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Y. Bai, A. Kealy, G. Retscher, L. Hoden:
"A Comparative Evaluation of Wi-Fi RTT and GPS Based Positioning";
Talk: International Global Navigation Satellite Systems (IGNSS) 2020, Sydney, Australia (invited); 2020-02-05 - 2020-02-07; in: "International Global Navigation Satellite Systems (IGNSS) 2020", (2020), Paper ID 10, 12 pages.

Wi-Fi-based positioning technology has grown rapidly over the past 20 years along with the fast development and applications of smartphones for indoor positioning. On the other hand, Wi-Fi is increasingly accepted for outdoor positioning due to the availability and popularity of public Wi-Fi in worldwide cities. Because GPS signals are often interrupted and unstable in the downtown areas with high-rise surrounded, Wi-Fi becomes an ideal positioning technology as a substitution of GPS. Especially after the release of the IEEE 802.11mc standard last year, researchers and specialists from industries were attracted immediately after the release. The new standard provides a fine time measurement (FTM) protocol for us to use multiple round-trip time (RTT) rather than the received signal strength indicator (RSSI) for calculating the distance between a Wi-Fi access point (AP) and a mobile end-user device. This paper presents an evaluation and comparison study between Wi-Fi RTT and GPS based localisations in an outdoor space located in a downtown area in Melbourne city. Based on the same testing environment and same testing points within a central city area, both GPS and Wi-Fi RTT are tested and analyzed. All the coordinates received from GPS were converted to the Australian grid coordinate system and then to the local coordinate system for the ease of comparison. Results showed that the average positioning accuracies from the two technologies are 2.6m and 1.2m respectively. The Wi-Fi RTT technology demonstrated a much better performance both in accuracy and stability.

GPS, Wi-Fi RTT, positioning, smartphone, LBS