Wireless Multicast Relay Networks with Limited-Rate Source-Conferencing
The authors investigate capacity bounds for a wireless multicast relay network where two sources simultaneously multicast to two destinations with the help of a full-duplex relay node. The two sources and the relay use the same channel resources (i.e. co-channel transmission). They assume Gaussian channels with time-invariant channel gains which are known by all nodes. The two source nodes are connected by orthogonal limited-rate error-free conferencing links. By extending the proof of the converse for the Gaussian relay channel and introducing two lemmas on conditional (co-)variance, they present two genie-aided outer bounds of the capacity region for this multicast relay network. They extend noisy network coding to use source cooperation with the help of the theory of network equivalence.