A CQI Feedback Reduction Scheme for Multi-User MIMO/OFDMA 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 (PU
²
RC) 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 PU
²
RC while it only requires far reduced feedback load.