Simple zero interference transmissions to users with rank deficient channels

We investigate linear zero interference transmission strategies when the MIMO channels of the users are rank deficient. It is a common case in downlink cellular systems, as the size of a user equipment is considerably more limited than a base station. We present two new simple zero interference transmission schemes for multiuser transmission when the MIMO channels of the users are rank deficient. One with MRC receivers and no power transmitted to the common null-space of the users, and the other based on generalized eigenvectors projected to transmit no power to the common null-space. We compare these schemes to simple schemes presented in literature and to a numerically optimized linear scheme.