Information densities for block-fading MIMO channels

This paper provides a characterization of the output and of the transition probability den- sity function (pdf ) of a MIMO block-fading channel, paving the way to its information-theoretic analysis. The information density, whose average in ergodic conditions gives the mutual information conveyed over the channel, is needed to characterize the chan- nels with arbitrary behavior, as one in this case can neither resort to ergodicity nor to consequences of any law of large numbers. The information density expression is then provided under several assump- tions on the channel model and also in the presence of multiple-antenna equipped interferers.