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A Low-Complexity linear Precoding for MIMO Channels With Finite Constellation Inputs

IEEE WIRELESS COMMUNICATIONS LETTERS 2019年第5期8卷 1415-1418页

作者： Yang, Pei Yang, Hongwen Beijing Univ Posts & Telecommun Sch Wireless Commun Ctr Beijing 100876 Peoples R China

This letter investigates linear precoding scheme that maximizes the mutual information (MI) of multiple-input multiple-output (MIMO) channel with arbitrary input constellations. Since traditional precoding schemes which rely on the relationship between MI and minimum mean-square error (MMSE) are too time consuming, this letter first proposes a lower bound of MI with which the computational complexity can be significantly reduced compared with direct computation of MI, and we prove that the bound is asymptotically optimal with a constant shift. Based on this lower bound, a low-complexity precoding scheme is obtained. Numerical results verify the effectiveness and high-performance of the proposed precoding method compared with traditional precoding schemes.

关键词： linear precoder finite-alphabet inputs mutual information maximization low-complexity

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linear precoder Designs over MIMO Interference Channels with Finite-Alphabet Inputs

Linear Precoder Designs over MIMO Interference Channels with...

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IEEE Global Communications Conference

作者： Yongpeng Wu Chengshan Xiao Xiqi Gao John D. Matyjas Zhi Ding National Mobile Communications Research Laboratory Southeast University Nanjing 210096 P. R. China Department of Electrical and Computer Engineering Missouri University of Science and Technology Rolla MO 65409 USA Air Force Research Laboratory/RIT Rome NY 13441 USA Department of Electrical and Computer Engineering University of California Davis CA 95616 USA

ISBN: (纸本)9781479913510

This paper investigates the linear precoder design for multiple-input multiple-output (MIMO) K-user interference channels with finite alphabet inputs. We first obtain the general explicit expressions of the achievable rate of each user in MIMO interference channel systems. We study optimal transmission strategies in both high signal-to-noise ratio (SNR) and low SNR regions. We show that given finite alphabet inputs, a simple power allocation design can achieve optimal performance. In contrast, the well-known interference alignment technique for Gaussian input scenarios, only utilizes a partial interference-free signal space for transmission and leads to a constant performance loss when it is applied to finite-alphabet input scenarios. We determine this constant rate loss at high SNR. Moreover, we establish necessary conditions for the linear precoder design of the weighted sum-rate maximization. We also develop an efficient iterative algorithm for determining precoding matrices of all the users. Our numerical results show that for the practical digital modulated signals from discrete constellations, the proposed iterative algorithm achieves considerably higher sum-rate than the existing methods.

关键词： linear precoder achievable rate proposed iterative Interference channels multiple input multiple output systems Iterative algorithms signal to noise ratios transmission strategies signal space linear optimum performance

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Performance Assessment of MIMO Precoding on Realistic mmWave Channels

Performance Assessment of MIMO Precoding on Realistic mmWave...

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IEEE International Conference on Communications (IEEE ICC)

作者： Rebato, Mattia Rose, Luca Zorzi, Michele Univ Padua Dept Informat Engn I-35131 Padua Italy Nokia Bell Labs Paris France

ISBN: (纸本)9781728123738

In this paper, the performance of multi-user Multiple-Input Multiple-Output (MIMO) systems is evaluated in terms of SINR and capacity. We focus on the case of a downlink single-cell scenario where different precoders have been studied. Among the considered precoders, we range from different Grid of Beams (GoB) optimization approaches to linear precoders (e.g., matched filtering and zero forcing). This performance evaluation includes imperfect channel estimation, and is carried out over two realistic mmWave 5G propagation channels, which are simulated following either the measurement campaign done by New York University (NYU) or the 3GPP channel model. Our evaluation allows grasping knowledge on the precoding performance in mmWave realistic scenarios. The results highlight the good performance of GoB optimization approaches when a realistic channel model with directionality is adopted.

