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Treating Content Delivery in Multi-Antenna Coded Caching as General Message Sets Transmission: A DoF Region Perspective

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2019年第6期18卷 3129-3141页

作者： Cao, Youlong Tao, Meixia Shanghai Jiao Tong Univ Shanghai Inst Adv Commun & Data Sci Dept Elect Engn Shanghai 200240 Peoples R China

Coded caching can create coded multicasting and, thus, significantly accelerates content delivery in broadcast channels with receiver caches. While the original delivery scheme in coded caching multicasts each coded message sequentially, it is not optimal for multiple-input multiple-output (MIMO) broadcast channels. This paper aims to investigate the full spatial multiplexing gain in multi-antenna coded caching by concurrently transmitting all coded messages. In specific, we propose to treat the content delivery as the transmission problem with general message sets where all possible messages are present, each with different length and intended for different user set. We first obtain inner and outer bounds of the degrees of freedom (DoF) region of a K-user (M, N) broadcast channel with general message sets, with M and N being the number of transmit and receive antennas, respectively. Then for any given set of coded messages, we find its minimum normalized delivery time (NDT) by searching the optimal DoF tuple in the DoF regions. The obtained minimum NDT is optimal at antenna configuration M/N is an element of (0, 1] boolean OR [ K, infinity) and is within a multiplicative gap of M/N to optimum at M/N is an element of (1, K). Our NDT results can be evaluated for any user demand with both centralized and decentralized cache placements.

关键词： Caching multiple-input multiple-output degrees of freedom region normalized delivery time general message sets coded multicasting

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Towards Higher Spectral Efficiency: Spatial Path Index Modulation Improves Millimeter-Wave Hybrid Beamforming

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2019年第6期13卷 1348-1359页

作者： Wang, Jintao He, Longzhuang Song, Jian Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Beijing Natl Res Ctr Informat Sci & Technol Beijing 100084 Peoples R China Tsinghua Univ Shenzhen Res Inst Shenzhen 518057 Peoples R China

The combination of millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems and index modulation (IM) technique has recently constituted a novel form of mmWave hybrid beamforming. Numerous studies have been conducted to show that such a system has the potential to outperform conventional mmWave-MIMOs with respect to spectral efficiency (SE). Most of the current works focused only on designing hybrid beamforming structures to empirically achieve higher SE performance. However, a fundamental question whether IM technique can truly improve the SE of current mmWave hybrid beamforming is still left unanswered. Against such a background, in this paper, we first extend the IM-assisted mmWave system to a more generalized version, i.e., a spatial path index modulation aided mmWave (SPIM-mmWave) system, which subsumes both IM-assisted and conventional mmWave-MIMO systems as its special cases. Based on the framework of SPIM-mmWave, a fundamental study is conducted towards a theoretic condition under which SPIM-mmWave guarantees to outperform conventional mmWave-MIMO schemes. It is demonstrated that, under a specific channel condition and noise level (which will be explicitly given by our study), the SPIM-mmWave guarantees to outperform conventional mmWave-MIMO systems.

关键词： multiple-input multiple-output millimeter wave communications index modulation spatial modulation hybrid beamforming spectral efficiency

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Reduced-Dimension DOA and DOD Estimation with Real-Valued Implementation for Bistatic MIMO Radars

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WIRELESS PERSONAL COMMUNICATIONS 2015年第3期85卷 1061-1070页

作者： Chang, Ann-Chen Ling Tung Univ Dept Informat Technol Taichung 408 Taiwan

In this paper, a reduced-dimension based direction of arrival (DOA) and direction of departure (DOD) estimator with real-valued implementation is presented by introducing a preprocessing transformation for bistatic multiple-input multiple-output radars is addressed. First, a two-dimensional searching estimator by exploiting unitary multiple signal classification (UMUSIC) technique with automatic pairing is presented. Second, this paper also presents a reduced-dimension (RD) UMUSIC (RD-UMUSIC) estimator by utilizing the characteristic of Kronecker product, which only requires a one-dimensional search for DOA estimation. Following this, the angle of DOD corresponding to the estimated DOA is obtained by using a shaping DOD steering vector approach. Furthermore, the DOA and DOD pairing is given automatically. The proposed estimator has low computational complexity due to the preprocessing unitary transformation and RD approaches. Finally, simulation results are presented to verify the efficiency of the proposed estimator.

