Achieving the degrees of freedom of 2×2×2 interference network with arbitrary antenna configurations

This paper studies the degrees of freedom (DoF) region of the 2 × 2 × 2 interference network, which is comprised of two sources, two relays and two destinations, each with arbitrary number of antennas. We prove that with linear transceivers, the cut-set outer bound can be achieved without any symbol extensions, except for one specific system setup, which has one-DoF gap to the cut-set bound. We show that to achieve the outer-bound, the transceivers include interference avoidance, cancelation, neutralization and alignment, depending on the antenna configuration.