Dupla-aproximação: um novo método para estimativas do backlog em sistemas RFID UHF passivos.

Abstract

This thesis presents a study about the Dynamic Framed Slotted ALOHA (DFSA) anti- collision algorithms applied to Radio Frequency Identification (RFID) systems that operate in

Ultra High Frequency (UHF) and use microchip and non-battery tags (passive tags). In this context, the author develops a new method that operates on DFSA algorithms and accelerates the performance of backlog estimators. Assuming a critical scenario where the number of tags to be read is much larger than the total of transmission intervals initially provided by the reader (called the initial frame), the proposed Double-Approximation (DA) method performs, in addition to the tag estimates toward to the tags transmitting, a second approximation, which systematically reduces the tags transmitting toward to the tag estimates. In the end, a more accurate estimation for the total of unidentified tags is quickly obtained. Simulated results show that DFSA algorithms using the DA method (called DA-DFSA algorithms) have higher and more stable throughput (gains between 3.5% and 12.24%) and smaller amounts of transmitted RFID signals (reductions between 15% and 43%) compared to the traditional DFSA algorithms.