A Tag Count Estimation Algorithm for Dynamic Framed ALOHA Based RFID MAC Protocols

The performance of RFID MAC algorithms is expressed in terms of the total time it takes by a reader to read all the tags in the reading range. One of the major MAC approaches for RFID systems is the framed slotted ALOHA based approach. It is proven that this class of algorithms achieve the smallest total reading time when, at each reading round, the frame length is set equal to the actual number of remaining unread tags. An important design challenge to increase the performance of this class of algorithms is to estimate the remaining tag count before each reading round. In this paper, we address this remaining tag count estimation problem for such RFID systems. The introduced algorithm is an a posteriori tag count estimation scheme from the collision statistics of the previous reading round. We compare the algorithm with the optimum, lower bound and other a posteriori estimation algorithms and demonstrate its efficiency. The performance of the algorithm is better than the current a posteriori tag count estimation algorithms. Another improvement brought by the algorithm is the reduction in reader side computational overhead existing in the previous schemes.