On the Optimality of Beamforming in MIMO Fading Ad-Hoc Networks

We consider MIMO fading ad-hoc networks with Rayleigh co-channel interference where, L transmitter/receiver pairs communicate independent information over the network, simultaneously. We assume perfect channel state information (CSI) of the desired receiver is available at each transmitter and receivers perform single-user detection. In this paper, we study the asymptotic capacity of the considered system, in the limit of a large number of pairs, i.e., L →∞ . Through asymptotic large- system analysis, we show that performing beamforming by all users approaches the optimum signaling in the sense of achieving the system capacity.