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13th IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB)

作者： Wu, Feiteng Wang, Jun Wang, Jintao Song, Jian Tsinghua Univ Dept Elect Engn Beijing Natl Res Ctr Informat Sci & Technol BNRis Beijing 100084 Peoples R China Tsinghua Univ Shenzhen Guangdong & Shenzhen City Res Inst Key Lab Digital TV Syst Shenzhen 518057 Peoples R China

ISBN: (纸本)9781538647295

Out-of-Band (OOB) emission and High Peak-toAverage Power Ratio (PAPR) are two main challenges for Orthogonal Frequency Division Multiplexing (OFDM) systems. There are many techniques that have been proposed to solve either one of the problems. precoding plays a role in the solution of both problems, but generally a specific precoding scheme only solves one of them. In this paper, we combine two precoding schemes which solve two problems separately, and then propose an improved precoding method to solve OOB emission and high PAPR problem simultaneously. So that we can use only one precoding matrix to achieve our two goals. The simulation results show that our method reaches a balance between the two problems and has similar BER performance.

关键词： OFDM OOB emission reduction PAPR reduction precoding method

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precoding methods for multi-input multi-ouput interference channels with channel covariance Feedback

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IET COMMUNICATIONS 2015年第4期9卷 517-525页

作者： Zhou, Wen Shantou Univ Dept Elect Engn Shantou Peoples R China Guangdong Prov Key Lab Digital Signal & Image Pro Guangzhou Guangdong Peoples R China

Usually, instantaneous channel information is required by the transmitter for the precoding in multi-input multi-output interference channels. In the case of fast fading channels, the resultant additional overhead of the system will be high. Against this, this study considers the scenario where the channel is spatially correlated and the transmitter only has the covariance information of the channel so that the system overhead can be reduced. On the basis of maximum signal-to-interference-plus-noise ratio (SINR) criterion, the author proposes two precoding methods, including the iterative precoding and bisection search precoding methods. The first method solves the optimal precoder of a given user provided that others' precoders are known, so that the SINR can be increased gradually. Whereas the second method introduces an auxiliary variable, transforms the original non-convex problem into a convex one, and solves it by convex optimisation softwares. Both the proposed methods are proved to be convergent and their computation complexity and overheads are also analysed. Under various system settings, the proposed two methods are compared with a few existing precoding or joint transceiver methods by numerical method and computer simulation, and the superiority of the proposed methods is also shown in most cases.

关键词： covariance matrices computational complexity convex programming fading channels radio transceivers feedback radiofrequency interference MIMO communication precoding channel coding precoding method channel covariance feedback instantaneous channel information transmitter fading channel spatial correlation system overhead reduction maximum signal-to-interference-plus-noise ratio criterion SINR criterion iterative precoding bisection search precoding method auxiliary variable nonconvex problem transformation convex optimisation software computation complexity joint transceiver method covariance matrix multiinput multioutput interference channel MIMO interference channels

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Practical linear precoder design for finite alphabet multiple-input multiple-output orthogonal frequency division multiplexing with experiment validation

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IET COMMUNICATIONS 2013年第9期7卷 836-847页

作者： Zheng, Yahong Rosa Wang, Mingxi Zeng, Weiliang Xiao, Chengshan Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA

A low complexity precoding method is proposed for practical multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. Based on the two-step optimal precoder design algorithm that maximises the lower bound of the mutual information with finite-alphabet inputs, the proposed method simplifies the precoder design by fixing the right singular vectors of the precoder matrix, eliminating the iterative optimisation between the two steps, and discretising the search space of the power allocation vector. For a 4 x 4 channel, the computational complexity of the proposed precoder design is reduced to 3 and 6% of that required by the original two-step algorithm with quadrature phase shift keying (QPSK) and 8 phase-shift keying (8PSK), respectively. The proposed method achieves nearly the same mutual information as the two-step iterative algorithm for a large range of signal-to-noise ratio (SNR) region, especially for large MIMO size and/or high constellation systems. The proposed precoding design method is applied to a 2 x 2 MIMO-OFDM system with 2048 subcarriers by designing 1024 precoders for extended channel matrices of size 4 x 4. A transceiver test bed implements these precoding matrices in comparison with other existing precoding schemes. Indoor experiments are conducted for fixed-platform non-line-of-sight channels, and the data processing results show that the proposed precoding method achieves the lowest bit error rate compared with maximum diversity, classic water-filling and channel diagonalisation methods.

