Interference Alignment Cancellation in Compounded MIMO Broadcast Channels With General Message Sets

This paper proposes an alignment based interference cancellation scheme for a multi-cell network with multiple-input multiple-output users under a Gaussian Interference compounded broadcast channel scenario. The basic idea is to split up the role of the transmit beamforming matrix according to the type of interference caused by each base station. It will be shown that, for a network of L base stations, the proposed method would result in achieving (L - 1) degrees of freedom per user and convert the multi-cell multi-user MIMO channel into a set of single-cell single-user MIMO channels. Finally, we derive the relationship between all the relevant network elements as Nt = (L - ds + 1)K'Nr + 1, where Nt and Nr are the numbers of transmit and receive antennas, respectively, L and ds denote the number of cells and the number of data streams transmitted from each base station, and K' is the number of users per cell defined under the proposed system model. Hence, we show that the proposed scheme makes it possible to implement interference alignment using less antenna resources.