Indoor Localization with Passive RFID System Based on Phase Difference of Displacement

The radio frequency identification (RFID) system is investigated for indoor localization. The phase difference between the relative displacement of the tag is used to estimate the range towards each anchor. The updated range information at each anchor is then used to compute the coordinates of the tag using analytical multilateration positioning. The localization performance of this multilateration method is demonstrated experimentally and compared with maximum likelihood positioning, which serves as an upper bound for localization performance. The experiments show that the passive RFID system with analytical multilateration positioning can achieve localization errors between 0.06 m and 0.18 m for the chosen trajectory.