957, 01 May 2001
準光学アンテナ・ミキサ[1]〜[5]は, 高周波信号(RF)と局部発振周波(LO)を空間的に受信すると同時に中間周波数(IF)信号へ変換する。本研究では, 3GHz帯で動作する磁流ループアンテナを試作し, 以前提案した準光学アンテナ・ミキサアレーによるビーム走査法[6]〜[11]の実験を行って理論と比較する。, The Institute of Electronics, Information and Communication Engineers, Japanese - Spatial Domain Multistage Interference Canceller with Error Correction
Nishimura Toshihiko, Ohgane Takeo, Ogawa Yasutaka, Proceedings of the IEICE General Conference, 2001, 1, 400, 400, 07 Mar. 2001
The Institute of Electronics, Information and Communication Engineers, Japanese - MIMOチャネルにおける下り回線ビーム形成法
西村寿彦, 信学技報, 2001, 23, 30, 2001 - Studies on a Reference Signal Synchronization Scheme for MMSE Adaptive Antennas
YONEZAWA N., OGAWA Y., NISHIMURA T., OHGANE T., DOI Y., Technical report of IEICE. RCS, 100, 347, 29, 35, 07 Oct. 2000
Timing synchronization of a reference signal with an incident desired signal is required to control an adaptive antenna based on the MMSE criterion. This paper proposes to use nsrrow-band filters whose bandwidth is narrower than that of the root Nyquist filter. In the first weight control, the adaptive antenna weights are determined almost properly, since the narrow-band filter increases the correlation between the incident desired signal and the reference signal with timing error. The second synchronization of the reference signal at the array output is accurate, and the adaptive antenna can determine the weights more precisely. The computer simulation results show the improvement of the synchronization accuracy, SINR, and the BER performance., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on High Resolution Time-Domain Estimation by the Beamspace MUSIC Algorithm under Multiple Incident Signal Environment
KIMURA Masatoshi, TANABE Yasuhiko, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, IEICE technical report. Antennas and propagation, 100, 218, 23, 28, 27 Jul. 2000
Time-domain measurements are widely spread, which estimate time delays of signals applying the inverse Fourier transform to frequency-domain data measured by a networkanalyzer. We can use the MUSIC algorithm for separating closely located signals. However, the performance of the MUSIC algorithm deteriorates under multiple signal environment. In this paper, we propose the beamspace MUSIC algorithm for the above environment. We also compare the results of the beamspace MUSIC with those of the gating technique. The beamspace MUSIC tends to show better performance than the gating technique., The Institute of Electronics, Information and Communication Engineers, Japanese - Performance of spatial domain-multistage interference canceller with timing estimation
NISHIMURA T., CHIBA T., TANABE Y., OHGANE T., OGAWA Y., KITAKADO J., DOI Y., Proceedings of the IEICE General Conference, 2000, 1, 412, 412, 07 Mar. 2000
The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Time Delay Estimation in Multipath Propagation Environment
TANABE Yasuhiko, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, Proceedings of the IEICE General Conference, 2000, 1, 492, 492, 07 Mar. 2000
The Institute of Electronics, Information and Communication Engineers, Japanese - A Studies on a Spatial-Domain Path-Diversity System with a Multibeam Adaptive Antenna
TANABE Y., FUJISHIMA K., NISHIMURA T., OGAWA Y., OHGANE T., Technical report of IEICE. RCS, 99, 638, 15, 20, 18 Feb. 2000
In a high speed TDMA system, frequency-selective fading is a serious problem.A spatial-domain path-diversity system using multibeam adaptive antenna has been proposed to reduce the frequency-selective fading, and to realize diversity.In this system, we need to estimate the time delays of multipath signals.If the estimation is not accurate, the system performance degrades.For this reason, the MUSIC algorithm has been proposed for the time delays estimation.However, the MUSIC algorithm needs a large quantity of operations.In this paper, we propose to use another scheme which is called an orthogonal vectors method.It needs much less operations, but the BER performance is almost the same as that of the MUSIC algorithm., The Institute of Electronics, Information and Communication Engineers, Japanese - マルチビームアダプティブアレーを用いた空間領域パスダイバーシチ受信に関する検討 (移動通信ワークショップ)
田辺 康彦, 藤嶋 堅三郎, 西村 寿彦, 電子情報通信学会技術研究報告, 99, 638, 15, 20, 18 Feb. 2000
電子情報通信学会, Japanese - The Quasi-Optical Antenna-Mixer Using a Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, 電子情報通信学会技術研究報告. ITS, 99, 631, 111, 116, 17 Feb. 2000
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. We presented a dual frequency operating microstrip antenna fed by coplanar waveguide as an essential part of the quasi-optical antenna-mixer before. Its manufacturing error was considerable, however, because it was a stacked-configuration. In this report, we make up a simple Quasi-Optical Antenna-Mixer using a magnetic loop antenna. In addition, the antenna that performs in 3.0GHz band is made and performance of beam scanning is confirmed experimentally with the arrayed ones., 一般社団法人電子情報通信学会, Japanese - The Quasi-Optical Antenna-Mixer Using a Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, Technical report of IEICE. RCS, 99, 637, 111, 116, 17 Feb. 2000
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. We presented a dual frequency operating microstrip antenna fed by coplanar waveguide as an essential part of the quasi-optical antenna-mixer before. Its manufacturing error was considerable, however, because it was a stacked-configuration. In this report, we make up a simple Quasi-Optical Antenna-Mixer using a magnetic loop antenna. In addition, the antenna that performs in 3.0GHz band is made and performance of beam scanning is confirmed experimentally with the arrayed ones., The Institute of Electronics, Information and Communication Engineers, Japanese - The Quasi-Optical Antenna-Mixer Using a Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, Technical report of IEICE. RCS, 99, 637, 111, 116, 17 Feb. 2000
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. We presented a dual frequency operating microstrip antenna fed by coplanar waveguide as an essential part of the quasi-optical antenna-mixer before. Its manufacturing error was considerable, however, because it was a stacked-configuration. In this report, we make up a simple Quasi-Optical Antenna-Mixer using a magnetic loop antenna. In addition, the antenna that performs in 3.0GHz band is made and performance of beam scanning is confirmed experimentally with the arrayed ones., The Institute of Electronics, Information and Communication Engineers, Japanese - The Quasi-Optical Antenna-Mixer Using a Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, Technical report of IEICE. SST, 99, 628, 111, 116, 17 Feb. 2000
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. We presented a dual frequency operating microstrip antenna fed by coplanar waveguide as an essential part of the quasi-optical antenna-mixer before. Its manufacturing error was considerable, however, because it was a stacked-configuration. In this report, we make up a simple Quasi-Optical Antenna-Mixer using a magnetic loop antenna. In addition, the antenna that performs in 3.0GHz band is made and performance of beam scanning is confirmed experimentally with the arrayed ones., 一般社団法人電子情報通信学会, Japanese - The Quasi-Optical Antenna-Mixer Using a Magnetic Loop Antenna
OYANE Hidehiko, NISHIMURA Toshihiko, ITOH Kiyohiko, Technical report of IEICE. RCS, 99, 637, 111, 116, 17 Feb. 2000
