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space-time multiplexing for MIMO multiuser downlink channels

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第7期5卷 1726-1734页

作者： Doostnejad, Roya Lim, Teng Joon Sousa, Elvino Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

In this paper, we study the downlink of a multiuser system, in which antenna arrays are employed at both the transmitter (base station) and the receivers (clients). A space-time modulation technique that can be seen as two-dimensional spreading is introduced. It provides full transmit diversity for every user, and accommodates N-t times the number of users as a single-antenna code-division multi-access (CDMA) scheme, where Nt is the number of transmit antennas. Thus multiple access is provided through spatial as well as code dimensions. In addition, the scheme forms groups of users that are orthogonal to each other. This feature translates into simplified detection strategies without loss of performance. The main detector structure of interest is a two-stage interference canceller because of its low complexity compared to other joint detectors. We will demonstrate that in conjunction with an unequal power allocation scheme, this receiver provides full diversity and suffers from only a small performance loss compared to the full-complexity maximum likelihood (NIL) receiver. In a single-user multiple antenna system, the same spreading scheme and unequal power allocation yields a new approach to designing full-rate, full-diversity space-time codes having good performance with successive interference cancellers.

关键词： broadcast MIMO ML multiuser power control SIC space-time coding

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Switching between diversity and multiplexing in MIMO systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第6期53卷 962-968页

作者： Heath, RW Paulraj, AJ Univ Texas Dept Elect & Comp Engn Wireless Networking & Commun Grp Austin TX 78712 USA Stanford Univ Informat Syst Lab Stanford CA 94305 USA

Multiple-input multiple-output (MIMO) wireless communication systems can offer high data rates through spatial multiplexing or substantial diversity using transmit diversity. In this letter, switching between spatial multiplexing and transmit diversity is proposed as a simple way to improve the diversity performance of spatial multiplexing. In the proposed approach, for a fixed rate, either multiplexing or diversity is chosen based on the instantaneous channel state and the decision is conveyed to the transmitter via a low-rate feedback channel. The minimum Euclidean distance at the receiver is computed for spatial multiplexing and transmit diversity and is used to derive the selection criterion. Additionally, the Demmel condition number of the matrix channel is shown to provide a sufficient condition for multiplexing to outperform diversity. Monte Carlo simulations demonstrate improvement over either multiplexing or diversity individually in terms of bit error rate.

关键词： multiple-input multiple-output (MIMO) systems space-time coding transmit diversity

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space-time Codebook Design for Spread Systems

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WIRELESS PERSONAL COMMUNICATIONS 2013年第4期69卷 1783-1797页

作者： Beko, Marko Dinis, Rui Univ Lusofona Humanidades & Tecnol Lisbon Portugal Univ Nova Lisboa Dept Engn Electrotecn Fac Ciencias & Tecnol Caparica Portugal Univ Nova Lisboa Monte De Caparica Portugal Inst Telecomunicacoes Lisbon Portugal

The problem of designing space-time constellations for communication in spread multiple-antenna wireless systems over Rayleigh fading channel is addressed. Using the asymptotic union bound on error probability as design criterion, codes based on general complex-valued symbols are obtained with a gradient search optimization technique. New space-time constellations are constructed and their performance is assessed. Simulation results show that the proposed technique achieves significant performance gains over existing schemes. Since the designed codebooks do not seem to possess any structure that could reduce the memory requirements for storing the corresponding codebook, the problem of designing structured space-time constellations is also addressed. To overcome this problem, a discrete Fourier transform-based approach is adopted to design structured codebooks and their performance is evaluated. The new structured codebooks also demonstrate significant improvement over state-of-art structured schemes.

关键词： Spread multiple-input multiple-output (MIMO) space-time coding Fading channels Performance analysis Diversity methods

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A reconfigurable Multiple-Input Multiple-Output communication system

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第5期7卷 1719-1733页

作者： Grau, Alfred Jafarkhani, Hamid De Flaviis, Franco Univ Calif Irvine Irvine CA 92697 USA

In this paper, we present a theoretical analysis on the gains offered by a reconfigurable Multiple-Input Multiple-Output (MIMO) system using Orthogonal space-time Block Codes (OSTBCs) and reconfigurable antennas at the receiver only. The proposed system using reconfigurable antennas selects the optimal radiation state of the receive antennas in which the receive Signal-to-Noise Ratio (SNR) is maximized. The theoretical findings show that under certain channel propagation conditions and using an appropriate codification and power allocation of the transmitted signal, the diversity order of the proposed reconfigurable MIMO system is given by the product of transmit and receive antennas as well as the number of reconfigurable radiation states of the receive antennas. The impact of correlated radiation states and imperfect channel estimation are also considered. The geometrical and physical constrains of reconfigurable antennas are also taken into account through the concept of antenna group. Assuming an ideally scattered Non-Line-of-Sight (NLOS) flat Rayleigh channel, the antenna design criteria is given. Finally, we evaluate the theoretical findings through simulations on the array gain, bit error rate and ergodic capacity, where the detrimental impact of channel estimation is observed.

