Beyond the limit: A fast tag identification protocol for RFID systems

This paper presents the design, experiment test and performance evaluation of FAST, a fast tag identification protocol in RFID systems. FAST includes a collision tolerant mechanism (CTM) that can identify tags in collision slots correctly. Each tag sends a randomly selected signature in its selected slot. When multiple tags select the same slot and a collision occurs, the reader can detect all the signatures correctly by exploiting the cross correlation. It then asks tags to send their tag IDs sequentially through a series of ACK commands, leading to no collision in the tag ID transmissions. By using CTM, all the tags in the collision slots can be identified successfully if the number of tags involved conforms to the signature detection limit. FAST also includes a dynamic frame length estimation mechanism to maximize the slot utilization so as to further improve the performance of tag identification. Theoretical analysis and experimental results from the USRP2 testbed demonstrate the feasibility of FAST. Simulation results show that FAST outperforms other protocols dramatically.