Experiments on localization of wireless sensors using airborne mobile anchors

An important aspect of Wireless Sensor Network (WSN) operation is identifying the physical location of each sensor in 3-D space - a process known as localization where an anchor with known location determines the location of other location-blind nodes. In this paper, we present a detailed performance analysis of three scenarios: (1) localization of blind nodes using an airborne mobile anchor; (2) fixed ground anchors only; and (3) using the combination of fixed anchor and mobile anchors. Matlab simulations were carried out to explore the impact on localization error based on random and designated positions of mobile anchors, the number of mobile anchor positions used, and the variability of Received Signal Strength Indicator (RSSI) range measurements as part of the objectives of this experiment. Results show that a designated flight path is better than random anchor positions, and that localization error increases quickly with RSSI variability, while poor anchor geometry yields large errors. Somewhat surprisingly, adding ground based anchors does not improve localization. Approximately 6 to 13 RSSI readings give the best localization accuracy.