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Multi-User MIMO downlink precoding with Dynamic User Selection for Limited Feedback

SENSORS 2025年第3期25卷 866页

作者： Bakulin, Mikhail Ben Rejeb, Taoufik Kreyndelin, Vitaly Pankratov, Denis Smirnov, Aleksei Moscow Tech Univ Commun & Informat MTUCI Radio & Televis Dept Moscow 111024 Russia

In modern (5G) and future Multi-User (MU) wireless communication systems Beyond 5G (B5G) using Multiple-Input Multiple-Output (MIMO) technology, base stations with a large number of antennas communicate with many mobile stations. This technology is becoming especially relevant in modern multi-user wireless sensor networks in various application scenarios. The problem of organizing an MU mode on the downlink has arisen, which can be solved by precoding at the Base Station (BS) without using additional channel frequency-time resources. In order to utilize an efficient precoding algorithm at the base station, full Channel State Information (CSI) is needed for each mobile station. Transmitting this information for massive MIMO systems normally requires the allocation of high-speed channel resources for the feedback. With limited feedback, reduced information (partial CSI) is used, for example, the codeword from the codebook that is closest to the estimated channel vector (or matrix). Incomplete (or inaccurate) CSI causes interference from the signals, transmitted to neighboring mobile stations, that ultimately results in a decrease in the number of active users served. In this paper, we propose a new downlink precoding approach for MU-MIMO systems that also uses codebooks to reduce the information transmitted over a feedback channel. A key aspect of the proposed approach, in contrast to the existing ones, is the transmission of new, uncorrelated information in each cycle, which allows for accumulating CSI with higher accuracy without increasing the feedback overhead. The proposed approach is most effective in systems with dynamic user selection. In such systems, increasing the accuracy of CSI leads to an increase in the number of active users served, which after a few cycles, can reach a maximum value determined by the number of transmit antennas at the BS side. This approach appears to be promising for addressing the challenges associated with current and future massiv

关键词： B5G MU-MIMO downlink precoding quantized precoding limited feedback user selection massive MIMO

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downlink precoding for Multiple Users in FDD Massive MIMO Without CSI Feedback

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JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY 2016年第2期83卷 151-163页

作者： Tang, Ming-Fu Su, Borching Natl Taiwan Univ Grad Inst Commun Engn Taipei 10617 Taiwan

Massive MIMO can provide downlink access to multiple user equipments (UEs) through appropriate precoding or beamforming. To obtain precoding matrices for users, channel state information at the transmitter (CSI-T) is usually mandatory, requiring downlink training and CSI feedback at least in the frequency division duplex mode. However, such training is typically considered impractical because of the considerable amount of pilot signals and feedback overhead. In this paper, we propose downlink precoding methods that do not require UEs to generate feedback CSI for massive MIMO systems with uniform linear arrays. By recognizing the similarity between uplink and downlink channels, the base station is assumed to have partial knowledge on downlink channels (more specifically, the angles of departure of the major propagation paths of each user). Using such partial channel knowledge, we propose two precoding design methods based on robust beamforming and the design of a spatial-domain optimum finite impulse response filter. The simulation results demonstrate that the proposed method achieves a sum rate near that of a feedback-based precoding method with ideal CSI-T. In contrast to an alternative method based on beamspace division, the numerical results also display the performance advantage of the proposed method.

关键词： Massive MIMO Frequency-division duplex Robust beamforming downlink precoding Parks-McClellan algorithm

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downlink precoding With Mixed Statistical and Imperfect Instantaneous CSI for Massive MIMO Systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2018年第4期67卷 3028-3041页

作者： Qiu, Shuang Chen, Da Qu, Daiming Luo, Kai Jiang, Tao Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan 430074 Hubei Peoples R China

In this paper, the feasibility of a new downlink transmission mode in massive multi-input multi-output (MIMO) systems is investigated with two types of users, i.e., the users with only statistical channel state information (CSI) and the users with imperfect instantaneous CSI. The problem of downlink precoding design with mixed utilization of statistical and imperfect instantaneous CSI is addressed. We first theoretically analyze the impact of the mutual interference between the two types of users on their achievable rate. Then, considering the mutual interference suppression, we propose an extended zero forcing and an extended maximum ratio transmission precoding methods to minimize the total transmit power of base station and to maximize the received signal power of users, respectively. Thanks to the exploitation of statistical CSI, pilot-based channel estimation is avoided enabling more active users, higher system sum rate, and shorter transmission delay. Finally, simulations are performed to validate the accuracy of the theoretical analysis and the advantages of the proposed precoding methods.