关键词： MIMO-OFDM system 8PSK Optimisation techniques bit error rate Codes precoding finite-alphabet inputs low complexity precoding method codecs water-filling methods fixed-platform nonline-of-sight channels optimisation QPSK two-step optimal precoder design algorithm OFDM modulation channel diagonalisation methods Codecs, coders and decoders SNR region channel coding iterative methods indoor radio transceiver test bed linear codes data processing frequency division multiplexing linear precoder design experiment validation radio transceivers phase shift keying maximum diversity precoding method finite alphabet multiple-input multiple-output orthogonal precoding matrices precoder matrix MIMO size multiplexing Interpolation and function approximation (numerical analysis) computational complexity Radio links and equipment quadrature phase shift keying two-step algorithm MIMO OFDM systems indoor experiments extended channel matrices MIMO communication transceivers

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Partially Non-Orthogonal Block Diagonalization-Based precoding in Multiuser MIMO with Limited Channel State Information Feedbacks

Partially Non-Orthogonal Block Diagonalization-Based Precodi...

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21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Tajika, Yuki Kimura, Ryosuke Watanabe, Masahiro Higuchi, Kenichi Tokyo Univ Sci Dept Elect Engn Grad Sch Sci & Technol Noda Chiba 2788510 Japan

ISBN: (纸本)9781424480166

We consider a precoding method in downlink multiuser multiple-input multiple-output (MIMO) transmission with multiple base station (BS) cooperation where some of the instantaneous channel state information (CSI) is not available at the BSs. The proposed precoding method is based on block diagonalization of the channel matrix. However, since some elements of the channel matrix are unknown, we allow a partially non-orthogonal transmission. More specifically, we allow inter-user interference to users with limited instantaneous CSI feedback from the channel where the instantaneous CSI of that user is not obtained at the BSs. The other inter-user interferences are set to zero based on the block diagonalization of the channel matrix. The proposed method efficiently uses the degree of freedom of the spatial channel compared to the case with full orthogonal transmission at the cost of increased inter-user interference to the users with limited instantaneous CSI feedback. Simulation results show that the proposed method increases the capacity for a given transmission power or decreases the transmission power for a given capacity requirement compared to the case with full orthogonal transmission.

关键词： CSI feedback MIMO communication block codes channel coding channel matrix interuser interference limited channel state information feedbacks multiple base station cooperation multiuser MIMO transmission multiuser multiple input multiple output transmission orthogonal codes orthogonal transmission orthogonal transmission partially nonorthogonal block diagonalization based precoding precoding precoding method

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Deflected Field-of-Views Receiver for Indoor MIMO Visible Light Communications

Deflected Field-of-Views Receiver for Indoor MIMO Visible Li...

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International Conference on Infocom Technologies and Unmanned Systems (Trends and Future Directions) (ICTUS)

作者： Song, Jian Wei, Ling Zhang, Hongming Tsinghua Univ TNList Beijing 100084 Peoples R China Tsinghua Univ Dept Engn Beijing 100084 Peoples R China Tsinghua Univ Shenzhen Res Inst Guangdong Prov Key Lab Digital TV Syst Shenzhen City Key Lab Digital TV Syst Shenzhen 518057 Peoples R China

ISBN: (纸本)9781538605141

Conventional non-imaging receiver for multiple-input-multiple-output (MIMO) visible light communications (VLC) systems always suffer from the problem of ill-conditioned channel matrix due to the high correlation among sub-channels. So in this paper, a deflected field-of-views (FOVs) receiver for MIMO VLC system is proposed to reduce the correlation and also have a compact planar structure. The receiver has a diaphragm with several apertures to cover the planar array of photodetectors (PDs), so each PD will own different deflected FOV. Considering the diversity of sub-channels, the precoding method and water-filling algorithm are applied at the transmitters to achieve higher data rate or lower power consumption. In the simulation, the optimal structure parameter of the receiver is demonstrated, and the BER performance of the receiver is also verified, where DC-biased Optical orthogonal frequency division multiplexing (DCO-OFDM) is applied. The results show that the precoding method can significantly improve the system performance and is therefore, perfectly suitable for the deflected FOVs receiver in MIMO-VLC systems.

关键词： deflected field-of-view receiver visible light communication (VLC) multiple-input-multiple-output (MIMO) DC-biased Optical orthogonal frequency division multiplexing (DCO-OFDM) precoding method

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The Limited Feedback precoding Based on the Triplex Codebooks 9

The Limited Feedback Precoding Based on the Triplex Codebook...

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International Conference on Cyber-Enabled Distributed Computing and Knowledge Discovery (CyberC)

作者： Kang, Guihua Xu, Kaiyue Kang, Hongbo Pan, Kun-bei Hohai Univ Coll Internet Things Engn Changzhou Campus Changzhou City Peoples R China

ISBN: (纸本)9781538622094

The precoding method based on the triplex codebooks with limited feedback has been put forward in the paper in order to solve the problem that the feedback accuracy of the CSI is not enough for the precoding based on the single codebook with limited feedback in the LTE-FDD mode. The triplex codebooks are composed of the original codebook, the enhanced codebook and the modified codebook. The enhanced codebook is used against the adverse circumstances that the condition number of channel matrix is too high, and the modified codebook could be used to reduce the quantization error. The simulation results of the proposed method show that the feedback overhead is only increased by 1bit, but the BER (bit error rate) performance can be enhanced about 2dB and the channel capacity can be improved about 1.2bps/Hz relative to the precoding method with the single codebook. Therefore, the precoding method proposed in the paper can significantly improve the precoding performance at the small cost of feedback overhead. In the practical application, the triplex codebooks can be designed by the off-line way, and the complexity of the proposed method will not be obviously increased.

