BER and Mutual Information of STBCS over Fading Channels with PSK/QAM Modulations

We present an exact analysis of STBCs over uncorrelated memoryless block-fading channels with unequal and generalized fading statistics. First, the exact BER of an ideal (rate-one-full-diversity) linear STBCs with PSK or QAM modulation in the aforementioned channel is given. The formulas derive from a careful review and aggregation of results scattered in the literature, and can be applied to STBCs of various constructions. The exactness and generality of these analytical BER expressions are illustrated by comparison against corresponding simulation results presented in classic papers on STBCs, e.g. (Alamouti et al., 1998). The exact BER formulas are then utilized to analyze the effect of unequal fading statistics and uneven average transmit power distribution across diversity branches, onto the performance of a hypothetical STBC of unitary rate and full-diversity, constructible to any number of transmit antennas. The study reveals the little impact of uneven diversity branch average power distribution on the performance of such a hypothetical STBC. Finally, the formulas are employed to derive the mutual information of linear STBCs over realistic PSK and QAM modulations with block-wise hard-decision, which are then applied to reveal the concrete throughput potential of linear STBCs, in comparison to the capacity of the equivalent SIMO AWGN channel with the same transmit power.