关键词： Bistatic radar Angle estimation multiple-input multiple-output multiple signal classification Unitary transformation Reduced-dimension

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Multi-User Angle-Domain MIMO-NOMA System for mmWave Communications

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IEEE ACCESS 2021年 9卷 129443-129459页

作者： Khaled, Israa Langlais, Charlotte El Falou, Ammar Elhassan, Bachar A. Jezequel, Michel UMR CNRS 6285 Lab STICC IMT Atlantique F-29238 Brest France Lebanese Univ Fac Engn Tripoli 1300 Libya Gustave Eiffel Univ EISEE Paris ESYCOM F-93160 Noisy Le Grand France

Thanks to the high directionality of millimeter-wave (mmWave) channels, angle-domain beamforming is an appealing technique for multi-user multiple-input multiple-output (MU-MIMO) in terms of sum-throughput performance and limited feedback. By utilizing only the angular information of users at the transmitter, we propose an angle-domain non-orthogonal multiple access (NOMA) scheme to enhance the sum-throughput of the mmWave MU-MIMO system, especially in congested cells. We first derive a set of angular-based performance metrics, such as the inter-user spatial interference, the user channel quality, and the sum-throughput, by exploiting the specific features of the mmWave propagation. Then, a multi-user clustering algorithm is developed based on the spatial interference metric, and a new user ordering strategy is proposed using the angular-based channel quality metric. Additionally, we design a power allocation method that maximizes the angular-based sum-throughput. Extensive numerical results show that the proposed scheme significantly improves the performance of the mmWave MU-MIMO system by achieving up to 39% increase in the spectral efficiency when the number of users is closed to the number of antennas. Moreover, we find that the proposed user ordering strategy outperforms other limited feedback strategies, and the angular-based power allocation allows for efficient successive interference cancellation.

关键词： NOMA Resource management Measurement Silicon carbide MIMO communication Array signal processing Clustering algorithms Millimeter-wave networks multiple-input multiple-output beamforming non-orthogonal multiple access

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QoS-aware multihop routing in wireless sensor networks with power control using demodulation-and-forward protocol

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2012年第1期2012卷 1-9页

作者： Wu, Jianjun Ren, Shubo Jiang, Yun Song, Lingyang Peking Univ Sch Elect Engn & Comp Sci State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China

In this article, we propose a low-complexity joint power allocation and route planning algorithm for multiple antennas wireless sensor networks using dynamic programming. The sensor nodes utilize orthogonal space time block codes with demodulation-and-forward protocol. Unlike the previous work which typically optimize all the parameters, we cast this Quality-of-Service aware packet forwarding problem into two disjoint procedures: dynamic programming based route planning and subsequent adaptive power allocation. Simulation results indicate that the proposed protocol obtains comparative performance with the optimal results and significantly outperforms classical routing algorithms.

关键词： wireless sensor networks multiple-input multiple-output space time block codes dynamic programming route planing

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On High Performance MIMO Communications with Imperfect Channel Knowledge

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2011年第2期10卷 602-613页

作者： Rezk, Meriam Friedlander, Benjamin Univ Calif Santa Cruz Dept Elect Engn Santa Cruz CA 95064 USA

This paper compares the performance of a MIMO system applying a Mismatched Maximum Likelihood Detector (MMLD) with that applying a Generalized Likelihood Ratio Detector (GLRD) in the presence of channel estimation errors. Two sources of error are considered: errors due to noise and errors due to time variations induced by Doppler effects. The MMLD relies on the available channel estimate whereas the GLRD combines the channel estimate with a block of received data and uses a joint channel-symbol estimation approach to solve for the transmitted symbols. The GLRD is shown to outperform the MMLD whenever errors in channel estimation are incurred and the performance gap depends on the amount of error. Furthermore, the GLRD provides a unified receiver structure which can also be applied to differentially encoded MIMO systems and to situation where no channel estimate is available as in blind MIMO. The improved performance of the GLRD comes with increased computational complexity. This problem is addressed through search efficient algorithms based on the branch-estimate-bound optimization framework. We analyze the performance of the GLRD and provide a tight upper bound on the BER of the system at high SNR. Simulation results are shown for a 2 x 2 MIMO system.

关键词： multiple-input multiple-output channel estimation error correlated block fading mismatched maximum likelihood detector generalized likelihood ratio detector ordered-branch-estimate-bound algorithm

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On the diversity-multiplexing tradeoff for wireless cooperative multiple access systems

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2007年第9期55卷 4627-4638页

作者： Ding, Zhiguo Ratnarajah, T. Cowan, Colin C. F. Queens Univ Belfast Inst Elect Commun & Informat Technol Belfast BT3 9DT Antrim North Ireland

A spectrally efficient strategy is proposed for cooperative multiple access (CMA) channels in a centralized communication environment with N users. By applying superposition coding, each user will transmit a mixture containing its own information as well as the other users', which means that each user shares parts of its power with the others. The use of superposition coding in cooperative networks was first proposed in [11], which will be generalized to a multiple-user scenario in this paper. Since the proposed CMA system can be seen as a precoded point-to-point multiple-antenna system, its performance can be best evaluated using the diversity-multiplexing tradeoff. By carefully categorizing the outage events, the diversity-multiplexing tradeoff can be obtained, which shows that the proposed cooperative strategy can achieve larger diversity/multiplexing gain than the compared transmission schemes at any diversity/multiplexing gain. Furthermore, it is demonstrated that the proposed strategy can achieve optimal tradeoff for multiplexing gains 0 <= r <= 1 whereas the compared cooperative scheme is only optimal for 0 <= r <= (1/N). As discussed in the paper, such superiority of the proposed CMA system is due to the fact that the relaying transmission does not consume extra channel use and, hence, the deteriorating effect of cooperative communication on the data rate is effectively limited.

