Interference mitigation and signal enhancement for K-user MIMO interference channels

The optimal signaling for K-user multiple-antenna Gaussian interference channels with single-user detection has been studied. It is shown that to achieve the boundary of the rate region, the rank of the optimal input covariance matrix is no greater than the rank of the direct link channel matrix as long as this transmitter has perfect channel state information of its direct link. Based on this, interference mitigation and signal enhancement are derived and shown to be necessary conditions for the optimal signaling. Different power constraints and channel availability scenarios are also considered.