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linear precoding With Low-Resolution DACs for Massive MU-MIMO-OFDM Downlink

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第3期18卷 1595-1609页

作者： Jacobsson, Sven Durisi, Giuseppe Coldrey, Mikael Studer, Christoph Ericsson Res S-41756 Gothenburg Sweden Chalmers Univ Technol Dept Elect Engn S-41296 Gothenburg Sweden Cornell Univ Sch Elect & Comp Engn Ithaca NY 14853 USA

We consider the downlink of a massive multiuser (MU) multiple-input multiple-output (MIMO) system in which the base station (BS) is equipped with low-resolution digital-to-analog converters (DACs). In contrast to most existing results, we assume that the system operates over a frequency-selective wideband channel and uses orthogonal frequency division multiplexing (OFDM) to simplify equalization at the user equipments (UEs). Furthermore, we consider the practically relevant case of oversampling DACs. We theoretically analyze the uncoded bit error rate (BER) performance with linear precoders (e.g., zero forcing) and quadrature phase-shift keying using Bussgang's theorem. We also develop a lower bound on the information-theoretic sum-rate throughput achievable with Gaussian inputs, which can be evaluated in closed form for the case of 1-bit DACs. For the case of multi-bit DACs, we derive approximate, yet accurate, expressions for the distortion caused by low-precision DACs, which can be used to establish the lower bounds on the corresponding sum-rate throughput. Our results demonstrate that, for a massive MU-MIMO-OFDM system with a 128-antenna BS serving 16 UEs, only 3-4 DAC bits are required to achieve an uncoded BER of 10(-4) with a negligible performance loss compared to the infinite-resolution case at the cost of additional out-of-band emissions. Furthermore, our results highlight the importance of considering the inherent spatial and temporal correlations caused by low-precision DACs.

关键词： Massive multiuser multiple-input multiple output low-resolution digital-to-analog converter linear precoding orthogonal frequency-division multiplexing Bussgang's theorem

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linear precoding Gain for Large MIMO Configurations With QAM and Reduced Complexity

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IEEE TRANSACTIONS ON COMMUNICATIONS 2016年第10期64卷 4196-4208页

作者： Ketseoglou, Thomas Ayanoglu, Ender Calif State Polytech Univ Pomona Elect & Comp Engn Dept Pomona CA 91768 USA Univ Calif Irvine Dept Elect Engn & Comp Sci Ctr Pervas Commun & Comp Irvine CA 92697 USA

In this paper, the problem of designing a linear precoder for multiple-input multiple-output (MIMO) systems in conjunction with quadrature amplitude modulation (QAM) is addressed. First, a novel and efficient methodology to evaluate the input-output mutual information for a general MIMO system as well as its corresponding gradients is presented, based on the Gauss-Hermite quadrature rule. Then, the method is exploited in a block coordinate gradient ascent optimization process to determine the globally optimal linear precoder with respect to the MIMO input-output mutual information for QAM systems with relatively moderate MIMO channel sizes. The proposed methodology is next applied in conjunction with the complexity-reducing per-group processing technique to both perfect channel state information (CSI) at the transmitter as well as statistical CSI (Statistical CSI) scenarios, with large transmitting and receiving antenna sizes, and for constellation size up to M = 64. We show by the numerical results that the precoders developed offer significantly better performance than the configuration with no precoder as well as the maximum diversity precoder for QAM with constellation sizes M = 16, 32, and 64 and for MIMO channel size up to 100 x 100.

关键词： linear precoding MIMO mutual information quadrature amplitude modulation

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linear precoding for Fading Cognitive Multiple-Access Wiretap Channel With Finite-Alphabet Inputs

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第4期66卷 3059-3070页

作者： Jin, Juening Xiao, Chengshan Tao, Meixia Chen, Wen Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200240 Peoples R China Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA Shanghai Jiao Tong Univ Shanghai Key Lab Nav & Locat Based Serv Shanghai 200240 Peoples R China Guilin Univ Elect Technol Sch Elect Engn & Automat Guilin 541004 Peoples R China

We investigate the fading cognitive multiple-access wiretap channel (CMAC-WT), in which two secondary-user transmitters (STs) send secure messages to a secondary-user receiver (SR) in the presence of an eavesdropper and subject to interference threshold constraints at multiple primary-user receivers (PRs). We design linear precoders to maximize the average secrecy sum rate for a multiple-input-multiple-output (MIMO) fading CMAC-WT under finite-alphabet inputs and statistical channel state information at STs. For this nondeterministic polynomialtime NP-hard problem, we utilize an accurate approximation of the average secrecy sum rate to reduce the computational complexity and then present a two-layer algorithm by embedding the convex-concave procedure into an outer-approximation framework. The idea behind this algorithm is to reformulate the approximated average secrecy sum rate as a difference of convex functions and then generate a sequence of simpler relaxed sets to approach the nonconvex feasible set. Subsequently, we maximize the approximated average secrecy sum rate over the sequence of relaxed sets by using the convex-concave procedure. Numerical results indicate that our proposed precoding algorithm is superior to the conventional Gaussian precoding method in the medium and high signal-to-noise ratio (SNR) regimes.

