ON SELECTING NODES TO IMPROVE ESTIMATED POSITIONS Erwan Ermel,^'^ Anne FladenmuUer,^ Guy Pujolle,^ and Andre Cotton,^ Laboratoire d'Informatique de Paris 6 Universite Pierre et Marie Curie Paris, France firstname.lastname(a)lip6.fr 2 Thales Communication BGCOM/TCF/SEA/TAI Colombes, France firstname.lastname@fr.thalesgroup.com Abstract We consider node localization problems in ad hoc wireless networks in which two types of nodes are considered: nodes with self-locating capability like GPS and nodes with no self-locating capability. Our simple algorithm for improving the position accuracy consists of selecting and processing only the nodes that are likely to enhance the position estimation. We focus our approach on defining a hull of neighboring nodes as key of position accuracy enhancement. 1, Introduction Recent developments of wireless technologies have allowed new types of networks to be envisaged. Mobile ad hoc networks (MANETs), which consist of wireless hosts establishing multi-hops communication with each others in the absence of fixed infrastructure, represent one of the current challenge of the networking research community. Many applications are considered for these new mobile ad hoc networks, for instance military ones to establish communi- cations in war theatres, for disasters relief or more basically to set a network in large zones when it is difficult to install a cable-based infrastructure. Routing in such conditions is quite challenging. For instance, due to the unpredictable mobility of nodes, the network topology is inherently unstable. Important aspects to consider include, the robustness of the solution, its com- patibility with existing solutions in wired environments, and its availability of routes. Most existing routing proposals are topology-based routing protocols