Reduced entropy parameterization of MIMO channel matrices for finite-rate feedback

By using perfect Channel State Information (CSI) at the transmitter significant gains in terms of sum rate can be obtained in the Multiple-Input Multiple-Output (MIMO) broadcast channel. In practice the links from the users to the transmitters allow only a limited amount of feedback for the CSI, which requires efficient compression schemes at the receivers. In this paper we consider the representation of Gaussian channel matrices by scalar parameters, which are quantized and fed back to the transmitter. This way also the numerically complex vector quantization can be avoided. A novel parameterization is presented which reduces the differential entropy of the parameters and improves the performance of the data transmission in the downlink compared to a state-of-the-art approach.