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constant envelope precoding in multi-cell massive MIMO systems with channel uncertainty

PHYSICAL COMMUNICATION 2019年第0期34卷 203-209页

作者： Shahabi, Seyyed MohammadMahdi Ardebilipour, Mehrdad Hosseini, Seyed MohammadReza Omid, Yasaman KN Toosi Univ Technol Dept Elect Engn Tehran Iran

In this paper, the downlink transmission of a multi-cell massive multiple input multiple output (MIMO) system is studied, in which constant envelope precoding (CEP) is utilized for the precoding operation. The single-cell realization of CEP is presented in the literature in case exact CSI is at hand. In this work we aim to extend this structure to a multi-cell scenario with noisy CSI available to the base stations (BS). To this end, first of all, a fully cooperative cellular structure is presented, and then, an effort is made to mitigate the overhead by proposing a limited cooperation setting where the amount of the exchanged CSI among the cells is significantly decreased. Finally, by suggesting a distributed realization of the system, the overhead is diminished to its lowest value. Furthermore, it is attempted to analyze the system performance in case of having a noisy CSI and to compensate for this effect in the proposed schemes. Numerical results demonstrate that by reduction of the overhead in the limited cooperation and the distributed structures compared to the fully cooperative one, the performance faces merely a negligible drop, which compared to the throughput gain, seems entirely worth the cost. (C) 2019 Published by Elsevier B.V.

关键词： Massive MIMO constant envelope precoding Channel state information

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constant envelope precoding With Extended Degrees of Freedom Through Per-User Symbol Scaling

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IEEE COMMUNICATIONS LETTERS 2021年第5期25卷 1620-1624页

作者： Wang, Yi Chen, Ning Liu, Fan Li, Ang Zhou, Jianming Masouros, Christos Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China Southern Univ Sci & Technol Dept Elect & Elect Engn Shenzhen 518055 Peoples R China Xi An Jiao Tong Univ Fac Elect & Informat Engn Sch Informat & Commun Engn Xian 710049 Peoples R China UCL Dept Elect & Elect Engn London WC1E 7JE England

In this letter, we propose a novel constant envelope precoding (CEP) design for multi-user multi-input single-output (MU-MISO) downlink, where we exploit the extra degrees of freedom (DoFs) by allowing individual rotation and scaling for each constellation point. By jointly optimizing the transmitting signal matrix and the complex scaling factors, the signal-to-interference-and-noise-ratio (SINR) at the receiver is maximized. The formulated optimization problem is divided into two sub-problems and solved by the alternating optimization approach. We further propose a simplified gradient descent algorithm and extend our algorithm to frame-level precoding design. Simulation results show that the proposed algorithms outperform the existing CEP algorithms in terms of both symbol error rate (SER) and computational complexity.

关键词： Optimization Interference Signal to noise ratio precoding Linear programming Transmitting antennas Standards Alternating optimization constant envelope precoding Dinkelbach method gradient projection per-user scaling and rotating

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constant envelope precoding in Multi-Cell Massive MIMO Systems: A High-Throughput Pilot Contamination Aware Scheme

Constant Envelope Precoding in Multi-Cell Massive MIMO Syste...

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Conference on Wireless Advanced (WiAd)

作者： Shahabi, Seyyed MohammadMahdi Omid, Yasaman Ardebilipour, Mehrdad KN Toosi Univ Technol Dept Elect Engn Tehran Iran

ISBN: (纸本)9781538654231;9781538654224

In this paper, we study the downlink transmission of a massive multiple input multiple output (M-MIMO) system in which constant envelop precoding (CEP) is utilized. We consider the realistic case of a multi-cell M-MIMO using full cooperation in the system, and aim to increase the system throughput by presenting a partially cooperative structure. We focus on a scenario where the channel state information (CSI) is imperfect due to pilot contamination, and seek to compensate for this effect using a pilot contamination aware CEP (PCA-CEP) algorithm. Finally, we attempt to reduce the system complexity by presenting a relaxed form of the proposed PCA-CEP algorithm. Numerical results demonstrate that for a large decrease in the system overhead in the partially cooperative structure compared to the fully cooperative one, the performance faces merely an insignificant degradation. Moreover, the effect of pilot contamination on the system performance is depicted and it is shown how the PCA-CEP algorithm can compensate for these effects. Also, this algorithm is compared with its relaxed form based on the comparison benchmarks of complexity and average data rate, and it is illustrated that in the relaxed PCA-CEP, in spite of a slight drop in performance, the complexity is reduced immensely.

