2022/09/21 更新

写真a

オオノ シュウイチ
大野 修一
OHNO Shuichi
担当
大学院情報学研究科 基幹情報学専攻 教授
工学部 情報工学科
職名
教授
所属
情報学研究院

担当・職階

  • 大学院情報学研究科 基幹情報学専攻 

    教授  2022年04月 - 継続中

  • 工学部 情報工学科 

    教授  2022年04月 - 継続中

取得学位

  • 博士(工学) ( 京都大学 )

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 通信工学

研究キーワード

  • ディジタル通信,信号処理,データ解析,機械学習

論文

  • Feature Comparison of Different Operator Data of a Hydraulic Excavator using LSTM 査読

    Shota Oguma, Yasuhiro Makino, Shuichi Ohno, Kazuhiro Iwasaki

    ICIAE2022 The 10th IIAE International Conference on Industrial Application Engineering 2022   2022年03月

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    掲載種別:研究論文(国際会議プロシーディングス)   共著区分:共著  

  • Recognition of Multiple Rectangular Labels for Construction Machines 査読

    Yuki Nakagawa, Shuichi Ohno, Shohei Yamamoto

    CANDAR2021 The Ninth International Symposium on Computing and Networking   2021年11月

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    掲載種別:研究論文(国際会議プロシーディングス)   共著区分:共著  

  • One-bit Error-Feedback Quantizer for Uniform Linear Antenna Array 査読

    Shuichi Ohno,Shenjian Wang

    2021 29th European Signal Processing Conference (EUSIPCO)   2021年08月

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    掲載種別:研究論文(国際会議プロシーディングス)   共著区分:共著  

  • Failure Prediction Based on Operational Data of Hydraulic Excavator with Machine Learning 査読

    Shota Oguma,Shigeru Omatsu,Shuichi Ohno,Kazuhiro Iwasaki,Yoshiaki Shishido

    IEEJ transactions on electrical and electronic engineering   16 ( 10 )   1438 - 1440   2021年07月

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    掲載種別:研究論文(学術雑誌)   共著区分:共著  

  • 建設機械の稼働データを活用した残存耐用時間予測の一提案 査読

    小熊尚太,大松繁,大野修一,岩崎和宏,宍戸義昭

    システム制御情報学会論文誌   34 ( 4 )   107 - 112   2021年04月

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    掲載種別:研究論文(学術雑誌)   共著区分:共著  

  • State space realizations robust to overloading for discrete-time LTI systems 査読

    Ohno Shuichi, Yoshimura Yuichi

    SIGNAL PROCESSING   156   12 - 20   2019年03月( ISSN:0165-1684

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.sigpro.2018.10.017

  • Min-Max Design of Error Feedback Quantizers Without Overloading 査読

    Ohno Shuichi, Ishihara Yuma, Nagahara Masaaki

    Institute of Electrical and Electronics Engineers Inc. IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS   65 ( 4 )   1395 - 1405   2018年04月( ISSN:1549-8328

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    掲載種別:研究論文(学術雑誌)  

    In this paper, we design a no-overloading error feedback quantizer based on a ΔΣ modulator, composed of an error feedback filter and a static quantizer. To guarantee no-overloading in the quantizer, we impose an l∞ norm constraint on the feedback signal in the quantizer. Then, for a prescribed l∞ norm constraint on the error at the system output induced by the quantizer, we design the error feedback filter that requires the minimum number of bits that achieves the constraint. Next, for a fixed number of bits for the quantizer, we investigate the achievable minimum l∞ norm of the error at the system output with the no-overloading quantizer. Numerical examples are provided to validate our analysis and synthesis.

    DOI: 10.1109/TCSI.2017.2758801

  • An iterative LMI algorithm for quantization noise reduction in Delta Sigma modulators 査読

    Tariq M. Rizwan, Ohno Shuichi

    SIGNAL PROCESSING   144   163 - 168   2018年03月( ISSN:0165-1684

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.sigpro.2017.10.018

  • Mean Squared Error Analysis of Quantizers With Error Feedback 査読

    Ohno Shuichi, Shiraki Teruyuki, Tariq M. Rizwan, Nagahara Masaaki

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING   65 ( 22 )   5970 - 5981   2017年11月( ISSN:1053-587X

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    掲載種別:研究論文(学術雑誌)  

