User selection in the MIMO BC

It is well-known that user selection not only leads to multiuser diversity but also to decreased suboptimality of simple beamforming (BF) techniques compared to optimal Dirty Paper Coding (DPC) approaches in the Broadcast Channel (BC), otherwise called the multi-user (MU) downlink, in a cell with a base station and mobile terminals equipped with multiple antennas (MU-MIMO). User selection by exhaustive search can be simplified to greedy approaches, in which one user gets added at a time. In this paper, we review an approximate criterion for MISO BF-style selection. For a sufficient amount of users, multiple receive antennas do not lead to increased spatial multiplexing, but we indicate how they affect the high SNR rate offset. The resulting added diversity can be exploited at the cost of more involved user selection and transceiver design. We thus propose a novel receiver design for BF-style MU-MIMO stream selection.