ELF: efficient location forwarding in ad hoc networks

Recently, a new family of protocols has been introduced for large scale ad hoc networks that makes use of the approximate location of nodes in the network for geography-based routing. Location management plays an important role in such protocols, and previous work in this area has shown that the asymptotic overhead of location management is heavily dependant on the service primitives (location registration, maintenance and discovery) supported by a location management protocol. Currently, SLALoM (C.T. Cheng et al., 2002), which is a grid-based protocol optimized for large node movements, achieves the best known upper bound on the asymptotic worst case overhead of location management. However, the location registration cost in SLALoM dominates other costs for all practical purposes, and thus novel schemes need to be designed to limit this control traffic. In this work, we use the idea of location forwarding to devise a new scheme called ELF that limits the signalling traffic, and thus enhances the scalability of location management in large ad hoc networks. We find that, while the asymptotic overhead cost by such an improvisation matches that of SLALoM, ELF outperforms SLALoM in average case scenarios.