Sum-rate capacity of correlated multi-user MIMO channels

This paper investigates the sum-rate capacity of a multi-user broadcast channel (BC) assuming that users have different transmit correlation matrices. The sum-rate capacity of two-user BC has recently been investigated. As an extension of the two-user BC case, we analyze the sum-rate capacity of a multi-user BC. It is shown by means of upper-bound analysis that the sum-rate capacity of a correlated multi-user BC is maximized when the phases of the transmit correlation coefficient of users are maximally scattered, which implies that the principal eigenvectors of the transmit correlation matrix of users are orthogonal to each other. Finally, the analytic results are verified by computer simulation.