Rapid mesh network setup for indoor RF tracking

In this paper we present a practical system for indoor tracking that is low-cost, quick and simple to setup, and accurate. The system consists of three types of nodes, GPS referenced anchor nodes, static nodes placed at fixed locations within a building, and mobile tags that are attached to objects to be tracked. The network of anchor and static nodes must be setup to be globally rigid which allows a unique determination of the location of the static nodes using cooperative localization. The static and anchor nodes are then used as the reference for tracking the mobile tags. We describe a technique to identify static nodes that cannot be uniquely solved so that they can be augmented or removed, and then present a fast and distributed algorithm for determining the locations of the rigid static nodes. We also present an algorithm based on particle filters for tracking the tags that utilizes the knowledge of the range error distribution. Finally we present results obtained using our WASP (Wireless Ad-hoc System for Positioning) platform in an indoor office environment.