While mobility in the sense of node movement,has been an intensively studied aspect of mobile ad-hoc networks (MANETs), another aspect of mobility has not yet been subjected to systematic research: nodes may not only move,around but also enter and leave the net- work. In fact, many proposed protocols for MANETs exhibit worst-case behavior when an intended communication partner is currently not present. Therefore, knowing whether a given node is currently present in the network can often help to avoid unnecessary overhead. In this paper, we present a solution to the presence detection problem. It uses a Bloom filter- based beaconing mechanism,to aggregate and distribute information about the presence of network nodes. We describe the algorithm and discuss design alternatives. We assess the algorithm’s properties both analytically and through simulation, and thereby underline the effectiveness and applicability of our approach. Key words: Presence Detection; Mobile Ad-Hoc Networks; MANETs; Soft State Bloom
