Scalable ad hoc routing in large, dense wireless networks using clustering and landmarks

In ad hoc, multihop wireless networks the routing protocol is key to efficient operation. The design of an ad hoc routing protocol is extremely challenging because of mobility, limited power, unpredictable radio channel behavior and constrained bandwidth. As the network grows large, two additional challenges must be faced: increasing node density, and large number of nodes. High density (i.e., a large number of neighbors within radio range) leads to "superfluous" forwarding of broadcast control messages. Large network size leads to large routing tables and high control traffic overhead. The two aspects are related and they both undermine the scalability of routing protocols. In this paper, we address scalability for a specific class of routing protocols, namely, proactive link state routing protocols. Link state protocols are desirable in many applications because of low access delay, ability to include QoS criteria in path selection, support of alternate routes, etc. Yet, these protocols are most affected by density and large scale. In the paper, we propose two techniques to overcome density and large scale, namely passive clustering and landmark routing. We compare via simulation our proposed solutions to other existing scalable schemes.