    Quantization is a fundamental process in digital signal processing, Delta Sigma Smodulators are often utilized for quantization, which can be easily implemented with static uniform quantizers and error feedback filters. In this paper, we analyze the mean squared quantization error of the quantizer with error feedback including the Delta Sigma modulators. First, we study the quantizer with an ideal optimal error feedback filter that minimizes the mean squared error (MSE) of quantization. We show that the amplitude response of the optimal error feedback filter can be parameterized by one parameter. This parameterization enables us to find the optimal error feedback filter numerically. Second, the relationship between the number of bits used for the quantizer and the achievable MSE is clarified by using the optimal error feedback filter. This makes it possible to investigate the efficiency of the quantizer with the optimal error feedback filter in terms ofMSE. Then, ideal optimal error feedback filters are approximated by practically implementable filters using the Yule-Walker method and the linear matrix inequality-basedmethod. Numerical examples are provided for demonstrating our analysis and synthesis.

    DOI: 10.1109/TSP.2017.2745450

  • Optimization of Noise Shaping Filter for Quantizer With Error Feedback 査読

    Ohno Shuichi, Tariq M. Rizwan

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS   64 ( 4 )   918 - 930   2017年04月( ISSN:1549-8328

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    掲載種別:研究論文(学術雑誌)  

    Noise shaping filters for quantizers with error feedback are designed to mitigate the effects of quantization errors. In this paper, we prove that if the transfer function from the quantization error to the signal-of-interest has minimum phase and there is no constraint on the feedback signal, then the scaled inverse of the transfer function is the optimal noise shaping filter. Next, we design a noise shaping filter to minimize the variance or the l(2) norm of the error in the signal-ofinterest under a constraint on the variance or the l(2) norm of the feedback signal, which can be expressed as bilinear matrix inequalities (BMIs). Although the BMIs are not convex, we prove that the minimization of the error variance under the constraint on the variance of the feedback signal can be cast into a convex optimization problem. This enables us to design optimal noise shaping filters using numerical methods. We formulate our design problem as a convex optimization problem using extended linear matrix inequalities to obtain noise shaping filters, except for the special case. Examples are provided to demonstrate the effectiveness of the designed noise shaping filters.

    DOI: 10.1109/TCSI.2016.2627031

  • Unified LMI-based design of Delta Sigma modulators 査読

    Tariq M. Rizwan, Ohno Shuichi

    EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING   2016   29   2016年02月( ISSN:1687-6180

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1186/s13634-016-0326-2

  • Tomlinson-Harashima Precoding with Substream Permutations Based on the Bit Rate Maximization for Single-User MIMO Systems 査読

    Kinjo Shigenori, Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E98A ( 5 )   1095 - 1104   2015年05月( ISSN:1745-1337

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    掲載種別:研究論文(学術雑誌)  

    In this paper, we propose a zero-forcing (ZF) Tomlinson-Harashima precoding (THP) with substream permutations based on the bit rate maximization for single-user MIMO (SU-MIMO) systems. We study the effect of substream permutations on the ZF-THP SU-MIMO systems, when the mean squared error (MSE) and the bit rate are adopted for the selection of the permutation matrix as criteria. Based on our analysis, we propose a method to increase the bit rate by substream permutations, and derive QR and Cholesky decomposition-based algorithms which realize the proposed method. Furthermore, to improve the error rate performance, we apply zero transmission to subchannels with low signal-to-noise ratios. Numerical examples are provided to demonstrate the effectiveness of the proposed THP MIMO system.

    DOI: 10.1587/transfun.E98.A.1095

    その他URL: http://dblp.uni-trier.de/db/journals/ieicet/ieicet98a.html#journals/ieicet/KinjoO15

  • Improved Data Embedding Method for Digital Image with Human Visual Systems 査読

    Fujii Atsuhiro, Nakamoto Masayoshi, Muneyasu Mitsuji, Ohno Shuichi

    WILEY-BLACKWELL ELECTRONICS AND COMMUNICATIONS IN JAPAN   97 ( 11 )   19 - 27   2014年11月( ISSN:1942-9533

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    掲載種別:研究論文(学術雑誌)  

    In this paper, we consider a data-embedding method in the discrete wavelet transform (DWT) domain of digital images. A bit pattern embedding method with the human visual system (HVS) and correlation-based detection have been proposed by Kino and Wada based on the watermarking scheme, which is referred to as the conventional method. In the conventional method, the capacity of embedding data depends on the potential correlation between the DWT coefficients of the host image and the watermark signal. We propose a new embedding and detection algorithm not affected by the potential correlation in order to increase the capacity of embedding data. The data-embedding and detection in the proposed method are performed by considering the absolute value of the correlation between the watermarked DWT coefficients and the watermark signal. In simulations, we show that the capacity of the embedding data in the proposed method is increased compared with the conventional method at the same PSNR value (image quality).

