Capacity of multi-antenna block-fading channels

We determine the performance limits of a multiple transmit and receive antenna system over a fading channel. We assume a frequency-flat block-fading additive white Gaussian noise channel with delay constraint, transmit-power constraint, and perfect channel-state information available at both transmitter and receiver. The delay constraint is met by assuming that a code word spans a finite number of channel realizations. The relevant performance limits are the information outage probability and the "delay-limited" (or "non-ergodic") capacity. We show that the optimum coding scheme is obtained as the concatenation of an optimal code for the unfaded AWGN channel with an optimal beamformer. Numerical results show that very high rates are achievable without the need of deep interleaving.