Opportunistic Interference Aligned User Selection in Multiuser MIMO Interference Channels

In this paper, we propose a practical interference alignment technique based on an opportunistic user selection in a three-user $2\times 2$ MIMO interference channel where no information is allowed to be shared among transmitters. In the proposed scheme, the user whose interference signals from other transmitters are most aligned with each other is selected at each transmitter. We also investigate optimal and suboptimal beamforming at the selected receiver using extra degrees of freedom by multiple receive antennas. The proposed opportunistic interference aligned user selection (OIAUS) schemes combined with various postprocessing vectors are shown to achieve notable capacity compared to conventional opportunistic user selection schemes while they significantly reduce not only the amount of feedback information but also computational complexity.