    DOI: 10.1002/ecj.11597

  • Design of Multi-Band Digital Filters and Full-Band Digital Differentiators Without Frequency Sampling and Iterative Optimization 査読

    Nakamoto Masayoshi, Ohno Shuichi

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS   61 ( 9 )   4857 - 4866   2014年09月( ISSN:0278-0046

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    掲載種別:研究論文(学術雑誌)  

    Most design problems of digital filters (or differentiators) are formulated with a set of grid point in the frequency region (frequency sampling). These problems are usually difficult to solve, and often require iterative optimization. The objective of this paper is to provide an efficient and simplified design approach to multi-band filters (including low-pass filters or high-pass filters) as well as full-band differentiators. The proposed method does not require frequency sampling and iterative optimization to compute the coefficients of the filters or that of the differentiators. The magnitude and phase specifications are simultaneously approximated, and the errors in the specified frequency bands are controlled by using frequency-weighting factors. In addition, a maximum pole radius, which corresponds to a stability margin, can be specified to robustly ensure the stability of the filters or the differentiators. To evaluate the efficiency of proposed method, we compare the proposed method with several established methods. Simulation results show that, although the propose method does not utilize frequency sampling and iterative optimization, the designed filters and differentiators have sufficient performance.

    DOI: 10.1109/TIE.2013.2290765

  • Pilot symbol assisted channel estimation for OFDM-based cognitive radio systems 査読

    Manasseh Emmanuel, Ohno Shuichi, Nakamoto Masayoshi

    SPRINGER INTERNATIONAL PUBLISHING AG EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING   2013   51   2013年03月( ISSN:1687-6180

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    掲載種別:研究論文(学術雑誌)  

    In this article, challenges regarding the provision of channel state information (CSI) in non-contiguous orthogonal frequency division multiplexing (NC-OFDM) cognitive radio (CR) systems are addressed. We propose a novel scheme that utilizes cross entropy (CE) optimization together with an analytical pilot power distribution technique to design pilot symbols that minimizes the channel estimate mean squared error (MSE) of frequency-selective channels. The optimal selection of pilot subcarriers is a combinatorial problem that requires heavy computations. To reduce the computational complexity, the CE optimization is utilized to determine the position of pilot subcarriers. Then, for a given pilot placement obtained by the CE algorithm, a closed form expression to obtain optimal pilot power distribution is employed. Simulation results indicate that, the proposed pilot symbol design provides better channel estimate MSE as well as the bit error rate (BER) performance when compared with the conventional equal powered pilot design.

    DOI: 10.1186/1687-6180-2013-51

  • Noise Reduction in Two-Dimensional Recursive Digital Filters with Discrete Optimized Error Feedback Coefficients 査読

    Nakamoto Masayoshi, Hinamoto Takao, Ohno Shuichi

    BIRKHAUSER BOSTON INC CIRCUITS SYSTEMS AND SIGNAL PROCESSING   31 ( 4 )   1359 - 1378   2012年08月( ISSN:0278-081X

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    掲載種別:研究論文(学術雑誌)  

    This paper treats the minimization problem for roundoff noise in two-dimensional (2-D) recursive digital filters with an error feedback (EF). The EF is known as an available scheme for the reduction of roundoff noise, and this can be achieved by extracting a roundoff error from the quantizer and feeding it back to the adder. Since the EF circuit is an additional device of the digital filter, the bit length of the coefficients should be as short as possible for the fast arithmetic and low-cost realization. In this paper, we propose an algorithm to optimize the EF coefficients in a discrete space. The proposed algorithm is based on the branch and bound method by estimating the lower bound of the optimal solution, and the optimality of the obtained solution can be guaranteed. Finally, we give a numerical example to demonstrate the effectiveness of the proposed method, and show the optimal solution can be found without using the round-robin algorithm.

