Study Of Blind Multi-user Detection Technology Based On Independent Component Analysis In CDMA Systems

Code Division Multiple Access is self-interfered system where multi-access interference(MAI) and Near-far effect are existing as the main factors restricting CDMA system capacity. These years, be considered as one of the key techniques for the 3'd Generation (3G) mobile communication system, Multiple User Detection (MUD) for CDMA system made its obvious progress. MUD reduces the mufti-access interference and solves the Near-far problem and improves system capacity. The blind adaptation schemes do not require training sequences and the interference user's information. It only needs the prior knowledge of the signature waveform and the timing of the desired user. The blind adaptation schemes are the promising one with acceptable implementation complexity, while simultaneously eliminating the need of a plenty of priori system information and can be implemented as a blind MUD.Firstly, CDMA systems were introduced, theory of spreading frequency communication and characters of spreading sequence were analyzed and pointed out essential reason of MAI and MUD is the key technique of 3G. Conventional MUD and blind adaptive MUD techniques were summarized and analyzed, as well as their advantages and disadvantages were listed. Further, this paper has summarized the basis concept and theory on the independent component analysis (ICA) and the blind mufti-user detection. Some kinds of optimized algorithm and performance index of algorithm are summarized.At last, the matrix DS-CDMA (Direct Sequence-CDMA) signal model and the noisy linear Independent Component Analysis (ICA) model are analyzed in this paper. Comparing these models shows that they have same form. The blind multiuse detection based on ICA is proposed. In this thesis, all algorithms are done with numerical simulations and performance analysis. The simulation results show the Algorithm performance and the increase in the number of the users proximity effect more severe cases can achieve better detection function.