Effect of Channel Estimation Errors on Turbo Equalization in ST Block Coded CDMA Downlink

Space-time (ST) block coding based transmit diversity is considered in the third generation mobile communication standards for wideband-CDMA downlink transmission. On the other hand, turbo equalization can be used to enhance the wireless system performance. Hence, recently we proposed a minimum mean-square error (MMSE)-based turbo equalization scheme for the ST block coded CDMA downlink. In the proposed scheme, we assumed that perfect channel information is available at the receiver. However, in practice, channel coefficients are unknown to the receiver and have to be obtained through channel estimation. In this paper, we investigate the effect of the channel estimation errors on the MMSE-based turbo equalization in the downlink of ST block coded CDMA systems. It is demonstrated through simulations that substantial performance improvements can be obtained using the MMSE-based turbo equalization for moderate-to-high channel estimation quality