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IEEE PHOTONICS JOURNAL 2018年第5期10卷 1-16页

作者： Jiang, Tao Tang, Ming Lin, Rui Feng, Zhenhua Chen, Xi Deng, Lei Fu, Songnian Li, Xiang Liu, Wu Liu, Deming Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan Natl Lab Optoelect Wuhan 430074 Hubei Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Natl Engn Lab Next Generat Internet Access Syst Wuhan 430074 Hubei Peoples R China KTH Royal Inst Technol Sch Informat & Commun Technol S-11428 Stockholm Sweden Wuhan Res Inst Posts & Telecommun State Key Lab Opt Commun Technol & Networks Wuhan 430074 Hubei Peoples R China

Orthogonal frequency-division-multiplexing (OFDM) technology is widely used in visible light communication (VLC) to achieve high data rate transmission. However, the traditional direct-current (DC)-biased optical OFDM (DCO-OFDM) VLC systems suffer from the high peak-to-average power ratio (PAPR) which causes signal clipping distortion, and, thus, performance degradation. Furthermore, severe high-frequency fading due to the limited system bandwidth results in poor bit error rate (BER) performance. precoding matrix (PM) techniques have been proposed to enhance the performance of VLC OFDM transmission, but a little or no work has been carried out in investigating the theory of PM used in OFDM VLC systems. In this paper, we aim to reveal the theory of PM-DCO-OFDM for a VLC system. To figure out the intrinsic laws of a PM method, we investigate the principles of PAPR reduction, clipping distortion optimization, and signal-to-noise ratio (SNR) distribution equalization. Based on the analysis of PAPR, we theoretically proved the simplicity of PM as a method to reduce the possibility of high PAPR by improving the autocorrelation performance of input symbols. The clipping distortion could be improved due to the reduction of high PAPR. Moreover, the relatively uniform SNR distribution can be achieved by PM through equalizing the clipping and channel noise, which is beneficial to improve the BER performance in high-frequency constrained systems. However, the PM method used in a DCO-OFDM VLC system should consider the transmitting power, modulation format, and transmission distance as a whole to achieve the transmission performance improvement. The simulation results demonstrate the complementary cumulative distribution function of PAPR can be reduced similar to 3 dB, while the performance of clipping distortion power and clipping error probability are significantly improved. Furthermore, experiment is carried out with results showing that the PM method can improve the BER perf

关键词： Visible light communication DC-biased optical OFDM PAPR SNR distribution precoding matrix

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Spatial Interference Alignment with Limited precoding matrix Feedback in a Wireless Multi-User Interference Channel for Smart Grids

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ENERGIES 2022年第5期15卷 1820页

作者： Peng, Shixin Chen, Xiaohui Lu, Wei Deng, Chao Chen, Jingying Cent China Normal Univ Natl Engn Res Ctr E Learning Natl Engn Lab Educ Big Data Wuhan 430079 Peoples R China State Grid Hunan Elect Power Co Ltd Informat & Commun Branch Changsha 410004 Peoples R China Air Force Early Warning Acad Wuhan 430019 Peoples R China Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan 430074 Peoples R China

Cellular communication provides an efficient, flexible, long-lived, and reliable communication technology for smart grids to improve the automated analysis, demand response, adoptive control, and coordination between the generator and consumers. With the expansion of wireless networks and the increase of access devices, interference has become a major problem that limits the performance of cellular wireless communication systems for smart grids. Spatial interference alignment (IA) is an effective method to eliminate interference and improve the capacity of wireless communication networks. This paper provides the sufficient conditions of spatial interference alignment operating with limited precoding matrix feedback for a K-user MIMO interference channel. Each receiver feeds the matrix index of the transmitting precoder back to the corresponding transmitter through an interference-free and error-free link. We calculated the number of feedback bits required to achieve the maximum theoretical multiplexing gain for the spatial interference alignment schemes considered and demonstrate the feasibility of spatial interference alignment under the limited feedback constraint investigated. It is shown that in order to maintain the same spatial multiplexing gain as that of the idealized scheme relying on perfect channel state information, the number of feedback bits per receiver scales as N-d & GE;d(i)(M-d(i))log(2)SNR, where M and d(i) denote the number of transmit (receive) antennas and the number of data steams for user i. Finally, the analytical results were verified by simulations for practical interference alignment schemes relying on limited precoding matrix feedback indices.

