Blind Adaptive Constrained Constant-Modulus Reduced-Rank Interference Suppression Algorithms Based on Interpolation and Switched Decimation

• Published in: IEEE transactions on signal processing Vol. 59; no. 2; pp. 681 - 695
• Main Authors: de Lamare, R C, Sampaio-Neto, R, Haardt, M
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive algorithms; Algorithm design and analysis; Algorithms; Applied sciences; Blind adaptive estimation; Blinds; Complexity theory; Constraints; Detection, estimation, filtering, equalization, prediction; Estimation; Exact sciences and technology; Information, signal and communications theory; Interference; Interference suppression; Interpolation; iterative methods; Miscellaneous; Optimization; reduced-rank techniques; Reduction; Signal and communications theory; Signal processing; Signal, noise; spread spectrum systems; Studies; Switches; Telecommunications and information theory; Transformations; Wireless communication; Wireless communications; Performance evaluation; Rank statistic; iterative methods; Adaptive algorithm; Blind adaptive estimation; Wireless telecommunication; Adaptive estimation; Stochastic method; Adaptive method; Optimization; Least squares method; Direct sequence; Multistage method; Model selection; Blind identification; Interference suppression; Interpolation; Dimension reduction; Telecommunication system; Code division multiple access; Recursive method; Signal processing; spread spectrum systems; Matrix method; Decimation; reduced-rank techniques
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2010.2091274

This work proposes a blind adaptive reduced-rank scheme and constrained constant-modulus (CCM) adaptive algorithms for interference suppression in wireless communications systems. The proposed scheme and algorithms are based on a two-stage processing framework that consists of a transformation matrix that performs dimensionality reduction followed by a reduced-rank estimator. The complex structure of the transformation matrix of existing methods motivates the development of a blind adaptive reduced-rank constrained (BARC) scheme along with a low-complexity reduced-rank decomposition. The proposed BARC scheme and a reduced-rank decomposition based on the concept of joint interpolation, switched decimation and reduced-rank estimation subject to a set of constraints are then detailed. The proposed set of constraints ensures that the multipath components of the channel are combined prior to dimensionality reduction. We develop low-complexity joint interpolation and decimation techniques, stochastic gradient, and recursive least squares reduced-rank estimation algorithms. A model-order selection algorithm for adjusting the length of the estimators is devised along with techniques for determining the required number of switching branches to attain a predefined performance. An analysis of the convergence properties and issues of the proposed optimization and algorithms is carried out, and the key features of the optimization problem are discussed. We consider the application of the proposed algorithms to interference suppression in DS-CDMA systems. The results show that the proposed algorithms outperform the best known reduced-rank schemes, while requiring lower complexity.