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Energy-Aware and Rate-Aware Heuristic Beamforming in Downlink MIMO OFDMA Networks With Base-Station Coordination

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2015年第7期64卷 2897-2910页

作者： Venturino, Luca Buzzi, Stefano Univ Cassino & Southern Lazio Dept Elect & Informat Engn DIEI I-03043 Cassino Italy Natl Interuniv Consortium Telecommun I-03043 Cassino Italy

This paper addresses the problem of coordinated beamforming across a group of base stations (BSs) and frequency slots in the downlink of a multiple-input multiple-output (MIMO) orthogonal frequency-division multiple-access (OFDMA) cellular network. Three figures of merit are considered for system design under a per-BS power constraint: 1) the weighted sum of the rates (WSR) on the frequency slots of the coordinated BSs;2) the global energy efficiency (GEE), defined as the ratio between the network sum rate and the corresponding consumed power;and 3) the weighted sum of the energy efficiencies (WSEE) on the frequency slots of the coordinated BSs. The Karush-Kuhn-Tucker (KKT) conditions of the considered optimization problems are first derived to gain insight into the structure of the optimal beam-formers. Then, we propose a suboptimal design method that can be applied to all considered figures of merit. Numerical results are provided to assess the performance of the proposed beamforming strategies.

关键词： Base-station (BS) coordination beamforming cellular network downlink energy efficiency linear detection linear precoding multiple-input multiple-output (MIMO) orthogonal frequency-division multiple access (OFDMA) spectral efficiency sum-rate

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Estimation and Mitigation of Channel Non-Reciprocity in Massive MIMO

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2018年第10期66卷 2711-2723页

作者： Raeesi, Orod Gokceoglu, Ahmet Valkama, Mikko Tampere Univ Technol Dept Elect & Commun Engn Tampere 33720 Finland

Time-division duplex (TDD)-based massive MIMO systems rely on the reciprocity of the wireless propagation channels when calculating the downlink precoders based on uplink pilots. However, the effective uplink and downlink channels incorporating the analog radio front-ends of the base station (BS) and user equipments (UEs) exhibit non-reciprocity due to non-identical behavior of the individual transmit and receive chains. When the downlink precoder is not aware of such channel non-reciprocity (NRC), system performance can be significantly degraded due to the NRC-induced interference terms. In this paper, we consider a general TDD-based massive MIMO system where frequency-response mismatches at both the BS and UEs, as well as the mutual coupling mismatches at the BS large-antenna system all coexist and induce channel NRC. Based on the NRC-impaired signal models, we first propose a novel iterative estimation method for acquiring both the BS and UE side NRC matrices and then also propose an efficient NRC-aware downlink precoder design which utilizes the obtained estimates. Furthermore, an efficient pilot signaling scheme between the BS and UEs is introduced in order to facilitate executing the proposed estimation method and the NRC-aware precoding technique in practical systems. Comprehensive numerical results indicate substantially improved spectral efficiency performance when the proposed NRC estimation and NRC-aware precoding methods are adopted, compared to the existing state-of-the-art methods.

关键词： Beamforming channel non-reciprocity channel state information frequency-response mismatch linear precoding massive MIMO mutual coupling time division duplexing (TDD)

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Optimum linear joint transmit-receive processing for MIMO channels with QoS constraints

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2004年第5期52卷 1179-1197页

作者： Palomar, DP Lagunas, MA Cioffi, JM Princeton Univ Dept Elect Engn Princeton NJ 08844 USA Tech Univ Catalonia Dept Signal Theory & Commun Barcelona 08034 Spain Telecommun Tech Ctr Catalonia Barcelona 08034 Spain Stanford Univ Dept Elect Engn Stanford CA 94305 USA