关键词： smart grid interference alignment MIMO spatial multiplexing gain limited feedback precoding matrix

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A Joint Optimized Scheme of Transceiver precoding matrix Based on Interference Alignment for Multi-cell MIMO Systems 3

A Joint Optimized Scheme of Transceiver Precoding Matrix Bas...

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3rd IEEE International Conference on Computer and Communications (ICCC)

作者： Liao, Wenbing Huo, Zhibin Cao, Wei Tang, Qixiang Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China

ISBN: (纸本)9781509063529

In downlink multi-cell multiple input multiple output (MIMO) systems, the inter-cell interference has become the main factor to restrict the system capacity. This paper proposes a joint optimized scheme of transceiver precoding matrices based on interference alignment technology to mitigate inter-cell interference. At the transmitter, via the singular value decomposition of target channels, the scheme selects the precoding vectors which are matched with the best characteristic sub-channel to transmit the signal and enhances the signal strength. At the receiver, the scheme selects the vectors of the most matching target received signal from the null space of interference to form the receiver matrix based on the zero-forcing (ZF) criterion, which further improves the target signal strength. The simulation results show that the proposed scheme has improved the system capacity compared with the existing precoding matrix design method.

关键词： MIMO multi-cell interference alignment precoding matrix joint optimized scheme

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Research on the Selection Algorithm of precoding matrix in TDD LTE

Research on the Selection Algorithm of Precoding Matrix in T...

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2011 IEEE 3rd International Conference on Communication Software and Networks(2011第三届通信软件与网络国际会议 ICCSN2011)

作者： Weihong Fu Zhiting Cui Fei Zhang Guo Yantao State Key Lab. of Integrated Service Networks Xidian University Xi'an China Science and Technology on Information Transmission and Dissemination in Communication Networks Labor

This paper presents an efficient method for calculating the precoding matrix Indicator (PMI) at a Long Term Evolution (LTE) User Equipment (UE).To solve problem of the high computational complexity in selection algorithm of precoding codebook for TDD LTE. A new selection algorithm based on singular value decomposition of channel matrix is presented. Our method reduces the computational complexity enormously by using the idea of channel average and maximizing effective power of transmitted signals. Then some simulations based on TDD-LTE downlink physical layer simulator are given. The simulations results show that the proposed algorithm greatly reduce the computational complexity compare to these two traditional algorithms while performance loss is very small, it is a good compromise of complexity and performance.

关键词： TDD-LTE Closed-loop MlMO precoding matrix Throughput Singular value decomposition

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Research on the Selection Algorithm of precoding matrix in TDD LTE

Research on the Selection Algorithm of Precoding Matrix in T...

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2011 IEEE 3rd International Conference on Communication Software and Networks(ICCSN 2011)

作者： Weihong Fu 1 ,Fei Zhang 1 ,Guo Yantao 2 ,Zhiting Cui 1 1 State Key Lab.of Integrated Service Networks,Xidian University, Xi'an,China 2 Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory, Shi Jiazhuang,China

This paper presents an efficient method for calculating the precoding matrix Indicator(PMI)at a Long Term Evolution(LTE)User Equipment(UE).To solve problem of the high computational complexity in selection algorithm of precoding codebook for TDD LTE.A new selection algorithm based on singular value decomposition of channel matrix is *** method reduces the computational complexity enormously by using the idea of channel average and maximizing effective power of transmitted *** some simulations based on TDD-LTE downlink physical layer simulator are *** simulations results show that the proposed algorithm greatly reduce the computational complexity compare to these two traditional algorithms while performance loss is very small,it is a good compromise of complexity and performance.