关键词： Cognitive multiple-access wiretap channel (CMAC-WT) finite-alphabet inputs linear precoding multiple-input multiple-output (MIMO) physical-layer security statistical channel state information (CSI)

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linear precoding for Broadcast Channels with Confidential Messages under Transmit-Side Channel Correlation

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IEEE COMMUNICATIONS LETTERS 2013年第6期17卷 1164-1167页

作者： Geraci, Giovanni Al-nahari, Azzam Y. Yuan, Jinhong Collings, Iain B. Univ New S Wales Sch Elect Engn & Telecommun Sydney NSW 2052 Australia CSIRO ICT Ctr Wireless & Networking Technol Lab Sydney NSW Australia Lund Univ Dept Elect & Informat Technol S-22100 Lund Sweden

In this paper, we analyze the performance of regularized channel inversion (RCI) precoding in multiple-input single-output (MISO) broadcast channels with confidential messages under transmit-side channel correlation. We derive a deterministic equivalent for the achievable per-user secrecy rate which is almost surely exact as the number of transmit antennas and the number of users grow to infinity in a fixed ratio, and we determine the optimal regularization parameter that maximizes the deterministic equivalent of the secrecy rate. Furthermore, we obtain deterministic equivalents for the secrecy rates achievable by: (i) zero forcing precoding and (ii) single user beamforming. The accuracy of our analysis is validated by simulations of finite-size systems.

关键词： Physical layer security channel correlation broadcast channel random matrix theory linear precoding

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linear precoding for V-BLAST systems in the presence of fading correlations

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IEICE TRANSACTIONS ON COMMUNICATIONS 2006年第11期E89B卷 3136-3138页

作者： Shi, Tingting Zhou, Shidong Yao, Yan Zhao, Ming Tsinghua Univ Natl Lab Informat Sci & Technol Beijing 100084 Peoples R China

This letter proposed a linear precoding scheme for the V-BLAST system that requires only knowledge of the statistical CSI;the transmitter does not need the instantaneous CSI. Power allocation on the eigenmodes of the transmit correlation matrix is one way to minimize bit error rate (BER). Simulation results show that the proposed precoding V-BLAST system provides a significant reduction in the BER compared with the conventional V-BLAST systems.

关键词： vertical Bell laboratories layered space-time (V-BLAST) linear precoding fading correlation channel state information (CSI) bit error rate (BER)

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linear precoding for MIMO Multiple Access Channels with Finite Discrete Inputs

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2011年第11期10卷 3934-3942页

作者： Wang, Mingxi Zeng, Weiliang Xiao, Chengshan Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA Tsinghua Univ Tsinghua Natl Lab Informat Sci & Technol Dept Elect Engn Beijing 100084 Peoples R China

In this paper, we study linear precoding for multiple-input multiple-output (MIMO) multiple access channels (MAC) with finite discrete inputs. We derive the constellation-constrained capacity region for the MIMO MAC with an arbitrary number of users and find that the boundary can be achieved by solving the problem of weighted sum rate maximization with constellation and individual power constraints. Due to the non-concavity of the objective function, we obtain a set of necessary conditions for the optimization problem through Karush-Kuhn-Tucker analysis. To find the optimal precoding matrices for all users, we propose an iterative algorithm utilizing alternating optimization strategy. In particular, each iteration of the algorithm involves the gradient descent update with backtracking line search. Numerical results show that when inputs are digital modulated signals and the signal-to-noise ratio is in the medium range, our proposed algorithm offers considerably higher sum rate than non-precoding and the traditional method which maximizes Gaussian-input sum capacity. Furthermore, a low-density parity-check coded system with iterative detection and decoding for MAC is presented to evaluate the bit error rate (BER) performance of precoders. BER results also indicate that the system with the proposed linear precoder achieves significant gains over the non-precoding system and the precoder designed for Gaussian inputs.

关键词： Multiple-input multiple-output (MIMO) multiple access channels (MAC) linear precoding finite discrete inputs

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linear precoding in distributed MIMO systems with partial CSIT

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

作者： Xu, Chongbin Zhang, Jianwen Zheng, Fuchun Ping, Li City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China Univ Reading Sch Syst Engn Reading RG6 6AY Berks England

We study the transmission problem in a distributed multiple-input multiple-output (MIMO) system consisting of several distributed transmitters and a common receiver. Assuming partial channel state information at the transmitter (CSIT), we propose a low-cost weighted channel matching and scattering (WCMS) linear precoding strategy. The proposed precoder can be decomposed into two parallel modules: channel matching (CM) and energy scattering. The signals generated by the CM modules from different transmitters provide a coherent gain with improved power efficiency. The use of the scattering modules provides robustness against CSIT uncertainty. By properly combining these two modules, WCMS can achieve coherent gain proportional to the accuracy of the available CSIT as well as robustness against CSIT error. WCMS is simple and fully decentralized and thus is highly suitable for a distributed MIMO system. Numerical results demonstrate that WCMS indeed achieves significant gains in distributed MIMO environments with partial CSIT.

