Algorithm for Deriving Optimal Frame Size in Passive RFID UHF Class1-Gen2 Standard Using Combinatorial Model Boundaries

Abstract

MAC level efficiency constraints of the RFID Reader-Tag communication require proper frame size selection in order to achieve maximum throughput. To set optimal frame size, one needs to estimate the number of tags. Deriving optimal frame size results in reducing time for identification of large RFID tag populations, and thus increases throughput of RFID system.In accordance with the standard Dynamic Framed Slotted ALOHA (DFSA) protocol, we propose model for frame size adaptation using number of collisions (C) and successful slots (S) within the frame length L. We found that expected number of tags N, linearly depends on S in the frame of length L, for fixed C. Proposed model for estimation of the number of tags can be described with 4 characteristic points, which can be calculated from proposed combinatorial model. Algorithm implementation in the first step estimates number of tags, and then in the second step, using the estimates, set the optimal frame size.In order to compare proposed system performance with the other approaches, we use standard measures, System Efficiency and Collision Ratio. Simulation results show that our method provide better performance than the Q-selection algorithm, specified within the UHF-Class1-Gen2 standard.