An ad hoc network is a collection of wireless mobile nodes without any centralized cellular infrastructure. It is characterized by dynamically changing topology and multi-hop wireless links. In ad hoc network, multiple “hops” may be needed, accordingly each node should act as a router.
While a variety of new routing protocols have been developed for this special environment recently, a class of routing schemes called on-demand protocols have attracted a lot of attentions because of their low routing overhead and high convergence rate. However, their efficiency is limited by the enormous query flooding overhead and the route acquisition latency. This paper describes two novel techniques that improve the performance of on-demand routing protocols based on the periodic Hello beaconing. First, Associativity Based Clustering (ABC) provides a proactive routing scheme that maintains routing information only to quasi-static nodes in the network. Second, Delayed Query (DQ) control excludes a lot of nodes from forwarding query packets. The major goal of ABC and DQ is to minimize the number of route request packets to surmount the performance bottleneck of on-demand protocols.
Simulation results demonstrate a great reduction of query packets especially in the network with frequently changing topology or high traffic load. To put together, these techniques also contribute to the reduction of network congestion and better end-to-end delay performance.