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15th IEEE/SP Workshop on Statistical Signal Processing

作者： Palally, H. R. Chen, S. Yao, W. Hanzo, L. Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

ISBN: (纸本)9781424427093

A novel scheme of semi-blind joint maximum likelihood (ML) channel estimation and data detection is proposed for multiple-input multiple-output (MIMO) systems by decomposing the joint ML optimisation over channel and data into an iterative two-level optimisation loop. Particle swarm optimisation (PSO) is invoked at the upper level to identify the unknown MIMO channel while an enhanced ML sphere detector is used at the lower level to detect the transmitted data. The scheme is semi-blind as a minimum pilot overhead is employed to aid the initialisation of the PSO based channel estimator.

关键词： multiple-input multiple-output joint maximum likelihood estimation particle swarm optimisation

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A HYBRID MIMO PHASED-ARRAY CONCEPT FOR ARBITRARY SPATIAL BEAMPATTERN SYNTHESIS

A HYBRID MIMO PHASED-ARRAY CONCEPT FOR ARBITRARY SPATIAL BEA...

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13th IEEE Digital Signal Processing Workshop/5th IEEE Signal Processing Education Workshop

作者： Browning, J. Paul Fuhrmann, Daniel R. Rangaswamy, Muralidhar USAF Res Lab Wright Patterson AFB OH 45433 USA Michigan Technol Univ Dept Elect & Comp Engn Houghton MI 49931 USA

ISBN: (纸本)9781424436767

multiple-input multiple-output (MIMO) radar is a multiple aperture technology characterized by the ability to transmit diverse signals at each aperture. This is in contrast to traditional phased-array radar whereby a single signal is transmitted with a phase shift applied at each element to enable steering of the transmit beam. The hybrid MIMO phased-array radar (HMPAR) concept is an outgrowth of the monostatic MIMO construct, in which all sensors have the same view of the far-field target. In the HMPAR, the full transmit array is partitioned into sub-arrays which can be electronically steered in different directions and driven by separate transmit waveforms;furthermore the configuration of the array into sub-arrays can be changed. Here we explore the variety of transmit beampatterns that could be achieved using such a system.

关键词： multiple-input multiple-output beamforming radar

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Robust Recursive Two-Dimensional Channel Estimators for the MIMO-OFDM Systems

Robust Recursive Two-Dimensional Channel Estimators for the ...

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1st International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology

作者： Golovins, Eugene Ventura, Neco Univ Cape Town Dept Elect Engn ZA-7701 Rondebosch South Africa

ISBN: (纸本)9781424440665

MIMO-OFDM systems operating in the wireless doubly-selective channels rely on the pilot-assisted transmissions to acquire channel state information. Application of the two-dimensional filtering algorithms to channel estimation in the MIMO configurations is challenging due to the complexity considerations. Furthermore, different pilot structures employed in different spatial links necessitate development of scalable and reconfigurable estimator structures. The estimation scheme should also be robust to the changes in channel statistics and operation mode restrictions. To address these problems, robust estimator architecture is presented, which is based on the transform-domain processing and separable adaptive filtering modules.

关键词： multiple-input multiple-output multipath mean square error forgetting factor

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Improved Codebook Design for Precoding of OSTBCs in Correlated MIMO Channels with Finite Rate Feedback

Improved Codebook Design for Precoding of OSTBCs in Correlat...

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European Wireless Conference

作者： Lu Lu Gang Wu Haiyang Huang Shaoqian Li Fan Sun Communication Theory Lab Royal Institute of Techonology (KTH) National Key Lab of Communications University of Electronic Science and Technology of China National Key Lab of Communications University of Electronic Science and Technologyof China Ericsson Research

In this paper, we propose a novel codebook-based precoding design for orthogonal space-time block codes (OSTBCs) over multiple-input multiple-output (MIMO) channels with finite rate feedback. The proposed approach aims at providing better system performance by utilizing the property of OSTBCs and the prior information of the statistical antenna correlation. Under a new way of controlling the average transmit power, a novel structure of precoding matrix is given, which is different from the unitary precoding. Moreover, with the information of the transmit correlation matrix, the codebook design is generalized to correlated channels. Both theoretical analyses and simulation results are provided.

