Location Service For Vehicular Delay Tolerant Networks

This paper considers the problem of routing in vehicular delay tolerant networks. Especially we analyzed the characteristics of a large scale vehicular network and proposed a new location service for such an environment.In recent years, vehicular ad hoc networks have attracted great interests among researchers, because VANET does not rely on any fixed infrastructure and can be widely used in some traffic applications. Currently, most of the routing protocols for DTN is based on the notation of 'epidemic'. The position based routings (PBR) for MANET are under the assumption that the location of other nodes are known, thus the route can be optimized. If such style of routing is also applied to DTN in VANET, we may drastically improve the performance. However, vehicular ad hoc networks are not always connected, which makes it a great challenge to implement a location service for DTN.We implemented a new location service—DELSD for vehicular delay tolerant networks in this paper. DELSD is a completely distributed location service. Mobile nodes can track and query other nodes' location through this service. Position based routing combined with DELSD provides a new method for DTN routing. DELSD is effective for a large scale network such as an urban vehicular ad hoc network. Each node works independently and updates position information when exchanging data bundles. Location query is done via local position database on each node.Simulation results show that DELSD is a suitable solution for location management in a large scale urban vehicular network. DELSD tolerates node failures well, failed nodes won't hurt the performance much. However, the speed and density of nodes will have great impact on DELSD. Higher mobility will lower its performance, while higher density will lead to better results. Finally, we find that DAER combined with DELSD can provide higher delivery ratio and lower bundle delay than pure epidemic routing.