The quasi-optical antenna mixer system transforms RF signal into intermediate frequency signal as soon as the system receives the RF signal and local oscillator's signal spatially. Using this system, we can reduce transmission loss, which causes serious problem in the millimeter-wave band. We presented a dual frequency operating microstrip antenna fed by coplanar waveguide as an essential part of the quasi-optical antenna-mixer before. Its manufacturing error was considerable, however, because it was a stacked-configuration. In this report, we make up a simple Quasi-Optical Antenna-Mixer using a magnetic loop antenna. In addition, the antenna that performs in 3.0GHz band is made and performance of beam scanning is confirmed experimentally with the arrayed ones., The Institute of Electronics, Information and Communication Engineers, Japanese - 磁流ループアンテナを用いた準光学アンテナ・ミキサ (移動通信ワークショップ)
大矢根 秀彦, 西村 寿彦, 伊藤 精彦, 電子情報通信学会技術研究報告, 99, 631, 111, 116, 17 Feb. 2000
電子情報通信学会, Japanese - 磁流ループアンテナを用いた準光学アンテナ・ミキサ
大矢根 秀彦, 西村 寿彦, 伊藤 精彦, 電子情報通信学会技術研究報告, 99, 637, 111, 116, 17 Feb. 2000
電子情報通信学会, Japanese - A Study on Uplink Performance Enhancement in SDMA
KISHIYAMA Yoshihisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. SAT, 99, 567, 17, 24, 21 Jan. 2000
Recently, with the demand on capacity increase, space division multiple access (SDMA) has been studied in order to improve the channel efficiency. The SDMA requires high performance interference canceller such as an adaptive array which reduces the interference signals by steering nulls to those. In this paper, we propose a channel response assisted adaptive array (CRA-AA), and compare its performance with MMSE adaptive array and joint detection. We also discusse degradation due to carrier frequency offset and its compensation. The computer simulations show that the CRA-AA provides a good performance in the situation having fast fading and carrier frequency offset., 一般社団法人電子情報通信学会, Japanese - A Study on Uplink Performance Enhancement in SDMA
KISHIYAMA Yoshihisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 569, 17, 24, 21 Jan. 2000
Recently, with the demand on capacity increase, space division multiple access (SDMA) has been studied in order to improve the channel efficiency. The SDMA requires high performance interference canceller such as an adaptive array which reduces the interference signals by steering nulls to those. In this paper, we propose a channel response assisted adaptive array (CRA-AA), and compare its performance with MMSE adaptive array and joint detection. We also discusse degradation due to carrier frequency offset and its compensation. The computer simulations show that the CRA-AA provides a good performance in the situation having fast fading and carrier frequency offset., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on Uplink Performance Enhancement in SDMA
KISHIYAMA Yoshihisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 569, 17, 24, 21 Jan. 2000
Recently, with the demand on capacity increase, space division multiple access (SDMA) has been studied in order to improve the channel efficiency. The SDMA requires high performance interference canceller such as an adaptive array which reduces the interference signals by steering nulls to those. In this paper, we propose a channel response assisted adaptive array (CRA-AA), and compare its performance with MMSE adaptive array and joint detection. We also discusse degradation due to carrier frequency offset and its compensation. The computer simulations show that the CRA-AA provides a good performance in the situation having fast fading and carrier frequency offset., The Institute of Electronics, Information and Communication Engineers, Japanese - SDMA方式における上り回線特性の改善に関する検討
岸山 祥久, 大鐘 武雄, 西村 寿彦, 電子情報通信学会技術研究報告, 99, 565, 17, 24, 21 Jan. 2000
電子情報通信学会, Japanese - Space Domain-Multistage Interference Canceler for SDMA
NISHIMURA Toshihiko, DOI Yoshiharu, OHGANE Takeo, OGAWA Yasutaka, KITAKADO Jun, Technical report of IEICE. RCS, 99, 357, 103, 108, 15 Oct. 1999
It is a serious problem that interference is not efficiently canceled when the interference signals arrive from close directions to that of desired signal in an SDMA system, in which an adaptive array is used as the interference canceler. In this paper, we propose space domain-multistage interference canceler for the SDMA as a method to overcome the problem. The performance of this method is evaluated by computer simulations considering the PHS reverse link environment. The results show the remarkable improvement in high spatial-correlation situations., The Institute of Electronics, Information and Communication Engineers, Japanese - Space Domain-Multistage Interference Canceler for SDMA
NISHIMURA Toshihiko, DOI Yoshiharu, OHGANE Takeo, OGAWA Yasutaka, KITAKADO Jun, Technical report of IEICE. RCS, 99, 357, 103, 108, 15 Oct. 1999
It is a serious problem that interference is not efficiently canceled when the interference signals arrive from close directions to that of desired signal in an SDMA system, in which an adaptive array is used as the interference canceler. In this paper, we propose space domain-multistage interference canceler for the SDMA as a method to overcome the problem. The performance of this method is evaluated by computer simulations considering the PHS reverse link environment. The results show the remarkable improvement in high spatial-correlation situations., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Spatial-Domain Path-Diversity System Using the MUSIC Algorithm
TANABE Yasuhiko, FUJISHIMA Kenzaburoh, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, Technical report of IEICE. RCS, 99, 356, 89, 95, 14 Oct. 1999
In high speed TDMA mobile communications, frequency-selective fading is a serious problem because a delay difference between multipath signals is large in comparison with symbol duration. We have proposed spatial-domain path-diversity using a multibeam adaptive antenna. In the spatial-domain path-diversity system, the multibeam adaptive antenna resolves multipath signals in the spatial domain, and the system combines array outputs aligning the delay time. In this paper, we propose the application of MUSIC algorithm to estimate the delay time. Because estimation of the delay time using the MUSIC algorithm is precise, the BER (Bit Error Rate) performance of the proposed scheme is improved. Furthermore, we propose weighting factors which easily realize the maximal ratio combining., The Institute of Electronics, Information and Communication Engineers, Japanese - Considerations on a Spatial-Domain Path-Diversity System Using the MUSIC Algorithm
TANABE Yasuhiko, FUJISHIMA Kenzaburoh, NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo, Technical report of IEICE. RCS, 99, 356, 89, 95, 14 Oct. 1999
In high speed TDMA mobile communications, frequency-selective fading is a serious problem because a delay difference between multipath signals is large in comparison with symbol duration. We have proposed spatial-domain path-diversity using a multibeam adaptive antenna. In the spatial-domain path-diversity system, the multibeam adaptive antenna resolves multipath signals in the spatial domain, and the system combines array outputs aligning the delay time. In this paper, we propose the application of MUSIC algorithm to estimate the delay time. Because estimation of the delay time using the MUSIC algorithm is precise, the BER (Bit Error Rate) performance of the proposed scheme is improved. Furthermore, we propose weighting factors which easily realize the maximal ratio combining., The Institute of Electronics, Information and Communication Engineers, Japanese - MUSICアルゴリズムを併用した空間領域パスダイバーシチ受信に関する検討
