研究者詳細 - 侯　亜飛

論文 - 侯　亜飛

分割表示 163 件中 141 - 160 件目／全件表示 >>

A Simple Method of Transmitting Stream Adaptation for Fixed-Matrix-Size Precoding on MU-MIMO Transmission 査読

Yafei Hou, Satoshi Sonobe, Kazuto Yano, Masahiro Uno, Kiyoshi Kobayashi

2012 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC) 136 - 141 2012年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

During the operation of multiuser multiple-input-multiple output (MU-MIMO) algorithms, some antennas of BS or UEs may neither transmit nor receive signals due to the long distance or unexpected damages. Therefore, the BS cannot obtain the channel state information (CSI) from/to these antennas. Without these CSI, the performance of algorithm is degraded. We call this effect as 'broken antenna effect (BAE).' To cope with this issue, this paper proposes a process to regularize the channel matrix by replacing the missing CSI with zero(s) and setting non-zero values to diagonal elements. Then, it is confirmed through computer simulation that the proposed method can adjust the number of transmitting parallel streams according to the number of 'broken' antennas, and provide MU-MIMO transmission with maximum diversity order without any change of the precoding process.

DOI： 10.1109/WCNC.2012.6213993

Channel Estimation Improvement with Frequency Domain MMSE Equalization for PCP-SC System 査読

Yafei Hou, Tomohiro Hase

IEICE TRANSACTIONS ON COMMUNICATIONS E94B ( 6 ) 1690 - 1698 2011年6月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we propose a simple but effective way of improving the performance of channel estimation (CE) for pilot cyclic prefixed single carrier (PCP-SC) system. The proposed method utilizes the property that the shifting signal of the PCP pilot signal can also be utilized to estimate the channel information. The receiver can continuously estimate the channel information by just shifting the received pilot signal. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the proposed method can achieve about a 1.72 dB performance gain in terms of the mean squared error (MSE) of channel estimation with a slight increase in computational complexity. The BER performance with the proposed CE improvement are evaluated in a multipath fading channel using a zero-forcing (ZF) equalizer and an minmum mean squared error (MMSE) equalizer by computer simulation. It is shown that the proposed CE improvment method using an MMSE equalizer which has an unbiased vlaue of noise variance (NV) estimator gives a promising BER performance. The proposed method also benefits the estimation of the SNR for the single carrier system.

DOI： 10.1587/transcom.E94.B.1690

Channel Estimation Improvement for MIMO Single-Carrier Block Transmission System 査読

Yafei Hou, Tomohiro Hase

2011 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) 2011年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

In this paper, we propose an effective way of improving the performance of channel estimation for MIMO single-carrier block transmission (SCBT) systems. The proposed method utilizes the property that the shift of the cyclic pilot signal of each antenna branch can also be utilized to catch the channel information as a new pilot for MIMO SCBT systems. The receiver can continuously estimate the channel information by just shifting the received pilot signal. The channel estimation performance is improved by averaging all channel estimators since this averaging process can reduce the power of noise component. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the proposed method can achieve about a 1.72 dB performance gain in term of the mean squared error (MSE) of channel estimation for each antenna branch with slightly computational complexity. The proposed method can be also utilized to most channel estimation methods for the MIMO SCBT system.

Channel and Noise Variance Estimation Improvement for PCP-SC System 査読

Yafei Hou, Tomohiro Hase

2010 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC 2010) 2010年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

In this paper, we propose a simple but effective way of improving the performance of channel estimation and catching the noise variance for pilot cyclic prefixed single carrier (PCP-SC) system. The proposed method utilizes the property that the shift of the PCP pilot signal can also be utilized to catch the channel information as a new pilot. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the proposed method can achieve about a 1.72 dB performance gain for the mean squared error (MSE) of channel estimation with slightly additional computational complexity. In addition, regardless of the pilot type, the receiver can generate a new random signal from the pilot signal. The new signal has an identical variance value to that of the mixed AWGN noise. The proposed estimation method for noise variance is independent of channel estimation errors. Therefore it simplifies the receiver design and improves the system performance.

Flexible Parallel Combinatory OFDM System 査読

Yafei Hou, Tomohiro Hase

2ND IEEE INTERNATIONAL CONFERENCE ON ADVANCED COMPUTER CONTROL (ICACC 2010), VOL. 1 436 - 441 2010年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

In this paper, combining the parallel combinatory (PC) code and the a flexible OFDM structure [7], we report the design of a new OFDM system with PC code for various applications with a moderate transmission rate. The system can select appropriate phase sets for all modulated subcarriers for each PC code for different design requirements such as peak-to-average power ratio (PAPR) reduction or HER performance improvement. The proposed system will achieve better PAPR characteristics and promising HER performance. In addition, due to the flexible OFDM structure, the proposed PC-OFDM system will also have properties of high adaptability and compatibility.

