A Non-Iterative Solution to Implement Interference Alignment and Cancellation Scheme for the Three-user MIMO X-channel Model

In this paper, we propose a closed-form interference alignment and cancellation scheme for the three-user multiple input multiple-output (MIMO) X-channel network without symbol extension. We first demonstrate the basic principle of how to design the beamforming matrices for this set-up, then we estimate the sum rate achievable under perfect and imperfect channel state information. It is shown that this scheme can achieve over 64 bits/s/Hz. We also derive its computational complexity.