Double-threshold opportunistic transmission strategy for MU-MIMO downlink

In this paper we introduced a double-threshold opportunistic transmission strategy for multiuser MIMO (MU-MIMO) downlink. Two thresholds are employed. In each time slot only mobile station (MS) whose channel gain exceeds the primary threshold is eligible for transmission and could feed back channel information. The secondary threshold is used for transmission mode adaptation, including beamforming (BF) and spatial multiplexing (SM), at each MS. With adaptive feedback information, the base station (BS) schedules one user out of candidate MSs. We investigated the design of both thresholds and analyzed the strategy theoretically. In evaluating the scheme, statistical analysis in company with Monte-Carlo simulation are employed. Results show that the proposed strategy can achieve high capacity as well as low outage probability with reduced feedback load.