PPP‑B2b‑RTK: a PPP‑B2b augmentation method by using the SSR corrections from a single reference station 

Leitong Yuan · Bofeng Li · Weikai Miao · Haibo Ge · Zhilu Wu

Abstract 

 The PPP-B2b service provided by the BeiDou global navigation satellite system (BDS-3) is regarded as a convenient approach for real-time precise point positioning (PPP). However, float PPP solutions with decimeter-level accuracy are typically achieved only after tens of minutes, which is unacceptable for real-time high-accuracy location services. Moreover, integer ambiguity resolution (IAR), a prerequisite for precise positioning, cannot be implemented only with current PPP-B2b prod ucts. To address this problem, a feasible method of PPP-B2b precise positioning is proposed, where fast IAR is enabled using extra state space representation (SSR) corrections generated by a single reference station. First of all, a full-rank version of the undifferenced and uncombined (UDUC) PPP model is formulated by considering the properties of PPP-B2b products. Then, the IAR-enabled PPP-B2b precise positioning (PPP-B2b-RTK) model is put forward. Augmentation corrections in the SSR format are generated in real time at a single reference station, compensating for the current PPP-B2b service. Finally, experiments with different baselines are carried out in kinematic mode to demonstrate the positioning performance. For traditional PPP-B2b positioning based on raw observations, the accuracy of better than 4.8, 3.2, and 8.9 cm in east, north, and up directions is achievable after about 20 min convergence. The results of single-station PPP-B2b-RTK on 27.6 km and 61.6 km baselines indicate that the ambiguities can be correctly fixed within tens of seconds and the positioning accuracy is improved to 1.1, 1.1, and 3.6 cm with relative improvements of 57.69%, 35.29%, and 32.08%, respectively. Furthermore, the ambiguities are still effectively fixed, and centimeter-level positioning solutions are obtained with the convergence time of about 10 min even if the baseline grows extremely as long as 674.8 km.