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Transmit-Power Efficient linear precoding Utilizing Known Interference for the Multiantenna Downlink

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2014年第9期63卷 4383-4394页

作者： Razavi, S. Morteza Ratnarajah, Tharmalingam Masouros, Christos Univ Edinburgh Inst Digital Commun Edinburgh EH9 3JL Midlothian Scotland UCL Dept Elect & Elect Engn London WC1E 7JE England

It has been shown that the knowledge of both channel and data information at the base station prior to downlink transmission can help increase the received signal-to-noise ratio (SNR) of each user without the need to increase the transmitted power. Achievability is based on the idea of phase alignment (PA) precoding, where instead of nulling out the destructive interference, it judiciously rotates the phases of the transmitted symbols. In this way, they add up coherently at the intended user and yield higher received SNRs. In addition, it is well known that regularized channel inversion (RCI) precoding improves the performance of channel inversion (CI) in multiantenna downlink communications. In line with this and similar to the RCI precoding, in this paper, we propose the idea of regularized PA (RPA), which is shown to improve the performance of original PA precoding. To do this, we first rectify the original PA precoding, deriving a closed-form expression to evaluate the amount of transmit-power reduction achieved for the same average output SNR compared with CI precoding. We then use this new analysis to select the appropriate regularization factor for our proposed RPA scheme. It is shown by means of theoretical analysis and simulations that the proposed RPA precoding outperforms CI, RCI, and PA precoders from both symbol error rate (SER) and throughput perspectives and provides a more power-efficient alternative. This is particularly pronounced as the number of transmit antennas becomes larger, where up to a 50-times reduction in the transmit power is achieved by RPA (PA) compared with RCI (CI) precoding for a given performance.

关键词： linear precoding multiantenna downlink transmission phase alignment (PA) power-efficient communications

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linear precoding of OFDMA Signals to Minimize their Instantaneous Power Variance

Linear Precoding of OFDMA Signals to Minimize their Instanta...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Falconer, David Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

ISBN: (纸本)9781424463985

Is there an optimum linear block precoding for orthogonal frequency division multiple access (OFDMA) signals that significantly reduces their instantaneous power variance? We explore this question for linear block-precoded OFDMA signals with contiguous frequency mapping. We find that there is an optimum linear block precoding, but its advantage over DFT precoding (such as that used for the uplink signaling in the 3GPP-LTE standard) is rather small.

关键词： OFDM multicarrier single carrier linear precoding peak to average power ratio nonlinear amplification instantaneous power

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linear precoding for MIMO Multiple Access Channels with Discrete-Constellation Inputs

Linear Precoding for MIMO Multiple Access Channels with Disc...

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54th Annual IEEE Global Telecommunications Conference (GLOBECOM)

作者： Wang, Mingxi Zeng, Weiliang Xiao, Chengshan Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65401 USA Tsinghua Univ Dept Elect Engn Beijing Peoples R China

ISBN: (纸本)9781424492688

In this paper, we study linear precoding for multiple-input multiple-output (MIMO) multiple access channels (MAC) with discrete-constellation inputs. We derive the constellation-constrained capacity region for the MIMO MAC with an arbitrary number of users. Due to the non-concavity of the objective function, we obtain the necessary conditions for the weighted sum rate (WSR) maximization problem through Karush-Kuhn-Tucker (KKT) analysis. To find the optimal precoding matrices, we propose an iterative algorithm utilizing alternating optimization strategy and gradient descent update. Numerical results show that when inputs are digital modulated signals and the signal-to-noise ratio (SNR) is in the medium range, our proposed algorithm offers significantly higher sum rate than non-precoding and the traditional method which maximizes Gaussian-input sum capacity. Furthermore, the bit error rate (BER) results of a low-density parity-check (LDPC) coded system also indicate that the system with the proposed linear precoder achieves significant gains over other methods.

关键词： BER Bit error rate Covariance matrix Gaussian-input sum capacity KKT analysis Karush-Kuhn-Tucker analysis LDPC coded system MIMO MIMO MAC MIMO communication Parity check codes Phase shift keying SNR Signal to noise ratio Vectors WSR maximization problem bit error rate channel coding constellation-constrained capacity region digital modulated signals discrete-constellation inputs error statistics gradient descent update gradient methods iterative algorithm iterative methods linear codes linear precoding low-density parity-check coded system multiple-input multiple-output multiple access channels optimal precoding matrices optimisation parity check codes signal-to-noise ratio weighted sum rate maximization problem wireless channels

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linear precoding Based on Switched Relaying Processing for Multiuser MIMO Relay Systems

Linear Precoding Based on Switched Relaying Processing for M...