New OFDM Structure with Parallel Combinatory Code 査読

Yafei Hou, Tomohiro Hase

IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 55 ( 4 ) 1854 - 1859 2009年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We have introduced a flexible OFDM structure based on a promising property of IFFT operation [7]. This structure can support uplink applications which include many transmitters using different numbers of subcarriers and one receiver with just one IFFT/FFT module with the subcarriers of the least common multiple (LCM) for the number of subcarriers of all the transmitters. In this paper, combining the Parallel combinatory (PC) code and the proposed flexible OFDM structure, we report the design of a new OFDM system with PC code for various applications with a moderate transmission rate. The system can select appropriate Phase sets for all modulated subcarriers for each PC code for different design requirements such ay peak-to-average power ratio (PAPR) reduction or BER performance improvement. The proposed system will achieve better PAPR characteristics and promising BER performance. In addition, due to the flexible OFDM structure, the proposed PC-OFDM system will also have properties of high adaptability and compatibility(1).

DOI： 10.1109/TCE.2009.5373742

Improvement on the Channel Estimation of Pilot Cyclic Prefixed Single Carrier (PCP-SC) System 査読

Yafei Hou, Tomohiro Hase

IEEE SIGNAL PROCESSING LETTERS 16 ( 8 ) 719 - 722 2009年8月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The pilot cyclic prefixed single carrier (PCP-SC) system has the ability to achieve channel estimation in a fast-fading environment. It also enables symbol recovery even when the frequency domain of the channel has nulls. This letter proposes a simple but effective way of improving the performance of channel estimation. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the receiver can achieve about a 1.72 dB performance gain for the mean squared error (MSE) of channel estimation if it implements the proposed method with slightly additional computational complexity. The proposed method can also be utilized in any type of pilot in PCP-SC and MIMO systems.

DOI： 10.1109/LSP.2009.2023953

New Flexible OFDM Structure for Consumer Electronics Communication Systems 査読

Yafei Hou, Tomohiro Hase

IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 55 ( 1 ) 191 - 198 2009年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper introduces a promising property in which the transmitter of an OFDM system can utilize an N-point IFFT operation to build the time-domain symbols of a KN-point IFFT operation. Based on this property, we propose a flexible OFDM structure. This structure will support uplink applications which include many transmitters using different numbers of subcarriers and one receiver with just one IFFT/FFT module with the subcarriers of least common multiple (LCM) for the number of subcarriers of all the transmitters. Therefore it reduces the design complexities of the receiver and increases the compatible characteristics for consumer electronics (CE). Compared with the original OFDM system, the proposed system improves the performance of the packet error ratio (PER) and the bit error ratio (BER) performance by using the appropriate K. In addition, the proposed structure can be designed to enlarge the bandwidth efficiency of the system and improve the performance of channel estimation compared with the OFDM/TDM system.(1)

DOI： 10.1109/TCE.2009.4814434

Parallel Combinatory OFDM/TDM System 査読

Yafei Hou, Tomohiro Hase

ISCE: 2009 IEEE 13TH INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 165 - + 2009年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

Combined with OFDM with time division multiplexing (OFDM/TDM) system and parallel combinatory (PC) code, we propose a new OFDM system which can be utilized to the communication systems of consumer electronics. Compared with the original OFDM system, the proposed system will achieve promising BER performance and better PAPR characteristics.

Improvement on the Channel Estimation of Pilot Cyclic Prefixed Single Carrier (PCP-SC) System 査読

Yafei Hou, Tomohiro Hase

2009 IEEE 70TH VEHICULAR TECHNOLOGY CONFERENCE FALL, VOLS 1-4 708 - + 2009年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper will propose a simple hut effective way to improve the performance of channel estimation of pilot cyclic prefixed single carrier (PCP-SC) system. The proposed method utilizes the property that the shift of pilot cyclic prefixed signal can also be utilized to catch the channel information as a new pilot. The receiver can continuously estimate the channel information by just shifting the received signal. Regardless or signal-to-noise ratio (SNR) and pilot type, the receiver can achieve about 1.72 dB performance gain for MSE of channel estimation if it implements the proposed method with a slight additional computational complexity. The proposed method can also be utilized in any types of pilot in PCP-SC and MIMO system.

New OFDM System without Guard Interval 査読

Yafei Hou, Tomohiro Hase

2009 IEEE INTERNATIONAL CONFERENCE ON CONSUMER ELECTRONICS 159 - 160 2009年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper proposes a new OFDM system without a guard interval (GI) based on the useful characteristics of IFFT operation. The system utilizes the pilot signal to capture the channel information as well as GI does. Therefore, the bandwidth efficiency of the system can be improved. In addition, it achieves promising peak-to-average power ratio (PAPR) characteristics which also decrease the cost of handsets.

OFDM transmitter structure with low PAPR 査読

Yafei Hou, Tomohiro Hase

2008 IEEE INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 590 - + 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper proposes a new OFDM transmitter structure which can be realized by a smaller FFT chip based on the useful characteristics of IFFT operation. The proposed system benefits the design of handsets. In addition, it achieves promising peak-to-average power ratio (PAPR) characteristics which also decreases the cost of handsets.