    DOI: 10.1007/s00034-011-9376-8

  • BLIND DETECTION OF PSK SIGNALS 査読

    Jin Yong, Ohno Shuichi, Nakamoto Masayoshi

    INTERNATIONAL JOURNAL OF INNOVATIVE COMPUTING INFORMATION AND CONTROL   8 ( 3B )   2329 - 2337   2012年03月( ISSN:1349-4198

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    掲載種別:研究論文(学術雑誌)  

  • Combined channel estimation and PAPR reduction technique for MIMO-OFDM systems with null subcarriers 査読

    Manasseh Emmanuel, Ohno Shuichi, Nakamoto Masayoshi

    SPRINGER INTERNATIONAL PUBLISHING AG EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING   2012   201   2012年( ISSN:1687-1472

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    掲載種別:研究論文(学術雑誌)  

    In this article, we address the challenges regarding the provision of channel state information as well as reducing peak-to-average power ratio (PAPR) of a multiple input multiple output orthogonal frequency multiplexing (MIMO-OFDM) system. The mean squared error (MSE) of the channel estimate is adopted as the optimization criterion to design pilot symbols for channel estimation in MIMO-OFDM systems with null subcarriers. We design the placement and power distribution to the pilot symbols for multiple transmit antennas to minimize the MSE of the least square (LS) channel estimates. To reduce interference of the pilot symbols transmitted from different antennas, an algorithm to guarantee that pilot symbols are disjoint from any other transmitter pilot set is proposed. To efficiently reduce the PAPR of the MIMO-OFDM signals, a method that mixes dummy symbols and phase information of the pilot symbols is presented. Simulation results based on IEEE 802.16e are presented to illustrate the superior performance of our proposed channel estimation method over the existing standard and the partially equi-spaced pilot symbols. We also demonstrate that, by mixing the dummy symbols and phase information of the pilot symbols, the PAPR of the MIMO-OFDM signals can significantly be reduced.

    DOI: 10.1186/1687-1499-2012-201

  • Preamble Based Channel and CFO Estimation for MIMO-OFDM Systems with Null Subcarriers 査読

    Manasseh Emmanuel, Ohno Shuichi, Nakamoto Masayoshi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E94A ( 11 )   2271 - 2278   2011年11月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    In this paper, challenges regarding the provision of channel state information (CSI) and carrier frequency synchronization for orthogonal frequency division multiplexing (OFDM) systems with null subcarriers are addressed. We propose novel maximum likelihood (ML) based schemes that estimate the aggregate effects of the CFO and channel by using two successive OFDM preambles. In the presented scheme, CFO is estimated by considering the phase rotation between two consecutive received OFDM preambles. Both single input single output (SISO) as well as multiple input multiple output (MIMO) OFDM systems are considered. The mean squared errors (MSE) of the channel and CFO are used to evaluate the performance of our proposed scheme. By using two successive OFDM preambles, the estimation of channel and the estimation of CFO are decoupled, which leads to a simple estimation method. Simulation results show that the BER performance of the proposed estimators is comparable to that of known channel state information and the CFO MSE performance achieves the Cramer-Rao bound (CRB) of the fully loaded OFDM system.

    DOI: 10.1587/transfun.E94.A.2271

    その他URL: http://dblp.uni-trier.de/db/journals/ieicet/ieicet94a.html#journals/ieicet/ManassehON11

  • Improvement of Detection Performance in DWT-Based Image Watermarking under Specified False Positive Probability 査読

    Nakamoto Masayoshi, Sayama Kohei, Muneyasu Mitsuji, Harano Tomotaka, Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E94A ( 2 )   661 - 670   2011年02月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    For copyright protection, a watermark signal is embedded in host images with a secret key, and a correlation is applied to judge the presence of watermark signal in the watermark detection. This paper treats a discrete wavelet transform (DWT)-based image watermarking method under specified false positive probability. We propose a new watermarking method to improve the detection performance by using not only positive correlation but also negative correlation. Also we present a statistical analysis for the detection performance with taking into account the false positive probability and prove the effectiveness of the proposed method. By using some experimental results, we verify the statistical analysis and show this method serves to improve the robustness against some attacks.

    DOI: 10.1587/transfun.E94.A.661

    その他URL: http://dblp.uni-trier.de/db/journals/ieicet/ieicet94a.html#journals/ieicet/NakamotoSMHO11

  • DESIGN OF LOW PAPR PREAMBLE AND PILOT SYMBOL FOR CHANNEL ESTIMATION IN OFDM SYSTEMS 査読

    Manasseh Emmanuel, Ohno Shuichi, Nakamoto Masayoshi

    INTERNATIONAL JOURNAL OF INNOVATIVE COMPUTING INFORMATION AND CONTROL   7 ( 1 )   39 - 50   2011年01月( ISSN:1349-4198

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    掲載種別:研究論文(学術雑誌)  

  • Performance of Alamouti's OSTBC with Channel Estimation 査読

    Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E92A ( 11 )   2844 - 2850   2009年11月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)   共著区分:単著  

    Alamouti's orthogonal space-time block code (OSTBC) is a simple yet important technique to take advantage of transmit diversity to mitigate fading channel effects. In this paper, we analyze the effects of time-selective channels and channel estimation errors on the bit error rate (BER) performance of Alamouti's OSTBC. We develop an analytical expression of the BER performance for the linear decoding with minimum mean squared error (MMSE) channel estimates in place of the true channel. Based on the expression. we derive a BER performance limit in decision-directed mode where the channel is tracked with Kalman filtering Numerical examples are provided to validate our analysis and to see the impact of time-selective fading and channel estimation errors on the BER performance.

