Partial Interference Alignment Schemes for the K-User MIMO Interference Channel

Abstract

Partial interference alignment (PIA) strategies for the K-user interference channel are considered. Two schemes are proposed to align the partial interference for the downlink interference channel in the case ofK>3. In the first scheme, strong interferences are limited as much as possible by aligning the two strongest interferers into a same subspace at the receiver. While the second scheme is to design its precoding matrix (or vector) by selecting the precoder pair which maximizes the chordal distance between designed signal subspace and interference signal subspace in the set of pecoding matrices (or vectors) at each transmitter. Simulation results show that compared with the existing schemes which don’t optimize the precoder, such as Fixed-PIA, the proposed schemes can improve the sum rates significantly by selecting IA forms in multi-input multi-output (MIMO) systems.