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Title: Blind Detection in DS CDMA Systems Based on Independent Component Analysis
Researcher: Jyoti Saxena
Guide(s): C.S. Rai and P.K. Bansal
University: Guru Gobind Singh Indraprastha University
Completed Date: 2007 2007
Abstract: newline The DS-CDMA systems employ PN spreading sequences instead of newlineorthogonal spreading codes to provide the feature of soft capacity. However, this newlinegives rise to MAI. The CDMA systems based on IS-95 standard employ matched newlinefilter detectors, which regard MAI as additive noise. This conventional detection newlinetechnique limits the number of users that can be supported in a DS-CDMA system. newlineFurther, the bit error rates of individual users degrade rapidly with an increase in the newlinenumber of users. The thesis presents ICA based blind detection techniques for the newlinedesired user in a DS-CDMA system supporting single rate, dual rate and multi rate newlinetransmission under different channel conditions. The mathematical model of DSCDMA newlinesystem under single path and multi path propagation conditions has been newlineshown to satisfy the ICA model. Further the problem of indeterminacy in the order newlineand sign of independent sources separated by ICA algorithms has been addressed. The newlinesolution has also been extended to DS-CDMA systems operating in Rayleigh block newlinefading channels. Keeping in mind the requirements of 3G systems, the ICA based newlinedetection approach has been further extended to dual rate and multi rate systems newlineunder single path and multi path propagation conditions. An information theoretic newlineICA algorithm based on Negentropy maximization has been proposed. By resolving newlinethe permutation and sign ambiguities, this algorithm has been applied for signal newlinedetection and has been shown to be near-far resistant. Simulation results have been newlineobtained and presented to demonstrate the BER performance of the proposed newlinetechniques. It has been shown that the BER performance of the proposed techniques is newlinesignificantly better than conventional matched filter detector and is comparable with newlinethat of Decorrelator and MMSE detector.
Appears in Departments:University School of Information and Communication Technology

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