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International Conference on Signal Processing and Communication (ICSC)

作者： Chauhan, Abha Mehra, Rajesh NITTTR Chandigarh India

ISBN: (纸本)9781479916054

Sphere Decoding (SD) algorithm has emerged as a highly effective detection scheme for multiple-input multiple-output (MIMO) systems. It offers a near maximum likelihood accuracy with reduced complexity. Despite this, there is a constant demand of even low complexity SD algorithms. This paper presents the FPGA implementation of Schnorr-Euchner SD algorithm with Early Termination (ET) scheme for uncoded multiple-input multiple output system. The ET scheme reduces the complexity of the decoder. The proposed decoder is designed for 4x4 Binary Phase Shift Keying (BPSK) MIMO system. The trade-off between the Bit Error Rate (BER) performance and the computational complexity is discussed. To compute the computational complexity synthesis of the proposed design is done on Xilinx Virtex 5 XC5VLX30T and Spartan 6 XC6SLX25T. An exhaustive comparison on the basis of resources utilized and frequency (MHz) at which the design can run is done on both the FPGAs.

关键词： Sphere Decoder Maximum likelihood detector multiple-input multiple-output Schnorr-Euchner algorithm Early Termination Field Programmable Gate Array Bit Error Rate

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Performance Analysis of the Imaging Receivers Using a Hemispherical Lens for Visible Light Communications

Performance Analysis of the Imaging Receivers Using a Hemisp...

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International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Li, Baolong Lai, Xiaoquan Wang, Jiaheng Liang, Xiao Zhao, Chunming Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Jiangsu Peoples R China

ISBN: (纸本)9781479903085

A hemispherical lens is often used in Visible Light Communication (VLC) systems to provide a wide field of view (FOV) and spatial multiplexing gain. Depending on the way of placing the lens, in practice there are generally two kinds of receivers, namely the flat-surface and curved-surface receivers, where the former one uses the flat surface of lens to collect light from the LED while the latter one uses the curved surface. We first derive the channel gain of the single-input single-output (SISO) VLC system with a finite receiving area, and then compare the channel gains of the two receivers in various scenarios. It is shown that the flat-surface receiver could provide a wider FOV than the curved-surface receiver. We further study the performance of two receivers in multiple-input multiple-output (MIMO) VLC systems. Through the BER performance analysis, we find that high spatial multiplexing gain could be achieved by both receivers if the receiving plane is properly located.

关键词： field of view hemispherical lens spatial multiplexing multiple-input multiple-output visible light communication

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Coding for relay networks with parallel Gaussian channels

Coding for relay networks with parallel Gaussian channels

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作者： Huang, Yu-Chih Texas A&M University

学位级别：Ph.D.

A wireless relay network consists of multiple source nodes, multiple destination nodes, and possibly many relay nodes in between to facilitate its transmission. It is clear that the performance of such networks highly depends on information forwarding strategies adopted at the relay nodes. This dissertation studies a particular information forwarding strategy called compute-and-forward. Compute-and-forward is a novel paradigm that tries to incorporate the idea of network coding within the physical layer and hence is often referred to as physical layer network coding. The main idea is to exploit the superposition nature of the wireless medium to directly compute or decode functions of transmitted signals at intermediate relays in a network. Thus, the coding performed at the physical layer serves the purpose of error correction as well as permits recovery of functions of transmitted signals. For the bidirectional relaying problem with Gaussian channels, it has been shown by Wilson et al. and Nam et al. that the compute-and-forward paradigm is asymptotically optimal and achieves the capacity region to within 1 bit; however, similar results beyond the memoryless case are still lacking. This is mainly because channels with memory would destroy the lattice structure that is most crucial for the compute-and-forward paradigm. Hence, how to extend compute-and-forward to such channels has been a challenging issue. This motivates this study of the extension of compute-and-forward to channels with memory, such as inter-symbol interference. The bidirectional relaying problem with parallel Gaussian channels is also studied, which is a relevant model for the Gaussian bidirectional channel with inter-symbol interference and that with multiple-input multiple-output channels. Motivated by the recent success of linear finite-field deterministic model, we first investigate the corresponding deterministic parallel bidirectional relay channel and fully characterize its capacity region. T

关键词： Network information theory wireless relay networks bidirectional relay channels inter-symbol interference multiple-input multiple-output compute-and-forward Thesis

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Robust precoder-decoder design for physical layer network coding-based MIMO two-way relaying system

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2013年第1期2013卷 1页

作者： Jayasinghe, Laddu Keeth Saliya Rajatheva, Nandana Latva-Aho, Matti Univ Oulu CWC Dept Commun Engn FIN-90570 Oulu Finland

