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Compact scalable frequency dependent precoding and its FPGA implementation for 5G massive MIMO wireless systems

ELECTRONICS LETTERS 2015年第23期51卷 1937-1938页

作者： Guan, L. Alcatel Lucent Ireland Bell Labs Dublin 15 Ireland

Massive multiple-input multiple-output has been broadly accepted as one of the key candidate technologies for enabling next generation (5G) wireless network. To ensure system performance, an efficient frequency dependent precoding has to be in place to pre-compensate the frequency selective channel response in real time. This Letter presents a compact scalable frequency dependent precoding approach and its area-efficient field programmable gate arrays (FPGA) implementation. The proposed approach has been validated and well compared with other architectures both in the Matlab/Simulink and Xilinx FPGAs.

关键词： 5G mobile communication MIMO communication field programmable gate arrays next generation networks precoding radiofrequency integrated circuits 5G massive MIMO wireless systems 5G wireless network Matlab-Simulink Xilinx FPGA field programmable gate arrays frequency dependent precoding frequency selective channel response multiple-input multiple-output systems next generation wireless network

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Space-time trellis code design with binary CPM

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ELECTRONICS LETTERS 2006年第3期42卷 168-170页

作者： Ahmadi, AR Rao, RK Univ Western Ontario Dept Elect & Comp Engn London ON N6A 5B9 Canada

Binary continuous phase modulation (CPM) is considered with space-time trellis codes (STTCs) for multiple-input multiple-output systems. Single-h CPM with rectangular, raised cosine and half cycle sinusoid is considered. The upper bound on the minimum product distance of this signalling scheme is determined over a quasi-static Rayleigh fading channel, Based on the rank and determinant criterion, best STTC/CPM combinations are identified for two transmit and an arbitrary number of receive antennas.

关键词： MIMO systems Rayleigh channels continuous phase modulation receivingantennas space-time codes trellis codes binary CPM binary continuous phase modulation minimumproduct distance multiple-input multiple-output systems quasi-static Rayleigh fading channe

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Mitigation of impairments in MGDM transmission with mode-selective spatial filtering

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IEEE PHOTONICS TECHNOLOGY LETTERS 2008年第13-16期20卷 1112-1114页

作者： Tsekrekos, C. P. Koonen, A. M. J. Eindhoven Univ Technol COBRA Res Inst NL-5600 MB Eindhoven Netherlands

A model for a mode group diversity multiplexing (MGDM) transmission system is derived. The factors that may limit MGDM transmission are identified. An optical method to reduce the spatial overlap among the fields of the detected mode groups could mitigate impairments that may occur in MGDM transmission. Mode-selective spatial filtering (MSSF) is such an optical method. Experimental results support that a robust five-channel MGDM system could be realized with MSSF, as long as modal noise is limited. MSSF facilitates the combination of MGDM with wavelength-division multiplexing.

关键词： multimode waveguides multiple-input multiple-output systems multiplexing optical fiber communication spatial filters

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Performance modeling of MIMO OFDM systems via channel analysis

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第9期5卷 2358-2362页

作者： Gao, Jie Ozdural, O. Can Ardalan, Sasan H. Liu, Huaping Intel Corp Wireless Networking Grp Hillsboro OR 97124 USA

multiple-input multiple-output (MIMO) antennas can be combined with orthogonal frequency division multiplexing (OFDM) to achieve diversity. gain and/or to increase system spectral efficiency through spatial multiplexing. In this letter, we derive the probability density function (pdf) expressions of the condition number (i.e., the maximum-to-minimum-singular-value ratio, MMSVR) of the channel state information (CSI) matrix. We show that this ratio is directly related to the noise enhancement in open-loop MIMO systems and provides a significant insight on the overall system capacity. The pdf of this ratio could be used to predict the relative performances of various MIMO configurations without complex system-level simulations. The pdf can also be used to compute the probability of whether certain channels will fail in the high-throughput mode. Extensive simulations are performed to validate the accuracy of the closed-form pdf of the MMSVR derived in this letter.

