Dircast: Flooding-reduced routing in MANETs without destination coordinates

Abstract

The majority of the routing protocols designed and implemented to date for mobile ad hoc networks (MANET) rely on flooding of route requests for the establishment of routes on demand, flooding of topology information, or the hop-by-hop dissemination of distances or paths for each destination. The signaling overhead incurred with these strategies consumes excessive amounts of the scarce bandwidth available in a MANET as the number of nodes and the number of information flows increase. We introduce Dircast as an alternative for routing in MANETs. Dircast assumes that each node knows its own geographical coordinates and the geometry of the terrain in which the network is deployed. To find the route to a destination, a node selects a limited number of relays to forward a route request mesage based on their coordinates and the boundary vertices of the terrain if the prior location of the destinartion is unknown, or based on the prior location of the destination if it is known. If the destination is reached, a route reply is sent back to the source containing its coordinates. We compare Dircast with OLSR and AODV, which are representatives of traditional proactive and on-demand routing approaches in MANETs, and show that Dircast attains much lower routing overhead, which also leads to better delivery rates and shorter end-to-end delays.