Scheduled Message Delivery in Delay-Tolerant Networks

With the proliferation of mobile communications, new kinds of network architectures are being defined over the existing static one. Delay-Tolerant Networks (DTN) come to fill in a gap in the existing networking technology: they provide support for communication between peers when there is no end-to-end path available between them. Message forwarding in DTNs can be handled in many ways. In this work the performance of a DTN is analyzed in the case of scheduled message delivery, with particular consideration to the different message delivery delays and to the usage of buffers that store a message during its propagation from its source to the destination. We introduce the K2 heuristic algorithm for location-aware message delivery, based on the k-nearest-neighbors technique, and compare simulation results with another basic message delivery technique, Message Forwarding with Flooding (MFF). The results of simulations on a simplified urban setting show that K2 reduces buffer usage while maintaining delivery delays approximately unchanged when compared to MFF. Simulations also suggest that adding a DTN-like message forwarding architecture with mobile access points to an existing fixed infrastructure can be an effective way to improve wireless coverage for delay-tolerant end-user applications such as e-mail, message passing and news broadcast.