On-Demand Multipath Distance Vector Routing in Ad Hoc Networks

On-demand routing protocols for ad hoc networks discover and maintain only the needed routes to reduce routing overheads. They use a flood-based route discovery mechanism to find routes when required. Since each route discovery incurs high overhead and latency, the frequency of route discoveries must be kept low for on-demand protocols to be effective. On-demand multipath protocols achieve this objective by computing multiple paths in a single route discovery. In this paper, we present AOMDV, an on-demand multipath distance vector protocol, in the framework of a well-known single path protocol (AODV) of similar nature. AOMDV computes multiple loop-free link disjoint paths during route discovery. We introduce the notion of an advertised hopcount to establish loop free multiple paths. We compare the performance of AOMDV with AODV using extensive simulation experiments based on ns-2. Simulation results show that AOMDV is able to reduce the frequency of route discoveries by as much as 30 % and also achieve a remarkable reduction in the end-to-end delay — often more than a factor of two.