Space-time block precoding scheme for time division duplex CDMA communications

Space-Time coding (STC) is an efficient technique to combat fading effects and improve the system capacity in wireless communications. The main disadvantage of the space-time coding with multi-antenna transmission for CDMA communications is that the multiple access interference (MAI) and co-channel interference might be enhanced. In this paper, a novel space-time precoding scheme is proposed to eliminate MAI and co-channel interference for time division duplex (TDD) downlink CDMA communications without complexity increase in the mobile stations. Simulations using the space-time block code (STBC) known as Alamouti's code, show that the system performance can be considerably improved by the proposed scheme compared with the conventional STBC receiver in frequency selective Rayleigh fading channels.