On the degrees of freedom of the three-user MIMO interference channel with delayed CSIT

The three-user multiple-input multiple-output interference channel under i.i.d. fading is studied, where the transmitters have the delayed channel state information. The case where all transmitters and all receivers are equipped with M and N antennas, respectively, is considered. For this case, a new transmission scheme is proposed that achieves a number of degrees of freedom higher than previously reported for the range of 3/4 <; M/N <; 1, where the parameters of the scheme are determined as functions of the ratio M/N. The degrees of freedom gains compared to the previous approaches are due to the more effective use of transmit and receive antennas.