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Performance evaluation at the system level of reconfigurable space-time coding techniques for HSDPA

EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2005年第11期2005卷 1656-1667页

作者： Peppas, K Alexiou, A Lazarakis, F Al-Gizawi, T Axiotis, DI Natl Tech Univ Athens Inst Commun & Comp Syst GR-15773 Athens Greece Bell Labs Lucent Technol Wireless Res Swindon SN5 7DJ Wilts England Demokritos Natl Ctr Sci Res Inst Informat & Telecommun GR-15310 Athens Greece

A reconfigurable space-time coding technique is investigated, for a high-speed downlink packet access multiple-antenna network, which combats the effects of antenna correlation. Reconfigurability is achieved at the link level by introducing a linear precoder in a space-time block coded system. The technique assumes knowledge of the long-term characteristics of the channel, namely the channel correlation matrix at the transmitter. The benefits of the proposed reconfigurable technique as compared to the conventional non-reconfigurable versions are evaluated via system-level simulations. In order to characterize the system-level performance accurately and, at the same time, use a feasible approach in terms of computational complexity, a suitable link-to-system interface has been developed. The average system throughput and the number of satisfied users are the performance metrics of interest. Simulation results demonstrate the performance enhancements achieved by the application of reconfigurable techniques as compared to their conventional counterparts.

关键词： space-time block coding linear precoding reconfigurability system-level performance link-to-system level interface high-speed downlink packet access

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Massive MIMO in the UL/DL of Cellular Networks: How Many Antennas Do We Need?

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2013年第2期31卷 160-171页

作者： Hoydis, Jakob ten Brink, Stephan Debbah, Merouane Alcatel Lucent Bell Labs D-70435 Stuttgart Germany Supelec Alcatel Lucent Chair Flexible Radio F-91192 Gif Sur Yvette France

We consider the uplink (UL) and downlink (DL) of non-cooperative multi-cellular time-division duplexing (TDD) systems, assuming that the number N of antennas per base station (BS) and the number K of user terminals (UTs) per cell are large. Our system model accounts for channel estimation, pilot contamination, and an arbitrary path loss and antenna correlation for each link. We derive approximations of achievable rates with several linear precoders and detectors which are proven to be asymptotically tight, but accurate for realistic system dimensions, as shown by simulations. It is known from previous work assuming uncorrelated channels, that as N -> infinity while K is fixed, the system performance is limited by pilot contamination, the simplest precoders/detectors, i.e., eigenbeamforming (BF) and matched filter (MF), are optimal, and the transmit power can be made arbitrarily small. We analyze to which extent these conclusions hold in the more realistic setting where N is not extremely large compared to K. In particular, we derive how many antennas per UT are needed to achieve eta% of the ultimate performance limit with infinitely many antennas and how many more antennas are needed with MF and BF to achieve the performance of minimum mean-square error (MMSE) detection and regularized zero-forcing (RZF), respectively.

关键词： massive MIMO time-division duplexing channel estimation pilot contamination large system analysis large random matrix theory linear precoding linear detection

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Asymptotic Capacity of the Separated MIMO Two-Way Relay Channel

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IEEE TRANSACTIONS ON INFORMATION THEORY 2011年第11期57卷 7542-7554页

作者： Yang, Hyun Jong Chun, Joohwan Paulraj, Arogyaswami Korea Ocean Res & Dev Inst Taejon South Korea Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Stanford Univ Dept Elect Engn Stanford CA 94305 USA

A multiple-input multiple-output two-way relay channel consisting of two communication nodes and a full-duplex relay node in which no direct link exists between the two communication nodes is considered. We propose an achievable scheme that employs horizontally encoded lattice codes combined with generalized singular value decomposition-based precoding for the first phase. The second phase of the proposed scheme follows the fundamentals of the previous scheme, which uses vertically encoded structural bining, with the only difference that the added codeword of the two codewords from the communication nodes, instead of those two individual codewords, is decoded and retransmitted in the proposed scheme. We show that the proposed scheme achieves the cut-set bound asymptotically as the signal-to-noise ratios of the channels tend to infinity.

