Adaptive mode switching in correlated multiple antenna cellular networks

This paper proposes an adaptive mode switching algorithm between two strategies in multiple antenna cellular networks: A single-user mode and a multi-user mode for the broadcast channel. If full channel state information is available at the base-station, it is known that a multi-user transmission strategy would outperform all single-user transmission strategies. In the absence of full side information, it is unclear what the capacity achieving method is, and thus there are few criteria to decide which of the myriad possible methods performs best given a system configuration. We compare a single-user transmission and a multi-user transmission with linear receivers in this paper where the transmitter and the receivers have multiple antennas, and find that neither strategy dominates the other. There is instead a transition point between the two strategies. Then, the mode switching point is determined both analytically and numerically for a multiple antenna cellular downlink with correlation between transmit antennas.