关键词： Massive MIMO constant envelope precoding Pilot Contamination

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Discrete-Phase constant envelope precoding for Massive MIMO Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2017年第5期65卷 2011-2021页

作者： Kazemi, Mohammad Aghaeinia, Hassan Duman, Tolga M. Amirkabir Univ Technol Dept Elect Engn Tehran 158754413 Iran Bilkent Univ Dept Elect & Elect Engn TR-06800 Ankara Turkey

We consider downlink of a multiuser massive multiple-input multiple-output (MIMO) system and focus on reducing the hardware costs by using a single common power amplifier and separate phase shifters (PSs) for antenna front-ends. In the previous literature, the use of analog PSs in this setup has been considered. Here, we study the use of practical digital PSs, which only support a limited set of discrete phases. Considering the sum of interference powers as a metric, we formulate the corresponding nonlinear discrete optimization problem and solve for the phases to be used during transmission. We devise a low-complexity algorithm, which employs a trellis structure providing suboptimal, but efficient and effective solutions. We demonstrate via examples that the proposed solutions have comparable performance to conventional analog PS-based algorithms. Furthermore, we prove that by utilizing discrete-phase constant envelope precoding, the interference can be made arbitrarily small by increasing the number of antennas. Therefore, the asymptotic gains promised by massive MIMO systems are preserved. We also obtain closed-form expressions for the rate loss due to errors in the phase and amplitude of the PSs, for both low and high SNR regimes.

关键词： constant envelope precoding massive MIMO multiuser MIMO digital phase shifter discrete optimization

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Per-Antenna constant envelope precoding and Antenna Subset Selection: A Geometric Approach

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2016年第23期64卷 6089-6104页

作者： Zhang, Jianjun Huang, Yongming Wang, Jiaheng Ottersten, Bjorn Yang, Luxi Southeast Univ Sch Informat Sci & Engn Nanjing 210096 Jiangsu Peoples R China Univ Luxembourg Interdisciplinary Ctr Secur Reliabil & Trust Luxembourg Luxembourg KTH Royal Inst Technol Elect Engn Stockholm Sweden

constant envelope (CE) precoding can efficiently control the peak-to-average power ratio (PAPR) and improve the power efficiency of power amplifiers in large-scale antenna array systems. Antenna subset selection (ASS), combined with CE precoding, can further improve power efficiency by using a part of antennas to combine the desired signal. However, due to the inherent nonlinearity, the joint optimization of CE precoding and ASS is very challenging and satisfactory solutions are yet not available. In this paper, we present new methods for CE precoding and ASS optimization from a geometric perspective. First, we show the equivalence between the CE precoder design and a polygon construction problem in the complex plane, thus transforming the algebraic problem into a geometric problem. Aiming to minimize the computational complexity, we further transform the CE precoder design into a triangle construction problem, and propose a novel algorithm to achieve the optimal CE precoder with only linear complexity in the number of used antennas. Then, we investigate the joint optimization of ASS and CE precoding to minimize the total transmit power while satisfying the QoS requirement. Based on the geometric interpretation, we develop an efficient ASS algorithm, which, using only addition and comparison operations, is guaranteed to find the globally optimal solution and provides robustness to channel uncertainty. The complexity of the proposed ASS algorithm is at most quadratic in the number of antennas in the worst case. The optimality and superiority of the proposed geometric methods are demonstrated via numerical results.

关键词： constant envelope precoding antenna subset selection large-scale multi-antenna systems

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Joint Quantized constant envelope precoding and Antenna Selection for Massive MU-MIMO Downlink Systems Using Higher-Order QAM

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IEEE ACCESS 2019年 7卷 80104-80109页

作者： Chen, Jung-Chieh Natl Kaohsiung Normal Univ Dept Optoelect & Commun Engn Kaohsiung 80201 Taiwan

This paper introduces the antenna selection (AS) mechanism into the quantized constant envelope (CE) precoding in massive multiuser multiple-input multiple-output systems to simultaneously reduce multiuser interference and hardware power consumption. However, this joint design problem requires optimizing over the precoding vector, the precoding factor, and the selected antenna subset. Unfortunately, these design parameters are connected. To address this problem, we propose an iterative algorithm developed from the alternating minimization (AltMin) framework to decouple the considered problem into two subproblems: the precoding factor design problem and the joint AS and the precoding vector design problem. The former can be easily solved approximately, whereas the latter incurs combinatorial complexity. We address this issue by using a simple yet effective coordinate update algorithm (CUA). We also develop a reduced-complexity version of CUA without performance loss. Moreover, the proposed CUA-based AltMin algorithm can be applied to the quantized CE precoding design problems without modification. The simulation results show that the proposed CUA-based AltMin algorithm considerably outperforms the existing algorithms for the quantized CE precoding design problems. In addition, when the AS mechanism is included in the quantized CE precoding design, CUA-AltMin with AS achieves the same or higher performance than CUA-AltMin without AS while providing further power savings.

关键词： Alternating minimization antenna selection constant envelope precoding coordinate update algorithm massive MIMO

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MISO Multicasting With constant envelope precoding

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IEEE WIRELESS COMMUNICATIONS LETTERS 2016年第6期5卷 588-591页

作者： Zhang, Shuowen Zhang, Rui Lim, Teng Joon Natl Univ Singapore Dept Elect & Comp Engn Singapore Singapore Natl Univ Singapore NUS Grad Sch Integrat Sci & Engn Singapore Singapore

In this letter, we study a multiple-input singleoutput (MISO) multicast system, where a multi-antenna transmitter sends a common message to multiple single-antenna users via constant envelope (CE) precoding. We aim to minimize the maximum symbol error rate over all users by jointly optimizing the CE precoding at the transmitter as well as the constellation scaling and rotation at each of the user receivers. First, we present a general problem formulation for any given symbol constellation. Then, we focus on the N-ary phase shift keying and show the corresponding problem is equivalent to a quadratically constrained quadratic program, which is non-convex and thus difficult to solve. We propose an approximate solution by applying the semi-definite relaxation technique and a customized Gaussian randomization method. Numerical results show that our proposed scheme significantly outperforms other benchmark schemes in MISO multicasting with CE precoding, and also performs closely to the optimal non-CE multicasting under the same total transmit power.