田辺 康彦, 藤嶋 堅三郎, 西村 寿彦, 電子情報通信学会技術研究報告, 99, 354, 89, 95, 14 Oct. 1999
電子情報通信学会, Japanese - MUSICアルゴリズムを併用した空間領域パスダイバーシチ受信に関する検討
田辺 康彦, 藤嶋 堅三郎, 西村 寿彦, 電子情報通信学会技術研究報告, 99, 356, 89, 95, 14 Oct. 1999
電子情報通信学会, Japanese - A Study on Simplification for Delay Estimation of Multipath Signals
NISHIMURA Toshihiko, TANABE Yasuhiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the Society Conference of IEICE, 1999, 1, 314, 314, 16 Aug. 1999
The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on reference signal synchronization for PHS/SDMA system
NISHIMURA Toshihiko, TANABE Yasuhiko, OHGANE Takeo, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 141, 61, 66, 24 Jun. 1999
Since the preamble in PHS is common for all users, it can not be used for training the adaptive array weight as it is. Considering the PHS/SDMA system, only one solution is to provide the transmission timing difference between the users accommodated in the same channel. Then, the timing detection is required. For the first user, it is easy to estimate it since there is no interference. However, the timing of the second user must be estimated in rich interfered situation. In this paper, with some estimation methods the estimation performance is evaluated., The Institute of Electronics, Information and Communication Engineers, Japanese - Weight estimation for down-link null forming in TDD/SDMA system
KISHIYAMA Yoshihisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 141, 67, 72, 24 Jun. 1999
In TDD/SDMA employing an adaptive array at a base station, generally, the array pattern for down-link is calculated from that for up-link. Considering the angle spread in the Rayleigh fading channel, time difference between up and down-link causes null position changes on the optimum array pattern. In this paper, we propose the weight estimation method for the down-link null forming. It is based on that the weight is uniquely determined by the array response vector. Here, we discuss the array response estimation and the performance of the down-link null forming., The Institute of Electronics, Information and Communication Engineers, Japanese - A Study on reference signal synchronization for PHS/SDMA system
NISHIMURA Toshihiko, TANABE Yasuhiko, OHGANE Takeo, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 141, 61, 66, 24 Jun. 1999
Since the preamble in PHS is common for all users, it can not be used for training the adaptive array weight as it is. Considering the PHS/SDMA system, only one solution is to provide the transmission timing difference between the users accommodated in the same channel. Then, the timing detection is required. For the first user, it is easy to estimate it since there is no interference. However, the timing of the second user must be estimated in rich interfered situation. In this paper, with some estimation methods the estimation performance is evaluated., The Institute of Electronics, Information and Communication Engineers, Japanese - Weight estimation for down-link null forming in TDD/SDMA system
KISHIYAMA Yoshihisa, OHGANE Takeo, NISHIMURA Toshihiko, OGAWA Yasutaka, DOI Yoshiharu, Technical report of IEICE. RCS, 99, 141, 67, 72, 24 Jun. 1999
In TDD/SDMA employing an adaptive array at a base station, generally, the array pattern for down-link is calculated from that for up-link. Considering the angle spread in the Rayleigh fading channel, time difference between up and down-link causes null position changes on the optimum array pattern. In this paper, we propose the weight estimation method for the down-link null forming. It is based on that the weight is uniquely determined by the array response vector. Here, we discuss the array response estimation and the performance of the down-link null forming., The Institute of Electronics, Information and Communication Engineers, Japanese - Analysis on Dual Frequency Operating Microstrip Antenna Fed by Coplanar Waveguide Using Method of Moments in Spectral Domain
KAICHIDA Tsuyoshi, ISHII Nozomu, YAMAMOTO Manabu, NISHIMURA Toshihiko, ITOH Kiyohiko, The Transactions of the Institute of Electronics,Information and Communication Engineers B, 82, 6, 1177, 1184, Jun. 1999
ミリ波帯においては，伝送線路による損失が大きいという問題が生じる．そこで，アンテナとミキサを一体化し，伝送損失を軽減することのできる準光学アンテナミキサがある．これは，高周波と局部発信周波の異なる二つの周波数を空間的に受信し，直後に中間周波数に変換するものである．これを実現することのできるアンテナとして，コプレーナ導波路給電による2周波動作可能なマイクロストリップアンテナがある．本論文においては，スペクトル領域モーメント法を用い，このアンテナの周波数1/20スケールモデルの入力特性をマイクロ波帝で解析し，異なる二つの周波数で独立に動作可能であることを示す．更に，本アンテナの放射指向性を絶対利得により評価する．, The Institute of Electronics, Information and Communication Engineers, Japanese - B-5-48 Effects of timing jitters to PHS signals in SDMA using an adaptive array
NISHIMURA Toshihiko, OHGANE Takeo, OGAWA Yasutaka, Proceedings of the IEICE General Conference, 1999, 1, 399, 399, 08 Mar. 1999
The Institute of Electronics, Information and Communication Engineers, Japanese - RF and LO Cancelation from the Quasi-Optical Antenna-Mixer Array
OYANE Hidehiko, NISHIMURA Toshihiko, ISHII Nozomu, ITOH Kiyohiko, IEICE technical report. Microwaves, 98, 198, 1, 6, 24 Jul. 1998
The quasi-optical antenna mixer system transforms the RF signal into the intermediate frequency signal (IF) as soon as the system receives the RF and the local oscillator's signal (LO) signals spatially. Using thes system, we can remove transmission loss that causes great problem in the millimeter-wave band. Generally, a low-pass-filter needs to prevent the RF and LO from mixer output. In this report, we propose a new configuration for canceling the RF and LO from total output on the quasi-optical antenna mixer without the filter. We fabricate a microwave band model to prove that the RF and LO are canceled from the output experimentally., The Institute of Electronics, Information and Communication Engineers, Japanese - Beam scanning by quasi-optical antenna-mixer array
ITOH Kiyohiko, OGAWA Yasutaka, NISHIMURA Toshihiko, FUKUCHI Hisanao, Proceedings of the IEICE General Conference, 1998, 2, 267, 268, 06 Mar. 1998
The Institute of Electronics, Information and Communication Engineers, Japanese - Quasi-Optical Antenna-Mixer System Fed by Coplanar Waveguide
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, The Transactions of the Institute of Electronics,Information and Communication Engineers. B-(0xF9C2), 80, 12, 1076, 1083, Dec. 1997
準光学アンテナ・ミキサは，高周波信号（RF）と局部発振周波（LO）を空間的に受信し，直後に中間周波数の信号に変換するシステムである．このシステムを用いることで，高周波回路は不要となり，特に周波数が高いときには，損失を大きく低減することができる．本論文では，準光学アンテナ・ミキサを実現するシステムとして，ミキサダイオードを装荷したコプレーナ導波路給電による2周波マイクロストリップアンテナを提案する．従来，準光学アンテナ・ミキサに用いられてきた受信部において，一方向からRFとLOを合成して入力していたため，LOの入射がRFの入射に干渉するという問題があった．そこで本論文では，基板の両側でRFとLOを独立して受信することができる構造を用いて準光学アンテナ・ミキサを構成した．まずミリ波帯において，受信部の設計を行い，電磁界シミュレータを用いてその特性を明らかにした．更に，マイクロ波帯において，本システムを試作し，受信部の2周波動作およびミキシング動作に関する実験を行った．その結果，本システムが準光学アンテナ・ミキサとして機能することが確認された., The Institute of Electronics, Information and Communication Engineers, Japanese - Beam Scanning of Quasi-Optical Antenna-Mixer Array
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, IEICE technical report. Antennas and propagation, 97, 382, 73, 78, 20 Nov. 1997
The quasi-optical antenna mixer system transforms the RF signal and the local oscillator's signal (LO) into the intermediate frequency signal as soon as the system receives the RF and LO signals spatially. We have proved a novel beam scanning system with the quasi-optical antenna-mixer array. In the report, we describe experimental results in the microwave band. The arrival direction of the RF signal can be controlled by the system without RF circuits such as phase shifters in the phased array. Therefore, not only losses in RF circuits are reduced but also the system is easily designed because of its simple structure., The Institute of Electronics, Information and Communication Engineers, Japanese - Multi-Element Quasi-Optical Antenna-Mixer System
