Social-aware relay node selection in delay tolerant networks

In Delay Tolerant Networks (DTNs), the connections between mobile nodes are intermittent and constant end-to-end paths rarely exist. In order to achieve high delivery ratio, most existing DTN routing algorithms favor the ''multi-hop forwarding'' fashion where a message can be forwarded by multiple relay nodes in the hope that one of the employed relay nodes can deliver the message to the destination node. Since aggressively employing relay nodes may incur intolerable delivery cost to resource-constrained mobile nodes in DTNs, it is significant to design a cost-efficient routing protocol that can achieves high delivery ratio. In this paper, we first utilize the small-world feature to limit the maximum forwarding hops in a reasonable way and then propose a greedy relay node selection strategy. A cost-efficient social-aware forwarding algorithm called TBSF (the-best-so-far) is then presented. Extensive simulations on real mobility traces are conducted to evaluate the performance of TBSF. Simulation results show that, in comparison with several well-known routing algorithms, TBSF can achieve high performance in terms of delivery ratio and delivery delay while with much lower delivery cost.