关键词： Precoding multiple-input multiple-output Orthogonal space-time block codes Antenna correlation Finite rate feedback Codebook

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Reduced-complexity equalization techniques for ISI and MIMO wireless channels in iterative decoding

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2008年第2期26卷 256-268页

作者： Wong, Kitty K. Y. McLane, Peter J. Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada

Two reduced-complexity soft-input soft-output trellis decoding techniques are presented in this paper for equalizing single-input single-output InterSymbol Interference (ISI) channels and multiple-input multiple-output (MIMO) frequency selective fading channels. Given a trellis representing an ISI channel, the Soft-output M-Algorithm (SOMA) reduces the complexity of equalization by retaining only the best M survivors at each trellis interval. The remaining survivors are discarded. The novelty of the SOMA is the use of discarded paths to obtain soft-information. Through a simple update-and-discard procedure, the SOMA extracts reliable soft-information from discarded paths which enables a large trellis to be successfully decoded with a relatively small value of M. To decode a trellis representing a MIMO frequency selective fading channel, two challenges are faced. Not only that the trellis has a large number of states, the number of branches per trellis interval is also enormous. The Soft-output Trellis/Tree M-Algorithm (SOTTMA) expands each trellis interval into a tree-like structure and performs the M-algorithm twice: once at each trellis interval to reduce the number of states and the other at each tree sub-level to remove unwanted branches. With the proposed technique, high-order trellises with million of branches per interval can be decoded with modest complexity.

关键词： equalization Intersymbol Interference M-algorithm multiple-input multiple-output sequential decoding soft-information turbo-detection

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Low-complexity MAP channel estimation for mobile MIMO-OFDM systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第3期7卷 774-780页

作者： Gao, Jie Liu, Huaping Oregon State Univ Sch Elect Engn & Comp Sci Corvallis OR 97331 USA

This paper presents a reduced-complexity maximum a posteriori probability (MAP) channel estimator with iterative data detection for orthogonal frequency division multiplexing (OFDM) systems over mobile multiple-input multiple-output channels. The optimal MAP estimator needs to invert an N N-T x N N-T data-dependent matrix each in OFDM symbol interval, where N is the number of subcarriers and N-T is the number of transmit antennas. We derive an expectation maximization (EM) algorithm with low-rank approximation to avoid inverting large-size matrices, and thus drastically reduce the receiver complexity. In the iterative process, channel parameters are initially obtained by a least square (LS) estimator for temporary symbol decisions. Then, inter-carrier interference (ICI) due to fast fading is approximated and canceled. Finally, the temporary symbol decisions and the ICI-canceled received signals are processed by the EM-based MAP estimator to refine the channel state information for improved detection. The proposed scheme achieves about 2 dB gain over the LS scheme in channels with medium to high normalized Doppler shifts.

关键词： multiple-input multiple-output orthogonal frequency division multiplexing fast fading inter-carrier interference maximum a posteriori probability estimation low-rank approximation

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Capacity and Error Performance of Reduced-Rank Transmitter Multiuser Preprocessing Based on Minimum Power Distortionless Response

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第11期7卷 4646-4655页

作者： Yang, Lie-Liang Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

In this contribution we first derive a transmitter multiuser preprocessing (TMP) scheme for a general multiuser multiple-input-multiple-output (MIMO) system based on the minimum power distortionless response (MPDR) criterion, which minimizes the power in the context of a given downlink mobile terminal (MT) under the distortionless condition. This optimization problem results in a solution, which has the same form as the minimum mean-square error (MMSE) multiuser detection (MUD). Hence, we then extend the well-known rank-reduction techniques in MMSE-MUD to the MPDR-TMP in order to mitigate the possible implementation problems of the MPDR-TMP. In our study three classes of rank-reduction algorithms are considered, which are derived, respectively, based on the eigen-analysis methods of principal components (PC) and cross-spectral metrics (CSMs) as well as on the Taylor polynomial approximation (TPA) approach, which does not depend on the eigen-analysis. In this contribution both the capacity and error performance of a downlink space-division multiple-access (SDMA) system is investigated, when either the full-rank or reduced-rank MPDR-TMP is invoked. From our study and simulation results, it can be shown that the MPDR-TMP scheme is highly efficient for achieving the capacity and for suppressing the multiuser interference (MUI). The reduced-rank techniques can be employed by the MPDR-TMP, so as to reduce its implementation complexity while achieving the near full-rank performance of the full-rank MPDR-TMP.

