GeoSpray: A geographic routing protocol for vehicular delay-tolerant networks

Vehicular networks are characterized by a highly dynamic network topology, and disruptive and intermittent connectivity. In such network environments, a complete path from source to destination does not exist on the most part of the time. Vehicular delay-tolerant network (VDTN) architecture was introduced to deal with these connectivity constraints. VDTN assumes asynchronous, bundle-oriented communication, and a store-carry-and-forward routing paradigm. A routing protocol for VDTNs should make the best use of the tight resources available in network nodes to create a multi-hop path that exists over time. This paper proposes a VDTN routing protocol, called GeoSpray, which takes routing decisions based on geographical location data, and combines a hybrid approach between multiple-copy and single-copy schemes. First, it starts with a multiple-copy scheme, spreading a limited number of bundle copies, in order to exploit alternative paths. Then, it switches to a forwarding scheme, which takes advantage of additional contact opportunities. In order to improve resources utilization, it clears delivered bundles across the network nodes. It is shown that GeoSpray improves significantly the delivery probability and reduces the delivery delay, compared to traditional location and non location-based single-copy and multiple-copy routing protocols.