关键词： channel capacity cooperative communications diversity-multiplexing tradeoff multiple-input multiple-output (MIMO) systems outage probability superposition coding

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On the Degrees of Freedom Region for Simultaneous Imaging & Uplink Communication

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2022年第6期40卷 1768-1779页

作者： Mehrotra, Nishant Sabharwal, Ashutosh Rice Univ Dept Elect & Comp Engn Houston TX 77005 USA

In this paper, we take the first step towards quantifying the fundamental performance trade-offs between imaging and communication supported simultaneously using the same network resources. We analyze an uplink system configuration with a full-duplex base station (BS) illuminating an imaging scene while receiving data from a communication user. Our main contributions are two-fold. First, we propose a unified signal space analysis framework based on the degrees of freedom metric to characterize the trade-offs between the two operations in the high signal-to-noise ratio regime. Second, we propose a dual-function joint processing scheme, decode-and-image, that allows the BS to simultaneously form an image of the scene while decoding the uplink user's data. Our analysis and proposed scheme highlight the benefits of exploiting the uplink signals for imaging, at the cost of increased cooperation between the BS and uplink user. Moreover, our proposed scheme outperforms traditional schemes that enable dual-function operation via spatial or temporal isolation of imaging and communication signals.

关键词： Imaging Uplink Radar imaging Measurement Lighting Decoding Reflectivity Degrees of freedom joint imaging and communication multiple-input multiple-output wireless imaging

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An Improved SIC-Based Detection Scheme for Non-Uniform Constellations in ATSC 3.0 MIMO

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IEEE TRANSACTIONS ON BROADCASTING 2022年第2期68卷 286-294页

作者： Kim, Hyeongseok Kim, Jeongchang Park, Sung-Ik Hur, Namho Korea Maritime & Ocean Univ Dept Elect & Commun Engn Interdisciplinary Major Maritime AI Convergence Busan 49112 South Korea Elect & Telecommun Res Inst Media Transmiss Res Grp Daejeon 34129 South Korea

This paper presents an alternative approach to real-valued signal representation and proposes an improved successive interference cancellation (SIC)-based detection scheme using the alternative signal representation for non-uniform constellations (NUCs) in Advanced Television Systems Committee (ATSC) 3.0. Since I/Q polarization interleaving in ATSC 3.0 multiple-input multiple-output (MIMO) precoding performs a non-linear operation, it makes it difficult to use conventional suboptimal detection schemes based on interference cancellation. Therefore, the alternative signal representation is designed to easily apply various suboptimal detection schemes. Further, to obtain more robustness and lower complexity, a suboptimal detection scheme based on the alternative signal representation and interference cancellation with QR decomposition is proposed. The proposed detection scheme exploits the structural properties of NUCs and jointly detects the real and imaginary parts as a block. In addition, by considering one or more candidate symbols in the interference cancellation for the proposed detection scheme, the performance and the complexity are trade-offs according to the number of the considering candidate symbols. Simulation results show that the proposed detection scheme with a slight increase of the complexity significantly outperforms a linear detection under fixed and mobile channels.

关键词： MIMO communication Interference cancellation Complexity theory Codes Maximum likelihood decoding Robustness Quadrature amplitude modulation Advanced television systems committee 3 0 multiple-input multiple-output real-valued representation suboptimal decoding successive interference cancellation

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Semidefinite Relaxation for Moving Target Localization in Asynchronous MIMO Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2024年第2期72卷 1075-1089页

作者： Wu, Xiaoping Mao, Xiaoting Qi, Hengnian Huzhou Univ Sch Informat & Engn Huzhou 313000 Peoples R China

Considering an asynchronous multiple input multiple output (MIMO) system, we propose to obtain the position and velocity of a moving target by applying differential time delay (DTD) and differential frequency shift (DFS) measurements. The asynchronous MIMO systems are generally divided into quasi-synchronous (QS) and fully-asynchronous (FA) systems. Applying the semidefinite relaxation (SDR), we further design two semidefinite programming (SDP) solutions: QS-SDP for quasi-synchronous systems and FA-SDP for fully-asynchronous systems. We give the conditions under which the QS-SDP and FA-SDP forms are shown to be sufficiently tight so that their solutions perform to the Cramer-Rao Lower Bound (CRLB) precision. The results from the simulations demonstrate that the QS-SDP and FA-SDP solutions require few transmitters and receivers to uniquely determine the unknown parameters of the moving target. Besides, the QS-SDP and FA-SDP solutions provide the equivalent performance to the CRLB even at high noise levels.

关键词： Moving target localization semidefinite programming multiple-input multiple-output asynchronous system

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