关键词： Preprocessing precoding multiple-input multiple-output space-division multiple-access minimum power distortionless response reduced-rank subspace

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Semi-Blind Adaptive Spatial Equalization for MIMO Systems with High-Order QAM Signalling

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第11期7卷 4486-4491页

作者： Chen, S. Yao, W. Hanzo, L. Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

This contribution investigates semi-blind adaptive spatial filtering or equalisation for multiple-input multiple-output (MIMO) systems that employ high-throughput quadrature amplitude modulation (QAM) signalling. A minimum number of training symbols, equal to the number of receivers (we assume that the number of transmitters is no more than that of receivers), are first utilized to provide a rough least squares channel estimate of the system's MIMO channel matrix for the initialization of the spatial equalizers' weight vectors. A constant modulus algorithm aided soft decision-directed blind algorithm, originally derived for blind equalization of single-input single-output and single-input multiple-output systems employing high-order QAM signalling, is then extended to adapt the spatial equalizers for MIMO systems. This semi-blind scheme has a low computational complexity, and our simulation results demonstrate that it converges fast to the minimum mean-square-error spatial equalization solution.

关键词： multiple-input multiple-output quadrature amplitude modulation spatial equalisation semi-blind adaptive algorithm concurrent constant modulus algorithm and soft decision-directed scheme

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Analytical performance of MIMO-SVD systems in Ricean fading channels with channel estimation error and feedback delay

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第4期7卷 1315-1325页

作者： Au, Edward K. S. Jin, Shi McKay, Matthew R. Mow, Wai Ho Gao, Xiqi Collings, Iain B. Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Hong Kong Peoples R China SE Univ Natl Mobile Commun Res Lab Nanjing Peoples R China UCL London WC1E 6BT England Commonwealth Sci & Ind Res Org Informat & Commun Technol Ctr Epping NSW 1710 Australia

This paper analyzes bit error rate (BER) and outage probability of singular value decomposition-based multiple-input multiple-output systems with channel estimation error and feedback delay over uncorrelated Ricean fading channels. By utilizing marginal unordered and ordered eigenvalue distributions of complex noncentral Wishart. matrices, we derive exact closed-form expressions on the average system performance and high signal-to-interference-plus-noise ratio (SINR) approximations on the individual eigen-subehannels, respectively, under the assumption of equal power allocation. Our expressions apply for various modulation formats and arbitrary numbers of transmit and receive antennas. Our results show that in low-to-moderate SINR regimes, both the BER and the outage probability increase with channel estimation error, feedback delay and the Ricean K-factor at a polynomial rate that is inversely proportional to the difference between the numbers of transmit and receive antennas. We also show that, with channel estimation, error and feedback delay, the diversity orders of the BER and outage probability are zero and an irreducible error floor exists at high SINR.

关键词： channel estimation error feedback delay multiple-input multiple-output singular value decomposition

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A zero-forcing multiuser transmitter preprocessing scheme for downlink communications

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IEEE TRANSACTIONS ON COMMUNICATIONS 2008年第6期56卷 862-865页

作者： Yang, Lie-Liang Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

In this letter a multiuser transmitter preprocessing (MUTP) approach is proposed for downlink wireless communications, such as in spatial-division multiple-access (SDMA) or direct-sequence code-division multiple-access (DS-CDMA) system. In the proposed MUTP the preprocessing matrix is obtained by constructing a subspace that is orthogonal to the interference subspace without relying on eigen-analysis. The proposed MUTP fully removes the downlink multiuser interference, resulting in the zero-forcing (ZF) solution. It is capable of achieving the same bit error rate (BER) performance as the conventional ZF-based MUTP (ZF-MUTP).

关键词： pre-filtering preprocessing zero-forcing multiple-input multiple-output space-division multiple-access direct-sequence code-division multiple-access orthogonal subspace

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