This paper considers vector communications through multiple-input multiple-output (MIMO) channels with a set of quality of service (QoS) requirements for the simultaneously established substreams. linear transmit-receive processing (also termed linear precoder at the transmitter and linear equalizer at the receiver) is designed to satisfy the QoS constraints with minimum transmitted power (the exact conditions under which the problem becomes unfeasible are given). Although the original problem is a complicated nonconvex problem with matrix-valued variables, with the aid of majorization theory, we reformulate it as a simple convex optimization problem with scalar variables. We then propose a practical and efficient multilevel water-filling algorithm to optimally solve the problem for the general case of different QoS requirements. The optimal transmit-receive processing is shown to diagonalize the channel matrix only after a very specific prerotation of the data symbols. For situations in which the resulting transmit power is too large, we give the precise way to relax the QoS constraints in order to reduce the required power based on a perturbation analysis. We also propose a robust design under channel estimation errors that has an important interest for practical systems. Numerical results from simulations are given to support the mathematical development of the problem.

关键词： array signal processing beamforming joint transmit-receive equalization linear precoding MIMO channels space-time filtering water-filling

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Blind Frequency Ambiguity Resolution in OFDM Systems Using a linear Precoder

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WIRELESS PERSONAL COMMUNICATIONS 2013年第1期71卷 577-588页

作者： Xu, Weiyang Fu, Xiaolin Chongqing Univ Coll Commun Engn Chongqing 400044 Peoples R China Chongqing Jiaotong Univ Sch Mechatron & Automot Engn Chongqing 400074 Peoples R China

This paper presents a technique of the blind frequency ambiguity resolution for orthogonal frequency division multiplexing systems. The basic idea behind this method is a linear precoding scheme applied to data in predefined subcarriers before the inverse discrete Fourier transform to deploy a correlation structure, thus the integer part of the carrier frequency offset can be estimated after the discrete Fourier transform via cross correlation operations among these subcarriers. Performance analysis is carried out to gain insight into the relationship between the false estimation probability and system parameters. Allocation of these predefined subcarriers is optimized to avoid false estimation. Finally, numerical simulations are conducted to demonstrate the efficiency of the proposed method and the performance comparison with the existing estimators.

关键词： OFDM IFO Blind estimation linear precoding

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Optimal Beamforming for Gaussian MIMO Wiretap Channels With Two Transmit Antennas

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2017年第10期16卷 6726-6735页

作者： Vaezi, Mojtaba Shin, Wonjae Poor, H. Vincent Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Seoul Natl Univ Dept Elect & Comp Engn Seoul 08826 South Korea

A Gaussian multiple-input multiple-output wiretap channel in which the eavesdropper and legitimate receiver are equipped with arbitrary numbers of antennas and the transmitter has two antennas is studied in this paper. The input covariance matrix that achieves the secrecy capacity is determined. In particular, it is shown that the secrecy capacity of this channel can be achieved by linear precoding. precoding and power allocation schemes that maximize the achievable secrecy rate, and thus achieve the secrecy capacity, are developed. The secrecy capacity is then compared with the achievable secrecy rate of generalized singular value decomposition (GSVD)-based precoding, which is the best previously proposed technique for this problem. Numerical results demonstrate that substantial gain can be obtained in secrecy rate between the proposed and GSVD-based precodings.

关键词： Physical layer security MIMO wiretap channel secrecy rate beamforming linear precoding

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A Virtual MIMO Dual-Hop Architecture Based on Hybrid Spatial Modulation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第9期62卷 3161-3179页

作者： Stavridis, Athanasios Basnayaka, Dushyantha Sinanovic, Sinan Di Renzo, Marco Haas, Harald Univ Edinburgh Inst Digital Commun Sch Engn Edinburgh EH9 3JL Midlothian Scotland Univ Edinburgh Joint Res Inst Signal & Image Proc Sch Engn Edinburgh EH9 3JL Midlothian Scotland Glasgow Caledonian Univ Sch Engn & Built Environm Glasgow G4 0BA Lanark Scotland Univ Paris 11 L2S French Natl Ctr Sci Res CNRS Ecole Super Elect SUPELEC F-91400 Paris France

