Multiple-landmark routing for large groups in ad hoc networks

A typical scenario in mobile ad hoc networks (MANET) consists of nodes having functional and motorial affinities (e.g., tanks in the some battalion). In order to achieve scalability for such a network having a large scale, we introduce, in this paper, a novel "multiple-landmark" ad hoc routing protocol (M-LANMAR). The protocol is an "implicit", flexible hierarchical routing scheme following the traditional hierarchical method for handling scalability in large, wired networks. M-LANMAR features dynamic distributed election of multiple landmarks (with scope constraints) and destination discovery within each group using landmark forwarding mesh or multicast fabric techniques plus route caching. The scalability is achieved through efficiently handling the group motion patterns, namely, the truncation of local routing tables and the "summarization" of routing information to remote groups of nodes. Different from the previous proposed landmark ad hoc routing (LANMAR), M-LANMAR allows separate maintenance/optimization of user group size and local routing scope, leading to unrestricted group size regardless of local routing scope. The simulation results not only show election stability of the multiple landmarks but also confirm the good scalability properties of M-LANMAR in general ad hoc network infrastructures (networks that are large in size and/or that contain large logical groups).