关键词： downlink precoding imperfect instantaneous CSI massive MIMO mutual interference statistical CSI

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downlink precoding for DP-UPA FDD Massive MIMO via Multi-Dimensional Active Channel Sparsification

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2022年第8期21卷 6698-6713页

作者： Yu, Han Yi, Xinping Caire, Giuseppe Univ Liverpool Dept Elect Engn & Elect Liverpool L69 3BX Merseyside England Tech Univ Berlin Dept Elect Engn & Comp Sci D-10587 Berlin Germany

In this paper, we consider user selection and downlink precoding for an over-loaded single-cell massive multiple-input multiple-output (MIMO) system in frequency division duplexing (FDD) mode, where the base station is equipped with a dual-polarized uniform planar array (DP-UPA) and serves a large number of single-antenna users. Due to the absence of uplink-downlink channel reciprocity and the high-dimensionality of channel matrices, it is extremely challenging to design downlink precoders using closed-loop channel probing and feedback with limited spectrum resource. To address these issues, a novel methodology - active channel sparsification (ACS) - has been proposed recently in the literature for uniform linear array (ULA) to design sparsifying precoders, which substantially reduces channel feedback overhead. Pushing forward this line of research, we aim to facilitate the potential deployment of ACS in practical FDD massive MIMO systems, by extending it from ULA to DP-UPA with explicit user selection and making the current ACS implementation simplified. To this end, by leveraging Toeplitz matrix theory, we start with the spectral properties of channel covariance matrices from the lens of their matrix-valued spectral density function. Inspired by these properties, we extend the original ACS using scalar-weight bipartite graph representation to the matrix-weight counterpart. Building upon such matrix-weight bipartite graph representation, we propose a multi-dimensional ACS (MD-ACS) method, which is a generalization of original ACS formulation and is more suitable for DP-UPA antenna configurations. The nonlinear integer program formulation of MD-ACS can be classified as a generalized multi-assignment problem (GMAP), for which we propose a simple yet efficient greedy algorithm to solve it. Simulation results demonstrate the performance improvement of the proposed MD-ACS with greedy algorithm over the state-of-the-art methods based on the QuaDRiGa channel models.

关键词： downlink Transmission line matrix methods Covariance matrices Bipartite graph Massive MIMO Sparse matrices Base stations FDD massive MIMO downlink precoding user selection active channel sparsification

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downlink precoding for Cell-Free FBMC/OQAM Systems With Asynchronous Reception

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IEEE COMMUNICATIONS LETTERS 2023年第9期27卷 2427-2431页

作者： Qi, Yuhao Dang, Jian Zhang, Zaichen Wu, Liang Wu, Yongpeng Southeast Univ Frontiers Sci Ctr Mobile Informat Commun & Secur Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China Shanghai Jiao Tong Univ Dept Elect Engn Minhang 200240 Shanghai Peoples R China

In this work, an efficient precoding design scheme is proposed for downlink cell-free distributed massive multiple-input multiple-output (DM-MIMO) filter bank multi-carrier (FBMC) systems with asynchronous reception and highly frequency selectivity. The proposed scheme includes a multiple interpolation structure to eliminate the impact of response difference we recently discovered, which has better performance in highly frequency-selective channels. Besides, we also consider the phase shift in asynchronous reception and introduce a phase compensation in the design process. The phase compensation also benefits from the multiple interpolation structure and better adapts to asynchronous reception. Based on the proposed scheme, we theoretically analyze its ergodic achievable rate performance and derive a closed-form expression. Simulation results show that the derived expression can accurately characterize the rate performance, and FBMC with the proposed scheme outperforms orthogonal frequency-division multiplexing (OFDM) in the asynchronous scenario.