关键词： Millimeter-wave multi-user MIMO 5G interference optimization linear precoder grid of beams

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Optimization of linear MIMO precoding assuming MMSE-based turbo equalization

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DIGITAL SIGNAL PROCESSING 2018年 75卷 45-55页

作者： Nhat-Quang Nhan Rostaing, Philippe Amis, Karine Collin, Ludovic Radoi, Emanuel Univ Bretagne Occidentale CNRS UMR 6285 Lab STICC 6 Ave Le GorgeuCS 93837 F-29238 Brest 3 France CNRS Technopole Brest Iroise IMT AtlantiqueSignal & Communicat Dept Inst Mines TelecomLab STICCUMR 6285CS 83818 F-29238 Brest 3 France

In this paper, we focus on the optimization of a linear multiple-input multiple-output (MIMO) precoder assuming an outer forward error correction code and an iterative minimum mean square error (MMSE)-based interference cancellation (turbo equalization) at the receiver side. Given perfect channel state information at both sides of the communication, we propose a novel precoder that is specifically designed to use with turbo equalization. In contrast to the conventional precoders that maximize the mutual information (MI) between finite alphabet input and the corresponding output over the precoded MIMO channel, the proposed precoder aims to maximize the MI between the finite alphabet input and the corresponding output of the equalizer. The precoder is targeted for applications that require low complexity, where forward error correction (FEC) codes with low-complex encoding and decoding structures are used. Simulation results show the error-rate performance gain of the resulting precoder compared to two other reference precoders presented in the literature, which are derived from the maximization of the precoded MIMO channel MI. (C) 2018 Elsevier Inc. All rights reserved.

关键词： linear precoder Turbo equalization MMSE interference canceller Iterative receiver

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A Zero-Forcing linear precoder for Downlink Multi-user LoS MIMO Channels

A Zero-Forcing Linear Precoder for Downlink Multi-user LoS M...

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6th International Symposium on Telecommunications (IST) with Emphasis on Information and Communication Technology

作者： Alimadadi, Mohammadreza Mohammadi, Abbas Abdipour, Abdolali Soltani, Mohammad Dehghani Amirkabir Univ Technol Tehran Iran

ISBN: (纸本)9781467320733

In this paper we introduce an algorithm to design a zero-forcing linear precoder for downlink multi-user Line-of-Sight (LoS) MIMO systems. We observe that the existence of LoS component, changes the restrictions of conventional SVD-BD approach on channel dimensions and correlation of users. In addition, we find a new criterion that relates the received signal to noise ratio and optimal form of pure LoS channel matrix. We perceive that this algorithm improves performance nearly 1.5dB in compare to the SVD-BD method for Rayleigh channels in the case of two users.

关键词： MIMO systems linear precoder block diagonalization LoS channel Shannon capacity uniform linear array

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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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Multiuser Two-Way Nonregenerative MIMO Relaying With Nonconcurrent Traffic

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2015年第7期64卷 3268-3273页

作者： Budhiraja, Rohit Ramamurthi, Bhaskar Indian Inst Technol Madras Dept Elect Engn Madras 600036 Tamil Nadu India

Multiuser two-way relaying (MWR) enables multiple users to exchange data with a base station (BS) via a half-duplex relay in two channel uses. MWR assumes a specific traffic pattern, where users concurrently transmit/receive data to/from the BS. In this paper, we design a multiple-input-multiple-output (MIMO) two-way relaying protocol for a nonconcurrent traffic scenario, where one set of users transmits data to the BS in the first channel use, whereas another set of users receives data from the BS in the second channel use. By designing a novel linear precoder at the nonregenerative relay and by applying dirty-paper coding (DPC) at the BS, we maximize the: 1) minimum rate among all users;and 2) weighted sum rate (WSR) of the system, via the formulation of two geometric programs. Simulation results demonstrate the improved performance of the proposed precoder over conventional ones.

