Dynamic group support in LANMAR routing ad hoc networks

In mobile ad hoc networks (MANET) mobile nodes are often organized into groups with different tasks and, correspondingly, different functional and operational characteristics. In particular, nodes in the same group have coordinated motion. The coordinated motion pattern considerably simplifies the mobility management and allows efficient and scalable routing. In this paper, we propose an efficient scheme to discover the group identifier of a given destination. Our scheme utilizes the underlying landmark ad hoc routing protocol (LANMAR) routing structures. In our scheme, when a communication is scheduled, the source queries the landmarks for destination group information. The newly retrieved group information is then used in normal LANMAR routing operations. Caches are used for retrieval optimization and for search overhead reduction. In contrast to the on-demand flood-search scheme, our new approach only generates a few unicast search packets to landmarks instead of flooding the whole network. The main advantages are that less search overhead is incurred by our scheme and as a result, there is no need to introduce into the system a separate distributed hashing based peer-to-peer look up scheme or a centralized name server. Simulation results show that LANMAR with group discovery outperforms a typical on-demand search scheme.