Opportunistic transmission in MU-MIMO downlink with reduced feedback and mode adaptation

In this paper we introduced an opportunistic transmission scheme in MU-MIMO downlink with reduced feedback and mode adaptation. In this strategy both base station (BS) and mobile station (MS) are equipped with multiple antennas. Threshold scheme is employed. Only eligible MS whose channel quality exceeds a preset threshold would select transmission mode, including beamforming (BF) and spatial multiplexing (SM) and adaptively feed back channel information. With feedback information, BS schedules one user out of candidate MSs at each time slot. In evaluating the scheme, statistical analysis is employed in company with Monte-Carlo simulation. Results show that with appropriate thresholds and mode adaptation, the proposed scheme can achieve high capacity as well as low feedback load and outage probability.