Mutual coupling and transmit correlation: Impact on the sum-rate capacity of the two-user MISO broadcast channels

In this correspondence, the effect of mutual coupling and transmit correlation on the sum-rate capacity of a multiuser system is investigated for the case of the two-user MISO broadcast channel. Mutual coupling between antenna elements of the antenna array and transmit correlation are taken into account via the coupling matrix and the correlation matrix, respectively. A closed form formula for the upper-bound capacity is derived. Our analysis shows that in the high SNR regime, the sum-rate capacity depends on the mutual impedances of the transmit antenna array as well as on the phases and magnitudes of the transmit correlation coefficients. Our results indicated that the derived upper-bound capacity gives insightful information on the behavior of the actual sum-rate capacity.