Carrier Measurements Based Autonomous Spatial Reference Establishment for Ground-Based Positioning Systems

As an important supplement and backup to the Global Navigation Satellite System (GNSS), the ground-based positioning system is desirable for low cost and high flexibility. In GNSS denied environments, the spatial reference cannot be determined via GNSS services. A large number of systems obtain the coordinates of base stations by artificial measurement, but this can be limited by terrain or other conditions and is difficult to achieve rapid deployment. The spatial reference establishment methods affect its deployment flexibility, while the accuracy of the coordinates of base stations has a crucial influence on the positioning performance. Some methods estimate the coordinates of base stations via code measurements, but cannot establish high-precision spatial references. Existing methods based on carrier measurements rely on the known calibration points of a receiver, which still need artificial measurement. To overcome the shortcomings of existing methods in accuracy or autonomy, this research proposes a carrier measurements based spatial reference establishment method, which can precisely estimate the coordinates of base stations without known calibration points. A theoretical model of the coordinate estimation problem is established for ground-based positioning systems, and the proposed algorithm obtains the maximum likelihood estimation based on the observations of a mobile receiver. The simulation results show that the proposed method can achieve centimeter-level accuracy of coordinate estimation without dependence on calibration points. Compared with existing methods, the proposed method has advantages in estimation accuracy and autonomy, and can be applied in the rapid deployment of ground-based positioning systems, thereby improving the flexibility and practicability.