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8th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM)

作者： Chen, Xi Li, Jiangpeng Ma, Jun Wang, Junfeng He, Guanghui Shanghai Jiao Tong Univ Sch Microelect Shanghai 200030 Peoples R China Panovel Technol Corp Shanghai Peoples R China

ISBN: (纸本)9781612846835;9781612846828

By exchanging soft information between the detector and the channel decoder, an iterative receiver can significantly improve the performance compared to the non-iterative receiver. In this paper, a low complexity soft-input soft-output (SISO) fixed-complexity sphere decoding (FSD) algorithm is proposed for iterative MIMO receiver. The algorithm introduces a simplified parallel candidate adding (SPCA) scheme to provide more accurate soft information. Furthermore, by employing our proposed improved hybrid-enumeration method, the SISO-FSD can reduce the computational complexity substantially. Simulation results show that the algorithm can achieve a near Max-Log optimal maximum a posteriori (MAP) detection performance under flat fading Rayleigh channels. Compared to the SISO K-Best algorithm (K=50), the proposed algorithm saves about 60% computations and provides almost the same performance for detecting 4 x 4 64-QAM MIMO signal, making it a promising scheme for real-life hardware implementation.

关键词： multiple-input multiple-output soft-input soft-output detection fixed complexity sphere decoding

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Limited feedback MIMO techniques for temporally correlated channels and linear receivers

Limited feedback MIMO techniques for temporally correlated c...

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作者： Zacarías Brach, Eduardo Aalto University

学位级别：master

Advanced mobile wireless networks will make extensive use of multiantenna (MIMO) transceivers to comply with high requirements of data rates and reliability. The use of feedback channels is of paramount importance to achieve this goal in systems employing frequency division duplexing (FDD). The design of the feedback mechanism is challenging due to the severe constraints imposed by computational complexity and feedback bandwidth *** thesis addresses the design of transmission strategies in both single-user and multi-user MIMO systems, based on compact feedback messages. First, recursive feedback mechanisms for single-user transmission scenarios are proposed, including stochastic gradient techniques, deterministic updates based on Givens rotations and low computational complexity schemes based on partial update filtering concepts. Thereafter, channel feedback algorithms are proposed, and a convergence analysis for static channels is presented. These algorithms can be used to provide channel side information to any multi-user MIMO solution. A limited-feedback decentralized multi-user MIMO solution is proposed, which avoids the need for explicit channel feedback. A feed-forward technique is proposed, which allows our methods to operate in presence of feedback *** performance of all the proposed algorithms is illustrated via link-level simulations, where the effect of different parameter values is assessed. Our results show that the proposed methods outperform existing limited-feedback counterparts over a range of low to medium mobile speeds, for moderate antenna array sizes that are deemed practical for commercial deployment. The computational complexity reduction of some of the proposed algorithms is also shown to be considerable, when compared to existing techniques

关键词： Electrical engineering multiantenna systems multiple-input multiple-output limited feedback wireless communications

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An optical MIMO transmission system over 80km of two-mode fiber using DSP

An optical MIMO transmission system over 80km of two-mode fi...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Li, Rongling Fang, Wuliang Tang, Chanjuan Chi, Nan Fudan Univ Informat Sch Dept Commun Sci & Engn State Key Lab ASIC & Syst 220 Handan Rd Shanghai 200433 Peoples R China

Simulations confirm stable MIMO transport of two channels over a two-mode fiber. Successful reception is achieved over 80km two-mode fiber at a bit error rate of 10(-6) -enabled by a new signal recovery algorithm we p... 详细信息

ISBN: (纸本)9780819489616

关键词： multiple-input multiple-output Two-mode Fiber Offset Launching Digital Signal Processing

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A MAC Protocol with Multi-Packet Reception for MIMO Ad Hoc Networks

A MAC Protocol with Multi-Packet Reception for MIMO Ad Hoc N...

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International Conference on Wireless Communications, Networking and Mobile Computing

作者： Miao Cui Yinglie Cao Shaoliang Lin Xiaomu Zhang School of Information Guangdong University of Technology China Electronics Technology Group Corporation No.7 Research Institute

ISBN: (纸本)9781612846842

multiple-input multiple-output (MIMO) systems are capable of simultaneously capturing more than one packet. Such capability is known as Multi-Packet Reception (MPR), which is new way to improve performance of Ad Hoc Networks. In order to effectively enhance throughput of Ad Hoc Networks, a novel MAC protocol (MIMO-MAC) with MIMO links that takes into account MPR is proposed. It can receive more than one RTS before responding CTS, which maximizes transmission links simultaneously. Receiver determines links according to the number of its own antennas and RTS. Compare to the existing protocol, it allows many communications at the same time in one competitive area. Finally, simulations are implemented in terms of load and source nodes number in OPNET environment, results show that MIMO-MAC outperforms CSMA/CA and CSMA/CA (k).

关键词： Ad Hoc Networks multiple-input multiple-output Multi-Packet reception MAC protocol

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Iterative Detection Scheme for Turbo-BLAST System with Adaptive Power Allocation in the Presence of Channel State Information Imperfection

Iterative Detection Scheme for Turbo-BLAST System with Adapt...