In this paper, we propose a novel Virtual Multiple-Input-Multiple-Output (VMIMO) architecture based on the concept of Spatial Modulation (SM). Using a dual-hop and Decode-and-Forward protocol, we form a distributed system, called Dual-Hop Hybrid SM (DH-HSM). DH-HSM conveys information from a Source Node (SN) to a Destination Node (DN) via multiple Relay Nodes (RNs). The spatial position of the RNs is exploited for transferring information in addition to, or even without, a conventional symbol. In order to increase the performance of our architecture, while keeping the complexity of the RNs and DN low, we employ linear precoding using Channel State Information (CSI) at the SN. In this way, we form a Receive-Spatial Modulation (R-SM) pattern from the SN to the RNs, which is able to employ a centralized coordinated or a distributed uncoordinated detection algorithm at the RNs. In addition, we focus on the SN and propose two regularized linear precoding methods that employ realistic Imperfect Channel State Information at the Transmitter. The power of each precoder is analyzed theoretically. Using the Bit Error Rate (BER) metric, we evaluate our architecture against the following benchmark systems: 1) single relay;2) best relay selection;3) distributed Space Time Block Coding (STBC) VMIMO scheme;and 4) the direct communication link. We show that DH-HSM is able to achieve significant Signal-to-Noise Ratio (SNR) gains, which can be as high as 10.5 dB for a very large scale system setup. In order to verify our simulation results, we provide an analytical framework for the evaluation of the Average Bit Error Probability (ABEP).

关键词： MIMO spatial modulation linear precoding relays decode-and-forward

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An Achievable Region for Double-Unicast Networks With linear Network Coding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第10期62卷 3621-3630页

作者： Xu, Xiaoli Zeng, Yong Guan, Yong Liang Ho, Tracey Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Natl Univ Singapore Dept Elect & Comp Engn Singapore 117583 Singapore CALTECH Dept Elect Engn Pasadena CA 91125 USA

In this paper, we present an achievable rate region for double-unicast networks by assuming that the intermediate nodes perform random linear network coding, and the source and sink nodes optimize their strategies to maximize the achievable region. Such a setup can be modeled as a deterministic interference channel, whose capacity region is known. For the particular class of linear deterministic interference channels of our interest, in which the outputs and interference are linear deterministic functions of the inputs, we show that the known capacity region can be achieved by linear strategies. As a result, for a given set of network coding coefficients chosen by the intermediate nodes, the proposed linear precoding and decoding for the source and sink nodes will give the maximum achievable rate region for double-unicast networks. We further derive a suboptimal but easy-to-compute rate region that is independent of the network coding coefficients used at the intermediate nodes, and is instead specified by the min-cuts of the network. It is found that even this suboptimal region is strictly larger than the existing achievable rate regions in the literature.

关键词： Network coding achievable rate region double-unicast networks linear precoding deterministic interference channels

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Asymptotic Rate Analysis of Downlink Multi-User Systems With Co-Located and Distributed Antennas

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第6期14卷 3046-3058页

作者： Wang, Junyuan Dai, Lin City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China

A great deal of efforts have been made on the performance evaluation of distributed antenna systems (DASs). Most of them assume a regular base-station (BS) antenna layout where the number of BS antennas is usually small. With the growing interest in cellular systems with large antenna arrays at BSs, it becomes increasingly important to study how the BS antenna layout affects the rate performance when a vast number of BS antennas are employed. This paper presents a comparative study of the asymptotic rate performance of downlink multi-user systems with multiple BS antennas either co-located or uniformly distributed within a circular cell. Two representative linear precoding schemes, maximum ratio transmission (MRT), and zero-forcing beamforming (ZFBF), are considered, with which the effect of BS antenna layout on the rate performance is characterized. The analysis shows that as the number of BS antennas L and the number of users K grow infinitely while L/K -> upsilon, the asymptotic average user rates with the co-located antenna (CA) layout for both MRT and ZFBF are logarithmic functions of the ratio.. With the distributed antenna (DA) layout, in contrast, the scaling behavior of the average user rate closely depends on the precoding schemes. With ZFBF, for instance, the average user rate grows unboundedly as L, K -> infinity and L/ K -> upsilon > 1, which indicates that substantial rate gains over the CA layout can be achieved when the number of BS antennas L is large. The gain, nevertheless, becomes marginal when MRT is adopted.