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, Technical report of IEICE. RCS, 96, 531, 25, 32, 21 Feb. 1997
The quasi-optical antenna mixer system transforms the RF signal and the local oscillator's signal (LO) into the intermediate frequency signal as soon as the system receives the RF and the LO spatially. In the report, we propose a novel receiving system with the multi-element quasi-optical antenna-mixer. The arrival direction of the RF signal can be controlled by the system without RF circuits such as phase shifters in the phased array. Therefore, not only losses in RF circuits are reduced but also the system is designed easily because of its simple structure. We made this system in the microwave band, and verified that experimental results agree with analytical ones very much., The Institute of Electronics, Information and Communication Engineers, Japanese - Multi-Element Quasi-Optical Antenna-Mixer System
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, IEICE technical report. Microwaves, 96, 534, 25, 32, 21 Feb. 1997
The quasi-optical antenna mixer system transforms the RF signal and the local oscillator's signal (LO) into the intermediate frequency signal as soon as the system receives the RF and the LO spatially. In the report, we propose a novel receiving system with the multi-element quasi-optical antenna-mixer. The arrival direction of the RF signal can be controlled by the system without RF circuits such as phase shifters in the phased array. Therefore, not only losses in RF circuits are reduced but also the system is designed easily because of its simple structure. We made this system in the microwave band, and verified that experimental results agree with analytical ones very much., 一般社団法人電子情報通信学会, Japanese - Multi-Element Quasi-Optical Antenna-Mixer System
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, IEICE technical report. Antennas and propagation, 96, 525, 25, 32, 21 Feb. 1997
The quasi-optical antenna mixer system transforms the RF signal and the local oscillator's signal (LO) into the intermediate frequency signal as soon as the system receives the RF and the LO spatially. In the report, we propose a novel receiving system with the multi-element quasi-optical antenna-mixer. The arrival direction of the RF signal can be controlled by the system without RF circuits such as phase shifters in the phased array. Therefore, not only losses in RF circuits are reduced but also the system is designed easily because of its simple structure. We made this system in the microwave band, and verified that experimental results agree with analytical ones very much., 一般社団法人電子情報通信学会, Japanese - Multi-Element Quasi-Optical Antenna-Mixer System
NISHIMURA Toshihiko, TSUCHIDA Katsumi, ISHII Nozomu, ITOH Kiyohiko, Technical report of IEICE. RCS, 96, 531, 25, 32, 21 Feb. 1997
The quasi-optical antenna mixer system transforms the RF signal and the local oscillator's signal (LO) into the intermediate frequency signal as soon as the system receives the RF and the LO spatially. In the report, we propose a novel receiving system with the multi-element quasi-optical antenna-mixer. The arrival direction of the RF signal can be controlled by the system without RF circuits such as phase shifters in the phased array. Therefore, not only losses in RF circuits are reduced but also the system is designed easily because of its simple structure. We made this system in the microwave band, and verified that experimental results agree with analytical ones very much., The Institute of Electronics, Information and Communication Engineers, Japanese - Complex Conductivity and Surface Impedance of Superconducter Based on Modified Two Fluid Model
KURIBAYASHI Masashi, OHSHIMA Kenji, NISHIURA Toshihiko, ITOH Kiyohiko, Technical report of IEICE. SAT, 96, 168, 67, 73, 22 Jul. 1996
Complex conductivity of superconductor (CCS) is a principal parameter in the case of estimation for surface impedance of superconductor. Usual investigation on CCS is based on two fluid model, which is constructed on the assumption that electron pair has not collission with phonon. However, real part of CCS and surface impedance that derived from above two fluid model are not agree with measured values. We formulate modified two fluid model provided that moving electron pair has characteristic of equivalent loss which depend on high frequency electric field, and both density of super and normal electron are related by Rate equation. Furthermore, CCS and surface impedance are formulated by using modified two fluid model. Finally, numerical results of real part of CCS and surface impedance which obtained by modified two fluid model are agree with measured values., The Institute of Electronics, Information and Communication Engineers, Japanese - Dual Frequency Operation Microstrip Antenna System Fed by Coplanar-waveguide
NISHIMURA Toshihiko, ISHII Nozomu, ITOH Kiyohiko, IEICE technical report. Antennas and propagation, 96, 35, 27, 34, 16 May 1996
In mm wave band, there is serious problem on the transmission line loss. The loss can be omitted by using the quasi-optical antenna mixer system, which can transfer RF and LO to IF without the transmission line. In this report, we propose "a dual frequency operation microstrip antenna system fed by coplanar waveguide" for the above system, and calculate its RF characteristics numerically. As a result, we find that the matching for two patches can be easily achieved by using the coplanar waveguide, because of the flexibility of the line design. The front to back ratio is better, because the patches are located on both side of the grand plane. And the antenna system can be operated at the two different frequencies when the resonant frequencies are somewhat separated., The Institute of Electronics, Information and Communication Engineers, Japanese - Analysis on Superconducting Circular Patch with Spectral Domain Method
Murata Tomohiro, Nishimura Toshihiko, Ishii Nozomu, Itoh Kiyohiko, IEICE technical report. Electromagnetic compatibility, 95, 134, 29, 34, 29 Jun. 1995
In this paper, we analyze resonance frequency and quality factor(Q-factor) of superconducting circular patch antennas. Superconductors have lower surface impedance than cuppers at the range of low frequency. On account of this, we expect application of superconductors to microwave devices to become characteristics better. We use the two-fluid model to consider frequency dependency of superconductors surface impedance. We use spectral-domain method to analyze the antennas. We find current expand function on circular patch on Fourier transform domain, in general we should use Hankel transform domain on circular, and formulate this process., The Institute of Electronics, Information and Communication Engineers, Japanese - 1p-A-12 Lattice constants of RS-ARS mixed crystals
Nishimura T., Suzuki F., Nozaki R., Shiozaki Y., Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 48, 2, 113, 113, 16 Mar. 1993
The Physical Society of Japan (JPS), Japanese - 25p-ZC-4 Dielectric study of RS-ARS mixed crystal
Ando K, Nishimura T, Nozaki R, Shiozaki Y, 秋の分科会講演予稿集, 1992, 2, 64, 64, 14 Sep. 1992
The Physical Society of Japan (JPS), Japanese
Lectures, oral presentations, etc.