In this paper, we investigate a robust joint precoder-decoder design scheme for a multiple-input multiple-output physical layer network coding (PNC)-based two-way relay system. An orthogonal training sequence is used to estimate the channels. The estimate is imperfect, and a robust design is proposed to find precoders at the source nodes and decoder at the relay node to facilitate PNC operations during multiple-access stage. Both channel estimation error and antenna correlations are used to formulate the optimization problem to minimize the weighted mean square error (WMSE) under a total power constraint. The problem becomes non-convex, and we propose an algorithm to solve it optimally. During the broadcast stage, an algorithm is proposed to find a precoder at the relay node and decoders at source nodes. The system performance is evaluated with estimation error and antenna correlation parameters. The effect of weighting parameters, relay location, and number of antennas at nodes are also considered in the numerical analysis. Numerical results confirm that our joint precoder-decoder algorithms provide the optimal solution to the minimization of WMSE with the total available power.

关键词： Bit error rate Imperfect channel state information Mean square error multiple-input multiple-output Non-convex optimization Physical layer network coding

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Channel Parameters Estimation for Multiuser MIMO MC-CDMA Systems

Channel Parameters Estimation for Multiuser MIMO MC-CDMA Sys...

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IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (PACRIM)

作者： Chou, You-Ren Ueng, Fang-Biau Chang, Yu-Kuan Natl Chung Hsing Univ Dept Elect Engn Taichung 40227 Taiwan

ISBN: (纸本)9781479915019

This paper investigates the channel estimation method for multiuser multiple inputmultiple output (MIMO) multi-carrier code division multiple access (MC-CDMA) communication systems. For the asynchronous uplink transmission situation, the receiver needs to estimate the channel parameters, including the multi-path gain coefficient, the carrier phase offset and the transmission time delay, to demodulate the received signals. Based on the knowledge of the spreading sequences, the proposed parameter estimation method employs the least mean-squared error (LMSE) criterion to the required parameters for the multiuser MIMO MC-CDMA systems. Some simulation examples for uplink scenario are given to demonstrate the effectiveness of the proposed methods.

关键词： multiple-input multiple-output quasi mean square accuracy coefficient multi-carrier code division multiple access

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Semi-blind Iterative Joint Channel Estimation and K-Best Sphere Decoding for MIMO

Semi-blind Iterative Joint Channel Estimation and K-Best Sph...

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IEEE Pacific Rim Conference on Communications, Computers and Signal Processing

作者： I. Dey G. G. Messier S. Magierowski Sheng Chen School of Electrical and Computer Engineering University of Calgary Electronics and Computer Science Faculty of Physical and Applied Sciences University of Southampton

ISBN: (纸本)9781479915002

An efficient and high-performance semi-blind scheme is proposed for multiple-input multiple-output (MIMO) systems by iteratively combining channel estimation with K-Best Sphere Decoding (SD). To avoid the exponentially increasing complexity of Maximum Likelihood Detection (MLD) while achieving a near optimal MLD performance, K-best SD is considered to accomplish data detection. Semi-blind iterative estimation is adopted for identifying the MIMO channel matrix. Specifically, a training-based least squares channel estimate is initially provided to the K-best SD data detector, and the channel estimator and the data detector then iteratively exchange information to perform the decision-directed channel update and consequently to enhance the detection performance. The proposed scheme is capable of approaching the ideal detection performance obtained with the perfect MIMO channel state information.

关键词： multiple-input multiple-output K-Best Sphere Decoding Joint channel estimation and data detection multiple input multiple output systems channel estimation DECODING channel matrix Spheres Iterative Metachromatic Leukodystrophy minimum lethal dose

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CLOSED EXPRESSIONS FOR THE OUTAGE PERFORMANCE OF DISTRIBUTED TRANSMIT-RECEIVE DIVERSITY SYSTEM

CLOSED EXPRESSIONS FOR THE OUTAGE PERFORMANCE OF DISTRIBUTED...

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IET International Conference on Information and Communications Technologies

作者： Lei Li Dong-mei Hu Xiao-dong Wang Information Technology Office Nanhai Fleet Command Naval Force of the PLA Zhanjiang China|c|

ISBN: (纸本)9781629931357

Outage performance of distributed transmit-receive diversity system subjected to composite Rayleigh-Lognormal fading channel is considered. Using random Wishart matrix theory and Gauss-Hermite quadrature, we derived closed form expressions for its outage probability. The theoretical expressions are validated by numerical results. It is show that distributed transmit-receive system promise significant diversity gains over collocated multiple antenna system.