关键词： smart antennas antennas and propagation MIMO systems transmission technology space-time coding reconfigurable antennas

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A new non-orthogonal space-time code with low decoding complexity

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第5期5卷 1115-1121页

作者： Maddah-Ali, Mohammad A. Khandani, Amir K. Univ Waterloo Dept Elect & Comp Engn Coding & Signal Transmiss Lab Waterloo ON N2L 3G1 Canada

A full diversity block space-time code over two transmit antennas and two symbol periods is introduced. In this method, each code is equal to the addition of two matrices;A(m) and DA(n), where A and D are the two constant matrices and m and n are the two data symbols. A is selected such that the set A(m), 0 <= m <= 2(b) - 1 is closed under the matrix multiplication. This structure allows a simple Maximum Likelihood (ML) decoding method, and at the same time, simplifies the optimization of the coding advantage. Simulations show that the performance of the new code is very close to that of the Damen code [1] which is the best known block space-time code in terms of the coding advantage. Moreover, the decoding complexity of the proposed method is significantly lower than that of the Damen code.

关键词： space-time coding multiple-antenna arrays transmit diversity Maximum Likelihood (ML) decoding wireless communications

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Algorithm for Generating All Optimal 16-QAM BI-STCM-ID Labelings

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WIRELESS PERSONAL COMMUNICATIONS 2015年第2期83卷 873-894页

作者： Krasicki, Maciej Poznan Univ Tech Chair Wireless Commun Poznan Poland

This paper focuses on 16-QAM labelings of bit-interleaved space-time coded modulation with iterative decoding (BI-STCM-ID). What is contributed is an algorithm to generate (with no random search) optimal labelings for BI-STCM-ID systems with any number of transmit- and receive antennas, transmitting over Rayleigh fading channel. Along with the algorithm, a couple of corollaries are brought, which give an account of the optimal labelings' features. Having a complete set of optimal 16-QAM BI-STCM-ID labelings at hand, it is possible to advance research on labeling diversity scheme by finding all such labeling pairs that-if applied to a system with two different labeling maps within adjacent transmit streams-bring maximum asymptotic coding gain .

关键词： Diversity MIMO systems Modulation space-time coding

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Cooperative Spectrum Sensing with Transmit and Relay Diversity in Cognitive Radio Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第12期7卷 4761-4766页

作者： Zhang, Wei Ben Letaief, Khaled Univ New S Wales Sch Elect Engn & Telecommun Sydney NSW 2052 Australia Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Kowloon Hong Kong Peoples R China

In the letter the problem of cooperative spectrum sensing is investigated in cognitive radio (CR) networks over Rayleigh fading channels. By taking into account the error effect on the decision reporting, a general performance analysis of cooperative spectrum sensing is given. The analytical detection results show that the performance of cooperative spectrum sensing is limited by the probability of reporting errors. To deal with this limitation, we propose a transmit diversity based cooperative spectrum sensing method. By regarding multiple CRs as a virtual antenna array, space-time coding and space-frequency coding are applied into CR networks over flat-fading and frequency-selective fading channels, respectively. Moreover, we propose a relay diversity based cooperative spectrum sensing approach to increase the diversity of detection when some CRs are in heavy shadowing. It is then shown that, when combined with algebraic coding, relay diversity can further improve the cooperative spectrum sensing performance.

