BER performance and optimum training strategy for uncoded SIMO and alamouti space-time block codes with MMSE channel estimation

In multiple antenna systems, channel estimation is of critical importance. In this paper, we investigate the effect of imperfect channel estimation on the performance of both uncoded singleinput multiple-output (SIMO) systems and multiple-input multiple-output (MIMO) systems using Alamouti space-time block codes. To this end we consider a mismatched receiver and a propagation channel that is affected by flat Rayleigh block fading. The receiver estimates the channel from known pilot symbols which are transmitted among the data. An analytical expression for the bit error rate (BER) with imperfect channel estimation is derived. Given a number of data symbols we find the optimal number of pilot symbols that minimizes the BER degradation, for both uncoded SIMO communication and Alamouti spacetime block coded MIMO communication. For best performance the number of data symbols in one transmission block is to be taken as high as possible, provided that the duration of a block does not exceed the channel coherence time. Analytical results are confirmed by computer simulations.