1. A method of MIMO communications in a wireless network, said network having a plurality of wireless units and at least first and second base stations, each of the first and second base stations having one or more transmit antennas, wherein the method comprises the steps of: forming a user group based at least in part on a semi-orthogonal selection of a subset of said plurality of wireless units; and transmitting data from at least the first and second base stations over an assigned transmission channel to the wireless units in said user group, wherein the data transmitted from at least the first and second base stations is transmitted according to a zero-forcing beamforming (ZFBF) operation and at least one designated transmission power constraint is applied to at least the first and second base stations, and wherein the at least one designated transmission power constraint comprises at least one of (1) a first transmission power constraint applied on a per-transmission basis for each of at least first and second transmit antennas respectively associated with at least the first and second base stations, and (2) a second transmission power constraint applied on a per-base station basis for all of the transmit antennas associated with each of at least the first and second base stations.