DTFR: A geographic routing protocol for wireless Delay Tolerant Networks

We introduce the Delay Tolerant Firework Routing (DTFR) protocol, a protocol designed for routing in wireless Delay Tolerant Networks (DTNs) that consist of very large numbers of highly mobile nodes. Under DTFR, each packet initially travels, using high priority transmissions, to a target region in the network where the destination is expected to be. Once there, the packet is replicated to a number of copies that spread across the target region, in search of the destination. As soon as a copy finds a known route to the destination, it follows it and gets delivered. To evaluate DTFR's performance, we have developed a simulation tool that can handle networks with numbers of nodes on the order of 104. The simulation is optimized for use in DTNs and is very detailed, taking into account, among other things, the Media Access sublayer and the contents of buffers. Our protocol is compared against (i) Spray and Wait, (ii) GeoCross, (in) GeoDTN+Nav, (iv) a simple flooding protocol (chosen as one extreme of the design space), and (v) Bethlehem Routing (BR), an idealistic protocol that upper bounds the performance of a wide class of protocols. For a wide range of parameters, our protocol is superior (in terms of packet delay and aggregate throughput) to Spray and Wait, GeoCross, GeoDTN+Nav, and the flooding protocol, and performs close to the Bethlehem upper bound.