Ground-based high-precision local positioning using single-difference carrier phase and sparse ranging model

In Intelligent Transportation System applications, there is an urgent need for high-precision positioning services. Currently, Global Navigation Satellite Systems in open areas can provide centimeter level high-precision services. However, in underground, tunnel, indoor and other environments, the user receiver is unable to receive the navigation signal transmitted by the satellite, which impacts the performance of positioning systems. This paper is based on the development of groundbased navigation systems in narrow and long indoor environments such as tunnels. It proposes a positioning method that combines single-difference carrier phase measurement with sparse ranging measurement. This method effectively improves the system's positioning accuracy under conditions where base station layout is restricted. The method incorporates sparse ranging measurements to improve the ill-conditioned properties resulting from nonlinearity in the system calculation. Finally, the optimization of positioning results is achieved through a combined weighted nonlinear least squares algorithm. The proposed positioning method is experimentally validated using actual carrier phase data collected in a 4.6 kilometers tunnel and simulated sparse ranging measurement. The experimental positioning result indicate that combining sparse ranging measurements with GH-LPS has the advantages of low cost, low complexity and high precision. When the ranging error is 0.5 m, the terminal positioning accuracy is approximately 55 cm. And when the ranging error decrease to 10 cm, the terminal positioning accuracy is improved to approximately 25 cm.