Landmark routing for large ad hoc wireless networks

We present an enhanced version of the routing protocol, Landmark Ad Hoc Routing (LANMAR). LANMAR combines the features of Fisheye State Routing (FSR) and Landmark routing. The enhanced version features landmark election to cope with the dynamic and mobile environment. Other advantages of LANMAR include the use of landmarks for each logical group (e.g., a team of co-workers at a convention or a tank battalion in the battlefield) in order to reduce routing update overhead in large networks, and the exchanging of neighborhood link state only with neighbors. When the network size grows, remote groups of nodes are "summarized" by the corresponding landmarks. As a result, each node will maintain accurate routing information about immediate neighborhood; at the same time it will keep track of the routing directions to the landmark nodes and thus, to remote groups. Simulation experiments show that the enhanced version suffers some performance degradation at steady state because of election overhead. However, it still provides an efficient and scalable routing solution in a mobile, ad hoc environment. Moreover, the election provides a much needed recovery from landmark failures.