- 〔Major achievements〕[Tutorial] Orbital Angular Momentum for Wireless Communications: From Fundamentals to Implementation and Extension,
T. Nishimura, F. Maehara, E. Sasaki, D. Lee
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC2022), 12 Sep. 2022, English, Public discourse
12 Sep. 2022 - 15 Sep. 2022
Courses
Affiliated academic society
Research Themes
- 無線信号のセンシングと通信の統合を実現する大規模MIMOシステムの高度化
科学研究費助成事業
01 Apr. 2024 - 31 Mar. 2027
西村 寿彦, 大鐘 武雄
日本学術振興会, 基盤研究(C), 北海道大学, 24K07470 - 細分化深層学習による到来方向推定と実測検証
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
大鐘 武雄, 筒井 弘, 西村 寿彦
各到来波数に対応した特化型DNNの設計を図ることが大きな目標であった．そのため，まず3波到来環境に適したDNNを構築した．さらに，SN比に応じて訓練したSNR特化型DNNで推定すると特性が向上することから，あるSNRと推定波数における特化型DNNの構築を図った．次に，これを用いて，2波到来環境と3波到来環境に対応可能なシステムを構築するため，到来波数を推定するDNNとSNRを推定するDNNとを用意し，これらの推定結果を基に，最適な特化型DNNを選択する手法を採用した．その結果，2波到来環境で約95%以上に，3波到来環境においても約85%の成功率を達成できた．しかし，低SNR環境や，3波到来環境の成功率はまだ不十分であることも明らかとなった．
低SNR環境での問題は，データに含まれる雑音が無駄な入力となっているということである．そこで，入力データに対して主成分分析を行い，SNRに応じて入力次元を削減することを新たに提案した．その結果，SNR=0dBの環境において，推定成功率を約10%から60%以上に改善することができた．
3波到来環境においては，推定失敗例を解析した結果，3波が約20度以内の範囲に集中している場合に推定誤りが多く発生していることがわかった．そこで，3波が約20度以内の範囲に集中している場合を想定した近接波特化型DNNを構築し，通常の特化型DNNでの推定結果において3波が約20度以内の範囲に集中している場合には，前記の近接波用DNNを再度適用し直すことを行なった．これにより，推定成功率を約99%に向上することができた．
実測用USRPに関しては，Lora変調を用いて通信実験を行うことができた．
日本学術振興会, 基盤研究(B), 北海道大学, 23K26101 - Terminal collaboration technology that both improves energy efficiency and communication performance
Grants-in-Aid for Scientific Research
01 Apr. 2023 - 31 Mar. 2027
村田 英一, 岡本 英二, 井田 悠太, 丸田 一輝, 岡田 啓, 實松 豊, 西村 寿彦, 牟田 修, 田野 哲, 眞田 幸俊
無線通信システムでは限られた周波数を有効利用できる新たな技術が強く望まれている．この新技術の有力候補が，近傍端末が高速無線通信を介して互いに協調することにより疑似的な大規模MIMOを形成し空間多重伝送を実現する端末協調である．最新の携帯端末では高周波数帯での通信機能が実装されており，これを端末間通信に活かせば端末協調が実現できる可能性が高い．端末協調では個々の端末の位置や電波伝搬を考慮して周辺基地局のアンテナ群と端末協調グループを構成する必要がある．また，近傍の無線端末を関与させるため端末間通信も含めた消費エネルギー削減も重要な課題となる．本研究では，周辺に遍在する無線端末と基地局アンテナを高度に協調させることによって，複数アンテナを自在に活用した周波数利用効率とエネルギー効率の高い新たな無線システムの創出を目指している．
このような端末連携システムの構築に向けて，本研究では，(1) 分散端末同期技術，(2) 高周波数帯協調通信技術，(3) 端末協調グループ構成技術，の確立に取り組んでいる．また，その成果の確認には，基地局分散アンテナと端末協調グループ間の伝搬特性の検証，端末グループ内の高周波数帯近距離協調通信の伝送特性の検証が必要となる．今年度はこれら3技術の特性評価と検証に必要とされる基地局分散アンテナと端末協調グループ間の伝搬特性，端末グループ内の高周波数帯近距離協調通信の伝送特性の把握に向けて実験装置系の構築を行った．実験装置としては12x12 MIMO伝送が可能な装置であり，基本的な動作確認を終えている．今後，この装置によって得られた知見を積極的に各技術の研究過程にフィードバックする. その他，各技術グループでは積極的に研究成果の発表を行い，論文雑誌2件，学会発表27件の成果を得ている．
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Yamaguchi University, 23H00474 - 細分化深層学習による到来方向推定と実測検証
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
大鐘 武雄, 筒井 弘, 西村 寿彦
日本学術振興会, 基盤研究(B), 北海道大学, 23H01406 - Realizing of loose beamforming in massive MIMO system
Grants-in-Aid for Scientific Research
01 Apr. 2020 - 31 Mar. 2023
Nishimura Toshihiko
In a multi-user large-scale MIMO system, the computational complexity of weight formation increases significantly due to the placement of more than 100 transmitting antenna elements at the base station. For this reason, a method called loose beam forming has been proposed to generate weights by simply selecting the antenna elements to be used for transmission. In this study, we apply combinatorial optimization methods such as binary differential evolution, quantum annealing, and direct binary search, which are evolutionary algorithms, to generate quasi-optimal solutions by using conventional and proposed evaluation functions, and then evaluate the performance of the quasi-optimal solutions using the total channel capacity of all users in a downlink. The performance is evaluated by various criteria based on the sum of channel capacities of all users in the downlink.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Principal investigator, 20K04460 - Detection of Large Scale and Overloaded Signals from Massive IoT devices Based on Belief Propagation
Grants-in-Aid for Scientific Research
01 Apr. 2018 - 31 Mar. 2021
Ohgane Takeo
For accommodating massive IoT devices in a common channel, we developed methods which can correctly detect all of the signals with much fewer observations and much lower complexity. We newly proposed convex optimization with ADMM based on discreteness and group sparseness and improved Gaussian belief propagation and approximate message passing with parameter optimization using deep unfolding. Consequently, we succeeded to establish light-weight and high-performance signal detectors.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 18H03765 - Beam control by antenna selection on massive MIMO system
Grants-in-Aid for Scientific Research
01 Apr. 2017 - 31 Mar. 2020
Nishimura Toshihiko
A massive Multiple-Input Multiple-Output (MIMO) system, which is an MIMO system evolution with multiple antenna elements on both sides of the transmitter and receiver, has been studied. In this study, a new signal processing method called compressed sensing is used to realize the multi-user access at low cost. In order to improve the user separation, we have investigated a method of distributing the antenna elements in a massive MIMO system. The experimental environment for estimating the direction of arrival of radio waves implementing compressed sensing was prepared. In addition, a method to introduce deep learning for estimating the direction of arrival is also investigated.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 17K06413 - Analysis of a large-scale bipartite factor graph with analog coupling
Grants-in-Aid for Scientific Research
01 Apr. 2015 - 31 Mar. 2018
Takeo Ohgane
