Outage Probability for Multiple Relay Networks with Supplementary Non-Broadcast Links

Recent large system analyses have shown that the per-node throughput of purely broadcast wireless networks goes to zero as the size of the network increases. Importantly, the problem appears to be physical in nature, i.e., it cannot be overcome through clever protocols, codes, or modulations. This fundamental problem, along with the proliferation of wireless devices that are able to communicate over multiple independent communication modes (frequency bands, channels), motivates the study of a novel kind of communication network composed of conventional wireless nodes along with "multimodal" nodes that can communicate simultaneously over broadcast wireless and other non-broadcast point-point modes, e.g., wires, infrared, acoustic, or free-space optical links. Here, we provide an information outage probability analysis of multiple relay networks with an arbitrary number of supplementary non-broadcast links. We find that the non-broadcast links provide benefits over a wide range of broadcast/non-broadcast power allocations.