A Tight Lower Bound on the Outage Probability of Spatially Correlated MIMO Channels

We present tight upper bounds on the channel mutual information of spatially correlated and uncorrelated multielement antenna (MEA) channels. Using these upper bounds, accurate lower bounds on the outage probability are derived. Similarly, tight upper bounds on the outage rate are obtained. Interestingly, these bounds are even tighter as the spatial correlation increases. Simulation results show that, in a highly correlated channel, the worst gap between our outage probability lower bounds and the exact values (given by simulation) is about 0.2 and 0.3 dBs, respectively for 2 times 2 and 3 times 3 MEA systems. This tightness suggests using the derived lower bounds on the outage probability in order to characterize the performance limits of MEA in terms of the finite-SNR diversity-multiplexing tradeoff in correlated and uncorrelated spatial fading channels.