Session E3b: Advanced Technologies in High Precision GNSS Positioning

High Precision and Cost Efficiency: The Realization of a Nationwide PPP-RTK System
Bowen Duan, Haohao Xin, Qiang Zhang, Mengxiang Tong, Yilong Yuan, Chang Liu Positioning Technology Center Tencent Technology (Beijing) Co., Ltd.
Location: Holiday 1 (Second Floor)

Peer Reviewed

In recent years, there has been a growing demand for high-precision GNSS positioning across various applications, including engineering surveying, structural monitoring, autonomous driving, and drone navigation. However, current high-precision GNSS solutions predominantly rely on Real-Time Kinematic (RTK) technology. While RTK offers excellent accuracy and reliability, it incurs high costs due to the typical requirement of base stations spaced approximately 50km apart. This paper presents the implementation of a nationwide Precise Point Positioning - Real-Time Kinematic (PPP-RTK) system across China, utilizing a network of only 800 GNSS reference stations—approximately one-third of the number required by existing nationwide RTK systems. In the implementation process, we utilized publicly available real-time SSR services to accurately obtain satellite positions and clocks. Additionally, we employed a series of methods to model pseudorange Differential Code Bias(DCB), carrier phase Uncalibrated Phase Delay (UPD), ionospheric, and tropospheric errors in real time. The corrections generated by the server exhibit precise variances, allowing users to determine the weight of each satellite and the search order for partial ambiguity fixing based on these correction variances. On the user side, we employed partial ambiguity fixing algorithm and dynamic positioning strategy to enhance the accuracy and reliability of positioning, enabling our PPP-RTK method to be applied for high-precision vehicle positioning. To validate the system, extensive testing was conducted, including 135 static tests and approximately 40 hours of vehicular testing. Experimental results show that in static tests, the average time to fix is 13.9s, with a fix rate exceeding 96% and a positioning error of less than 5 cm. In dynamic tests, the overall fix rate is 89.4%, with a horizontal RMSE of 15.1 cm and a vertical RMSE of 24.1 cm. These results demonstrate that the improved PPP-RTK method achieves high-precision positioning comparable to RTK, while significantly reducing the costs of base station construction and maintenance. This efficiency promotes the broader application of high-precision satellite positioning.