关键词： Generalized singular value decomposition (GSVD) lattice coding linear precoding multiple-input multiple-output (MIMO) channels two-way relay channels (TWRC)

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A New Precoder Design for Blind Channel Estimation in MIMO-OFDM Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2014年第12期13卷 7011-7024页

作者： Noh, Song Sung, Youngchul Zoltowski, Michael D. Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea

A new precoder for precoding-based blind channel estimation for MIMO-OFDM systems is proposed. In the proposed scheme, only a small number of data symbols, commensurate with the channel length, are linearly precoded prior to transmission to induce the signal correlation needed for the scheme to blindly estimate the channels. Similar to how pilot symbols are transmitted, the subcarriers carrying these linearly precoded data symbols are equi-spaced across the frequency band. The other subcarriers carry data symbols in the standard way, enabling MLD per subcarrier and also allowing for MIMO linear precoding across antennas at each subcarrier. This is in contrast to previous precoding-based blind channel estimation schemes which precode all of the data symbols so that every subcarrier carries a linear combination of symbols, aking the resulting joint MLD problem infeasible. In addition, this also makes it infeasible to employ MIMO precoding per subcarrier across the transmit antennas. The proposed precoder is designed via a multi-stage optimization process that seeks to minimize both channel estimation error and symbol estimation error. For channel estimation purposes, the resulting optimal design offers low-cost features such as sign change and FFT while providing reasonable channel estimation performance for low mobility applications.

关键词： Blind channel estimation linear precoding OFDM MIMO Hadamard matrix

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Low Complexity Iterative-QR (IQR) Precoder Design Based on Structure Blocks for Massive MIMO System

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WIRELESS PERSONAL COMMUNICATIONS 2018年第1期102卷 19-30页

作者： Mok, Li Suet Noordin, Nor K. Sali, Aduwati Hashim, Fazirulhisyam Ng, Chee Kyun Univ Putra Malaysia Fac Engn Dept Comp & Commun Syst Engn Serdang 43400 Selangor Darul Malaysia Univ Putra Malaysia Fac Engn Wireless & Photon Network WiPNet Res Ctr Serdang 43400 Selangor Darul Malaysia Univ Putra Malaysia Malaysian Res Inst Ageing Serdang 43400 Selangor Darul Malaysia

Massive multiple-input multiple-output (MIMO) technology is a promising technique having a high spectral efficiency for future wireless systems. Counterintuitively, the practical issues of transmitted signals are being attenuated by fading, propagation limitations, and implement non-linear precoding are solved by enlarging system dimensions. However, the computational complexity of precoding grows with the system dimensions. The existence block diagonalization (BD) precoding, which completely pre-cancels the multiuser interference is very complicated to implement with the use of a large number of BS antennas, since it considers full multiplexing order. Motivated by the high performance of the BD and generalized for the case when the users have multiple antennas, we propose a structure blocks based on iterative QR decompositions (IQRDs) to compute the precoding scheme. The proposed BLIQR-based precoder designed partitioned the channel matrix into capable square-wise blocks matrix and the IQRDs are applied to the blocks channel matrix. The channel matrix is partitioned such that it can fulfill the multiplexing order for the use in Massive MIMO. The computational complexity of the proposed design is effectively reduced and the sum-rate performance is improved, especially in large number of BS antennas. The performance of the proposed scheme achieves a good trade-off between throughput and computational complexity.

关键词： Massive MIMO linear precoding Downlink channel Block diagonalization Computational complexity Multi-antennas users

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linear Precoder Design Through Cut-Off Rate Maximization in MIMO-OFDM Coded Systems With Imperfect CSIT

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第3期58卷 1741-1755页

作者： Rey, Francesc Lamarca, Meritxell Vazquez, Gregori Univ Politecn Cataluna Dept Signal Theory & Commun ES-08034 Barcelona Spain

This paper proposes a linear transmitter design that aims at minimizing the packet error rate (PER) using partial channel state information at the transmitter (CSIT). The design is based on the maximization of the channel cut-off rate, which provides an upper bound on the codeword error probability over the ensemble of random codes. The advantage of this optimization criterion is that it allows to get a low PER while keeping the design independent of the specific channel code used in the system. The algorithm is derived for a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system, and adopts a Bayesian approach to design an algorithm robust to CSI errors. The proposed algorithm converges to the open-loop transmission scheme for the case of no channel knowledge and it converges to the closed-loop design with perfect CSI for the case of no uncertainty. Simulation results evidence the performance gain in terms of PER and throughput of the proposed algorithm when compared to more commonly used optimization criteria.

