Joint space-time block code and downlink beamforming in FDD DS-CDMA systems

Joint space-time block coding (STBC) and beamforming schemes for DS-CDMA are introduced in this paper. STBC scheme and beamforming technique have been considered separately as means to increase the bit rate and capacity in DS-CDMA systems. In STBC scheme, a user´s stream is split two independent streams to transmit in two antennas, which will result in intersymbol interference at receiver in multipath environment. Thus, a STBC-beamforming scheme is discussed to compensate for the intersymbol interference. The beamforming weight is determined by downlink channel covariance (DCCM). Computer simulations show that using the STBCB scheme can provider better BER performance than conventional STBC scheme and single array diversity.