Time Reversal Indoor Tracking with Centimeter Accuracy

In a rich-scattering environment, radio frequency (RF) devices communicate through multipath channels and the channel state information (CSI) is uniquely determined by the location of the transmitter or receiver devices along with surrounding environments. Whenever one of the devices moves, the CSI changes accordingly. In other words, there is a one-to-one mapping between the CSI and the location of RF devices. Inspired by the relationship, we propose a real-time indoor tracking system that utilizes time-reversal (TR) technique to capture differences in the CSI and then accurately locate the moving RF device along its trajectory. Moreover, a real-time speed estimation algorithm is designed based on the spatial distribution of the TR resonance. A prototype is built to validate the accuracy and robustness of the proposed system through a train tracking experiment. It illustrates the TR technique as a promising solution to high-precision indoor tracking applications.