A Random Precoding Technique for the Downlink of Multiuser MIMO Systems

Several preceding techniques have been proposed to spatially multiplex users in the downlink of multiuser MIMO systems. These techniques are computationally complex and require that channel state information (CSI) of all users is available at the base station (BS). In this paper, we propose a random preceding technique that needs only limited feedback from the mobile stations to the BS. We investigate the performance of the proposed technique for various system parameters. We show that at low-to-medium SNR, the system with the proposed technique results in larger capacity gains than the system with full CSI and which uses a multiple access scheme to schedule users for spatial multiplexing.