Topology and RSSI-based localization for ad hoc networks
Al Agha, Khaldoun
In wireless ad hoc networks, node's location information is useful for efficient routing and location-aware applications. Ad hoc localization systems permit nodes in sensor networks to fix their positions in a global coordinate system. This is usually performed with the use of location measurement devices, such as GPS. However, low-end systems or indoor systems, which cannot use GPS, must locate themselves based only on information available locally, such as distance of neighboring nodes. In this thesis, we propose the development of a ‘cooperative’ geolocalization protocol based on the properties of an ad hoc network.
Particularly, we introduce a localization framework that is compatible with a fully distributed and constantly evolving environment and it considers a priori and reliability information. It is an improvement of the Kamada-Kawai method, a popular localization method first used in graph theory. The weakness of Kamada-Kawai method is that it does not mention all the available information. The proposed localization algorithm observes the whole network topology and precisely indicates that if the unlocated node is not an one-hop neighbour with another node it is likely that their distance is maximal. Each unknown node is aware of the network topology. The distances between neighboring nodes are calculating by using the RSSI technique. Moreover, real RSSI measurements have been performed in order to find the correlation between the signal strength and the distance. The performance of our approach is evaluated with simulations in real-world conditions in different environments.