关键词： TDD-LTE Closed-loop MIMO precoding matrix Throughput Singular value decomposition

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Advanced Codebook Generation Using High-Resolution k-Means Clustering to PMI Data

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IEEE WIRELESS COMMUNICATIONS LETTERS 2025年第2期14卷 549-553页

作者： Park, Sangchun Sung, Wonjin Sogang Univ Dept Elect Engn Seoul 04107 South Korea

An enhanced codebook generation approach based only on precoding matrix indicator (PMI) feedback information is proposed. By utilizing the kernel density estimation (KDE) to produce higher-resolution distributions from discrete PMI data and applying the k-means clustering algorithm, the approach iteratively updates the set of beamforming vectors to autonomously adapt to the channel characteristics and user equipment (UE) positions. The proposed codebook is 3GPP standard compliant in the sense that it can be applied to existing systems to achieve significantly enhanced beamforming performance, without any alterations to reference signaling or channel measurement report.

关键词： 3GPP codebook beamforming precoding matrix k-means clustering

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Spread Spectrum OFDM-IM With Efficient Precoded matrix and Low Complexity Detector

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IEEE ACCESS 2024年 12卷 192293-192300页

作者： Waheed, Ahmed Mohammady, Somayeh Technol Univ Dublin TUD Sch Elect & Elect Engn Dublin 7 Ireland

This paper introduces a novel scheme that employs efficient precoded matrices for index modulation orthogonal frequency division multiplexing namely (EP-OFDM-IM). This technique implements Discrete Fourier Transform (DFT) and Fast Walsh Hadamard Transform (FWHT) precoded matrices for spreading the subset of active M-ary data symbols and their indices to transmit additional information. This aims to enhance the system's transmit diversity (TD) by exploiting multipath and index diversities. Moreover, a low complex minimum means square error greedy detector (MMSE-GD) is proposed that can achieve optimal performance for perfect channel state information (CSI) and superior performance compared to maximum likelihood (ML) under imperfect CSI. The theoretical analysis based on pair-wise error probability is derived to estimate the bit error probability (BEP) of the proposed scheme for the performance analysis. Simulation results demonstrate that our proposed scheme EP-OFDM-IM significantly outperforms various existing competitive benchmark IM schemes. Specifically, at a spectral efficiency (SE) of 1.5 bps/Hz, and BEP of 10-3, our proposed scheme achieves addition of 15dB gain.

关键词： Discrete Fourier transforms OFDM Indexes Computational complexity Detectors Symbols precoding Modulation Vectors Diversity methods Index modulation precoding matrix maximum likelihood greedy detector MMSE Walsh-Hadamard fast Walsh-Hadamard transform discrete Fourier transform 5G 6G

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IMPLEMENTATION OF THE PRECODER matrix INDICATOR SELECTION USING MMSE TRACE CRITERION FOR THE DOWNLINK TRANSMISSION IN LTE 41

IMPLEMENTATION OF THE PRECODER MATRIX INDICATOR SELECTION US...

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41st IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

作者： Chung, Chang-Han Liu, Tsung-Hsien Chu, Yuan-Sun Natl Chung Cheng Univ 168 Univ Rd Chiayi Taiwan

ISBN: (纸本)9781479999880

Based on the minimum mean squared error (MMSE) trace criterion, selection of the precoding matrix indicator (PMI) from the downlink codebook of the LTE system is considered in this paper. Due to the codebook of 16 member precoding matrices and up to 1200 sub-carriers in this MIMO-OFDM system, the PMI selection needs to compute matrix inversion of up to 19,200 matrices. To satisfy this required workload, LDLH decomposition is applied at the algorithmic level, and, pipeline matrix multiplication and backward substitution modules are used at the architectural level. The VLSI implementation results of our architecture under the TSMC 90 nm CMOS technology reveals that our architecture requires 124.6K gates at operating frequency 120 MHz. Thus, our designed architecture can finish the 19,200 matrix inversions in about 1.60 ms and meets the requirement of 2 ms period of periodic channel state report.