关键词： multiple-input multiple-output systems orthogonal frequency division multiplexing channel analysis condition number minimum mean-square error detection

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Interpolation based pilot-aided channel estimation for STBC spatial modulation and performance analysis under imperfect CSI

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IET COMMUNICATIONS 2016年第14期10卷 1820-1828页

作者： Acar, Yusuf Dogan, Hakan Basar, Ertugrul Panayirci, Erdal Istanbul Kultur Univ Dept Elect & Elect Engn TR-34156 Istanbul Turkey Istanbul Univ Dept Elect & Elect Engn TR-34320 Istanbul Turkey Istanbul Tech Univ Fac Elect & Elect Engn TR-34469 Istanbul Turkey Kadir Has Univ Dept Elect & Elect Engn TR-34083 Istanbul Turkey

A combination of space-time block coding and spatial modulation (STBC-SM) has been recently proposed for multiple input-multiple output systems to obtain both spatial diversity gain and more capacity simultaneously while assuming the perfect channel state information (P-CSI) was available at the receiver. However, in practical scenarios the CSI is unknown to the receiver and should be estimated in order to detect the transmitted data in a reliable way. Therefore, channel estimation (CE) is a major challenge in designing the STBC-SM systems. In this study, the problem of CE is investigated and a new pilot-aided channel estimation (PA-CE) technique, coupled with an interpolation, is proposed for the STBC-SM systems operating in the presence of rapidly time-varying mobile channels. Several interpolation schemes such as the linear, nearest neighbour, piecewise cubic Hermite and the low-pass interpolations are applied and their performances are compared to determine the best suitable interpolation technique to be employed in STBC-SM systems. Bit error rate (BER) performance of the proposed CE technique is then investigated in time-varying channels with different modulation. Moreover, the pairwise error probability of the STBC-SM scheme is derived and its average bit error probability is evaluated analytically in the presence of CE errors.

关键词： channel estimation space-time block codes diversity reception MIMO communication interpolation mobile radio time-varying channels error statistics quadrature phase shift keying quadrature amplitude modulation interpolation-based pilot-aided channel estimation STBC spatial modulation imperfect CSI space-time block coding multiple-input multiple-output systems spatial diversity gain perfect channel state information P-CSI STBC-SM systems PA-CE technique time-varying mobile channels linear nearest neighbour piecewise cubic Hermite low-pass interpolation bit error rate performance BER performance quadrature phase shift keying QPSK 16-quadrature amplitude modulation 16-QAM 64-QAM pairwise error probability bit error probability

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Grassmannian Beamforming for MIMO Amplify-and-Forward Relaying

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2008年第8期26卷 1397-1407页

作者： Khoshnevis, Behrouz Yu, Wei Adve, Raviraj Univ Toronto Edward S Rogers Sr Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

We consider the problem of beamforming codebook design for limited feedback half-duplex multiple-input multipleoutput (MIMO) amplify-and-forward (AF) relay system. In the first part of the paper, the direct link between the source and the destination is ignored. Assuming perfect channel state information (CSI), we show that the source and the relay should map their signals to the dominant right singular vectors of the source-relay and relay-destination channels. For the limited feedback scenario, we prove the appropriateness of Grassmannian codebooks as the source and relay beamforming codebooks based on the distributions of the optimal source and relay beamforming vectors. In the second part of the paper, the direct link is considered in the problem model. Assuming perfect CSI, we derive the optimization problem that identifies the optimal source beamforming vector and show that the solution to this problem is uniformly distributed on the unit sphere for independent and identically distributed (i.i.d) Rayleigh channels. For the limited feedback scenario, we justify the appropriateness of Grassmannian codebooks for quantizing the optimal, source beamforming vector based on its distribution. Finally, a modified quantization scheme is presented, which introduces a negligible penalty in the system performance but significantly reduces the required number of feedback bits.

关键词： Amplify-and-forward relaying Beamforming Grassmannian codebooks multiple-input multiple-output systems

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Soft-Heuristic Detectors for Large MIMO systems

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2013年第18期61卷 4573-4586页

作者： Svac, Pavol Meyer, Florian Riegler, Erwin Hlawatsch, Franz Vienna Univ Technol Inst Telecommun A-1040 Vienna Austria

We propose low-complexity detectors for large MIMO systems with BPSK or QAM constellations. These detectors work at the bit level and consist of three stages. In the first stage, maximum likelihood decisions on certain bits are made in an efficient way. In the second stage, soft values for the remaining bits are calculated. In the third stage, these remaining bits are detected by means of a heuristic programming method for high-dimensional optimization that uses the soft values ("soft-heuristic" algorithm). We propose two soft-heuristic algorithms with different performance and complexity. We also consider a feedback of the results of the third stage for computing improved soft values in the second stage. Simulation results demonstrate that, for large MIMO systems, our detectors can outperform state-of-the-art detectors based on nulling and canceling, semidefinite relaxation, and likelihood ascent search.

