Mercator: Self-organizing Geographic Connectivity Maps for Scalable Ad-Hoc Routing

A fundamental problem of future networks is to get fully selforganized routing protocols with good scalability properties that produce good paths in a wide range of network densities. Current approaches, geographic routing and table based routing, fail to provide very good scalability with good paths in sparse networks. We propose a method based on the discovery of connectivity between geographic regions that are self-organized in a multilevel hierarchy. The Mercator protocol builds lightweight connectivity maps in a fully decentralized manner and shows a scalable and resilient behaviour. Each node builds and maintains its own hierarchical map that summarizes connectivity information of all the network around itself using geographic regions. Link state routing is used over the multilevel connectivity graph of the map to obtain global paths. The analysis and simulation of our approach shows that routing state and communication overhead grows logarithmically with network size while producing good paths.