Beamforming for physical layer multicasting

A systematic scheme is proposed to facilitate arbitrary virtual channel (VC)-to-user mappings in space dimension, through multiple-input multiple-output physical layer multicasting. It is a divide-and-conquer strategy, which breaks down the VC-to-user mapping to manageable orthogonal sub-mappings, each represented in terms of a multicast antenna group (MAG). A generalized form of block diagonalization is proposed to make transmissions pertaining to distinct MAGs orthogonal. Known non-iterative coordinated beamforming techniques are investigated for intra-MAG beamforming. The approach enables physical layer multicasting with non-iterative beamforming techniques alone.