Efficient Adaptive Routing in Delay Tolerant Networks

Conventional routing algorithms in mobile ad hoc networks (MANETs), i.e., multi-hop forwarding, assume the existence of contemporaneous source-destination paths and are not scalable to large networks. On the other hand, in delay tolerant networks (DTNs), routing protocols use the mobility- assisted, store-carry-forward paradigm which allows delivery among disconnected network components. Adaptive routing, which combines multi-hop and mobility-assisted routing protocols, is of practical value: it allows efficient multi-hop forwarding while providing the flexibility to deliver messages among disconnected network components. However, existing adaptive routing protocols use mobility-assisted routing protocols as an alternative only when the former fails. In this paper, we propose to improve the performance of adaptive routing from a resource allocation point of view, in situations where bandwidth is a critical and limited resource affecting routing performance. We propose an adaptive routing protocol, named efficient adaptive routing (EAR), which allocates bandwidth (or forwarding opportunities) between its multi-hop forwarding component and its mobility-assisted routing component dynamically to improve bandwidth utility. Simulations are conducted to evaluate the routing performance of EAR under different network parameters.