It is known that we can obtain the global solution of a complex problem by decomposing it into multiple sub-problems and solving the small problems with exchanging the partial solution (reliability information) among them. The correct solution may not be obtained when some reliability exchange loops exist. However, an exception, i.e., an appropriate convergence can be seen if the problem size is very large. In this project, we tried many tests under various situations and obtained the fact that the effect of incorrect reliability propagation decreases with the problem size. From this results, we have succeeded developing a method adjusting the reliability information. In addition, the validity of the obtained method has been confirmed by another optimization approach.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 15H02252 - Routing for wireless mesh networks with beam/null control
Grants-in-Aid for Scientific Research
01 Apr. 2012 - 31 Mar. 2015
OHGANE Takeo, OGAWA Yasutaka, NISHIMURA Toshihiko, WEBBER Julian
Wireless mesh networks are considered as an efficient candidate for a substitution of communication infrastructure in disaster situations. Such a network is suffered by mutual interferences between nodes since all nodes are reachable. We studied a cross layer processing to exploit this overreach by using beam/null control at each node. Specifically, beam/null control and its experimental test using USRP in the layer 2 were carried out. In addition, we clarified that the alternative routing with beam/null control in the layer 3 improved the throughput performance.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 24360144 - Evaluation of MIMO Chanel Capacity Based on Propagation Measurement and its Improvement
Grants-in-Aid for Scientific Research
01 Apr. 2011 - 31 Mar. 2014
OGAWA YASUTAKA, OHGANE Takeo, NISHIMURA Toshihiko
A transmitter side needs channel state information in multi-user MIMO downlinks. In time-varying environments, channels at the actual downlink transmission time are different from estimated channels, which situation causes interference and performance degradation. The purpose of this study was to improve the multi-user MIMO system performance predicting channels at the transmission time.
As for the channel prediction scheme, we examined autoregressive (AR)-model-based prediction and Lagrange extrapolation. We evaluated the MIMO transmission performance using channels obtained in a measurement campaign in indoor environments. It has been shown that the Lagrange extrapolation that is easy to implement can predict channels in the range over 0.1 wavelengths without significant performance degradation.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 23360166 - 圧縮サンプリング手法を使用したマルチバンドMIMOレーダの検証実験
戦略的情報通信研究開発推進制度 (SCOPE)
Nov. 2013 - Mar. 2014
西村 寿彦
総務省, Principal investigator, Competitive research funding - Study on Direction-of-Arrival Estimation with Metaheuristics
Grants-in-Aid for Scientific Research
2010 - 2012
OHSHIMA Kohzoh, MURASMOTO Mitsuru, OGAWA Yasutaka, KASHIWA Tatsuya, TAGUCHI Kenji, IMAI Suguru, OHGANE Takeo, NISHIMURA Toshihiko
In this research, we tried to apply Genetic Algorithm, Immune Algorithm andParticle Swarm Optimization to high resolution direction of arrival estimation.When the incident wave in the near field sources becomes a spherical wave, the complex calculation is needed with theMUSIC method though the incident wave was assumed to be a plane wave in conventional ways ofDOA estimation.As results of simulations, we confirmed the accuracy of direction of arrival estimation with metaheuristics and have shown its effectiveness.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Asahikawa National College of Technology, 22560400 - Relative position detection of radio terminals adapting a MIMO rada
Grants-in-Aid for Scientific Research
2010 - 2012
NISHIMURA Toshihiko, OGAWA Yasutaka, OHGANE Takeo
In this research, the method of relative position detection oftransmission and reception terminals, i.e. realization of a multi-input-multi-output (MIMO) radar, has examined by using the MIMO system which carries multi antenna elements in both terminals. As a problem, when many terminals existed, or when a multipass wave existed, many interference waves will enter into a receiving side, and it was predicted that the position estimate became difficult. Then, the technique of the position estimate of the terminals was developed by using the broadband signals. The broadband signal is divided into multi narrow band signals. Then, a conventional direction of arrival estimation method is adopted by rising from low frequency without the influence of a grating robe to the high frequency from which high resolution is obtained
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Principal investigator, Competitive research funding, 22560355 - Distributed network optimization based on information potential
Grants-in-Aid for Scientific Research
2009 - 2011
OHGANE Takeo, OGAWA Yasutaka, NISHIMURA Toshihiko, WEBBER Julian
In the wireless mesh network with nodes capable beam-forming, we have obtained the following three major achievements. (1) The approximate solution for maximizing sum-capacity has been developed and its high performance has been shown in network-coded links. (2) An suboptimum routing has been proposed for a wireless mesh network with nodes capable beam-forming and its high throughput performance has been indicated. (3) We have derived an approximated solution for the optimum beam-forming at the source node in a two-step relay.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 21360175 - Study on Highly Reliable Radio Communications Using Transmit Beam-forming with a Virtual Antenna Array
Grants-in-Aid for Scientific Research
2007 - 2009
OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko
