Contact Duration-Aware Routing in Delay Tolerant Networks

Delay Tolerant Networks (DTNs) are sparse mobile ad-hoc networks in which there is typically no complete path between the source and destination. While much work has been done in the design of forwarding algorithms, little work has focused on studying forwarding under the presence of short contact durations. In this paper, we study a single-copy contact duration-aware (CDA) routing strategy. We address two key issues: (1) to which next hop relay node should messages be forwarded and (2) in which order should messages be forwarded. To reduce the transmission cost, we select relay nodes from both current and past contacts based on the one-hop and two-hop delivery probability, respectively. We derive the delivery probability from the distribution of contact duration time and inter-contact time. For the message scheduling, messages with the highest delivery probability are prioritized to be transmitted first. Extensive simulation results based on the Cabspotting trace show that our scheme can achieve up to 13% higher delivery rate, 12% lower delay, and 23% lower transmission cost compared to other routing strategies.