关键词： precoding method limited feedback feedback overhead single codebook triplex codebooks channel state information

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Modified Raptor Code For Distributed Storage Systems

Modified Raptor Code For Distributed Storage Systems

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International Conference on Information Technology for Manufacturing Systems

作者： Chen Zheng Wang Xiaojing Univ Elect Sci & Technol China Chengdu 610054 Peoples R China Chinese Acad Sci Chengdu Inst Comp Appl Chengdu Peoples R China

ISBN: (纸本)9780878492879

We provide a prototype system for a distributed storage model, the goal of this system is to store information in a p2p network of n nodes, and the original information could be recovered later in a computationally simple way from (1+e)k of nodes for some small e>0. For solving this problem, we employ a class of B-J codes with dimension 2 as base code and obtain a new class of LDPC code by using q-tuples to substitute the elements of GF(q), to modify and improve Raptor code. The improved Raptor Code has many advantages such as high decoding rate, flexibility in choices of the code length and rate of. As the benefits of the above characters, the storage system based on modified Raptor code has great improvement in decoding probability and parameter flexibility, and a simulation is also illustrated to prove our assumption.

关键词： Distributed storage Raptor code precoding method P2P Systems

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On the Evaluation of IMT-Advanced Candidates: methodologies, Current Work and Way Forward

On the Evaluation of IMT-Advanced Candidates: Methodologies,...

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6th International Conference on Wireless Communications, Networking and Mobile Computing (WICOM)

作者： Wang, Ying Wang, Tan Ling, Lisha Shi, Cong Beijing Univ Posts & Telecommun Wireless Technol Innovat Inst Beijing 100876 Peoples R China

ISBN: (纸本)9781424437092

Currently and thereafter, evaluations and consensus-building process will be performed for the 4G candidates from ITU-R membership, standards organizations, and other external evaluation groups. Among them, the Chinese Evaluation Group (ChEG) is also responsible for submitting the evaluation report to ITU-R. This paper addresses the evaluation methodology and relevant activities. Descriptions to the basic rules in the evaluation are given, according to the requirements of ITU-R, where the simulation methods are highlighted. Next taking the 3rd Generation Partner Project Long Term Evolution Advanced (3GPP LTE-A) as an example, the calibration steps of simulators are shown for the potential readers to reproduce the evaluation work. Finally the analysis and latest evaluation results for the multi-user multiple-input multiple-output (MU-MIMO) technology are presented, which currently is the most effective technology that could already achieve the requirements and still being improved. The improvement might include the methods of precoding and user group selection.

关键词： 3G mobile communication 3rd Generation Partner Project Long Term Evolution Advanced 4G candidates 4G mobile communication Chinese Evaluation Group ITU-R membership International Mobile Telecommuniation Advanced MIMO communication MU-MIMO evaluation methodology multiuser multiple-input multiple-output technology precoding precoding method user group selection

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The Limited Feedback precoding Based on the Triplex Codebooks

The Limited Feedback Precoding Based on the Triplex Codebook...

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第九届网络分布式计算与知识发现国际会议( 2017 International Conference on Cyber-enabled distributed computing and knowledge discovery)

作者： Guihua Kang Kaiyue Xu Hongbo Kang Kun-bei Pan College of Internet of Things Engineering Hohai University Changzhou Campus Changzhou CityChina

The precoding method based on the triplex codebooks with limited feedback has been put forward in the paper in order to solve the problem that the feedback accuracy of the CSI is not enough for the precoding based on the single codebook with limited feedback in the LTE-FDD *** triplex codebooks are composed of the original codebook,the enhanced codebook and the modified *** enhanced codebook is used against the adverse circumstances that the condition number of channel matrix is too high,and the modified codebook could be used to reduce the quantization *** simulation results of the proposed method show that the feedback overhead is only increased by 1bit,but the BER(bit error rate)performance can be enhanced about 2dB and the channel capacity can be improved about 1.2bps/Hz relative to the precoding method with the single ***,the precoding method proposed in the paper can significantly improve the precoding performance at the small cost of feedback *** the practical application,the triplex codebooks can be designed by the off-line way,and the complexity of the proposed method will not be obviously increased.

关键词： precoding method limited feedback feedback overhead single codebook triplex codebooks channel state information

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