An encounter-based multicast scheme for disruption tolerant networks

Some ad hoc network scenarios are characterized by frequent partitions and intermittent connectivity. Hence, existing ad hoc routing schemes that assume that an end-to-end path exists from a source to a destination do not work in such challenging environment. A store-and-forward network architecture known as the disruption tolerant network (DTN) has been designed for such challenging network environments. Several unicast and multicast routing schemes have been designed for DTNs. However, the existing multicast routing schemes assume a route discovery process that is similar to the existing ad hoc network routing approach. Thus, in this paper, we design an encounter-based multicast routing (EBMR) scheme for DTNs which uses fewer hops for message delivery. We first describe how the EBMR scheme works and then present an analytical framework to estimate the delivery performance of the EBMR scheme. Next, we present some comparisons of the analytical and simulation results to show that our analytical framework provides delivery performance estimates that match closely the observed simulation results. Last but not least, we present simulation results to study the delivery performance of EBMR in different scenarios, e.g. different mobility models, different multicast group size, different number of multicast groups and different node speed. We also compare the performance of the EBMR scheme with other DTN multicast strategies. Our simulation results indicate that the EBMR scheme can achieve higher delivery ratio while maintaining high data transmission efficiency compared to other multicast strategies. 2008 Elsevier B.V. All rights reserved.