关键词： Channel state information (CSI) cut-off rate imperfect CSI joint transceiver optimization linear precoding MIMO channels OFDM packet error rate (PER) power allocation wireless communications

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Precoder Design for Massive MIMO Downlink With Matrix Manifold Optimization

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2024年 72卷 1065-1080页

作者： Sun, Rui Wang, Chen Lu, An-An Gao, Xiqi Xia, Xiang-Gen Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China Univ Delaware Dept Elect & Comp Engn Newark NJ 19716 USA

We investigate the weighted sum-rate (WSR) maximization linear precoder design for massive multiple-input multiple-output (MIMO) downlink. We consider a single-cell system with multiple users and propose a unified matrix manifold optimization framework applicable to total power constraint (TPC), per-user power constraint (PUPC) and per-antenna power constraint (PAPC). We prove that the precoders under TPC, PUPC and PAPC are on distinct Riemannian submanifolds, and transform the constrained problems in Euclidean space to unconstrained ones on manifolds. In accordance with this, we derive Riemannian ingredients, including orthogonal projection, Riemannian gradient, Riemannian Hessian, retraction and vector transport, which are needed for precoder design in the matrix manifold framework. Then, Riemannian design methods using Riemannian steepest descent, Riemannian conjugate gradient and Riemannian trust region are provided to design the WSR-maximization precoders under TPC, PUPC or PAPC. Riemannian methods do not involve the inverses of the large dimensional matrices during the iterations, reducing the computational complexities of the algorithms. Complexity analyses and performance simulations demonstrate the advantages of the proposed precoder design.

关键词： linear precoding manifold optimization per-antenna power constraint per-user power constraint total power constraint weighted sum-rate

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Impact of General Channel Aging Conditions on the Downlink Performance of Massive MIMO

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第2期66卷 1428-1442页

作者： Papazafeiropoulos, Anastasios K. Imperial Coll London Dept Elect & Elect Engn London SW7 2AZ England

Recent works have identified massive multiple-input multiple-output (MIMO) as a key technology for achieving substantial gains in spectral and energy efficiency. Additionally, the turn to low-cost transceivers, being prone to hardware impairments, is the most effective and attractive way for cost-efficient applications concerning massive MIMO systems. In this context, the impact of channel aging, which severely affects performance, is investigated herein by considering a generalized model. Specifically, we show that both Doppler shift due to the users' relative movement, as well as phase noise due to noisy local oscillators, contribute to channel aging. To this end, we first propose a joint model, encompassing both effects, to investigate the performance of a massive MIMO system based on the inevitable time-varying nature of realistic mobile communications. Then, we derive the deterministic equivalents for the signal-to-noise-and-interference ratios (SINRs) with maximum ratio transmission (MRT) and regularized zero-forcing (RZF) precoding. Our analysis not only demonstrates a performance comparison between MRT and RZF under these conditions but, most importantly, also reveals interesting properties regarding the effects of user mobility and phase noise. In particular, the large antenna limit behavior profoundly depends on both effects, but the burden due to user mobility is much more detrimental than phase noise even for moderate user velocities (approximate to 30 km/h), whereas the negative impact of phase noise is noteworthy at lower mobility conditions. Moreover, massive MIMO systems are favorable even in general channel aging conditions. Nevertheless, we demonstrate that the transmit power of each user to maintain a certain quality of service can be scaled down, at most, by 1 root M (M is the number of base station antennas), which indicates that the joint effects of phase noise and user mobility do not degrade the power scaling law but only the achievable sum-r

关键词： Channel estimation Doppler shift hardware impairments linear precoding massive multiple-input multiple-output (MIMO) phase noise time-division duplex (TDD) systems

