A Comparative Evaluation of Wi-Fi RTT and GPS Based Positioning

Wi-Fi-based positioning technology has snowballed 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 global cities. Since 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 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 central downtown area in Melbourne city. Based on the same testing environment and the same testing points within a central city area, both GPS and Wi-Fi RTT are tested and analysed. Results showed that the average positioning accuracies from the two technologies are 5.10 m and 1.40 m, respectively. The Wi-Fi RTT technology demonstrated a much better performance both in accuracy and stability.