A scalable distributed positioning system augmenting WiFi technology

This paper presents a distributed localization system for indoor environment based on a network of compact anchor nodes. The system is based on available low-cost commercial components and it is capable of standard WiFi connectivity at 2.45 GHz. The basic node is equipped with a switch-beam antenna, which is the enabling technology for a Direction of Arrival (DoA) estimation based on Maximum-Likelihood criteria. The adopted DoA estimation procedure is tolerant to noisy power measurements, making it suitable for low-cost effective solutions based on RSSI measurements. The node is designed to be placed in an unobtrusive area for the movement of a mobile target node and is capable to operating as an independent anchor, but it is optimized to cooperate with other identical nodes to form a coordinated network of anchors, capable to monitor an extended indoor area. An experimental characterization demonstrates the DoA performance of the single node.