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2012 International Conference on Nano Materials and Electric Devices(ICNMED 2012)

作者： Xiaomin Chen Xiaodan Yu Wei Tan Xiangbin Yu College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics

We propose an iterative detection scheme for Turbo-BLAST system with optimal power allocation in the presence of channel state information imperfection. The proposed scheme uses the channel estimation matrix for detection and treats the interference caused by channel estimation errors and additive white Gaussian noise as equivalent noise where the channel estimation matrix and the statistical characteristic of channel estimation errors are necessitated. Simulation results show the proposed algorithm is effective to improve bit error rate(BER) performance through iterative detection for modified Turbo-BLAST system with optimal power allocation in the presence of imperfect channel state information.

关键词： multiple-input multiple-output Iterative detection scheme Transmit Power Allocation Turbo-BLAST Imperfect-Channel State Information(I-CSI)

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Dual-Hop MIMO Amplify-and-Forward Relay Channel Capacity with Keyhole Effect

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IEEE COMMUNICATIONS LETTERS 2011年第10期15卷 1050-1052页

作者： Firag, Abdulla Suraweera, Himal A. Smith, Peter J. Yuen, Chau Univ Canterbury Dept Elect & Comp Engn Christchurch 1 New Zealand Singapore Univ Technol & Design Singapore Singapore

Keyhole fading present in some relay based applications can degrade the system performance. In this paper, we investigate the effect of multi-keyhole fading on the ergodic capacity of fixed infrastructure based multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems. Specifically, considering a Rayleigh-multi-keyhole MIMO AF relay channel, we derive an expression for the system's ergodic capacity. Our capacity expression is valid for arbitrary number of antennas, number of keyholes, keyhole power distribution and all signal-to-noise ratio values.

关键词： Relay systems multiple-input multiple-output capacity keyhole

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Performance analysis of MIMO-SESS with Alamouti scheme over Rayleigh fading channels

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2011年第1期2011卷 1-13页

作者： Ma, Shichuan Lim Nguyen Yang, Yaoqing (Lamar) Jang, Won Mee Univ Nebraska Dept Comp & Elect Engn Omaha NE 68182 USA

Self-encoded spread spectrum (SESS) is a novel modulation technique that acquires its spreading sequence from the random input data stream rather than through the use of the traditional pseudo-noise code generator. It has been incorporated with multiple-input multiple-output (MIMO) systems as a means to combat fading in wireless channels. In this paper, we present the analytical study of the bit-error rate (BER) performance of MIMO-SESS systems under Rayleigh fading. The BER expressions are derived in closed form, and the veracity of the analysis is confirmed by numerical calculations that demonstrate excellent agreement with simulation results. The performance analysis shows that the effects of fading can be effectively mitigated by taking advantage of spatial and temporal diversities. For example, a 2 x 2 MIMO-SESS system can achieve about 7 dB performance improvement at 10-4 BER over a MIMO PN-coded spread spectrum system.

关键词： self-encoded spread spectrum iterative detection multiple-input multiple-output Alamouti scheme

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Complexity Reduction by Using QR-Based Scheme in Computing Capacity for Optimal Transmission

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WIRELESS PERSONAL COMMUNICATIONS 2011年第2期58卷 391-405页

作者： Pan, Chien-Hung Natl Chiao Tung Univ Dept Commun Engn Hsinchu 300 Taiwan

multiple-input-multiple-output (MIMO) technique is often employed to increase capacity in comparing to systems with single antenna. However, the computational complexity in evaluating channel capacity or transmission rate (data rate) grows proportionally to the number of employed antennas at both ends of the wireless link. Recently, the QR decomposition (QRD) based detection schemes have emerged as a low-complexity solution. After conducting QRD on a full channel matrix that results in a triangular matrix, we claim that computational complexity can be simplified by the following ways. First, to simplify channel capacity calculation, we prove that eigenvalues of the full channel matrix multiplication equals eigenvalues of the triangular channel matrix multiplication. Second, to simplify the calculation of the optimal transmission rate constrained constellation, we propose a simplistic multiplication of the resulted simple triangular matrix and a transmitted signal vector. Then, we also propose a modified mutual information calculation (MMIC) to achieve a quite low-complexity via the divided calculation. By using computer simulation and field- programmable gate array (FPGA) implementation, simulation results show that the proposed QRD-based schemes are capable of achieving conventional performance, but at a low-complexity level.

关键词： multiple-input multiple-output Channel capacity QR decomposition Eigenvalues Mutual information Field-programmable gate array

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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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Belief Propagation for Distributed Downlink Beamforming in Cooperative MIMO Cellular Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2011年第12期10卷 4140-4149页

作者： Sohn, Illsoo Lee, Sang Hyun Andrews, Jeffrey G. Univ Texas Austin Wireless Networking & Commun Grp Dept Elect & Comp Engn Austin TX 78712 USA

We propose a new graphical model approach to cooperative multiple-input multiple-output (MIMO) cellular networks. The objective is to optimize downlink transmit beamforming at each BS in order to maximize the sum throughput over the entire network. While ideal centralized beamforming requires full channel state information (CSI) sharing among all BSs in the network and huge computational complexity for combinatorial optimization, the proposed graphical model enables distributed beamforming which requires only local CSI sharing between neighboring BSs and efficiently solves the optimization problem in a distributed manner. As distributed solvers for this problem, we derive message-passing algorithms which can be implemented with polynomial-time computational complexity. Furthermore, we make a slight approximation on the objective function to derive a simpler graphical model, providing further complexity saving. Simulation results indicate that the proposed distributed downlink beamforming achieves average cell throughput typically within just 2% of ideal centralized beamforming.

关键词： multiple-input multiple-output base station cooperation cellular network transmit beamforming intercell interference belief-propagation

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