Opportunistic transmission scheduling for multiuser MIMO systems

An opportunistic transmission scheduling scheme is proposed to make better use of the multiuser diversity gain in a MIMO system. The performance of a MIMO link is quantified by its information-theoretic capacity. Even though the base station has no knowledge of the transmission channel, the proposed algorithm generates a transmission randomizing matrix according to the distribution of the channel, so that it is likely that some user is near the "water-filling" configuration. The mobile users measure and feedback the channel quality. Based on this information, the base station schedules transmission to the user whose instantaneous channel capacity is the largest. Simulation results show that, over slow varying channels, or over Rician channels with a large K factor, opportunistic transmission scheduling can improve system performance in terms of channel capacity.