关键词： multiple input multiple output (MIMO) system precoding matrix LTE PMI report

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Spectrum efficiency analysis of signal alignment-based beamspace millimetre wave MIMO-NOMA systems

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IET COMMUNICATIONS 2020年第5期14卷 818-829页

作者： Salem, Ahmed Abdelaziz Benaya, A. M. El-Rabaie, Sayed Shokair, Mona Menoufia Univ Fac Elect Engn Menoufia 32952 Egypt

Non-orthogonal multiple access (NOMA) has been integrated with beamspace multi-input multi-output (MIMO) to enhance system spectrum efficiency (SE) by serving more than one user per dedicated radio frequency (RF) chain. However, balancing the system performance with significant RF reduction is still challenging. In this study, the authors propose beamspace MIMO-NOMA system based on signal alignment (SA) concept, where they will be able to tackle the issue of hardware complexity with a significant performance. Spectrum and energy efficiencies are analysed through two main stages. First, the excess degrees-of-freedom of beamspace MIMO-NOMA are exploited by SA to suppress the inter-beam/pair interference through designing user detection vectors and precoding matrix. Accordingly, a significant RF-chains reduction is provided. Second, power allocation coefficients are evaluated upon the optimal SE in order to mitigate intra-beam/pair interference. Moreover, the authors derive a tight closed formula for optimal SE based on Karush-Kuhn-Tucker analysis, which is validated by a heuristic-based optimal solution. Simulation results show a superior performance gain over orthogonal multiple access technique. Furthermore, the Monte-Carlo numerical solution depicts the marginal performance gap between the analytical and heuristic-based optimisation approach. This confirms the accuracy and rigidity of the proposed system.

关键词： optimisation antenna arrays MIMO communication precoding Monte Carlo methods spectrum efficiency analysis signal alignment-based beamspace MIMO-NOMA systems beamspace concept millimetre wave multiinput multioutput hardware complexity required radio frequency chains system capacity RF chains user numbers nonorthogonal multiple access system spectrum efficiency dedicated RF chain system performance RF reduction authors propose beamspace MIMO-NOMA signal alignment concept energy efficiencies excess degrees-of-freedom user detection vectors precoding matrix significant RF-chains reduction optimal SE Karush-Kuhn-Tucker analysis heuristic-based optimal solution superior performance gain orthogonal multiple access technique marginal performance gap analytical based optimisation approach heuristic-based optimisation approach

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Improving the DMT Performance for MIMO Communication With Linear Receivers

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第3期62卷 1189-1200页

作者： Tang, Ti-Wen Chen, Min-Kun Lu, Hsiao-Feng Natl Chiao Tung Univ Dept Elect Engn Hsinchu 300 Taiwan

Multiple-input-multiple-output (MIMO) linear receivers are often of more practical interest than maximum-likelihood (ML) receivers due to their low decoding complexity but at the cost of worse diversity gain performance. Such a statement on performance loss is due to the assumption of using an independent identically distributed complex Gaussian vector as channel input. By removing this assumption, we find that the diversity performance of MIMO linear receivers can be significantly improved. In an extreme case, it can be the same as that of ML receivers. Specifically, in this paper, we investigate the diversity-multiplexing tradeoff (DMT) performance of MIMO linear receivers with colored and possibly degenerate Gaussian channel inputs. By varying the rank of the covariance matrix of the channel input vector and by allowing temporal coding across multiple channel uses, we show that the MIMO linear receiver can achieve a much better DMT performance than the currently known one. Explicit optimal code constructions are provided, along with simulation results, to justify the above findings. For the case of (2 x 2) and (3 x 3) MIMO linear receivers, simulation results show that the newly proposed codes provide significant gains of 10 and 12.08 dB in E-b/N-0 at bit error rate 10(-4) compared to the conventional schemes, respectively.

关键词： Diversity-multiplexing tradeoff (DMT) explicit optimal code constructions linear receivers precoding matrix quasi-static multiple-input-multiple-output (MIMO) channel

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