Blind Detection Algorithm In DS_CDMA System

CDMA technology became one of the communication technology with developing prospect, and has being applied to military communications and civilian communications extensively.. Especially in recently about ten years, the requirement of wireless multimedia is increasing significantly, and one effective methodology is to improve the spectrum utilization. CDMA technology is an effective way to improve the utilization of the spectrum, but it's performance under the impact of MAI. Therefore, the multi-user detection technology, which has been used to reduce multiple-access interference in CDMA Communication system, has became a new hotspot in the research of wireless communication.In this paper, we do far-ranging research on blind detection algorithm in DS_CDMA system, and focusing on multi-user detection blind multi-user detection in the Gauss channel, At first, the paper summarize the recent development and research of blind multi-user detection algorithm, and established the DS_CDMA mathematical model, then introduced the model of match-filter detector and one of anti-ISI broadband detector, and discussed the need for multi-user detection, and discussed the optimum detector,linear decorrelating detector,linear MMSE detector,adaptive MMSE detector of multi-user detection. On this basis, introduced the blind multi-user detection, and analyzed and simulated LMS, RLS, Kalman algorithm of blind multi-user detection. Finally, on the basis of the Blind multi-user detection, proposed PC tracking algorithm on the base of the first order perturbation theory has been applied to blind multi-user detection, and theoretical analyzed and simulated.The main work of this paper can be summarized as follows:①The DS_CDMA multi-user model has been established, and using the additive white Gaussian noise (AWGN) and Rayleigh model to simulate signals transmitting in the wireless space and to discuss resolving of the MAO.②By studied multi-user detection algorithm in synchronization DS_CDMA system under AWGN channel, the paper analyzed the suboptimal algorithm of the multi-user detection and several typical blind multi-user detection algorithm, and introduced the typical blind multi-user detection algorithm and discussed Improvement algorithm.. The paper introduced the perturbation theory of subspace tracking based on subspace blind multi-user detection algorithm.)③It is a effective low-complexity blind multi-user detection algorithm improved by simulating,analyzing,and comparing..