    DOI: 10.1587/transfun.E92.A.2844

    その他URL: http://dblp.uni-trier.de/db/journals/ieicet/ieicet92a.html#journals/ieicet/Ohno09

  • Viterbi-Type Inter-Carrier Interference Equalization for OFDM over Doubly Selective Channels 査読

    Ohno Shuichi, Teo Kok Ann Donny

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E92A ( 8 )   1905 - 1912   2009年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    Orthogonal Frequency Division Multiplexing (OFDM) transmission is robust to frequency-selective channels but sensitive to time-selective channels. Time variations of channels generate inter-carrier interference (ICI), which degrades system performance. In this paper, we develop frequency-domain Viterbi-type algorithm to effectively suppress the ICI, by exploiting the property of ICI terms in OFDM symbols. Null subcarriers, which are embedded in OFDM symbols for the reduction of interferences from/to adjacent bands. are exploited to reduce the complexity of the algorithm. Then, an approximate BER expression of Viterbi-type equalizer is derived. Simulations are provided to show the Viterbi-type equalizer works well in time- and frequency-selective (doubly selective) channel with affordable complexity.

    DOI: 10.1587/transfun.E92.A.1905

    その他URL: http://dblp.uni-trier.de/db/journals/ieicet/ieicet92a.html#journals/ieicet/OhnoT09

  • Performance tradeoff in multiuser equalization for CDMA over flat channels 査読

    Teo Kok Ann Donny, Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E91A ( 8 )   2008 - 2015   2008年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    We study the bit-error rate (BER) for different code lengths and number of users in CDMA system with linear minimum mean squared error (MMSE) and non-linear equalizations. We first show that for a fix channel and a fix number of users, BER of each symbol after linear equalization degrades with a decrease in the code length. Then, we prove that for a fix code length, the BER averaged over random channels improves with a decrease in the number of users. Furthermore, in the non-linear serial-interference cancellation (SIC) scheme, we prove analytically that the BER improves with each step of symbol cancellation for any channel not just at high signal-to-interference noise ratio (SINR) but at all range of SINR. Simulation results are presented to substantiate our theoretical findings.

    DOI: 10.1093/ietfec/e91-a.8.2008

  • Finite parameter model for doubly-selective channel estimation in OFDM 査読

    Teo Kok Ann Donny, Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E90A ( 11 )   2395 - 2403   2007年11月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    To describe joint time- and frequency-selective (doublyselective) channels in mobile broadband wireless communications, we propose to use the finite parameter model based on the same Bessel functions for each tap (Bessel model). An expression of channel estimation mean squared error (MSE) based on the finite parameter models in Orthogonal Frequency Division Multiplexing (OFDM) systems is derived. Then, our Bessel model is compared with commonly used finite parameter models in terms of the channel estimation MSE. Even if the channel taps have different channel correlations and some of the taps do not coincide with the Bessel function, the channel estimation MSE of the Bessel model is shown to be comparable or outperform existing models as validated by Monte-Carlo simulations over an ensemble of channels in typical urban and suburban environments.

    DOI: 10.1093/ietfec/e90-a.11.2395

  • Universal BER performance ordering of MIMO systems over flat channels 査読

    Ohno Shuichi, Teo Kok Ann Donny

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS   6 ( 10 )   3678 - 3687   2007年10月( ISSN:1536-1276

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    掲載種別:研究論文(学術雑誌)  

    We present universal BER performance ordering for different antenna sizes in Multiple-Input Multiple-Output (MIMO) wireless systems with zero-forcing (ZF) equalization, which hold for all SNR. We first show that when the number of transmit antennas is fixed, BER of each symbol degrades with a decrease in the number of receive antennas even if the received SNR is kept constant. Then, we prove that when the number of receive antennas is fixed, the average BER improves with a decrease in the number of transmit antennas, which shows the tradeoff between BER and bandwidth efficiency in MIMO with ZF equalization. Furthermore, discussions on the relation of BER with the same change in the number of receive and transmit antennas show that there is no universal order in BER for any particular channel. These highlight the advantage and the limit of MIMO with ZF equalization.

