In this paper, we present an UHF RFID location tracking system, which is based on measuring the phases of back scattered signals from RFID tag using multiple spatially distributed antennas at a single carrier frequency. The wavelength ambiguity of the phase measurements is resolved by using the extended Kalman filter (EKF) and the Rauch-Tung-Striebel (RTS) smoother, where the state includes the position, velocity and the phase offsets of antennas. The performance of the method is experimentally verified at 890 MHz using a commercially available RFID reader.
- Extended Kalman filter
- RTS smoother
- wireless sensors
Särkkä, S., Viikari, V., Huusko, M., & Jaakkola, K. (2012). Phase-based UHF RFID tracking with nonlinear Kalman filtering and smoothing. IEEE Sensors Journal, 12(5), 904-910. https://doi.org/10.1109/JSEN.2011.2164062