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linear Massive MIMO Precoders in the Presence of Phase Noise-A Large-Scale Analysis

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2016年第5期65卷 3057-3071页

作者： Krishnan, Rajet Khanzadi, M. R. Krishnan, N. Wu, Y. Graell i Amat, Alexandre Eriksson, Thomas Schober, R. Chalmers Univ Technol Dept Signals & Syst S-41296 Gothenburg Sweden Qualcomm San Diego CA 92121 USA Univ Erlangen Nurnberg Inst Digital Commun D-91058 Erlangen Germany

We study the impact of phase noise on the downlink performance of a multiuser multiple-input-multiple-output (MIMO) system, where the base station (BS) employs a large number of transmit antennas M. We consider a setup where the BS employs M-osc free-running oscillators, and M/M-osc antennas are connected to each oscillator. For this configuration, we analyze the impact of phase noise on the performance of zero forcing (ZF), regularized ZF, and matched filter precoders when M and the number of users K are asymptotically large, whereas the ratio M/K = beta is fixed. We analytically show that the impact of phase noise on the signal-to-interference-plus-noise ratio (SINR) can be quantified as an effective reduction in the quality of the channel state information (CSI) available at the BS when compared with a system without phase noise. As a consequence, we observe that as M-osc increases, the SINR performance of all considered precoders degrades. On the other hand, the variance of the random phase variations caused by the BS oscillators reduces with increasing M-osc. Through Monte Carlo simulations, we verify our analytical results and compare the performance of the precoders for different phase noise and channel noise variances. For all considered precoders, we show that when beta is small, the performance of the setup where all BS antennas are connected to a single oscillator is superior to that of the setup where each BS antenna has its own oscillator. However, the opposite is true when beta is large and the signal-to-noise ratio (SNR) at the users is low.

关键词： Broadcast channel (BC) linear precoding massive multiple-input multiple-output (MIMO) multiuser (MU) MIMO phase noise random matrix theory (RMT)

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Design of isotropic orthogonal transform algorithm-based multicarrier systems with blind channel estimation

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IET COMMUNICATIONS 2012年第16期6卷 2695-2704页

作者： Du, J. Xiao, P. Wu, J. Chen, Q. Royal Inst Technol KTH Sch Elect Engn SE-10044 Stockholm Sweden Univ Surrey Guildford CCSR Fac Engn & Phys Sci Surrey GU2 7XH England Alcatel Lucent Pudong Jinqiao Bell Labs Shanghai 201206 Peoples R China Southwest Jiaotong Univ Key Lab Informat Coding & Transmiss Chengdu 610031 Peoples R China

Orthogonal frequency division multiplexing (OFDM) technique has gained increasing popularity in both wired and wireless communication systems. However, in the conventional OFDM systems the insertion of a cyclic prefix (CP) and the transmission of periodic training sequences for purpose of channel estimation decrease the system's spectral efficiency. As an alternative to OFDM, isotropic orthogonal transform algorithm (IOTA)-based multicarrier system adopts a proper pulse shaping with good time and frequency localisation properties to avoid interference and maintain orthogonality in real field among sub-carriers without the use of CP. In this study, the authors propose linearly precoded IOTA-based multicarrier systems to achieve blind channel estimation by utilising the structure of auto-correlation and cross-correlation matrices introduced by precoding. The results show that the proposed IOTA-based multicarrier systems achieve better power and spectral efficiency compared with the conventional OFDM systems.

关键词： orthogonal frequency division multiplexing technique Electromagnetic compatibility and interference wireless communication system cyclic prefix insertion Signal processing and detection autocorrelation structure Codes precoding correlation methods blind channel estimation interference avoidance frequency localisation property cyclic codes linear precoding matrix algebra OFDM modulation channel estimation IOTA multicarrier system orthogonal codes periodic training sequence transmission Algebra CP insertion OFDM technique pulse shaping isotropic orthogonal transform algorithm- cross-correlation matrix wired communication system Communication channel equalisation and identification spectral efficiency interference suppression

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