关键词： constant envelope precoding constellation scaling and rotation multicasting semi-definite relaxation

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A decentralized AoA-driven constant envelope precoding for multi-cell massive MIMO systems

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PHYSICAL COMMUNICATION 2021年 47卷 101391-101391页

作者： Mosleh, Marjan Abbasi Parizi, Mahboubeh Irannezhad Shahabi, Seyyed MohammadMahdi Ardebilipour, Mehrdad KN Toosi Univ Technol Tehran Iran KN Toosi Univ Technol Dept Elect Engn Tehran Iran

This paper encounters the problem of multi-cell precoding in downlink transmission of a massive multiple input multiple output (MIMO) system, where a constant envelope precoding (CEP) structure is employed with the aim of alleviating the implementation cost as well as improving the hardware efficiency. For this purpose, first, the optimization problem of the angle of arrival (AoA)-driven multi-cell CEP is arranged in a centralized form. In the following, the resultant problem is relaxed so that the equivalent problem would be convex. In addition, a new decentralized construction is proposed, in which the base station (BS) of each cell is able to independently determine its own precoding coefficients. Furthermore, a realistic situation with imperfect channel state information (CSI) is appended to the proposed structure in a way that the precoder undergoes a negligible performance loss. Numerical analysis demonstrates, from the downlink data rate per user standpoint, the performance of the proposed method confronts a slight loss in comparison with the general realization of the CEP, while the overall complexity of the system is markedly reduced. (C) 2021 Published by Elsevier B.V.

关键词： Massive MIMO constant envelope precoding Angle of arrival Channel state information

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constant-envelope precoding FOR SATELLITE SYSTEMS

CONSTANT-ENVELOPE PRECODING FOR SATELLITE SYSTEMS

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

作者： Tsinos, Christos G. Arora, Aakash Ottersten, Bjorn Univ Luxembourg SnT Interdisciplinary Ctr Secur Reliabil & Trust Luxembourg Luxembourg

ISBN: (纸本)9781509066315

In this paper, constant-envelope precoding techniques are presented for satellite-based communication systems. In the developed transmission technique the signals of the antennas are designed to be of constant amplitude, improving the robustness of the latter to the non-linear distortions on satellite systems, introduced by the employed on-board Traveling-Wave-Tube-Amplifiers. We consider the forward link of a multi-beam broadband satellite system where the aim is to design the signals at the gateway such that the desired symbols are transmitted to the intended user terminals and the transmitted signals from the satellite terminal are of constant amplitude. At first, the gateway signals are designed given that a fixed on-board beamformer is applied to the satellite terminal. Then, the case of an adaptive on-board beamformer is considered which is designed jointly with the gateway signals. The design of the gateway signals and the adaptive on-board beamformer, in the second case, requires solving difficult nonconvex problems. Efficient algorithmic solutions are developed based on the saddle point method. The effectiveness of the proposed approaches is verified via numerical results.

关键词： constant envelope precoding On-board Beamforming Ground-based precoding Non-linear precoding Satellite Communications

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Symbol-Level precoding for Low Complexity Transmitter Architectures in Large-Scale Antenna Array Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第2期18卷 852-863页

作者： Domouchtsidis, Stavros Tsinos, Christos G. Chatzinotas, Symeon Ottersten, Bjorn Univ Luxembourg Interdisciplinary Ctr Secur Reliabil & Trust SnT L-2721 Luxembourg Luxembourg

In this paper, we consider three transmitter designs for symbol-level-precoding (SLP), a technique that mitigates multiuser interference (MUI) in multiuser systems by designing the transmitted signals using the channel state information and the information-bearing symbols. The considered systems tackle the high hardware complexity and power consumption of existing SLP techniques by reducing or completely eliminating fully digital radio frequency (RF) chains. The first proposed architecture referred to as, Antenna Selection SLP, minimizes the MUI by activating a subset of the available antennas and thus, reducing the number of required RF chains to the number of active antennas. In the other two architectures, which we refer to as RF domain SLP, the processing happens entirely in the RF domain, thus eliminating the need for multiple fully digital RF chains altogether. Instead, the analog phase shifters directly modulate the signals on the transmit antennas. The precoding design for all the considered cases is formulated as a constrained least squares problem and efficient algorithmic solutions are developed via the Coordinate Descent method. Simulations provide insights into the power efficiency of the proposed schemes and the improvements over the fully digital counterparts.

关键词： Symbol level precoding non linear precoding phase shifters antenna selection constant envelope precoding multi-user system low complexity/low power transceiver large-scale antenna array systems

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