An efficient CQI feedback scheme for multiuser MIMO systems

An opportunistic scheduling is adopted to improve the capacity of the system by exploiting the multiuser diversity of multiuser MIMO (MU MIMO) systems. However, it requires a large amount of feedback carrying the channel quality information (CQI) of each user to the transmitter. The considered Per User Unitary and Rate Control ((PURC)-R-2) needs to feedback the preferred precoding index and its CQIs, and it has a defect in scheduling the streams for the grouped user. In order to overcome these drawbacks, a novel feedback reduction scheme is proposed and is modified for OFDMA systems in this paper. It employs transmitter controlled precoding and opportunistic feedback (TCP OFB) in conjunction with frequency scheduling. The simulation results demonstrate that TCP OFB/OFDMA shows comparable performance to (PURC)-R-2 while it only requires far reduced feedback load.