Interference Alignment for the Multi-Cell Multiuser Interference Channel

We propose an interference alignment scheme for the L cell multiuser interference channel, where M antennas are used at the base stations and N antennas are used at user terminals. To handle the large number of interference vectors from other cells, the proposed method aligns interference vectors such that they fall in a rank one vector space at the other cell base station receivers. After the alignment, we can achieve the sum DoF (K) values of, K=M when N <; 2(L-1), K=L(M-1) when N≥ (L-1)M. For other cases, we can achieve K=M-L+(L-1) [N/L-1] in the L cell interference network, where [·] is the integer floor function.