Greedy Distributed Tree Routing algorithm for wireless ad hoc networks

As ad hoc networks are continuously growing in size, we are facing the prospect of emerging wireless networks with millions of nodes. Geographic routing algorithms are a better alternative to traditional ad hoc routing algorithms in this new domain for point-to-point routing. But deployments of such algorithms are currently very uncommon because of some practical difficulties. This paper explores techniques that address two major issues in the deployment of geographic routing algorithms: (i) the costs associated with distributed planarization and (ii) the non availability of location information of a node. We present and evaluate a new algorithm for geographic routing: Greedy Distributed Tree Routing (GDTR). The previous geographic routing algorithms require the planarization of the network connectivity graph where as GDTR switches to routing on a spanning tree instead of a planar graph when packets end up at dead ends during greedy forwarding. To opt a direction on the tree that is most likely to make progress towards the destination, each GDTR node maintains a summary of the area covered by the subtree below each of its tree neighbors using convex hulls. This distributed data structure is called a hull tree. GDTR not only requires an order of magnitude less resource to maintain these hull trees than the Cross-Link Detection Protocol CLDP, the only distributed planarization algorithm that is known to work with practical radio networks, it often achieves better routing performance than previous planarization-based geographic routing algorithms.