Multi-user MIMO downlink eigen-mode transmission over jointly correlated MIMO channels

The study of multi-user multiple-input multiple-output (MU-MIMO) systems has emerged recently as an important research topic because such systems have the potential to combine the high capacity that can be achieved through MIMO processing with the benefits of spatial-division multiple-access. However, receiver and transmitter channel state information (CSI) is generally required, especially for the downlink channel. In this paper, MU-MIMO downlink transmission systems with statistical CSI at the transmitter are studied for jointly correlated MIMO channels. Eigen-mode space division multiple access transmission is derived based on the maximization of the ergodic sum rate, and two eigen-mode power allocation algorithms are proposed using matrix permanent and convex optimization theory. The new algorithms can overcome the limitations of the existing multi-user downlink transmission algorithm in practical applications.