Efficient Median Estimation for RFID Systems

Radio frequency identification (RFID) tags are used in a lot of applications such as production line and inventory management. Sensors are also a widely adopted wireless technology. This large scale deployment of both RFID technology and sensor technology has opened the door to innovative ways to integrate RFID and sensor technology. Sensor-tags are tags that can report sensed information to an RFID reader. The traditional way to obtain information from tags is to query each tag for its value. This works, however, only for a relatively small number of tags. When the number of tags becomes large it is prohibitive to query one by one due to the high delay. In this paper we present a probabilistic algorithm for estimating the median of a set of RFID tags using binary search. We then evaluate the accuracy and time efficiency of our algorithm.