Exploiting Additional Transmit Antennas for More Degrees of Freedom in 3-User MIMO Interference Channel with Delayed CSIT

In this paper, we consider the three-user multiple-input multiple-output interference channel, where the transmitters and the receivers have M and N antennas, respectively, and there is the delayed channel state information at the transmitters (CSIT). For this scenario, we propose a new transmission scheme, which achieves a number of degrees of freedom greater than that known in the literature for the region of antenna configurations of 1 < M/N < 2. The proposed transmission scheme has a three-phase transmission structure, where in phases 1 and 2 a novel approach of using the delayed CSIT is employed.