Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...

Probabilistic Protocols for Node Discoveryin Ad Hoc Multi-channel Broadcast NetworksG. Alonso 1 , E. Kranakis 2 , C. Sawchuk 2 , R. Wattenhofer 1 , and P. Widmayer 11 Department of Computer Science, Swiss Federal Institute of Technology, ETHZurich, Switzerland2 School of Computer Science, Carleton University, Ottawa, ON, K1S 5B6, CanadaAbstract. Ad hoc networks consist of wireless, self-organizing nodesthat can communicate with each other in order to establish decentralizedand dynamically changing network topologies. Node discovery is afundamental procedure in the establishment of an ad hoc network, asa given node needs to discover what other nodes are in its communicationrange. Existing multi-channel node discovery protocols are typicallyconstrained by the network configuration that will be imposed on thenodes once they are discovered. We present a communication model thatis independent of the network configuration that will be established afternode discovery. We present a pair of node discovery protocols fork ≥ 2 nodes in a multi-channel system and analyze them using the givencommunication model.1 IntroductionAd hoc networks consist of wireless, self-organizing nodes that can communicatewith each other in order to establish decentralized and dynamically changingnetwork topologies. Since these networks are an integral part of the new wirelesssolutions sought for home or personal area networks, sensor networks, and variousother commercial and educational networks, eliminating the shortcomingsof ad hoc networks is an important goal in network research [12].Before a node can communicate with the other nodes in its communicationrange, it must be aware of those nodes and thus node discovery is an essentialpart of the rendezvous layer for any node that engages in ad hoc network formation[16]. Efficient network formation requires that the rendezvous layer beable to find all nodes in communication range in the shortest time and withthe smallest energy expenditure possible. Obviously, the complexity of node discoveryis a function of both the number of nodes present and the number ofcommunication channels available to these nodes. Until recently, nearly all adhoc networks were formed by nodes that used single channel technology such as802.11 or IR LANs and thus most of the research about node discovery in ad hocnetworks assumes there is a single broadcast channel [15]. The introduction ofBluetooth [8], however, has boosted interest in node discovery in multi-channelsystems with frequency-hopping. Such research is especially important since theS. Pierre, M. Barbeau, and E. Kranakis (Eds.): ADHOC-NOW 2003, LNCS 2865, pp. 104–115, 2003.c○ Springer-Verlag Berlin Heidelberg 2003