Collision-captured multicarrier modulation system 査読

Yafei Hou, Tomohiro Hase

2008 IEEE SARNOFF SYMPOSIUM 345 - + 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper proposes a new system called the collision-captured multicarrier modulation system which can realize the capture of a packet collision. Based on the OFDM system using partial symbol transmission, the transmitter can select a specific duration to achieve promising PAPR characteristics and realize the capture of a packet collision. The simulated results show that over 90% collision occurrences and the correct position of the collided part can be captured even in severe near-far situations. The proposed system can also achieve a PAPR reduction with an acceptable BER performance degradation.

Collision-Recovery Method for Collided OFDM Based Packets 査読

Yafei Hou, Tomohiro Hase

2008 IEEE 19TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS 688 - 693 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

We present an effective method of collision recovery for orthogonal frequency division multiplexing (OFDM)-based communications. For the OFDM system, the modulated message data can be demodulated using the partial time-domain OFDM symbol. Therefore, the partial time-domain symbol can be adopted to reconstruct the whole OFDM time-domain symbol with estimated channel information. This property can be utilized to recover packets from the collisions. Since most collisions are cases in which a long packet collides with short packets, the collided part is assumed to be short. The simulated results show that the method can recover all packets with different specific probabilities and can be developed to solve the problem of hidden terminals.

OFDM system for capturing collision 査読

Yafei Hou, Tomohiro Hase

2008 IEEE INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 601 - + 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper proposes a new system called the collision-captured OFDM system which can realize the capture of a packet collision based on the OFDM system using partial symbol transmission. The simulated results show that over 90% of collision occurrences and the correct position of the collided part can be captured even in severe near-far situations.

A new way of PAPR reduction for OFDM system 査読

Yafei Hou, Tomohiro Hase

2008 IEEE INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 586 - + 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

This paper proposes a new peak-to-average power ratio (PAPR) reduction technique for OFDM systems. The proposed system selects the specific duration of each time-domain OFDM symbol which can achieve a promising PAPR, to transmit equal bits of data. Compared with the OFDM system using amplitude clipping, PST can obtain comparable PAPR performance and achieve a 0.5 - 3 dB BER performance gain by choosing the appropriate parameters. In addition, PST does not need any complex modules to fix the original phases of the clipped samples, so it decreases the cost of transmitters.

A novel modulation with parallel combinatory and high compaction multi-carrier modulation 査読

Yafei Hou, Masanori Hamamura

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E90A ( 11 ) 2556 - 2567 2007年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we propose a new modulation named parallel combinatory/high compaction multi-carrier modulation (PC/HC-MCM) using the techniques of parallel combinatory orthogonal frequency division multiplexing (PC-OFDM) and high compaction multi-carrier modulation (HC-MCM). Two types of PC/HC-MCM systems, which are named as modulated PC/HC-MCM system and (unmodulated) PC/HC-MCM system, can be designed. The modulated PC/HC-MCM system achieves better bit-error rate (BER) performance than that of HC-MCM system with equal bandwidth efficiency (BWE). The PC/HC-MCM system can obtain the better peak-to-average power ratio (PAPR) characteristics by selecting appropriate constellation for each subcarrier. On the other hand, since PC/HC-MCM can divide the PC-OFDM symbol duration into multiple time-slots, the advantages of frequency hopping (FH) can be applied in the PC/HC-MCM system. Therefore, we also combine the PC/HC-MCM and frequency hopping multiple access (FHMA) to propose a novel multiple access (MA) system. It can simultaneously transmit multiple users' data within one symbol duration of PC-OFDM.

DOI： 10.1093/ietfec/e90-a.11.2556

Collision recovery for OFDM system over wireless channel 査読

Yafei Hou, Masanori Hamamura

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E90A ( 7 ) 1312 - 1322 2007年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We present an effective method of collision recovery for orthogonal frequency division multiplexing (OFDM)-based communications. For the OFDM system, the modulated message data can be demodulated using the partial time-domain OFDM signal. Therefore, the partial time-domain signal can be adopted to reconstruct the whole OFDM time-domain signal with estimated channel information. This property can be utilized to recover packets from the collisions. Since most collisions are cases in which a long packet collides with a short packet, the collided part is assumed to be short. The simulated results show that the method can recover the two collided packets with a certain probability and can be developed to solve the problem of hidden terminals. This method will dramatically benefit the protocol design of wireless networks, including ad hoc and sensor networks.

DOI： 10.1093/ietfec/e90-a.7.1312

Fast index for XML data 査読

Ping Yi, Yafei Hou, Yue Wu, Jianhua Li

Journal of Computational Information Systems 3 ( 1 ) 97 - 107 2007年2月

Novel parallel combinatory system with high compaction multicarrier modulation 査読

Journal on Communications 28 ( 1 ) 69 - 74 2007年1月

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