Propagation delay detection based on I-Q modulation for indoor positioning system

An indoor positioning system has become a hot issue to provide a location-based service such as direction tracking, geofencing and private tracking. This paper addresses a phase-detection algorithm based on the Wi-Fi for proximity estimation between a transmitter and a receiver. In addition, the mathematical analysis of the phase-detection is shown based on the I-Q modulation. The algorithm has been designed with a combination of round-trip time measurement and quadrature modulation technique, that can have a positioning accuracy of 1m. Moreover, the quadrature modulation utilizes low frequencies, so the power consumption can be reduced. The accurate performance of the proposed estimation was verified by means of simulation results.