Fast two dimensional position update system for UHF RFID tag tracking

This paper presents a novel and efficient system for tracking of passive ultra high frequency (UHF) radio frequency identification (RFID) tags based on the phase difference of arrival technique. All required information for a tag position update is captured within only one communication cycle between a UHF RFID reader and a tag. The system provides two dimensional position updates that allow the tracking of a tag on arbitrary tracks. The current tag position is calculated analytically based on a specific bistatic reader antenna arrangement. Initial verification measurements in a realistic application environment show mean absolute errors of 8.4 cm and 1.3 cm for the x-coordinate and the y-coordinate, respectively.