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General minimum Euclidean distance-based precoder for MIMO wireless systems

EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2013年第1期2013卷 1页

作者： Quoc-Tuong Ngo Berder, Olivier Scalart, Pascal Univ Rennes 1 IRISA Rennes France

In this article, we investigate the linear precoder based on the maximization of the minimum Euclidean distance between two received data vectors. This new precoding matrix is expressed as the product of a power allocation matrix and an input-shaping matrix. The input-shaping matrix is selected as a normalized discrete Fourier transform-matrix, and the optimal power allocation depends on the channel characteristics. For each number of available datastreams, we propose a general form of the optimized precoding matrix. These forms are suitable for different transmit channels and especially for all rectangular quadrature amplitude modulation modulations. We show, in the simulation results, that the proposed precoder provides a significant improvement in terms of bit error rate performance compared to other traditional precoding strategies.t

关键词： MIMO CSIT linear precoder Spatial multiplexing ML receiver Minimum Euclidean distance

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precoder Design for BICM-MIMO Systems Under Channel Estimation Error

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WIRELESS PERSONAL COMMUNICATIONS 2013年第4期72卷 2823-2835页

作者： Andalibi, Zohreh Nguyen, Ha H. Salt, J. Eric Univ Saskatchewan Dept Elect & Comp Engn Saskatoon SK S7N 5A9 Canada TRLabs Saskatoon SK Canada

If properly designed, the use of a linear precoder can achieve the maximum coding gain and diversity order in bit-interleaved coded modulation with multiple-input multiple-output systems. However, such maximum coding gain and diversity order are compromised under the practical scenario of having imperfect channel state information (CSI) at the receiver. To alleviate the impact of imperfect CSI on the coding gain and diversity order, joint linear precoder and training pattern are designed in this paper. The design is carried out by considering both the pairwise error probability and the mean square error of the channel estimator. The effectiveness of the proposed design is illustrated by comparing its performance with the performance obtained when only the training pattern is designed for an precoder optimized under the perfect CSI. In particular, simulation results show that a dB gain is achieved by the proposed design.

关键词： BICM-MIMO Pairwise error probability Diversity order Coding gain linear precoder Pilot symbols Mean-square error Iterative receiver

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Robust WMMSE-Based precoder With Practice-Oriented Design for Massive MU-MIMO

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IEEE WIRELESS COMMUNICATIONS LETTERS 2024年第7期13卷 1858-1862页

作者： Wang, Kexuan Liu, An Zhejiang Univ Coll Informat Sci & Elect Engn Hangzhou 310027 Peoples R China

The challenge induced by imperfect channel state information (CSI) at the transmitter promotes the research of robust precoder design, among which stochastic weighted minimum mean square error (SWMMSE) has gained wide attention due to its excellent performance. However, its considerable computational complexity and extremely slow convergence rate make it impractical to be applied in real massive multi-user multiple-input (MU-MIMO) systems. To combat these drawbacks, in this letter, we first propose a robust weighted minimum mean square error (WMMSE)-based precoder with a practice-oriented design, namely PO-WMMSE. On one hand, it can be approximately seen as a deterministic equivalent of the classical SWMMSE, and thus yield a satisfying performance. On the other hand, due to the low complexity and closed-form approximation of the expectation terms in PO-WMMSE, it can quickly converge with linear complexity (in contrast, the expectation terms are approximated using sample average in SWMMSE). Then, the proposed algorithm is unfolded into a layer-wise neural network, namely PO-WMMSE Net, in which several trainable matrices are induced to compensate for the approximate loss and further accelerate convergence. Finally, numerical comparisons under imperfect CSI with existing algorithms demonstrate the significant advantages of the developed PO-WMMSE Net.

关键词： Convergence Approximation algorithms Neural networks Complexity theory Precoding Mean square error methods Iterative algorithms Robust WMMSE linear precoder deep unfolding

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precoder design for space-time coded MIMO systems with imperfect channel state information

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第6期7卷 1977-1981页

作者： Huang, Jane W. An, Edward K. S. Lau, Vincent K. N. Univ British Columbia Dept Elect & Comp Engn Vancouver BC V5Z 1M9 Canada Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Hong Kong Peoples R China

We address the problem of designing a linear precoder for space-time coded multiple-input multiple-output (MIMO) system with imperfect knowledge of channel state information at the transmitter (CSIT), subject to a total transmit power constraint. Assuming an uncorrelated flat-fading channel and using a maximum likelihood decoder at the receiver, we analytically reveal that the derived precoder is a function of the noise variance, the eigenvalues of the estimated channel matrix and the eigenvalues of the codeword distance matrix. Furthermore, the power allocation on the eigenvalues of the precoder is shown to follow the water-pouring policy and hence the proposed precoder allocates more power to the stronger channels.

