Space-Time Signal Processing Technology For CDMA Communication System

ABSTRACTCo-channel interference (CCI) and Inter-symbol interference (ISI) are two major factors limiting performance of CDMA communication system. Although ISI can be compensated in time-domain and CCI can be restrained in space-domain, these two interferences cannot be eliminated simultaneously by only using time-domain or space-domain processing technique because of their simultaneous existence in the wireless communication system. So it is necessary to study Space-Time processing technique.This dissertation proposes a blind adaptation space-time 2D-RAKE receiving algorithm----ST-DRCMA (Space-Time De-Re-spread Constant Modulus algorithm) by studying techniques of scattering-concentrate receiving and RAKE receiver. This algorithm, an improved method based on CMA (Constant Modulus algorithm), utilizes the information of spread codes and the performance of constant modulus in CDMA communication system. The results of the computer simulation can prove that this algorithm can improve the capacity of the receiver.Analyzing the theories and methods of Multiuser Detection (MD) and space-time optimizing principles, this dissertation proposes two schemes of Space-Time MD combining the space-time processing and Multiuser Detection. One is the Space-Time MMSE Decorrelating MD, and another is Space-Time MLSE Decision-Feedback MD. The results of the computer simulation also prove that these two schemes not only inherit the ability to resist "the near far problem" in Decorrelating MD and Decision-Feedback MD, but also improve the performance of communication system.