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Efficient transceiver beamforming in multiple-input-multiple-output cognitive radio network

IET COMMUNICATIONS 2014年第15期8卷 2729-2736页

作者： Zhu, Fangjun Guo, Yan Li, Ning PLA Univ Sci & Technol Coll Commun Engn Nanjing 210007 Jiangsu Peoples R China

Owing to the ability of improving spectrum utilisation and quality-of-service (QoS) in wireless communications, multiple-input-multiple-output (MIMO) cognitive radio (CR) network has been identified as an excellent choice for the next generation communication. To protect primary users (PUs) from excessive interference while ensuring a meaningful QoS of secondary users (SUs), one key challenge of such system is the joint design of transceiver beamforming for SUs. In this study, the authors investigate the beamforming in MIMO CR network, and two optimisation problems in terms of the minimisation of the total transmission power and the maximisation of the smallest received signal-to-interference-plus-noise ratio (SINR) are considered. The problems can be formulated as indefinite quadratic optimisation programs which are known to be non-convex NP-hard. Hence, a distributed algorithm based on semi-definite programming and minimum-mean-squared-error is proposed to achieve the optimal beamforming weight vector. The findings of this study demonstrated that the proposed algorithm outperforms the existing ones with respect to the total transmitted power and SUs SINR.

关键词： radio transceivers array signal processing MIMO communication cognitive radio quality of service minimisation computational complexity distributed algorithms least mean squares methods concave programming radio spectrum management radiofrequency interference quadratic programming multiple-input-multiple-output cognitive radio network spectrum utilisation quality-of-service QoS wireless communication MIMO CR network next generation communication primary user protection excessive interference secondary user transceiver beamforming efficiency optimisation problem total transmission power minimisation signal-to-interference-plus-noise ratio SINR maximisation indefinite quadratic optimisation program nonconvex NP-hard distributed algorithm semidefinite programming minimum-mean-squared-error optimal beamforming weight vector

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A Variable Momentum Factor Algorithm for a priori SNR Estimation in Speech Enhancement

A Variable Momentum Factor Algorithm for a priori SNR Estima...

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International Congress on Image and Signal Processing

作者： Haidong Sun Shifeng Ou Ruohan Liu Ying Gao Sch. of Opto-Electron. Inf. Sci. & Technol. Yantai Univ. Yantai China

ISBN: (纸本)9781479958368

The estimation of the a priori signal-to-noise ratio (SNR) is a very significant issue for many speech enhancement algorithms. The widely-used decision-directed (DD) algorithm largely depresses the musical noise, but the estimated a priori SNR suffer from one frame delay which results in the degradation of speech quality. In this paper, we propose a novel algorithm to a priori SNR estimation which solves the above problem while keeping the advantage of the DD approach. First, a momentum term is added and incorporated into the traditional DD approach to accelerate the tracking speed for the a posteriori SNR. Then a self-adaptive momentum factor is achieved in the minimum-mean-squared-error (MMSE) sense to improve the allover performance of the proposed algorithm. Simulation experiment results show that our proposed algorithm brings significant improvement compared to the DD and fixed momentum factor algorithms under various noisy types and levels.

关键词： least mean squares methods speech enhancement DD algorithm MMSE a priori SNR estimation decision-directed algorithm frame delay minimum-mean-squared-error self-adaptive momentum factor speech enhancement algorithms speech quality variable momentum factor algorithm Estimation Noise measurement Signal processing algorithms Signal to noise ratio Speech Speech enhancement a priori SNR decision-directed approach momentum term

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Enhanced Iterative Max-Sum-Rate Algorithm for Linear MU-MIMO Precoding

Enhanced Iterative Max-Sum-Rate Algorithm for Linear MU-MIMO...

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22nd IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Na, Chongning Hou, Xiaolin Harada, Atsushi DOCOMO Beijing Commun Labs Co Ltd Beijing 100190 Peoples R China

ISBN: (纸本)9781457713484

Multi-user multiple input multiple output (MU-MIMO) systems can achieve high spectral efficiency for wireless communication. The design of optimal transmit precoding for max-sum-rate (MSR) MU-MIMO downlink transmission is a non-trivial problem. Recent research approached this problem by exploiting the relationship between max-sum-rate and the minimum-mean-squared-error (MMSE) and proposed several iterative schemes. Based on these research results, we propose enhanced iterative MSR algorithms for linear MU-MIMO precoding which improve the sum rate performance and reduce the computational complexity. The effectiveness of the proposed method is verified by numerical simulations.

关键词： MIMO communication MU-MIMO downlink transmission communication complexity computational complexity iterative max-sum-rate algorithm iterative methods linear MU-MIMO precoding mean square error methods minimum-mean-squared-error multiuser multiple input multiple output system optimal transmit precoding precoding spectral efficiency wireless communication

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Performance analysis of general pilot-aided linear channel estimation in LTE OFDMA systems with application to simplified MMSE schemes

Performance analysis of general pilot-aided linear channel e...

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19th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Omar, Samir Ancora, Andrea Slock, Dirk T. M. NXP Semicond Business Line Cellular Syst 505 Route Lucioles F-06560 Sophia Antipolis France EURECOM Institute Mobile Commun Dept F-06904 Sophia Antipolis France

ISBN: (纸本)9781424426430

In this paper we provide a general framework for the performance analysis of pilot-aided linear channel estimators class including the general interpolation, Least Squares (LS), regularized LS, minimum-mean-squared-error (MMSE) and approximated MMSE estimators. The analysis is performed from the perspective of Long Term Evolution Orthogonal Frequency Division Multiple Access (LTE OFDMA) down-link systems. We also propose two novel modified MMSE schemes, an Exponential Mismatched MMSE and a Simplified MMSE, to overcome the high implementation complexity of the MMSE and offering improvements to other known approximated methods. At the end, we verify the analytical results by means of Monte-Carlo simulations in terms of Normalized mean Square error (NMSE) and coded Bit error Rate (BER).

关键词： OFDMA channel estimation interpolation Least-Squares minimum-mean-squared-error

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