Spray and Locate Routing for Vehicular Delay-Tolerant Networks

Vehicular Delay-Tolerant Networks (VDTNs) are networks where there are no permanent end-to-end connections. VDTNs have a variable topology, with frequent partitions in the connections. Given the dynamic characteristics of these networks, routing protocols can take advantage of dynamic information, such as the node's location, to route messages. Geolocation-based routing protocols choose the node that moves closer to the location of the message destination as the message carrier. In this article, the Spray and Locate geographical routing protocol was proposed. First, the protocol replicates a limited number of messages in the network, and then it uses the direction of movement of the nodes to route messages in the known destination's direction. In order to obtain the locations of nodes in the network, a VDTN localization system, known as VDTNLocate, in which each node in the network maintains a dictionary with the last location information known, including position, movement direction, speed and age, was also proposed. The performance of Spray and Locate was compared with geographic and non-geographic routing protocols. The results show that the Spray and Locate protocol has a higher delivery rate and lower latency than the other evaluated protocols.