关键词： Dirty-paper coding (DPC) geometric program (GP) linear precoder nonconcurrent traffic two-way relay

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Base Station Cooperation for Confidential Broadcasting in Multi-Cell Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第10期14卷 5287-5299页

作者： He, Biao Yang, Nan Zhou, Xiangyun Yuan, Jinhong Australian Natl Univ Res Sch Engn Canberra ACT 0200 Australia Univ New S Wales Sch Elect Engn & Telecommun Sydney NSW 2052 Australia

We design linear precoders that perform confidential broadcasting in multi-cell networks for two different forms of base station (BS) cooperation, namely, multi-cell processing (MCP) and coordinated beamforming (CBf). We consider a two-cell network where each cell consists of an N-antenna BS and K single-antenna users. For such a network, we design a linear precoder based on the regularized channel inversion (RCI) for the MCP and a linear precoder based on the generalized RCI for the CBf. For each form of BS cooperation, we derive new channel-independent expressions to approximate the secrecy sum rate achieved by the precoder in the large system regime where K, N -> infinity with a fixed ratio beta = K/N. Using these results, we determine the optimal regularization parameters of the RCI and the generalized RCI precoders that maximize the secrecy sum rate for the MCP and the CBf, respectively. We further propose power-reduction strategies that significantly increase the secrecy sum rate at high transmit signal-to-noise ratios when the network load is high. Our numerical results substantiate the derived expressions, verify the optimality of the determined optimal regularization parameters, and demonstrate the performance improvement offered by the proposed power-reduction strategies.

关键词： Physical layer security confidential broadcasting multi-cell processing coordinated beamforming linear precoder

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Spatial Separation of Closely-Spaced Users in Measured Massive Multi-User MIMO Channels

Spatial Separation of Closely-Spaced Users in Measured Massi...

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IEEE International Conference on Communications (ICC)

作者： Flordelis, Jose Gao, Xiang Dahman, Ghassan Rusek, Fredrik Edfors, Ove Tufvesson, Fredrik Lund Univ Dept Elect & Informat Technol Lund Sweden

ISBN: (纸本)9781467364324

Fully-synchronous measurements of a massive multi-user multiple-input multiple-output (MU-MIMO) radio propagation channel are presented. We evaluate the ability of a massive MIMO system to spatially separate users located close to each other in line-of-sight (LOS) propagation conditions. The system consists of a base-station (BS) antenna array equipped with 64 dual-polarized antenna elements (128 ports) arranged in a cylindrical configuration, and eight single-antenna users. The users are confined to a five-meter diameter circle and move randomly at pedestrian speeds. The BS antenna array is located on top of a 20 m tall building and has LOS to the users. We examine user separability by studying singular value spread of the MU-MIMO channel matrix for several subsets of BS antenna array ports, along with sum-rate capacity and achievable sum-rates with both zero-forcing and matched-filtering linear precoders. We also analyze the performance of the user with the lowest rate. Finally, a comparison between the performance offered by the massive MIMO system and that of a conventional MU-MIMO system is provided. To the best of our knowledge, this is the first report of fully-synchronous dynamic measurements of a massive MIMO system. Our investigation shows that even users located close to each other in LOS propagation conditions can be spatially separated in a massive MIMO system.

关键词： multi-user multiple-input multiple-output systems MU-MIMO massive MIMO large-scale MIMO MIMO channel measurements spatial separation singular value spread sum-rate capacity sum-rate linear precoder

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Association and Joint Optimization of max-d_(min) precoder with MIMO Turbo Equalization

Association and Joint Optimization of max-d_(min) Precoder w...

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IEEE Global Communications Conference

作者： Nhat-Quang Nhan Philippe Rostaing Karine Amis Ludovic Collin Emanuel Radoi Universite Europeenne de Bretagne Universite de Brest Institut Mines-Telecom Telecom Bretagne Signal and Communications department CNRS

ISBN: (纸本)9781479959532

In this paper, we investigate the concatenation of the multiple input multiple output (MIMO) max-d_(min) linear precoder with an outer forward error correction (FEC) code at the transmitter. At the receiver side, the turbo equalization is taken into account, which iteratively exchanges the extrinsic information between a minimum mean square error interference canceller (MMSE IC) and a FEC decoder. The analysis done by extrinsic information transfer (EXIT) chart shows that a higher mutual information (MI) at the convergence state of the turbo equalization is observed thanks to the linear precoder. In addition, we exploit this property to propose a new precoder named max-d_(min)-mod. Numerical simulations are in accordance with the theoretical analysis, which exhibits a significant improvement of the error-rate of the turbo equalization as well as a significant gain of max-d_(min)-mod compared to original max-d_(min) precoder.

关键词： linear precoder Turbo equalization Iterative receiver

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