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12th IEEE International Workshop on Signal Processing Advances in Wireless Communications

作者： Cai, Yunlong Le Ruyet, Didier de Lamare, Rodrigo C. Roviras, Daniel CNAM Elect & Commun Lab F-75141 Paris France Univ York Dept Elect York YO10 5DD N Yorkshire England

ISBN: (纸本)9781424493326

In this work, we propose a linear base station (BS) precoding strategy based on switched relaying (SR) processing for downlink multiuser multiple-input multiple-output (MIMO) relay systems. The BS and the MIMO relay station (RS) are both equipped with a codebook of interleaving matrices. For a given channel state information (CSI) the selection function at the BS chooses the optimum interleaving matrix from the codebook based on the maximum sum received signal-to-interference-plus-noise ratio (SINR) or sum rate to design the linear BS precoder. Prior to the payload transmission the BS sends the index corresponding to the selected interleaving matrix to the RS, where the optimum interleaving matrix is selected as the optimum relay processing matrix. The entries of the codebook are randomly generated unitary matrices. Simulation results show that the performance of the proposed techniques is significantly better than prior art in the case of perfect CSI.(1)

关键词： Antennas Joints MIMO MIMO communication Quantization Relays Signal to noise ratio Switches codebook linear base station precoding strategy linear precoding multiuser MIMO relay system optimum interleaving matrix precoding signal-to-interference-plus-noise ratio switched relaying processing

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Achievable Sum-Rate of MU-MIMO Cellular Two-Way Relay Channels: Lattice Code-Aided linear precoding

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2012年第8期30卷 1304-1318页

作者： Yang, Hyun Jong Choi, Youngchol Lee, Namyoon Paulraj, Arogyaswami Stanford Univ Dept Elect Engn Stanford CA 94305 USA Korea Inst Ocean Sci & Technol Taejon South Korea Univ Texas Austin Wireless Networking & Commun Grp Austin TX 78712 USA

We derive a new sum-rate lower bound of the multiuser multi-input multi-output (MU-MIMO) cellular two-way relay channel (cTWRC) which is composed of a base station (BS) and a relay station (RS), both with multiple antennas, and non-cooperative mobile stations (MSs), each with a single antenna. In the first phase, we show that network coding based on decode-and-forward relaying can be generalized to arbitrary input cardinality through proposed lattice code-aided linear precoding, despite the fact that precoding is permitted only at the BS due to non-cooperation among the MSs. In addition, a new sum-rate lower bound for the second phase is derived by showing that the two spatial decoding orders at the BS and MSs for one-sided zero-forcing dirty-paper-coding must be identical. From the fundamental gain of network coding, our sum-rate lower bound achieves the full multiplexing gain regardless of the number of antennas at the BS or RS, and strictly exceeds the previous lower bound which is based on traditional multiuser decoding in the first phase. Furthermore, it is shown that our lower bound asymptotically achieves the sum-rate upper bound in the presence of signal-to-noise ratio (SNR) asymmetry in high SNR regime, and sufficient conditions for this SNR asymmetry are drawn.

关键词： Multiuser (MU)-MIMO cellular two-way relay channel (cTWRC) decode-and-forward (DF) nested lattice codes linear precoding achievable sum-rate

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Finite Word Length Effects on Transmission Rate in Zero Forcing linear precoding for Multichannel DSL

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2009年第4期57卷 1469-1482页

作者： Sayag, Eitan Leshem, Amir Sidiropoulos, Nicholas D. Bar Ilan Univ Sch Engn IL-52900 Ramat Gan Israel Ben Gurion Univ Negev Dept Math IL-84105 Beer Sheva Israel Delft Univ Technol Fac Elect Engn Math & Comp Sci Delft Netherlands Tech Univ Crete Dept Elect & Comp Engn Khania Greece

Crosstalk interference is the limiting factor in transmission over copper lines. Crosstalk cancellation techniques show great potential for enabling the next leap in DSL transmission rates. An important issue when Implementing crosstalk cancellation techniques In hardware is the effect of finite word length on performance. In this paper, we provide an analysis of the performance of linear zero-forcing precoders, used for crosstalk compensation, in the presence or finite word length errors. We quantify analytically the tradeoff between precoder word length and transmission rate degradation. More specifically, we prove a simple formula for the transmission-rate loss as a function of the number of bits used for precoding, the signal-to-noise ratio, and the standard line parameters. We demonstrate, through simulations on real lines, the accuracy or our estimates. Moreover, our results tire stable in the presence of channel estimation errors. Lastly, we show how to use these estimates as a design tool for DSL linear crosstalk precoders. For example, we show that for standard VDSL2 precoded systems, 14 bit representation of the precoder entries results in capacity loss below 1 % for lines over 300 m.

关键词： Capacity estimates linear precoding multichannel DSL quantization vectoring

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Joint Design of Optimal Cooperative Jamming and Power Allocation for linear precoding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第9期62卷 3285-3298页

作者： Yang, Jun Kim, Il-Min Kim, Dong In Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada Sungkyunkwan Univ SKKU Sch Informat & Commun Engn Suwon 440746 South Korea

linear precoding and cooperative jamming for multiuser broadcast channel is studied to enhance the physical layer security. We consider the system where multiple independent data streams are transmitted from the base station to multiple legitimate users with the help of a friendly jammer. It is assumed that a normalized linear precoding matrix is given at the base station, whereas the power allocated to each user is to be determined. The problem is to jointly design the power allocation across different users for linear precoding and the cooperative jamming at the friendly jammer. The goal is to maximize a lower bound of the secrecy rate, provided that a minimum communication rate to the users is guaranteed. The optimal solution is obtained when the number of antennas at the friendly jammer is no less than the total number of antennas at the users and eavesdropper. Moreover, a suboptimal algorithm is proposed, which can be applied for all the scenarios. Numerical results demonstrate that the proposed schemes are effective for secure communications.