    DOI: 10.1109/TWC.2007.060064

  • Simple but efficient antenna selection for MISO-OFDM systems 査読

    Ohno Shuichi, Yamaguchi Kenichi, Teo Kok Ann Donny

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E90A ( 8 )   1594 - 1600   2007年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    Simple but efficient antenna selection schemes are proposed for the downlink of Orthogonal Frequency Division Multiplexing (OFDM) transmission with multiple transmit antennas over frequency selective fading channels, where transmit antennas are selected at the mobile terminal and the base station is informed of the selected antennas through feedback channel. To obtain the optimal antenna selection, channel frequency responses are required and performances have to be evaluated at all the subcarriers. To reduce the computational complexity at mobile terminal, time-domain channels are utilized for antenna selection in place of channel frequency responses. Our scheme does not guarantee the optimal antenna selection but is shown by numerical simulations to yield reasonable selections. Moreover, by using a specially designed pilot OFDM preamble, an antenna selection without channel estimation is developed. Efficiencies of our suboptimal antenna selections with less computational complexities are verified by numerical simulations.

    DOI: 10.1093/ietfec/e90-a.8.1594

  • Adaptive subcarrier allocation for multi-user OFDM system 査読

    Teo Kok Ann Donny, Otani Yoshiyuki, Ohno Shuichi

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E89A ( 11 )   3131 - 3137   2006年11月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    Orthogonal Frequency Division Multiple Access (OFDMA) allows multiple users to make use of the same bandwidth as the sin-le-user OFDM for data transmission and is a promising candidate to be used for future cellular systems. A key issue at hand is the rate-adaptive resource allocation problem. In this paper, we propose two basic subcarrier allocation schemes with low complexities based on the magnitude of the channel frequency responses. The proposed algorithms ensure a fair resource allocation in terms of the number of subcarriers with affordable bit-rates. Through extensive discussions and Monte Carlo simulations, a comprehensive comparison with previously derived subcarrier allocation schemes is performed which depicts the pros and cons of our proposed algorithms.

    DOI: 10.1093/ietfec/e89-a.11.3131

  • Performance of single-carrier block transmissions over multipath fading channels with linear equalization 査読

    Ohno Shuichi

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING   54 ( 10 )   3678 - 3687   2006年10月( ISSN:1053-587X

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    掲載種別:研究論文(学術雑誌)   共著区分:単著  

    We study uncoded bit-error-rate (BER) performances of single-carrier block transmissions, zero-padded (ZP), and cyclic-prefixed (CP) transmission, when linear equalizers are applied and the BERs are averaged over one block. We show analytically that the BER of ZP transmission with linear equalization degrades as the bandwidth efficiency increases, i.e., there is a tradeoff between BER and bandwidth efficiency in ZP transmission. It is also proven that when minimum mean-squared-error (MMSE) equalization is adopted, ZP transmission outperforms CP transmission and uncoded orthogonal frequency-division multiplexing (OFDM) on the average over random channels. However, the difference between the ZP and the CP transmission becomes smaller as the block size gets larger, since the average BER performance of the ZP transmission degrades, while the average BER performance of CP transmission improves, as a function of the block size. Numerical examples are provided to validate our theoretical findings and to compare the block transmission systems.

    DOI: 10.1109/TSP.2006.879321

  • Optimal synthesis of a class of 2-D digital filters with minimum L-2-sensitivity and no overflow oscillations 査読

    Hinamoto Takao, Iwata Ken-Ichi, Omoifo Osemekhian I., Ohno Shuichi, Lu Wu-Sheng

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E89A ( 7 )   1987 - 1994   2006年07月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    The minimization problem of an L-2-sensitivity measure subject to L-2-norm dynamic-range scaling constraints is formulated for a class of two-dimensional (2-D) state-space digital filters. First. the problem is converted into an unconstrained optimization problem by using linear-algebraic techniques. Next, the unconstrained optimization problem is solved by applying an efficient quasi-Newton algorithm with closed-form formula for gradient evaluation. The coordinate transformation matrix obtained is then used to synthesize the optimal 2-D state-space filter structure that minimizes the L-2-sensitivity measure subject to L-2-norm dynamic-range scaling constraints. Finally, a numerical example is presented to illustrate the utility of the proposed technique.

