Poster: Position-Based Multicast Routing for Mobile Ad-Hoc Networks
Martin Mauve Holger, Joerg Widmer, Thomas Lang · 2003
In this paper we present a Position-Based Multicast routing protocol (PBM), which uses the geographic position of the nodes to make forwarding decisions. In contrast to existing approaches PBM neither requires the maintenance of a distribution structure (i.e., a tree or a mesh) nor resorts to flooding. PBM is a generalization of existing position-based unicast routing protocols, such as face-2 [1] or Greedy Perimeter Stateless Routing (GPSR) [3]. As it is common for position-based approaches, we assume that the position of the destination(s) is known to the sender (e.g., by means of a location service), that each node knows its own position (e.g., by use of GPS), and that each node knows the position of its direct neighbors (e.g., by means of periodic beacons). In position-based unicast routing the forwarding node selects one of its neighbors as a next hop such that the packet makes progress toward the geographical position of the destination. It is possible that there is no neighbor with progress toward the destination while there still exists a valid route to the destination. The packet is then said to have reached a local optimum. In this case a recovery strategy is used to escape the local optimum and to find a path toward the destination. In order to extend position-based routing to multicast two key problems have to be solved. First, at certain nodes a multicast packet has to be split into multiple copies in order to reach all destinations, the challenge being to decide when such a copy should be created. Second, the recovery strategy used to escape from a local optimum needs to be adapted to take multiple destinations into account. The key contributions of this work are solutions for both problems. The proposed algorithms have been evaluated by means of simulation.