Future mobile communications need to use a higher frequency band to accommodate a wider frequency bandwidth. In a higher frequency band, the attenuation of electromagnetic waves is severely large. In an uplink channel, we may have difficulties to realize reliable transmission because the transmit power of a user terminal is limited due to battery use. In this study, we have proposed a virtual antenna array in which plural user terminals cooperate with each other and operate as a single terminal. The virtual antenna array forms transmit beams toward a base station. We have proposed several elemental technologies to realize the virtual antenna array. It has been shown that when four user terminals cooperate each other, we can reduce transmit power by about 6dB comparing with a conventional single user terminal case.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 19360168 - 疑似固有ビーム伝送技術の研究開発
戦略的情報通信研究開発推進制度 (SCOPE)
2007 - 2008
大鐘武雄
総務省, Competitive research funding - High resolution position detection of mobile terminal in MIMO-UWB-IR communication system
Grants-in-Aid for Scientific Research
2006 - 2008
NISHIMURA Toshihiko
MIMO-UWB-IR(Multiple-Input Multiple-Output:多入力‐多出力- Ultra-Wide-Band:超広帯域- Impulse Radio)通信システムを用いて移動体の高精度位置検出を行うための基礎研究を行った。MIMO-UWB通信の実験装置の構築、MIMOチャネルの取り扱い(テストベット構築、実伝搬環境での実験、チャネル推定法の検討)、信号到来方向推定アルゴリズムの提案を行った。
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (A), Hokkaido University, Principal investigator, Competitive research funding, 18686033 - トライポールアンテナを用いたMIMOチャネル通信の実現
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
2004 - 2005
西村 寿彦
1.昨年度は、市販のオムニアンテナによりトライポールアンテナを構成したが、指向性や物理的大きさに制限があり、本研究の目的を遂行するには十分でない部分があった。そこで、本年度は、小型のオムニアンテナを製作し、理想的なトライポールアンテナを試作した。さらに、比較のため、トライポールアンテナと同じ素子で構成した3素子リニアアレーアンテナ、3素子円アレーアンテナも試作した。
2.前述の3種類のアレーアンテナによるMIMOチャネル通信がどのような環境で有効に働くかに重点を置き、周囲の散乱状況の異なる環境で複数の測定を行って伝搬データを取得した。取得したデータを用いて、フェージング相関、平均ビット誤り率特性、チャネルによって生成される行列の固有値分布、および、通信容量について計算機による数値解析を行い、その結果を比較した。その結果、トライポールアンテナは低いフェージング相関を与えること、ビット誤り率等では同等の特性を示すことがわかった。実験環境のような見通し内環境では、フェージング相関よりも受信電力の絶対値がその特性に大きく作用するためと結論付けられる。反射による偏波回転の多い環境が存在すればトライポールアンテナの使用が効果的であると予想される。
3.MIMOチャネル通信を実現する有効な方式として注目されているE-SDM(Eigenbeam-Space Division Multiplexing)方式を実装したテストベットを構築した。さらに、本テストベットを使用してフェージングシミュレータを用いた3×2MIMOチャネル実験を行い、提案アルゴリズムのリアルタイム動作を検証した。また、前年度に、送信リソース制御による計算負荷を軽減する方法を提案したが、今年度は素子数(ストリーム数)の制限のない方式を提案し、更なる計算負荷の軽減に成功した。
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, Principal investigator, Competitive research funding, 16760282 - Studies on High-speed Radio Transmission Using MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) Systems
Grants-in-Aid for Scientific Research
2003 - 2005
OGAWA Yasutaka, OHGANE Takeo, NISHIMURA Toshihiko
1. Evaluation of the channel estimation and BER performance using an experimental system :
An OFDM demodulation system was built up using DSP boards. Experimentally, we validated the OFDM channel estimation scheme proposed by our group. The channel was calculated by FFT applying to the impulse response obtained by the minimum square error method in the time domain. Then, we evaluated the bit error rate (BER) performance of the proposed OFDM system. Also, we examined an ordered successive detection method and transmission with error correcting codes.
2. Joint estimation of channel and frequency offset :
We proposed a joint estimation scheme of the channel and frequency offset using only 4 OFDM training symbols. It was shown that we can estimate them accurately and can obtain good BER performance.
3. Reduction of the amount of channel state information (CSI) feedback :
Eigenbeam-space division multiplexing (E-SDM) requires the feedback of CSI in frequency division duplex systems. In order to reduce the amount of the feedback, we proposed a new scheme. The scheme estimates the impulse response using the minimum square error method in the time domain, and feedback the impulse response. This reduces the amount of CSI feedback comparing with the feedback of all the subcarrier channel.
4. Evaluation of MIMO propagation :
The performance of MIMO systems depends on electromagnetic wave propagation environments. We conducted propagation measurement in line-of-sight (LOS) and nonline-of-sight (NLOS) environments. It was shown that the BER performance is better in LOS environments than that in NLOS ones. However, it was also shown that the performance depends highly on the MIMO configurations in LOS environments.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 15360198 - 固有ビーム分割多重方式の実現に関する研究
戦略的情報通信研究開発推進制度 (SCOPE)
2003 - 2004
小川恭孝
総務省, Competitive research funding - A Study on transmit power control per subcarrier in OFDM
Grants-in-Aid for Scientific Research
2001 - 2003
OHGANE Takeo, YAMAMOTO Manabu, NISHIMURA Toshihiko, OGAWA Yasutaka
In multiple-input multiple-output systems, most common application is space division multiplexing (SDM) where individual data substreams are transmitted from multiple antennas with the same power and the same rate. SDM applications assume that MIMO channel information in not available at the transmitter. If we know all of MIMO channel information, it is possible to assign matched beam to each substream where the optimum weight for beamforming is obtained by singular value decomposition of MIMO channel matrix. We call SDM with eigenbeam-forming as E-SDM, hereafter. In E-SDM, we have to consider resource (transmit power and data rate) adaptation. In this research, we employed minimum brt error rate (BER) criterion as expansion of transmit power control per sucarrier previously used in OFDM systems. As a result, E-SDM with the resource adaptation obtained higher BER performance in comparison to conventional SDM. However, the MIMO channel information required at the transmitter includes estimation and tracking errors. Under such errors, we also evaluated the E-SDM performance. The results show that degradation due to the channel estimation error is almost the same to E-SDM and SDM applications. Although the channel tracking error caused by a time lag until transmission degrades E-SDM performace severely when the maximum Doppler frequency is very high, we have shown that it can be compensated by employing the first-order extrapolation of estimated channel.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 13650390 - 第4世代移動通信システムにおける伝搬環境模擬実験
