Chordal Distance-Based User Selection Algorithm for the Multiuser MIMO Downlink with Perfect or Partial CSIT

In this paper, we consider user selection algorithms for Multi-user MIMO systems with perfect or partial channel state information at the transmitter (CSIT). A novel user selection algorithm based on chordal distance is proposed. The basic principle is to serve the user subset in which one is approximately orthogonal to the others. Since the chordal distance relies only on the channel direction information, the proposed algorithm has a low computational complexity, and can be extended straightly to the limited feedback system. Analysis and simulations verify the effectiveness of the proposed method.