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