关键词： Distributed multiple-input multiple-output (MIMO) systems Channel state information at the transmitter (CSIT) linear precoding Iterative detection

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linear precoding of unitary space-time code for GLRT decoder

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2008年第2期E91A卷 695-699页

作者： Guo, Yongliang Zhu, Shihua Liang, Zhonghua Xian Jiaotong Univ Dept Informat & Commun Engn Xian Peoples R China

For unitary space-time code (USTC), the impact of spatial correlation on error performance is investigated. A tighter and simpler upper bound is derived for generalized likelihood ratio test decoder. We establish that the spatial correlation does not change the diversity gain, whereas it degrades the error performance of USTC. Motivated by the precoding of space-time block code, we designed a precoder for USTC to handle the case of the joint transmit-receive correlation. Numerical results show that the degradation in performance due to spatial correlation can be considerably compensated by the proposed algorithm.

关键词： linear precoding pair-wise error probability generalized likelihood ratio test decoder unitary space-time code

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linear precoding Game for MIMO MAC With Dynamic Access Point Selection

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IEEE WIRELESS COMMUNICATIONS LETTERS 2015年第2期4卷 153-156页

作者： Mai, Ruikai Nguyen, Duy H. N. Le-Ngoc, Tho McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 0E9 Canada

This paper examines a non-cooperative game in pre-coding design for MIMO multiple-access channels with dynamic access point (AP) selection. This game is first shown to be a potential game, where the potential function is the sum rate achieved by successive interference cancellation. Due to the mixed-integer nature of the optimization variable, it is challenging to directly characterize the maximum of the potential function, which are closely related to the Nash equilibrium (NE) of the game. Instead, we establish the existence and achievability of the maximum through non-decreasing and upperbounded properties of the potential function as a direct result of our proposed update scheme. A distributed algorithm is designed where each player selfishly optimizes its AP selection and linear precoding strategy in a sequential manner. Convergence is a by-product of the established properties of the potential function which are materialized by an iterative waterfilling algorithm. Numerical results show that the algorithm is able to reach fast convergence and provides a system sum rate nearing that of the optimal centralized solution.

关键词： Resource allocation access point selection linear precoding potential games MIMO-OFDM

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linear precoding Based on Polynomial Expansion: Large-Scale Multi-Cell MIMO Systems

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2014年第5期8卷 861-875页

作者： Kammoun, Abla Mueller, Axel Bjornson, Emil Debbah, Merouane SUPELEC Alcatel Lucent Chair Flexible Radio F-91190 Gif Sur Yvette France KTH Royal Inst Technol ACCESS Linnaeus Ctr Signal Proc Lab S-10044 Stockholm Sweden

Large-scale MIMO systems can yield a substantial improvements in spectral efficiency for future communication systems. Due to the finer spatial resolution and array gain achieved by a massive number of antennas at the base station, these systems have shown to be robust to inter-user interference and the use of linear precoding appears to be asymptotically optimal. However, from a practical point of view, most precoding schemes exhibit prohibitively high computational complexity as the system dimensions increase. For example, the near-optimal regularized zero forcing (RZF) precoding requires the inversion of a large matrix. To solve this issue, we propose in this paper to approximate the matrix inverse by a truncated polynomial expansion (TPE), where the polynomial coefficients are optimized to maximize the system performance. This technique has been recently applied in single cell scenarios and it was shown that a small number of coefficients is sufficient to reach performance similar to that of RZF, while it was not possible to surpass RZF. In a realistic multi-cell scenario involving large-scale multi-user MIMO systems, the optimization of RZF precoding has, thus far, not been feasible. This is mainly attributed to the high complexity of the scenario and the non-linear impact of the necessary regularizing parameters. On the other hand, the scalar coefficients in TPE precoding give hope for possible throughput optimization. To this end, we exploit random matrix theory to derive a deterministic expression of the asymptotic signal-to-interference-and-noise ratio for each user based on channel statistics. We also provide an optimization algorithm to approximate the coefficients that maximize the network-wide weighted max-min fairness. The optimization weights can be used to mimic the user throughput distribution of RZF precoding. Using simulations, we compare the network throughput of the proposed TPE precoding with that of the suboptimal RZF scheme and show that our

关键词： Large-scale MIMO linear precoding multi-user systems polynomial expansion random matrix theory

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