Fundamental bounds on RSS-based wireless localization in passive UHF RFID systems Radio-Frequency IDentification (RFID) systems carry critical importance for reaping the benefits of a diverse set of applications that will be enabled by the emerging Internet of Things (IoT). In particular,RFID based position estimation and tracking will facilitate a wide array of location based services. Considering a monostatic RFID configuration with a three dimensional antenna radiation pattern, this paper investigates the limits of localization accuracy for received signal strength (RSS) based wireless localization using passive UHF RFID systems. The Cramer-Rao Lower Bound (CRLB) for the localization accuracy are derived, and are compared with the localization accuracy of maximum likelihood estimators for various RFID antenna topologies. Numerical results show that due to the directional antenna pattern used in RFID systems, the localization accuracy can degrade at blind locations that remain outside of the RFID readers’ main beam patterns.Cramer-Rao Lower Bound (CRLB) for the localization accuracy are derived, and are compared with the localization accuracy of maximum likelihood estimators for various RFID antenna topologies. Numerical results show that due to the directional antenna