关键词： channel state information linear precoder MIMO space-time code

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Minimum Euclidean Distance-Based Precoding for Three-Dimensional Multiple Input Multiple Output Spatial Multiplexing Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2012年第7期11卷 2486-2495页

作者： Ngo, Quoc-Tuong Berder, Olivier Scalart, Pascal Univ Rennes 1 ENSSAT IRISA Equipe Rech CAIRN F-22305 Lannion France

Through a feedback link, the channel state information acquired at the receiver is known at the transmitter and MIMO precoding techniques can be applied according to various criteria. In this paper, an efficient linear precoder based on the maximization of the minimum Euclidean distance between two received data vectors for three data-stream MIMO spatial multiplexing systems is proposed. By using a singular value decomposition, the precoding matrix can be parameterized as the product of a power allocation matrix and an input shaper matrix. According to this representation, the optimal precoders are proposed for the case of three independent data-streams. Simulation results over Rayleigh fading channels show considerable bit-error-rate improvement with the proposed solution in comparison with other precoding strategies.

关键词： MIMO CSI linear precoder spatial multiplexing ML receiver minimum Euclidean distance

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Statistical Transceiver Designs with ICI Reduction for MIMO-OFDM Systems

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WIRELESS PERSONAL COMMUNICATIONS 2013年第2期71卷 821-837页

作者： Qian, Fengyong Leung, Shuhung Mai, Ruikai Zhu, Yuesheng City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China Peking Univ Shenzhen Grad Sch Commun & Informat Secur Lab Shenzhen Peoples R China

In this paper, transceiver designs that take into account inter-carrier interferences (ICI) in the framework of game theory for multiple-input multiple-output orthogonal frequency division multiplexing systems are presented. With statistical channel state information at the transmitter, two transceivers: minimal mean-squared-error equalizer and minimal mean-squared-error decision-feedback equalizer are designed. The transceiver designs with the objective of minimizing the expectation of detection mean squared error become a complicated strategic non-cooperative game problem. In the paper, heuristic algorithms based on the best reply dynamic in game theory are proposed, whose convergence to Nash equilibrium can be numerically verified. Compared with traditional transceivers which ignore ICI effect by assuming perfect orthogonality between subcarriers, our designs require a moderate increase in design complexity. Nevertheless, the proposed transceivers have the same implementation complexity as the traditional counterparts. Numerical results verify that the proposed transceivers are more robust to ICI effect from the perspective of bit error rate than the traditional ones.

关键词： Time-varying impairments Inter-carrier interference (ICI) linear precoder Strategic non-cooperative game Best replay dynamic Heuristic algorithms

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Blind CFO Estimation for linearly Precoded OFDMA Uplink

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第9期58卷 4698-4710页

作者： Movahhedian, Mohammad Ma, Yi Tafazolli, Rahim Univ Surrey Ctr Commun Syst Res Surrey GU2 7XH England

This paper presents a novel method for blind carrier-frequency-offset (CFO) estimation in linearly precoded OFDMA uplink. Our investigation starts from the single-user equivalent (SUE) scenario presented in [ 2] where active users in the network are categorized into a number of reference (synchronized) users (RUs) and a new (asynchronous) user (NU). The major idea is to take advantage of time correlation induced by the linear precoder, which offers a second-order moments-based blind CFO estimation. The precoder design is carefully performed in terms of CFO identifiability, estimation accuracy and overall system performance. In the multiuser scenario, where all users can be misaligned in frequency domain, the proposed CFO estimator is capable of mitigating a considerable portion of interference from neighboring users through exploitation of a novel time-frequency multiuser data-mapping (MU-DM) scheme. To demonstrate the multiuser interference (MUI)-resilience feature of proposed scheme, theoretical analysis is performed through derivation of approximate minimum-mean-square error (MMSE) in both SUE and multiuser scenarios. It is shown that by exploitation of the proposed MU-DM scheme, the approximate multiuser MMSE is very close to that of SUE scenario. Simulation results show that the proposed approach outperforms state-of-the-art approaches in both SUE and multiuser scenarios.

