MORHE: A Transparant Multi-level Routing Scheme for Ad Hoc Networks

This paper presents a transparent multi-level routing scheme, named MORHE, that improves the scalability of the OLSR protocol by exploiting the heterogeneous nature of nodes in the network. While ad hoc networks have been an active research topic over the past few years, the majority of the studies have focused on the homogeneous nature of the network. In our work we try to take a different approach by focusing on scenarios where ad hoc technology can be applied, but where we also find nodes in the network with varying capacity. The MORHE protocol makes use of nodes which have a large capacity (e.g. more energy, larger transmission range) to build something that could best be described as an ad hoc infrastructure. Nodes are grouped in clusters that need to be interconnected by specific nodes. This implies that a node no longer needs to know the entire network topology as is the case of the OLSR protocol, but only needs to maintain routes to the nodes inside its own cluster and to the other clusters. Using this approach the signalling overhead which is one of the main reasons why OLSR is not scalable is greatly reduced. We also introduce a simple mobility management scheme to allow nodes to roam the different ad hoc clusters.