    DOI: 10.1093/ietfec/e89-a.7.1987

  • Multicarrier multiple access is sum-rate optimal for block transmissions over circulant ISI channels 査読

    Ohno Shuichi, Giannakis Georgios B., Luo Zhi-Quan

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS   24 ( 6 )   1256 - 1260   2006年06月( ISSN:0733-8716

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    掲載種別:研究論文(学術雑誌)  

    Multicarrier multiple access with channel knowledge and prescribed power at the transmitters is shown to maximize the sum-rate for circulant intersymbol-interference (ISI) channels. A low-complexity iterative algorithm is derived for optimal subcarrier allocation to multiple users, while power is loaded per user by specializing an existing iterative algorithm to circulant ISI channels. It is analytically shown that each subcarrier should be allocated to the user having relatively better subcarrier gain and that different users may share certain subcarriers.

    DOI: 10.1109/JSAC.2005.864006

  • Bit-rate maximization for multiuser OFDM systems 査読

    Tase H, Ohno S, Hinamoto T

    SCRIPTA TECHNICA-JOHN WILEY & SONS ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE   89 ( 1 )   1 - 9   2006年( ISSN:1042-0967

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    掲載種別:研究論文(学術雑誌)  

    In the downlink of multiuser OFDM (Orthogonal Frequency Division Multiplexing) systems, subcarriers of one OFDM symbol can be allocated to multiple users to enable multiplexing. System performance can be enhanced by appropriate subcarrier allocation and bit-loading. In this paper, while guaranteeing a fixed BER performance, we impose a fixed transmitted power constraint on each user to achieve a fair resource allocation. Based on this condition, we propose an algorithm to maximize the sum-rate of the system. This sum-rate optimization is a discrete optimization problem which is hard to solve by conventional methods. We relax the problem into a continuous convex optimization problem so that the subcarrier allocation to each user can be determined numerically. Using the subcarrier allocation for the continuous problem, bits are then loaded to each user. The effectiveness of the proposed method is substantiated by numerical simulations. (c) 2005 Wiley Periodicals, Inc.

    DOI: 10.1002/ecjc.20198

  • Recursive channel estimation based on finite parameter model using reduced-complexity maximum likelihood equalizer for OFDM over doubly-selective channels 査読

    Teo KAD, Ohno S, Hinamoto T

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E88A ( 11 )   3076 - 3084   2005年11月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    To take intercarrier interference (ICI) attributed to time variations of the channel into consideration, the time- and frequency-selective (doubly-selective) channel is parameterized by a finite parameter model. By capitalizing on the finite parameter model to approximate the doubly-selective channel, a Kalman filter is developed for channel estimation. The ICI suppressing, reduced-complexity Viterbi-type Maximum Likelihood (RML) equalizer is incorporated into the Kalman filter for recursive channel tracking and equalization to improve the system performance. An enhancement in the channel tracking ability is validated by theoretical analysis, and a significant improvement in BER performance using the channel estimates obtained by the recursive channel estimation method is verified by Monte-Carlo simulations.

    DOI: 10.1093/ietfec/e88-a.11.3076

  • Pilot tone design with low peak-to-average power ratio in OFDM 査読

    Hosokawa S, Teo KAD, Ohno S, Hinamoto T

    IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E88A ( 8 )   2117 - 2123   2005年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

    In Orthogonal Frequency Division Multiplexing (OFDM), the composite time signal exhibits a high peak-to-average power ratio (PAPR). Due to non-linearities of the transmit power amplifiers, this high PAPR generates in-band distortion, out of band noise (OBN) or spectral spreading, which degrades the bit-error rate (BER) performance. In this paper, we propose a simple way to combat this problem without sacrificing channel estimation and frequency-offset tracking accuracy, by designing a sub-optimal configuration of the pilot tones. The effectiveness of the newly designed pilot tones in reducing PAPR is validated by Monte-Carlo simulations. The corresponding improvement in BER is also verified by simulations under IEEE 802.11 a standard settings, by using the channel with perfect CSI and the designed pilot-aided estimated channel for coherent detection.

    DOI: 10.1093/ietfec/e88-a.8.2117

  • Capacity maximizing MMSE-optimal pilots for wireless OFDM over frequency-selective block Rayleigh-fading channels 査読

    Ohno S, Giannakis GB

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON INFORMATION THEORY   50 ( 9 )   2138 - 2145   2004年09月( ISSN:0018-9448

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    掲載種別:研究論文(学術雑誌)  

    The location, number, and power of pilot symbols embedded in multicarrier block transmissions over rapidly fading channels, are important design parameters affecting not only channel estimation performance, but also channel capacity. Considering orthogonal frequency-division multiplexing (OFDM) systems with decoupled information-bearing symbols from pilot symbols transmitted over wireless frequency-selective Rayleigh-fading channels, we show that equispaced and equipowered pilot symbols are optimal in terms of minimizing the mean-square channel estimation error. We also design the number of pilots, and the power distributed between information bearing and pilot symbols, using as criterion a lower bound on the average capacity. Numerical results corroborate our theoretical findings.