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
2001 - 2002
西村 寿彦
第4世代の移動通信に必要不可欠な大容量高速通信を実現するために、送信側・受信側にそれぞれ複数のアンテナが存在する(Multiple-Input Multiple-Output : MIMO)環境での検討が進められている。本研究では、このように複雑な伝搬環境をシミュレーションし、その環境下で最も効率良く通信を行うための信号処理法式を開発することが目的であった。
本年度の研究では、MIMO環境に適した多重接続方式として、固有ビーム空間分割多重接続(Eigenbeam-Space Division Multiplexing : E-SDM)方式の提案を行った。この方式は、MIMO環境のチャネル情報をもとに送受信間で複数の固有ビームを形成し,それらに複数のストリームを対応させて通信を行うものである。固有ビームは直交しているため受信側で最大比合成を行うだけで干渉なく送信ストリームを取り出すことができる。ただし、その場合、送信側でMIMOチャネル情報を正確に知る必要があるが、実際のシステムではそれを完全に行うことが難しいため、チャネル情報の誤差の影響について考察し、また、一次外捜によってチャネル情報を推定した場合の特性についても調査した。
E-SDMでは、各ストリームの品質に応じて送信信号の電力と送信ビット数を調節して通信容量を最適化する。この手法は単純に各送信アンテナから異なるストリームを送信するSDM方式にも適用できるため、受信側でBLASTを用いる重みつきBLAST (w-BLAST)の特性と比較した。最後に、第4世代移動通信で用いられると予測されているパケット通信を、想定し、E-SDMとw-BLASTのスループット特性をシミュレーションし、特性を評価した。
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, Principal investigator, Competitive research funding, 13750320 - 人工生命の概念に基づく通信システムの最適化に関する基礎研究
Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
1996 - 1998
小川 恭孝, 西村 寿彦, 大鐘 武雄
本研究は、種々の通信システムの最適化問題に人工生命の概念を導入することを目的としたものである。本研究においては、主に遺伝的アルゴリズムを用いた、移動通信の固定チャネル割り当て、ATM網のルーテイング、および、フェーズドアレーアンテナの低サイドローブ化について検討を行った。さらに、移動通信の最適受信法についても研究した。以下にその実施結果を述べる。
1. セルラー方式を用いた移動通信の固定チャネル割り当ては組み合わせ論的問題になるため、一般に膨大な演算が必要とされる。本研究では、まず、遺伝的アルゴリズムを適用することにより、チャネル割り当てを実現する方法の定式化を行った。ここで、遺伝的アルゴリズムの交鎖においてチャネル間干渉が生じない染色体構造を提案するなど、チャネル割り当てへの遺伝的アルゴリズムの適用にいくつかの新知見を得た。
2. ATM網のリンクコストを最小化する最適アルゴリズムも組み合わせ論的問題となる。このようなルーティングを遺伝的アルゴリズムにより実現する方法の定式化を行い、シミュレーションにより本アルゴリズムの評価を行った。
3. フェーズドアレーアンテナのサイドローブレベルを低減する励振位相を求めることは非線形最適化問題となる。各移相器の励振位相を連結したものを染色体とみなし、交鎖、突然変異、選択の遺伝的アルゴリズムの操作を適用した。これにより、短い演算時間でフェーズドアレーアンテナの低サイドローブ化が実現できることが分かった。
4. 多重伝搬波および干渉波が存在する環境下における移動通信の受信を最適化するアダプティブシステムを検討し、その特性の評価を行った。
Japan Society for the Promotion of Science, Grant-in-Aid for Exploratory Research, Hokkaido University, Coinvestigator not use grants, Competitive research funding, 08875073
Industrial Property Rights
- 送信装置
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 西本 浩, 三洋電機株式会社, 国立大学法人北海道大学
特願2006-151200, 31 May 2006
特開2007-324813, 13 Dec. 2007
特許第4836186号
07 Oct. 2011
201303068050995420 - 通信方法ならびにそれを利用した無線装置および通信システム
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人北海道大学
特願2005-376529, 27 Dec. 2005
特開2007-180855, 12 Jul. 2007
特許第4591969号
24 Sep. 2010
201103046624654432 - 送信方法および装置ならびにそれを利用した通信システム
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人北海道大学
特願2005-301934, 17 Oct. 2005
特開2007-110632, 26 Apr. 2007
特許第4593435号
24 Sep. 2010
200903097832858322 - 移動通信システム、基地局装置及び方法
Patent right, 岸山 祥久, 大渡 裕介, 西村 寿彦, 大鐘 武雄, 小川 恭孝, 株式会社エヌ・ティ・ティ・ドコモ, 国立大学法人 北海道大学
特願2007-170870, 28 Jun. 2007
特開2009-010752, 15 Jan. 2009
200903053357021377 - 通信方法ならびにそれを利用した端末装置および基地局装置
Patent right, 中岡 謙, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人 北海道大学
特願2007-074334, 22 Mar. 2007
特開2008-236483, 02 Oct. 2008
200903077200031090 - 通信方法およびそれを利用した無線装置
Patent right, 中岡 謙, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人 北海道大学
特願2007-073549, 20 Mar. 2007
特開2008-236409, 02 Oct. 2008
200903023185796383 - 推定方法ならびにそれを利用した推定装置、受信装置および受信システム
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人 北海道大学
特願2007-023092, 01 Feb. 2007
特開2008-193222, 21 Aug. 2008
200903011747641860 - 受信方法および装置
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人 北海道大学
特願2007-023094, 01 Feb. 2007
特開2008-193224, 21 Aug. 2008
特許第4903593号
200903002659163762 - 推定方法ならびにそれを利用した推定装置、受信装置および無線受信システム
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三洋電機株式会社, 国立大学法人 北海道大学
特願2007-023093, 01 Feb. 2007
特開2008-193223, 21 Aug. 2008
200903081372126987 - ウエイトベクトルの導出方法ならびにそれを利用した送信装置および通信システム
Patent right, 中尾 正悟, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 西本 浩, 三洋電機株式会社, 国立大学法人 北海道大学
特願2006-151200, 31 May 2006
特開2007-324813, 13 Dec. 2007
200903096685597902 - 無線通信システム、ユーザ端末および基地局
Patent right, 田中 豊久, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 三菱電機株式会社
特願2005-257379, 06 Sep. 2005
特開2007-074189, 22 Mar. 2007
200903015581968003 - 送信装置
Patent right, 鷹取 泰司, 長 敬三, 大鐘 武雄, 小川 恭孝, 西村 寿彦, 日本電信電話株式会社
特願2002-058276, 05 Mar. 2002
特開2003-258770, 12 Sep. 2003
特許第3798325号
28 Apr. 2006
200903060960127275 - 同期検出装置および無線装置
Patent right, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 土居 義晴, 国立大学法人 北海道大学, 三洋電機株式会社
特願2004-158146, 27 May 2004
特開2005-006300, 06 Jan. 2005
特許第3775604号
03 Mar. 2006
200903067615996060 - 無線受信システム
Patent right, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 岩見 昌志, 北門 順, 土居 義晴, 国立大学法人 北海道大学, 三洋電機株式会社
特願2001-530213, 10 Oct. 2000
特許第3648202号
18 Feb. 2005
201103004104737420 - 同期検出装置および無線装置
Patent right, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 土居 義晴, 国立大学法人 北海道大学, 三洋電機株式会社
特願2004-158142, 27 May 2004
特開2005-006299, 06 Jan. 2005
200903068800111861 - 無線受信システム
Patent right, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 岩見 昌志, 北門 順, 土居 義晴, 北海道大学長, 三洋電機株式会社
JP2000007041, 10 Oct. 2000
WO2001-028107, 19 Apr. 2001
200903006988723480 - 同期検出装置およびそれを備える無線装置
Patent right, 小川 恭孝, 大鐘 武雄, 西村 寿彦, 土居 義晴, 北海道大学長, 三洋電機株式会社
特願平11-177399, 23 Jun. 1999
特開2001-007783, 12 Jan. 2001
200903051433318578
