Feedback Reduction for CDI-Based Beamforming in the MIMO Broadcast Channel

Recent research has demonstrated that for the multi-antenna broadcast channel, applying transmit precoding based on the channel spatial covariance matrices leads to temporal stability of the achievable network sum rate. This approach allows reduction in the frequency of channel information feedback events at the expense of increased feedback complexity. While recent work has demonstrated the possibility of feedback complexity reduction through matrix decompositions, this paper demonstrates significant additional feedback reduction through compression of the covariance matrices using the Karhunen-Loève Transform.