Opportunistic communications at the downlink of mobile systems in the presence of inaccurate channel information

The throughput of a multi-user broadcast opportunistic communications system is highly affected by the accuracy of the available channel state information (CSI) at the transmitter side. It is a questionable assumption to have almost perfect knowledge of the user SNRs at the transmitter due to the error in the channel measurement, or due to reporting feedback errors from users to the transmitter. As a result such errors, the system can not gain its maximum throughput. In this paper, we investigate the performance of opportunistic communications system considering imperfect SNR reports. We show that in order to maximize the throughput, the transmitter needs to estimate the channel state information. The imposition of a correlation constraint will prevent the estimate of channel from fluctuating too widely. Employ Kalman filter, we estimate the channel state information and show that the throughput is significantly improved.