Performance analysis of Alamouti Transmit Diversity using partial channel knowledge

In this paper, we consider Alamouti Transmit Diversity (ATD) system in spatially independent and slowly time varying Rayleigh flat fading channels. The channel is modeled by second order autoregressive (AR2) processes such that it will remain constant for a pair of two consecutive symbols and vary with one pair to another. We consider a frame of N+2 symbols, where Channel State Information at Receiver (CSIR) is available only in the beginning for two consecutive symbols. Using this CSIR, we predict channel for the remaining N symbols and detect them. For this partially coherent system, we have derived closed-form expression of BER for BPSK constellation. We have also presented simulation results and compared with analytical expressions. We have shown the effects of frame size N and of doppler frequency (f_d) normalized by symbol time T_s.