Experimental performance evaluation of passive UHF RFID systems under interference

Performance of passive ultrahigh frequency radio-frequency identification (UHF RFID) systems is determined by the ability of the RFID reader to precisely decode the RF signal backscattered by the RFID tag. For a successful operation, two conditions must be met: (1) the power level of the impinged signal on the RFID tag must be above its threshold to power up its internal circuitry, and (2) the backscattered signal received by the RFID reader must be higher than its sensitivity threshold. The environment in which such systems are deployed has a major effect on these two conditions. In this paper, performance of a passive UHF RFID system is experimentally evaluated for potential deployment in industrial settings where many sources that generate ambient electromagnetic interference (EMI) exist. This interference will inevitably affect the performance of the deployed passive UHF RFID systems. Three different types of EMI are considered in this work: impulsive continuous wave interference and interference with Gaussian and Rayleigh distributions. The performance metric used in this paper is the reading rate per second. The obtained experimental results show that the performance of passive UHF RFID system depends on the nature and the strength of the ambient EMI. The results reported are of particular interest to those who deploy passive UHF RFID systems for industrial applications particularly in situations that already have machines in use that generate unpredictable EMI.