Evaluation of an RSS-based indoor location system

Evaluation of received signal strength (RSS)-based indoor location system (ILS) using a ZigBee-based sensor network is presented. The proposed method is based on the field amplitude decay law in free-space conditions, that is used jointly with RSS measurements in a set of static receivers (Rx) to establish a cost function, whose minimum gives the estimated transmitter position (Tx). It is assumed that the Tx is attached to the object to be located/tracked. The method is tested in a real indoor scenario, using different sets of RSS measurements to evaluate its accuracy when determining the Tx position. The RSS degradation at the Rx′s due to multipath effects is studied, proposing different techniques to improve the ILS accuracy. Practical considerations of the location system implementation using the ZigBee-based sensor network are also discussed.