Interfering channel alignment and degrees of freedom for downlink multiceli MIMO networks

To solve the multi-cell interference problem in downlink cellular networks, we study G-cell multiple input multiple output Gaussian interfering broadcast channels (MIMO-IFBC) with K users on the cell-boundary of each base station (BS). The main idea is to align interfering channels from each BS to its non-intended users onto a small dimensional subspace. This is called interfering channel alignment (ICA). We analytically derive both the feasibility conditions for the ICA to achieve a total number of degrees of freedom (DoF) of GK and the maximum number of DoF, which is achieved by the ICA for a given antenna confguration. The numerical results show that our analysis is valid and the achievable DoF of the proposed ICA outperforms that of conventional schemes.