Uplink Interference Alignment for Two-Cell MIMO Interference Channels

In this paper, we present uplink interference alignment (IA) schemes for two-cell multiple-input-multiple-output (MIMO) channels. Assuming that each cell has
K
interfering users, we propose an IA scheme for the full interference channel (FIC) and derive the achievable degrees of freedom (DOFs). The proposed scheme is extended to a two-cell Z-interference channel (ZIC), where only one of the two cells is subject to interference. The achievable DOF for the two-cell ZIC channel is also derived, and it is compared with that of the FIC with the IA and that of the conventional orthogonal scheme based on numerical results.