关键词： Symbols precoding Interpolation OFDM downlink Time-frequency analysis Frequency division multiplexing Cell-free DM-MIMO FBMC downlink precoding asynchronous reception strong frequency selectivity

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Multiple Antenna MMSE Based downlink precoding with Quantized Feedback or Channel Mismatch

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IEEE TRANSACTIONS ON COMMUNICATIONS 2008年第11期56卷 1859-1868页

作者： Dabbagh, Amir D. Love, David J. Qualcomm Inc San Diego CA 92121 USA Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA

In this paper, we consider the downlink of a multiuser wireless communication system with multiple antennas at the base station and users each with a single receive antenna. It is known that when channel state information (CSI) is available at the transmitter a large performance gain can be achieved. In a system employing time-division duplexing (TDD), CSI can be obtained at the base station if there is reciprocity between the forward and reverse channels. CSI can also be conveyed from the users to the base station via a limited-rate feedback channel in a frequency-division duplexing (FDD) system. In any case, channel estimation errors are inevitable due to the presence of background noise in the estimated signal and due to the finite number of feedback bits used in a limited-rate feedback system model. In this paper, we first consider the general case when partial CSI is available at the transmitter. We derive an MMSE based precoding technique that considers channel estimation errors as an integral part of the system design. Using rate-distortion theory and the generalized Lloyd vector quantization algorithm, we then specialize our results for the more practical limited-rate feedback system model. Compared to previously proposed precoding techniques such as channel inversion and regularized channel inversion, it is shown that the proposed precoding technique significantly improves the average bit error rate (BER) in the system. Furthermore, the performance of the proposed technique is investigated in the high signal-to-noise ratio (SNR) regime, and similar to [1], [2], it is shown that the proposed technique suffers from a ceiling effect that asymptotically limits the system performance.

关键词： MIMO broadcast channels downlink precoding channel inversion regularized channel inversion

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Near-Optimal downlink precoding for Two-Tier Priority-Based Wireless Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第2期14卷 628-638页

作者： Park, Ki-Hong Alouini, Mohamed-Slim King Abdullah Univ Sci & Technol Comp Elect & Math Sci & Engn CEMSE Div Thuwal 239556900 Saudi Arabia

In this paper, we study a two-tier priority-based wireless cellular network in which the primary base station (BS) has multiple antennas and the other terminals have a single antenna. We assume that we have two classes of users: high priority users and low priority users. We consider a rate maximization problem of the low priority users under signal-to-interference-plus-noise-ratio constraints on the high priority user to guarantee a certain quality-of-service for the high priority user. Since the interference due to the low priority users which communicate with each other via direct transmission may severely degrade the performance of the high priority user, we propose a BS-aided two-way relaying approach in which the BS helps relay the low priority users' signals instead of allowing them to communicate with each other via a direct path between them. In addition, an algorithm to find a near-optimal beamforming solution at the BS is proposed. The asymptotic results in the high power regime are derived to verify the average sum rate performance in the proposed scheme. Finally, based on some selected numerical results, we show that the proposed scheme outperforms the direct transmission scheme over a wide transmit power range.

关键词： Priority-based cellular network downlink precoding two-way relaying

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Particle swarm optimization assisted B-spline neural network based predistorter design to enable transmit precoding for nonlinear MIMO downlink

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NEUROCOMPUTING 2021年 458卷 336-348页

作者： Chen, Sheng Ng, Soon Xin Khalaf, Emad Morfeq, Ali Alotaibi, Naif Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England King Abdulaziz Univ Elect & Comp Engn Dept Fac Engn Jeddah 21589 Saudi Arabia

