The Performance of CDMA Systems withSpace-Time Spreading Approach underthe Conditions of Multi-users and Multipaths
采用空时扩谱技术的CDMA系统在多用户多径条件下的性能

The paper studies the performance of CDMA systems with the space-time approach under the conditions of multi-users and multipaths. The space-time spreading scheme with a novel algorithm can improve the downlink performance by using two antenna elements at the base station and one antenna at the mobile terminal. Different from the present other results, the multi-user systems have been analyzed, the detailed theory analysis and expression of bit-error-probability have been provided, based on the scheme of single-user systems. Moreover, the simulation results show that this scheme obtains an improvement of the CDMA system performance comparing to the conventional approaches, demonstrating that it is a practical way to decrease the bit error rate and improve the quality of the downlink of CDMA systems. Meantime, the implementation complexity of the systems has increased, there are many new technical requirements for mobiles to be satisfied, and the STS technique needs to be improved.