RFID Tag Ranging Measurement Based on Multi-frequency Carrier Phase Difference

With the development of communication technology and the rapid augment in data and multimedia services, the demand for indoor localization is increasing. Radio Frequency Identification (RFID) based real time localization system is an effective positioning system. However, due to the complex multi-path interference of indoor environment, most of the localization methods are lack of positioning accuracy. In this paper, we present a multi-frequency carrier phase difference based ranging measurement for passive RFID system in the real experiment scenario. Kalman filter is used to calibrate the phase difference value and a least square method is employed to estimate the environmental influencing factor. Real environment experiment results indicate high ranging accuracy of our approach, which lay a foundation for further two or three dimensions measurement. The paper explains the basic measurement principle, experimental setup and performance analysis.