Opportunistic Geocast in Disruption-Tolerant Networks

Disruption-tolerant networks (DTNs) have gained great attractions recently by addressing intermittent network connectivity suffered due to short radio transmission range, high node mobility, sporadic node densities, etc. Data communication across DTN is achieved over store-carry-forward (SCF) paradigm by exploiting temporary wireless links and connections opportunistically arising from mobility nature of nodes. In the literature, multi-copy-based routing approaches are widely considered to overcome mobility randomness and subsequently the uncertainty of future network states, while routing information such as mobility statistics and context is employed to control the number of message copies. However, none of the existing approaches can be directly implemented for recent emerging geocast services. This is because instead of specifying any particular node as the destination in advance, the message generated by a geocast service falls into a certain geographical area addressed by the location descriptions. As a result, this paper introduces a novel opportunistic geocasting message delivery scheme for DTNs. To improve the efficiency, the expected visiting rate to the destined region of a message is proposed for an intermediate node to choose a next-hop with larger visiting likelihood. Simulation results demonstrate the enhanced delivery performance offered by the proposed opportunistic geocasting message delivery scheme.