Exponential Diversity Achieving Spatio-Temporal Power Allocation Scheme for MIMO Fading Channels

We analyze optimum (space-time) adaptive power transmission policies for Rayleigh fading MIMO channels when CSIT and CSIR are available. We show that our power allocation policy provides exponential diversity $gain^2$ $BER\leq\alpha{e}{^-^f^(^{n_t}^,^{n_r}^)}$ where $\alpha{>}{0}$ is a constant, and $f>0$ is an increasing function of $n_t$ & $n_r$ if perfect CSIT is available. Exponential diversity is lost at high SNR if the quality of CSIT degrades