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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Performance Analysis of Blind Subspace-Based Signature Estimation Algorithms for DS-CDMA Systems with Unknown Correlated Noise | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 83863 14 pages doi 10.1155 2007 83863 Research Article Performance Analysis of Blind Subspace-Based Signature Estimation Algorithms for DS-CDMA Systems with Unknown Correlated Noise Keyvan Zarifi and Alex B. Gershman Department of Communication Systems Darmstadt University of Technology Merckstrafe 25 64283 Darmstadt Germany Received 3 October 2005 Revised 30 March 2006 Accepted 1 April 2006 Recommended by Vincent Poor We analyze the performance of two popular blind subspace-based signature waveform estimation techniques proposed by Wang and Poor and Buzzi and Poor for direct-sequence code division multiple-access DS-CDMA systems with unknown correlated noise. Using the first-order perturbation theory analytical expressions for the mean-square error MSE of these algorithms are derived. We also obtain simple high SNR approximations of the MSE expressions which explicitly clarify how the performance of these techniques depends on the environmental parameters and how it is related to that of the conventional techniques that are based on the standard white noise assumption. Numerical examples further verify the consistency of the obtained analytical results with simulation results. Copyright 2007 K. Zarifi and A. B. Gershman. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION In recent years extensive research efforts have been devoted to develop different strategies for multiuser detection in DS-CDMA systems 1 . One of the most challenging problems in multiuser detection is that of the effect of unknown multipath channel which may result in a significant mismatch between the actual user signature and its presumed value used in the multiuser detection algorithms. Since signature mismatches may .
