Optimal Frame Length Analysis and an Efficient Anti-Collision Algorithm With Early Adjustment of Frame Length for RFID Systems

This paper proposes an efficient anti-collision algorithm to improve the read performance of the EPCglobal ultra-high frequency (UHF) Class-1 Generation-2 radio-frequency identification (RFID) standard. Optimal frame length is one of the most important parameters to be adjusted in RFID anti-collision algorithms. Hence, we first derive the optimal frame length by analyzing the maximum of normalized throughput and by taking into account the unequal time intervals of successful, collision, and empty slots. We find that the optimal frame length should be set to 1.89 times of the number of tags when the ratio between collision-slot duration and empty-slot duration is 5. The proposed anti-collision algorithm is based on the mechanism of early adjustment of frame length and examines the fitness of frame length only at an optimal time slot in each read round. The primary advantage of our algorithm is the ability to achieve a good compromise between computation complexity and throughput performance. The results show that the proposed method provides up to 400 tags/s read speed and can obtain 5%-10% time-saving efficiency, as compared with typical dynamic framed-slotted ALOHA.