BFCE: A Constant-time cardinality estimator for large-scale RFID systems

Cardinality estimation is of primary importance in many RFID systems and applications. To ensure the time efficiency of estimation, numerous probability-based approaches have been proposed, most of which aim at meeting arbitrary accuracy requirement and follow a similar way of only minimizing the number of required time slots from tags to reader. In this paper, we propose BFCE, a constant-time Bloom Filter based Cardinality Estimator, for particular scenarios where slightly low accuracy and high efficiency are pursued. Comparing with existing approaches, BFCE only needs constant number of bit-slots, and the overall communication overhead is also significantly cut down, as the reader only needs to broadcast a constant number of messages for parameter setting. Results from extensive simulations under various tagIDs distributions shows that BFCE is accurate and highly efficient. In terms of the overall execution time, BFCE is 30 times faster than ZOE and 2 times faster than SRC in average, the two state-of-the-arts estimation approaches.