Graph model and network coding gain of multibeam satellite communications

The objective of this paper is to investigate whether or not network coding offers increased throughput with respect to routing in satellite multibeam communications. To this aim, we depart from the traditional system level oriented design of multibeam communications and propose a novel networking approach based on graph modelling. Specifically, for the multi-beam geometry, a graph model based on Kronecker product of matrices is presented. The model captures the broadcasting transmission nature as it embeds a physical description of the underlying multibeam coverage. In order to introduce the interference limitation inherent to multibeam communications, we propose realistic system and transmission models which render connectivity constraints that we introduce into the graph model. Cut-capacity analysis adapted to the multibeam scenario is proposed and the comparison of the cut-capacity achievability for the derived graphs is investigated under routing and network coding assumptions. We obtain that, under the assumed system and transmission models, network coding gain is 1.75.