关键词： Genetic algorithm heuristic programming ICI mitigation large MIMO systems MIMO detection multiple-input multiple-output systems OFDM spatial multiplexing

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Blind Channel Estimation in Orthogonally Coded MIMO-OFDM systems: A Semidefinite Relaxation Approach

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2009年第6期57卷 2354-2364页

作者： Sarmadi, Nima Shahbazpanahi, Shahram Gershman, Alex B. Tech Univ Darmstadt Dept Commun Syst NTS D-64283 Darmstadt Germany Univ Ontario Inst Technol Fac Engn & Appl Sci Oshawa ON L1H 7K4 Canada

A new blind channel estimation approach for orthogonally coded multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems is proposed. The main idea of our technique is, using specific properties of the orthogonal space-time block codes (OSTBCs), to estimate the finite impulse response (FIR) channel parameters in the time domain instead of doing this in the frequency domain independently for each subcarrier. This results in a substantially improved parsimony of the channel parametric model as compared to the direct per subcarrier channel estimation methods and allows coherent processing across the subcarriers. It is shown that using the semidefinite relaxation (SDR) technique, our channel estimation problem can be approximated as a convex semidefinite programming (SDP) problem and, hence, can be solved efficiently using modern convex optimization methods. Our simulations validate the performance and/or computational complexity advantages of the proposed method as compared to some current state-of-the-art blind MIMO-OFDM channel estimation methods.

关键词： Channel estimation multiple-input multiple-output systems orthogonal frequency-division multiplexing semidefinite relaxation space-time block coding

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A Refined Channel Estimation Method for STBC/OFDM systems in High-Mobility Wireless Channels

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第11期7卷 4312-4320页

作者： Ku, Meng-Lin Huang, Chia-Chi Natl Chiao Tung Univ Dept Commun Engn Hsinchu 300 Taiwan

In this paper, we investigate channel estimation for orthogonal frequency division multiplexing (OFDM) systems with space-time block code (STBC) in mobile wireless channels. Our proposed method consists of two-stage processing and is developed on the basis of the classical discrete Fourier transform (DFT)-based channel estimation method. In the initialization stage, we employ a multipath interference cancellation technique to estimate multipath delays and multipath complex gains. In the tracking stage, we develop a refined decision-feedback (DF) DFT-based channel estimation method in which a few pilot tones inserted in OFDM data symbols are applied to form an optimal gradient vector at the first iteration such that the error propagation effect is mitigated. In order to reduce computational complexity, an approximate weighting matrix is adopted to avoid matrix inversion. We demonstrate the proposed method through computer simulation of an STBC/OFDM system with two transmit antennas and a single receive antenna. The results show that our method outperforms the classical DFT-based method, the STBC-based minimum mean square error (MMSE) method, and the Kalman filtering method as well, and that significant signal-to-noise ratio (SNR) performance improvement can be achieved, especially when a high-level modulation scheme, e.g. 16QAM, is adopted in high-mobility environments.

关键词： multiple-input multiple-output systems space-time coding orthogonal frequency division multiplexing channel estimation IEEE 802.16e

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Maximising capacity of MIMO systems with receive antenna subarray formation

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ELECTRONICS LETTERS 2008年第20期44卷 1204-1206页

作者： Theofilakos, P. Kanatas, A. G. Univ Piraeus Dept Digital Syst Wireless Commun Lab GR-18534 Athens Greece

Antenna subarray formation is a novel RF pre-processing technique that reduces hardware complexity of multiple-input multiple-output systems while alleviating the performance degradation of conventional antenna selection techniques. With this method, each RF chain is allocated to a lineal combination of the responses of a subset of the available antenna elements, which is performed in the radio frequency domain. A novel. analytical. suboptimal algorithm is introduced for antenna subarray formation based on instantaneous channel information that maximises the effective channel capacity.

关键词： receive antenna subarray formation performance degradation maximising capacity MIMO systems antenna accessories multiple-input multiple-output systems antenna arrays conventional antenna selection techniques RF preprocessing technique radio frequency domain channel capacity hardware complexity antenna elements Antenna accessories Antenna arrays instantaneous channel information Radio links and equipment receiving antennas

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