User scheduling schemes based on limited feedback in cognitive radio networking

In this paper, a joint user scheduling and beamforming method based on limited feedback is studied for a cognitive radio (CR) multi-user multi-input multi-output (MU-MIMO) network, where a large number of secondary users (SUs) coexist with a primary user (PU). In the proposed approach, secondary users feed precoding vector indices (PVIs) and signal to interference plus noise ratio (SINR) related channel quality information (CQIs) back to the secondary base station (SBS), and then SBS chooses appropriate SUs according to the knowledge about the link information from itself to the primary user and the quality of service (QoS) requirement of the PU. Simulation results show that the proposed algorithm can achieve good performance in a robust manner.