关键词： Cognitive radio diversity technique relay channels space-frequency coding space-time coding

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MAP Decoding for Multi-Antenna Systems with Non-Uniform Sources: Exact Pairwise Error Probability and Applications

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IEEE TRANSACTIONS ON COMMUNICATIONS 2009年第1期57卷 242-254页

作者： Behnamfar, Firouz Alajaji, Fady Linder, Tamas Nortel Networks Ottawa ON K2H 8E9 Canada Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada Hungarian Acad Sci Comp & Automat Res Inst H-1111 Budapest Hungary

We study the maximum a posteriori (MAP) decoding of memoryless non-uniform sources over multiple-antenna channels. Our model is general enough to include space-time coding, BLAST architectures, and single-transmit multi-receive antenna systems which employ any type of channel coding. We derive a closed-form expression for the codeword pairwise error probability (PEP) of general multi-antenna codes using moment generating function and Laplace transform arguments. We then consider space-time orthogonal block (STOB) coding and prove that, similar to the maximum likelihood (ML) decoding case, detection of symbols is decoupled in MAP decoding. We also derive the symbol PEP in closed-form for STOB codes. We apply these results in several scenarios. First, we design a binary antipodal signaling scheme which minimizes the system bit error rate (BER) under STOB coding. At a BER of 10(-6), this constellation has a channel signal-to-noise ratio (CSNR) gain of 4.7 dB over conventional BPSK signaling for a binary non-uniform source with p(0) (sic) P(0) = 0.9. We next design space-time linear dispersion (LD) codes which are optimized for the source distribution under the criterion of minimizing the union upper bound on the frame error rate (FER). Two codes are given here: one outperforms V-BLAST by 3.5 dB and Alamouti's code by 12.3 dB at an FER of 10(-2) for a binary source with p(0) = 0.9, and the other outperforms V-BLAST by 4.2 dB at an FER of 10(-3) for a uniform source. These codes also outperform the LD codes of [13] constructed under a different criteria. Finally, the problem of bit-to-signal mapping is studied. It is shown that for a binary source with p(0) = 0.9, 64-QAM signaling, and SER = 10(-3), a gain of 3.7 dB can be achieved using a better-than-Gray mapping. For a system with one transmit and two receive antennas that uses trellis coding with 16-QAM signaling, a 1.8 dB gain over quasi-Gray mapping and ML decoding is observed when MAP decoding is used for binary so

关键词： Joint source-channel coding space-time coding MAP decoding pairwise error probability statistical redundancy convolutional codes trellis coding maximum-ratio combining multi-antenna fading channels diversity wireless communications

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Optimal constellation labeling for iteratively decoded bit-interleaved space-time coded modulation

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IEEE TRANSACTIONS ON INFORMATION THEORY 2005年第5期51卷 1865-1871页

作者： Huang, YH Ritcey, JA Qualcomm Inc San Diego CA 92121 USA Univ Washington Dept Elect Engn Seattle WA 98195 USA

We consider the design of iteratively decoded bit-interleaved space-time coded modulation (BI-STCM) over fast Rayleigh-fading channels with N-t transmit and N-r receive antennas. We propose the design criterion to achieve the largest asymptotic coding gain inherited in the constellation labeling. In particular, for orthogonal space-time block codes, the labeling design criterion reduces to maximizing the (-NtNr)th power mean of the complete set of squared Euclidean distances associated with all "error-free feedback" events in the constellation. Based on this power mean criterion, we show that the labeling optimization problem falls into the category of quadratic assignment problems for constellations of any shape and with an arbitrary number of transmit and receive antennas. For a set of practical values of N-t and N-r, we present optimal labeling maps for 8-PSK, 16-QAM, and 64-QAM constellations.

关键词： bit-interleaved coded modulation (BICM) constellation labeling multiple antennas optimal code search quadratic assignment problem (QAP) space-time coding

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Differential distributed space-time modulation for cooperative networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第11期5卷 3097-3108页

作者： Wang, Genyuan Zhang, Yimin Amin, Moeness Villanova Univ Ctr Adv Commun Villanova PA 19085 USA

In this paper, we develop a protocol for the construction of cooperative networks when the channel state information is not available at the transmitters and the receivers. In the proposed protocol, differential space-time codewords are generated at the source terminal. In the broadcast phase, each row of the differential space-time codeword is transmitted to a different relay, whereas in the relay phase, the relaying terminals retransmit the codeword through simple amplify-and-forward algorithm. The performance of the cooperative diversity system is analyzed for a two-user case for different channel environments in terms of the diversity gain and the diversity product. The optimization of the power allocation between source and relay terminals is considered for the maximization of the diversity product. When the same modulation scheme is used, the performance of differential detection is degraded by 3 dB noise enhancement compared with coherent detection.

关键词： cooperative diversity MIMO space-time coding differential coding

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