关键词： Distributed antenna system Rayleigh-Lognormal fading multiple-input multiple-output Transmit-Receive Diversity Outage performance

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Device-to-Device (D2D) Communications Underlaying MU-MIMO Cellular Networks

Device-to-Device (D2D) Communications Underlaying MU-MIMO Ce...

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IEEE Global Communications Conference

作者： Lili Wei Rose Qingyang Hu Tao He Yi Qian Department of Electrical and Computer Engineering Utah State University USA School of Aeronautics & Astronautics University of Electronic Science and Technology of China Department of Computer and Electronics Engineering University of Nebraska-Lincoln USA

ISBN: (纸本)9781479913510

Device-to-device (D2D) communication underlaying cellular networks will become an important technology in the future networks such as International Mobile Telecommunications-Advanced (IMT-Advanced) to improve spectral efficiency. For the multi-user multi-input multi-output (MU-MIMO) architecture with multi-antenna base station, design and optimization of D2D communications underlaying such a network is an interesting research area that has not been fully investigated yet. In this paper, we consider a cellular network with multiple cellular user equipments (UEs) and multiple direct D2D pairs underlaying communications with a central base station equipped with multiple antennas. We generalize a joint optimization problem to maximize the overall rate of the cellular UEs and D2D pairs, with regard to the continuous beamforming vector design for all cellular UEs and the binary D2D pair association status search. In addition, to solve the mixed optimization problem approximately, we investigate three precoder design methods and propose a D2D pair association vector search algorithm. Simulation results show the performance gain under different precoder methods with the D2D association vector search algorithm.

关键词： Device-to-device communication cellular network multiple-input multiple-output multi-user beamforming precoder Cellular networks multi-user multiple input multiple output systems Beamforming UNDERLAYERS Communication Research multiple antenna Device-to-device communication

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A Novel Optical Wireless MIMO Architecture and Its Application

A Novel Optical Wireless MIMO Architecture and Its Applicati...

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International Conference on Computing, Networking and Communications

作者： Mingbo Niu Julian Cheng Jonathan F. Holzman Sch. of Eng. Univ. of British Columbia Kelowna BC Canada|c|

ISBN: (纸本)9781467352871

A novel coherent optical multiple-input multiple-output architecture is proposed for wireless communication links to mitigate atmospheric turbulence effects. Transmitter optical signals operate at distinct carrier frequencies to allow the received optical signals to be separately processed. The accumulated phase noise in each transmission branch can be independently compensated electronically. Based on the proposed architecture, several popular diversity combining techniques are considered for system performance evaluation. The presented results demonstrate substantial error performance improvement over a single-input single-output coherent optical wireless link.

关键词： multiple-input multiple-output optical communications optical scintillation phase noise

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Vector Precoding for Gaussian MIMO Broadcast Channels: Impact of Replica Symmetry Breaking

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IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第3期58卷 1413-1440页

作者： Zaidel, Benjamin M. Muller, Ralf R. Moustakas, Aris L. de Miguel, Rodrigo Norwegian Univ Sci & Technol NTNU Dept Elect & Telecommun N-7491 Trondheim Norway Univ Athens Elect Lab Dept Phys Athens 15784 Greece Norwegian Univ Sci & Technol NTNU Dept Elect & Telecommun N-7034 Trondheim Norway

The "replica method" of statistical physics is employed for the large-system analysis of vector precoding for the Gaussian multiple-input multiple-output broadcast channel. The transmitter comprises a linear front-end combined with nonlinear precoding, minimizing transmit energy by means of input alphabet relaxation. For the common discrete lattice-based relaxation, the problem violates replica symmetry and a replica symmetry breaking (RSB) ansatz is taken. The limiting empirical distribution of the precoder's output and the limiting transmit energy are derived for one-step RSB. Particularizing to a "zero-forcing" (ZF) linear front-end, a decoupling result is derived. For discrete lattice-based relaxations, the impact of RSB is demonstrated for the transmit energy. The spectral efficiencies of the aforementioned precoding methods are compared to linear ZF and Tomlinson-Harashima precoding (THP). Focusing on quaternary phase shift-keying (QPSK), significant performance gains of both lattice and convex relaxations are revealed for medium to high signal-to-noise ratios (SNRs) when compared to linear ZF precoding. THP is shown to be outperformed as well. Comparing certain lattice-based relaxations for QPSK against a convex counterpart, the latter is found to be superior for low and high SNRs but slightly inferior for medium SNRs in terms of spectral efficiency.

关键词： Antenna arrays broadcast channel decoupling principle lattice multiple-input multiple-output precoding R-transform replica method zero-forcing (ZF)

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