    DOI: 10.1109/TIT.2004.833365

  • Optimal training for block transmissions over doubly selective wireless fading channels 査読

    Ma XL, Giannakis BB, Ohno S

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING   51 ( 5 )   1351 - 1366   2003年05月( ISSN:1053-587X

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    掲載種別:研究論文(学術雑誌)  

    High data rates give rise to frequency-selective propagation, whereas carrier frequency-offsets and mobility-induced Doppler shifts introduce time-selectivity in wireless links. To mitigate the resulting time- and frequency-selective (or doubly selective) channels, optimal training sequences have been designed only for special cases: pilot symbol assisted modulation (PSAM) for time-selective channels and pilot tone-assisted orthogonal frequency division multiplexing (OFDM) for frequency-selective channels. Relying on a basis expansion channel model, in this paper, we design low-complexity optimal PSAM for block transmissions over doubly selective channels. The optimality in designing our PSAM parameters consists of maximizing a tight lower bound on the average channel capacity that is shown to be equivalent to the minimization of the minimum mean-square channel estimation error. Numerical results corroborate our theoretical designs.

    DOI: 10.1109/TSP.2003.810304

    CiNii Article

  • Equivalence of a cumulant maximization criterion for blind deconvolution and a cumulant matching criterion for blind identification 査読

    Ohno S, Inouye Y

    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E86A ( 3 )   605 - 610   2003年03月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

  • Optimal training and redundant precoding for block transmissions with application to wireless OFDM 査読

    Ohno S, Giannakis GB

    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON COMMUNICATIONS   50 ( 12 )   2113 - 2123   2002年12月( ISSN:0090-6778

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    掲載種別:研究論文(学術雑誌)  

    The adoption of orthogonal frequency-division multiplexing by wireless local area networks and audio/video broad. casting standards testifies to the importance of recovering block precoded transmissions propagating through frequency-selective finite-impulse response (FIR) channels. Existing block transmission standards invoke bandwidth-consuming error control codes to mitigate channel fades, and training sequences to identify the FIR channels. To enable block-by-block receiver processing, we design redundant precoders with cyclic prefix and superimposed training sequences for optimal channel estimation and guaranteed symbol detectability, regardless of the underlying frequency-selective FIR channels. Numerical results are presented to access the performance of the designed training and precoding schemes.

    DOI: 10.1109/TCOMM.2002.806547

    CiNii Article

  • Average-rate optimal PSAM transmissions over time-selective fading channels 査読

    Ohno S, Giannakis GB

    IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS   1 ( 4 )   712 - 720   2002年10月( ISSN:1536-1276

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1109/TWC.2002.804183

  • Convergence behavior of the LMS algorithm in subband adaptive filtering 査読

    Ohno S, Sakai H

    SIGNAL PROCESSING   81 ( 5 )   1053 - 1059   2001年05月( ISSN:0165-1684

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    掲載種別:研究論文(学術雑誌)  

  • Studies on the convergence speed of over-sampled subband adaptive digital filters 査読

    Ohno S, Sakai H

    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E83A ( 8 )   1531 - 1538   2000年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

  • Spectral analysis of subband adaptive digital filters 査読

    Ohno S, Sakai H

    IEEE TRANSACTIONS ON SIGNAL PROCESSING   48 ( 1 )   254 - 257   2000年01月( ISSN:1053-587X

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    掲載種別:研究論文(学術雑誌)  

  • On delayless subband adaptive filtering by subband/fullband transforms 査読

    Ohno S, Sakai H

    IEEE SIGNAL PROCESSING LETTERS   6 ( 9 )   236 - 239   1999年09月( ISSN:1070-9908

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    掲載種別:研究論文(学術雑誌)  

  • Blind identification of multichannel systems by exploiting prior knowledge of the channel 査読

    Ohno S, Sakai H

    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES   E82A ( 8 )   1552 - 1557   1999年08月( ISSN:0916-8508

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    掲載種別:研究論文(学術雑誌)  

  • Optimization of filter banks using cyclostationary spectral analysis 査読

    Ohno S, Sakai H

    IEEE TRANSACTIONS ON SIGNAL PROCESSING   44 ( 11 )   2718 - 2725   1996年11月( ISSN:1053-587X

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    掲載種別:研究論文(学術雑誌)  

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