METHOD AND APPARATUS FOR TRANSMIT BEAMFORMING

A technique determines a transmit beamforming vector for multi-lobe beamforming of a signal that is transmitted in common - multicast - for a corresponding group of receivers. The multiple lobes correspond to the spatial distribution of receivers within the population. The technique, which may be referred to as multi-lobe or group-based beamforming and which may be used with a single group or with multiple groups, relies on an advantageous iterative update procedure that revises the transmit beamforming vector(s) in dependence on identifying a representative receiver in each group of receivers. In particular, the iterative revisions include incremental changes calculated to improve received- signal quality for the representative receiver(s). When there are two or more groups, the technique accounts for mutual interference between the per-group signals being beamformed. Each group of receivers may be referred to as a "population."