Research On Technologies Of Blind Multiuser Detection For CDMA Communication

The advantages of CDMA communication system in 3G are large capacity, soft capacity, soft handover, higher spectral efficiency and the ability to resist the effects of multi-path fading, and so on. In code-division multiple-access (CDMA) systems, multi-access interference (MAI) and near-far problems are the predominant factor. The third generation mobile communication system regards multi-user detection as an effective method to overcome MAI. Most of the researches focus on the blind multi-user detector, because it has no needs of training sequence and the prior knowledge of interferential users.This thesis puts focus on blind MUD algorithms through theory analysis and simulations based on the current MUD technologies. The main contributions of this thesis are in the following :(1)Make analysis and simulations on Signal Interference Rate (SIR), minimal output energy and anti-interference performance of LMS algorithm, RLS algorithm of the blind multi-user measures. Simulation results show that RLS algorithm is of great convergence performance, stable SIR and accurate tracking, but high complexity.(2)LMS algorithm is of lower complexity but poor convergence performance. Because of the disadvantage of blind MUD LMS algorithm, author adopts an improved type of blind MUD LMS algorithm and makes analysis and simulation of its SIR and anti-interference performance. Simulation results show that the convergence performance of this algorithm is superior to LMS algorithm.(3)Make analysis about Kalman algorithm. Author proposes an improved type of blind MUD Kalman algorithm. Simulation results show that the blind adaptive algorithm discussed in this thesis has the advantages of quicker convergence and better signal-to-noise rate.