Adaptive codebook based channel prediction and interpolation for multiuser MIMO-OFDM systems

In MIMO-OFDM communications, the channel state information (CSI) of the forward link is needed for precoder design at the transmitter to achieve the maximal performance gains. In frequency division duplex (FDD) systems, the CSI estimated at the receivers needs to be fed back to the transmitters. Because of the limited network resources, there will be CSI feedback errors due to quantization, delay and clustering (where one CSI feedback is used to represent a cluster of adjacent subcarriers for feedback reduction). Consequently, the system performance degrades and the gains expected from using MIMO diminish. To mitigate this performance degradation, an adaptive codebook-based CSI prediction and interpolation scheme is proposed for multiuser MIMO-OFDM systems. In this scheme, geodesic CSI prediction is employed at the receiver to mitigate the feedback delay and geodesic CSI interpolation is performed at the transmitter to mitigate the cluster feedback effect. Since the performance gain assumed by the CSI prediction and interpolation is limited by the low resolution CSI quantization, a simplified adaptive codebook is developed to support the CSI prediction and interpolation. Simulation results show that the proposed scheme is effective in mitigating the performance loss due to quantization, feedback delay and cluster feedback.