From Prototype to Nationwide Deployment: A 5-year Retrospect of a WiFi-based Outdoor Localization System

While GPS-based outdoor localization has become a norm, it still faces severe issues in challenging environments such as urban canyons. In this work, we share our 5-year experience on utilizing Wi-Fi to help GPS-based outdoor localization. We analyze the coverage of outdoor Wi-Fi in the urban area on a large scale to demonstrate the feasibility of employing Wi-Fi signals for outdoor localization. For the first time, we design a Wi-Fi-GPS fusion approach to build nationwide Wi-Fi outdoor fingerprints for localization. We propose solutions to address not just technical challenges but also real-life practical challenges. Our system has been deployed nationwide in more than 300 cities to serve millions of users. We evaluate the Wi-Fi helped localization system in terms of service coverage, response time, and accuracy in different areas (e.g., office area vs. residential area) and different cities. We compared the accuracy of our localization system with that of two well-known companies, such as Apple's location services. Our proposed system demonstrated superior performance, outperforming other commercial localization systems. Additionally, the fingerprint dataset collected during this study will be publicly released to support further research.