MIMO Capacity Through Correlated Channels in the Presence of Correlated Interferers and Noise: A (not so) Large N Analysis

The use of multi-antenna arrays in both transmission and reception promises huge increases in the throughput of wireless communication systems. It is therefore important to analyze the capacities of such systems in realistic situations, including correlated channels and correlated noise, as well as correlated interferers with known channel. Here we present an approach that provides analytic expressions for the statistics, i.e. the moments of the distribution of the mutual information of multi-antenna systems with arbitrary correlations, interferers and noise. Although this method is valid formally for large antenna numbers, it produces extremely accurate results even for arrays with two or three antennas. We also develop a method to calculate analytic closed-loop capacities with covariance feedback. We show that this closed-loop capacity is quite close to the full closed loop capacity in which the transmitter has full channel knowledge. We apply this analytic approach to a number of important examples and also compare to simulations to establish its validity. This analytic approach provides a simple tool to analyze the statistics of throughput for arrays of any size.