Tracking with asynchronous binary readings and layout information in RFID systems with sense-a-tags

This paper addresses the problem of real-time indoor tracking of tagged objects in Ultra High Frequency Radio Frequency IDentification (RFID) systems with layout information and asynchronous readings. The method is based on binary detections and the model for the probability of detection is a function of both distance and angle between a tag and a reader and accounts for the possibility of a tag being in a dead-zone. A newly developed RFID component, called sense-a-tag, is used to improve the tracking performance, especially in areas with intersections and at portals, where the estimation of the direction of movement is important. A multi-hypothesis particle filtering method is applied for the tracking and its performance is demonstrated by computer simulations.