Precise Localization with Smart Antennas in Ad-Hoc Networks

In this paper, we study precise localization using Angle of Arrival (AOA) estimations by smart-antenna equipped beacons in Ad-Hoc networks. The node to be localized sends a signal to its surrounding beacons. The beacons estimate the signal directions with high resolution AOA methods and feed them back to the node for position calculation. In other words, position calculation is not required at beacons. When AOA estimates from three or more beacons are received, ambiguity occurs. Three resolution methods, namely (a) simple averaging (b) Minimax and (c) Precision-weighted averaging are proposed and compared. As estimation bias is heavily dependent on antenna orientations the center-facing approach is found to give better performance in a square field.