Greedy Zone Routing: Robust and Scalable Routing in Wireless Ad-hoc Networks

Greedy routing is an appealing routing mechanism, which does not require to build and maintain routing tables. Although, it requires a specific geometric coordinate assignment for underlying network nodes. Such a coordinate assignment is called a greedy embedding, where messages are routed over a distance decreasing path from the source to the destination. Despite various research on computation of greedy embeddings, robustness of greedy coordinates in dynamic topologies has not investigated thoroughly. In this paper, we propose Greedy Zone Routing (GZR), an alternative routing architecture, which constructs a greedy embedding of a logical network graph, namely the zone graph. Distinctively, GZR assigns greedy coordinates to each zone, as oppose to individual nodes. Messages are routed in two levels: greedy geographic routing is performed between zones and classical tree-based routing is performed within a zone. This way, trees have a manageable sizes as their depths are limited by the diameter of the zones. Greedy zone routing eliminates the need of re-computing the coordinates on changes in the network topology, hence being efficient in terms of the protocol overhead. Our simulations demonstrate that, GZR produces routes with low stretch and required to maintain small routing tables, while accounting to 50% less control overheads compared to a state of the art greedy routing protocol.