关键词： Cooperative jamming linear precoding multiuser broadcast channel physical layer security

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Interference-Driven linear precoding in Multiuser MISO Downlink Cognitive Radio Network

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2012年第6期61卷 2531-2543页

作者： Khan, Faheem A. Masouros, Christos Ratnarajah, Tharmalingam Queens Univ Belfast Inst Elect Commun & Informat Technol Belfast BT3 9DT Antrim North Ireland

We consider linear precoding in the downlink of a multiuser multiple-input-single-output (MISO) overlay cognitive radio (CR) network, wherein a primary base station (PBS) and a cognitive base station (CBS) share the same frequency band to transmit to a number of primary users (PUs) and secondary users. Conventionally, linear precoding techniques in a CR network aim to limit or completely cancel interference to the PUs while achieving maximum downlink throughput of the CR system. In this paper, we investigate novel adaptive linear precoding techniques at the CBS to exploit the interference to the primary and secondary systems, instead of its cancellation, by exploring the potential of making use of interference energy when the interference between the two systems is mutually constructive on an instantaneous basis. By doing so, the received signal-to-noise ratio (SNR) is enhanced by the signal energy gleaned from the constructive interference. In this direction, constructive-interference-based adaptive linear precoding techniques are proposed for the CR network, assuming a simple zero-forcing precoder at the PBS and noncausal knowledge of the primary message at the CBS. The presented analysis and simulations show that the proposed precoding techniques outperform conventional techniques, as the CR transmission actively enhances the performance of the PUs through constructive interference while achieving significant throughput for its own transmission.

关键词： Cognitive radio (CR) linear precoding multiple-input-multiple-output (MIMO) overlay zero-forcing (ZF)

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Channel Estimation and linear precoding in Multiuser Multiple-Antenna TDD Systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2011年第5期60卷 2102-2116页

作者： Jose, Jubin Ashikhmin, Alexei Whiting, Phil Vishwanath, Sriram Univ Texas Austin Dept Elect & Comp Engn Austin TX 78712 USA Bell Labs Alcatel Lucent Inc Commun & Stat Sci Dept Murray Hill NJ 07974 USA

Traditional approaches in the analysis of downlink systems decouple the precoding and the channel estimation problems. However, in cellular systems with mobile users, these two problems are, in fact, tightly coupled. In this paper, this coupling is explicitly studied by accounting for the channel training overhead and estimation error while determining the overall system throughput. This paper studies the problem of utilizing imperfect channel estimates for efficient linear precoding and user selection. It presents precoding methods that take into account the degree of channel estimation error. Information-theoretic lower and upper bounds are derived to evaluate the performance of these precoding methods. In typical scenarios, these bounds are close.

关键词： Cellular downlink channel estimation linear precoding wireless communication

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Knowledge Distillation-Aided End-to-End Learning for linear precoding in Multiuser MIMO Downlink Systems With Finite-Rate Feedback

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2021年第10期70卷 11095-11100页

作者： Kong, Kyeongbo Song, Woo-Jin Min, Moonsik Pukyong Natl Univ Coll Liberal Arts Busan 48513 South Korea Pohang Univ Sci & Technol Dept Elect Engn Pohang 37673 South Korea Kyungpook Natl Univ Sch Elect Engn Daegu 41566 South Korea Kyungpook Natl Univ Sch Elect & Elect Engn Daegu 41566 South Korea

We propose a deep learning-based channel estimation, quantization, feedback, and precoding method for downlink multiuser multiple-input and multiple-output systems. In the proposed system, channel estimation and quantization for limited feedback are handled by a receiver deep neural network (DNN). Precoder selection is handled by a transmitter DNN. To emulate the traditional channel quantization, a binarization layer is adopted at each receiver DNN, and the binarization layer is also used to enable end-to-end learning. However, this can lead to inaccurate gradients, which can trap the receiver DNNs at a poor local minimum during training. To address this, we consider knowledge distillation, in which the existing DNNs are jointly trained with an auxiliary transmitter DNN. The use of an auxiliary DNN as a teacher network allows the receiver DNNs to additionally exploit lossless gradients, which is useful in avoiding a poor local minimum. For the same number of feedback bits, our DNN-based precoding scheme can achieve a higher downlink rate compared to conventional linear precoding with codebook-based limited feedback.

关键词： precoding Receivers Channel estimation Auxiliary transmitters Downlink MIMO communication Quantization (signal) Deep learning multiple-input multiple-output limited feedback spatial multiplexing linear precoding

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