关键词： Asymptotic rate analysis downlink multi-user system distributed antenna system (DAS) linear precoding maximum ratio transmission (MRT) zero-forcing beamforming (ZFBF)

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Partial Stream Relaying in MIMO Relay Communications

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第1期62卷 205-218页

作者： Ryu, Jong Yeol Choi, Wan Kim, Dong In Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Sungkyunkwan Univ Sch Informat & Commun Engn Suwon 440746 South Korea

For a decode-and-forward (DF)-based multiple-input-multiple-output (MIMO) relaying system, we propose a novel partial-information relaying scheme that adaptively controls the number of streams to be forwarded to the destination. In the first transmission phase, a source node broadcasts data streams that consist of nonforwarding and forwarding streams. In the second transmission phase, a relay node forwards only forwarding streams to the destination, and a destination node decodes both nonforwarding and forwarding streams by successive interference cancellation. We consider two possible scenarios according to the availability of the channel-state information (CSI) at the source. The first scenario is that no CSI is available at the source, and therefore, a source node broadcasts data streams with equal power allocation. In this scenario, the number of data streams to be forwarded by the relay is determined according to the available CSI at the relay. For the second scenario, where the perfect CSI is available at the source, we propose a linearly combined precoding matrix for rate maximization. We also propose suboptimal schemes to reduce the complexity of the precoding design. Our analytical and numerical results show that the proposed scheme achieves a substantially higher rate than both the conventional relaying scheme, which forwards all the received streams, and the direct transmission scheme without relaying, regardless of CSI availability at the source.

关键词： Decode-and-forward (DF)-based relaying linear precoding multiple-input-multiple-output (MIMO)

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Performance Analysis of Multi-User Massive MIMO Downlink Under Channel Non-Reciprocity and Imperfect CSI

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IEEE TRANSACTIONS ON COMMUNICATIONS 2018年第6期66卷 2456-2471页

作者： Raeesi, Orod Gokceoglu, Ahmet Zou, Yaning Bjornson, Emil Valkama, Mikko Tampere Univ Technol Dept Elect & Commun Engn Tampere 33720 Finland Tech Univ Dresden Vodafone Chair Mobile Commun Syst D-01187 Dresden Germany Linkoping Univ Dept Elect Engn S-58183 Linkoping Sweden

This paper analyzes the performance of linearly precoded time division duplex based multi-user massive MIMO downlink system under joint impacts of channel non-reciprocity (NRC) and imperfect channel state information. We consider a generic and realistic NRC model that accounts for transceiver frequency-response as well as mutual coupling mismatches at both user equipment (UE) and base station (BS) sides. The analysis covers two most prominent forms of linear precoding schemes, namely, zero-forcing (ZF) and maximum-ratio transmission (MRT), and assumes that only the statistical properties of the beamformed channel are used at the UE side to decode the received signal. Under the approximation of i.i.d. Gaussian channels, closed-form analytical expressions are derived for the effective signal to interference and noise ratios (SINRs) and the corresponding capacity lower bounds. The expressions show that, in moderate to high SNR, the additional interference caused by imperfect NRC calibration can degrade the performance of both precoders significantly. Moreover, ZF is shown to be more sensitive to NRC than MRT. Numerical evaluations with practical NRC levels indicate that this performance loss in the spectral efficiency can be as high as 42% for ZF, whereas it is typically less than 13% for MRT. It is also shown that due to the NRC, the asymptotic large-antenna performance of both precoders saturate to an identical finite level. The derived analytical expressions provide useful tools and valuable technical insight, e.g., into calculating the NRC calibration requirements in BSs and UEs for any given specific performance targets in terms of effective SINR or the system capacity bound.

关键词： Capacity channel reciprocity frequency-response mismatch inter-user interference linear precoding multi-user massive MIMO mutual coupling SINR

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