A GNSS PPP framework augmented using asynchronous ground-based positioning systems

Precise Point Positioning (PPP) has attracted considerable research interest due to its high accuracy and flexibility. However, its long convergence time remains a major barrier to wide adoption, particularly in real-time applications. Synchronized Ground-Based Positioning Systems (GBPS) have been shown to effectively augment PPP, but they require precise time synchronization, which is complex and costly, significantly limiting their practical deployment. In contrast, Asynchronous Ground-Based Positioning Systems (A-GBPS) eliminate the need for time synchronization, offering a more practical augmentation solution for PPP, owing to their ease of deployment, strong signal power, and rapid convergence. This paper proposes a tightly coupled PPP augmentation algorithm with A-GBPS. The algorithm employs a static Clock Bias Monitor (CBM) station, requiring no prior knowledge of its position, to correct A-GBPS carrier-phase measurements and uses an Extended Kalman Filter (EKF) to tightly fuse observations from multiple sources. This paper provides a theoretical analysis proving the performance gains achievable through A-GBPS augmentation. Both numerical simulations and field experiments validate the effectiveness of the proposed approach. Results show that A-GBPS significantly accelerates PPP convergence and enhances steady-state positioning accuracy.