For the multiple-input multiple-output (MIMO) downlink employing high-order quadrature amplitude modulation signaling and with nonlinear high power amplifiers (HPAs) at base station transmitter, the existing precoding designs relying on the linear MIMO channel can no longer work. We propose an effi-cient and accurate predistorter design to enable transmit precoding for nonlinear MIMO downlink. Specifically, we obtain the closed-form least squares estimates of the nonlinear HPA's amplitude and phase response using two B-spline neural networks during training. The estimated HPA's phase response automatically yields the estimate of the predistorter's phase response. Based on the B-spline neural net-work estimate of the HPA's amplitude response, we construct a B-spline neural network model for the predistorter amplitude response, and we adopt a particle swarm optimization (PSO) algorithm to solve this highly nonlinear optimization problem. Using our accurate predistorter estimate to pre-compensate for the nonlinear distortions of the transmit HPAs, a standard full-digital transmit precoding design can readily be adopted to combat the MIMO channel interference. A simulation study is conducted to demonstrate the effectiveness of our proposed PSO assisted predistorter design. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Particle swarm optimization B-spline neural network Nonlinear inversion Nonlinear high power amplifier Predistorter Multi-input multi-output downlink precoding

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Power Allocation in 1-Bit Massive MIMO downlink with Zero-Forcing precoding 34

Power Allocation in 1-Bit Massive MIMO Downlink with Zero-Fo...

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IEEE 34th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Askerbeyli, Ferhad Xu, Wen Nossek, Josef A. Huawei Technol Dusseldorf GmbH Munich Res Ctr Munich Germany Tech Univ Munich Munich Germany

ISBN: (纸本)9781665464833

The use of 1-bit digital-to-analog converters (DACs) is a promising way to improve the energy efficiency of massive multiple-input-multiple-output (MIMO) systems. Many linear and nonlinear precoding techniques mitigating the severe quantization distortions have been introduced in order to enable the use of 1-bit DACs in the massive MIMO downlink. However, the vast majority of the proposed designs do not account for the channel strength imbalances between the users, which are highly likely to occur in the downlink scenarios. To achieve high sum rates in such scenarios, a user-specific power allocation scheme (USPA) is needed. In this paper, we propose a quantization aware USPA technique for the linear zero-forcing (ZF) precoder. Numerical results illustrate that higher achievable sum rates than the existing linear methods can be achieved with the proposed method, especially in the systems with low order modulated inputs. In the systems with higher modulation, the proposed method achieves similar performance to the existing methods, yet with a lower computational complexity.

关键词： massive MIMO user-specific power allocation 1-bit DACs downlink precoding constant envelope transmission

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Quantum Annealing for Large MIMO downlink Vector Perturbation precoding

Quantum Annealing for Large MIMO Downlink Vector Perturbatio...

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IEEE International Conference on Communications (ICC)

作者： Kasi, Srikar Singh, Abhishek Kumar Venturelli, Davide Jamieson, Kyle Princeton Univ Princeton NJ 08544 USA Univ Space Res Assoc Washington DC USA

ISBN: (纸本)9781728171227

In a multi-user system with multiple antennas at the base station, precoding techniques in the downlink broadcast channel allow users to detect their respective data in a noncooperative manner. Vector Perturbation precoding (VPP) is a non-linear variant of transmit-side channel inversion that perturbs user data to achieve full diversity order. While promising, finding an optimal perturbation in VPP is known to be an NP-hard problem, demanding heavy computational support at the base station and limiting the feasibility of the approach to small MIMO systems. This work proposes a radically different processing architecture for the downlink VPP problem, one based on Quantum Annealing (QA), to enable the applicability of VPP to large MIMO systems. Our design reduces VPP to a quadratic polynomial form amenable to QA, then refines the problem coefficients to mitigate the adverse effects of QA hardware noise. We evaluate our proposed QA based VPP (QAVP) technique on a real Quantum Annealing device over a variety of design and machine parameter settings. With existing hardware, QAVP can achieve a BER of 10(-4) with 100 mu s compute time, for a 6x6 MIMO system using 64 QAM modulation at 32 dB SNR.

关键词： Vector Perturbation downlink precoding Quantum Computation Quantum Annealing Optimization

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