OPPO: An optimal copy allocation scheme in mobile opportunistic networks

Abstract

Mobile Opportunistic Networks (MONs) use the store-carry-and-forward scheme to transmit packets, so as to deal with the intermittently connected links. This new communication paradigm makes them very different from the traditional multi-hop wireless networks. To improve the delivery performance, some smart forwarding schemes have been proposed by injecting multiple copies of packets into the temporal network. Unfortunately, these schemes allocate data copies following the aggregate contact information, i.e., information obtained by considering the samples from all pairs. They ignore the individual contact feature of nodes. We show that the aggregate contact can be very different from the contact of individual pairs, therefore, using the former to guide copy allocation is not correct in general, although it works well in some cases. In this paper, we propose OPPO, an optimal copy allocation scheme in MONs. OPPO exploits the transient contact ratio of nodes to spray data copies. Theoretical analysis proves that OPPO achieves the optimal delivery delay, and experimental results verify it simultaneously improves the packet delivery ratio compared to the SprayWait and HS, two state-of-the-art works.