GPS-Aided Automatic Site Survey Method for WiFi RTT-Based Positioning

The fine timing measurement protocol defined in the IEEE 802.11-2016 standard leads to precise ranging between WiFi devices. However, because the locations of WiFi access points (APs) are required for locating mobile devices, a site survey must be performed prior to the deployment of positioning services, which is extremely time-consuming. This article studies an automated site survey method that utilize the global positioning system (GPS) and built-in sensors in mobile devices. When a user enters an indoor site from outside, the outside trajectory is obtained using GPS and built-in sensors, and the indoor trajectory can be estimated solely relying on the sensor measurements. Thereafter, the locations of APs can be determined using the ranging results obtained at multiple positions on the estimated indoor trajectory. The experimental results revealed that the difference in average positioning error obtained using the estimated and perfect AP locations was 30 cm.