Snail Crawling: An Enhanced Method for DTNs Routing

To deal with the intermittent connectivity environment in Delay-tolerant networks (DTNs), both single-copy and multi-copy routing protocols have been proposed. Compared with the multi-copy routings, the single-copy ones generate less consumption of resources but also lower delivery rate. Inspired by the crawling trace of the snail, we propose an enhanced method, Snail Crawling (SC), to improve the delivery rate of single-copy routing protocols with no adding resources consumption except little buffer management. In our method, the node will hold a replica of the message that routed through it. And the replica can only be routed in Direct Transmission. Furthermore, we present a more general version of SC to get higher delivery rate and bring in controlled overhead by loosing the replica's routing scheme. By this way, we can enhance many existing routing protocols by through combination of different schemes. We apply our method to enhance the PROPHET routing protocol and get SCPROPHET. Simulation results show that both the delivery rate and the overhead of SCPROPHET are better than PROPHET.