Increased Connectivity at Lower Cost: The Case for Multi-Radio Nodes in Multi-Hop Wireless Networks

We address multi-radio networks, i.e., wireless networks where the nodes are equipped with multiple air interfaces. We analyze, both analytically and via simulation, various gains that the multi-radio environment can provide. First we investigate the gain in network connectivity by modeling the topology of a multi-radio network by a multigraph. The gain is captured by introducing the novel graph theoretic concept of the multigraph advantage. It is the surplus of connectivity over the sum of the individual connectivities, as we put together several graphs to form a multigraph sum. We first prove that in the traditional random graph model it results in a strict super-additive behavior. We validate the theoretical results via simulations and show that similar phenomena occur in geometric random graph models. We then investigate, via ns2-based simulations, the nodal energy consumption as well as the end-to-end packet latency needed to route packets in a multi-radio network.