关键词： Blind estimation carrier frequency offset (CFO) linear precoder multiuser interference (MUI) orthogonal frequency-division multiple-access (OFDMA) uplink

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An opportunistic scheduling algorithm using aged CSI in massive MIMO systems

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COMPUTER NETWORKS 2017年第Part1期129卷 284-296页

作者： Lee, Hyunjoong Park, Sangkyu Bahk, Saewoong Seoul Natl Univ Dept Elect & Comp Engn INMC Seoul South Korea

In time-division duplex (TDD) massive multiple-input multiple-output (MIMO) systems, the spatial multiplexing gain cannot be fully achieved since available pilot resources at each channel coherence time interval are limited. In this paper, we propose an Opportunistic user Scheduling algorithm, termed OpSAC, that uses Aged Channel state information (CSI) to increase spatial multiplexing gain without incurring additional pilot overhead. Assuming the base station (BS) employs two popular precoders of maximum ratio transmission (MRT) and zero-forcing (ZF), we first derive their closed-form lower bounds on the achievable sum-rate under channel aging. According to the analysis results, we develop a heuristic solution that estimates the amount of channel variation for each user by using correlation of CSI samples, and exploits channel conditions to opportunistically schedule more users by using aged CSI, thereby enhancing spectral efficiency. Through numerical analysis and simulation we confirm that the proposed lower bounds are very tight, and show the impact of channel aging on the performance of massive MIMO systems. In addition, it is shown that OpSAC achieves near-optimal performance and considerably outperforms the conventional user scheduling algorithm that uses current CSI only. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Massive MIMO Large-scale MIMO Multi-user MIMO Channel aging Beamforming linear precoder Scheduling

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Minimum BER linear transceivers for MIMO channels via primal decomposition

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2005年第8期53卷 2866-2882页

作者： Palomar, DP Bengtsson, M Ottersten, B Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Royal Inst Technol Dept Signals Sensors & Syst SE-10044 Stockholm Sweden

This paper considers the employment of linear transceivers for communication through multiple-input multiple-output (MIMO) channels with channel state information (CSI) at both sides of the link. The design of linear MIMO transceivers has been studied since the 1970s by optimizing simple measures of the quality of the system, such as the trace of the mean-square error matrix, subject to a power constraint. Recent results showed how to solve the problem in an optimal way for the family of Schur-concave and Schur-convex cost functions. In particular, when the constellations used on the different transmit dimensions are equal, the bit-error rate (BER) averaged over these dimensions happens to be a Schur-convex function, and therefore, it can be optimally solved. In a more general case, however, when different constellations are used, the average BER is not a Schur-convex function, and the optimal design in terms of minimum BER is an open problem. This paper solves the minimum BER problem with arbitrary constellations by first reformulating the problem in convex form and then proposing two solutions. One is a heuristic and suboptimal solution, which performs remarkably well in practice. The other one is the optimal solution obtained by decomposing the convex problem into several subproblems controlled by a master problem (a technique borrowed from optimization theory), for which extremely simple algorithms exist. Thus, the minimum BER problem can be optimally solved in practice with very simple algorithms.

关键词： BER convex optimization theory decomposition techniques linear precoder MIMO channel transceiver waterfilling

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Reconfigurable Intelligent Surface-Aided MIMO Secure Communication System With Finite-Alphabet Inputs

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TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES 2024年第12期35卷

作者： Wu, Yingjie Wang, Shilian Luo, Junshan Chen, Weiyu Natl Univ Def Technol Coll Elect Sci & Technol Changsha Peoples R China

Existing research in the field of reconfigurable intelligent surface (RIS)-aided physical layer security assumed Gaussian signal inputs, which is inapplicable to practical communication systems, where finite-alphabet inputs are used. This paper considers an RIS-aided secure multiple-input multiple-output wireless communication system with finite-alphabet inputs, where artificial noise (AN) is invoked at the transmitter to enhance the secure performance. In order to maximize the secrecy rate (SR), the data precoder, the AN precoder, and RIS's reflection coefficients are jointly optimized subject to the constraints of the maximum transmit power and the finite resolution of the phase shifts of RIS. Particularly, due to the finite-alphabet input, the exact expression of the SR involves multiple integrals and lacks a closed-form expression. To tackle this, a closed-form lower bound of the SR is derived as the objective function, which is theoretically proved to be equal to the SR in the high signal-to-noise ratio region. Numerical results show that the RIS can significantly improve the secure performance, and the maximum possible SR (due to the finite-alphabet inputs) can be achieved by increasing the number of the RIS's elements or by increasing the transmit power, which shows the performance advantage of the proposed optimization algorithm.

关键词： artificial noise finite-alphabet inputs Intelligent reflecting surface linear precoder secrecy rate

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