Multigroup Multicast With Application-Layer Coding: Beamforming for Maximum Weighted Sum Rate
In a multicast scenario, the performance is usually determined, and therefore limited, by the weakest link present in the system. With multiple co-channel multicast groups, the problem is further exacerbated due to interference from other transmissions. In this paper, the authors investigate an alternative communication scheme, in which additional coding at the application layer is used, spanning over a number of channel realizations. Aiming at maximization of the weighted sum of rates achieved in each group, they show that the optimal transmission strategy depends only on the current channel realization, which, assuming multiple antennas at the base station, allows for formulation of an interesting transmit beamforming problem.