Performance analysis of two-branch space-time block coded DS-CDMA systems in time-varying multipath Rayleigh fading channels

Based on Alamouti code, two-branch transmit diversity DS-CDMA systems, namely, space-time block coded DS-CDMA (STBC-DS-CDMA) systems are discussed. Besides the simple maximum-likelihood (SML) detector, three novel detectors are applied to improve the STBC-DS-CDMA systems. Additionally, for random binary spreading code (RBSC), the performance of all systems in spatially uncorrelated time-varying multipath Rayleigh fading channels are derived theoretically. In consequence of the simple expression for the variances of the multipath interference (MPI) and the multiuser interference (MUI), our analytical results are easy to calculate. Numerical outcomes have revealed that significant performance improvement can be achieved even when the systems are operated in highly selective channels.