Analysis of PPP-B2b positioning performance enhanced by high-precision ionospheric products

Objectives: The BeiDou-3 Navigation Satellite System (BDS-3) can provide real-time Precise Point Positioning (PPP) services to China and neighboring regions through PPP-B2b signals. Because PPP-B2b signals do not contain ionospheric model products, the current positioning research mainly adopts ionospheric-free combination. The positioning accuracy can reach decimeter level, but requires about 30 minutes of convergence time. In this paper, aiming at the long convergence time of PPP-B2b positioning, the improvement of positioning convergence performance based on ionospheric model products is analyzed. Methods: We introduced the Q4DIM (Quasi-4 dimensional ionospheric modeling) model into regional ionospheric delay modeling in China and adopted four schemes of 50,100,150 and 200 reference stations uniformly distributed in China (day of year 201-207) for ionospheric modeling. Results: The results show that when the number of stations used in ionospheric modeling increases from 50 to 200, the accuracy of ionospheric model products increases from 2-3 TECU to better than 0.8 TECU. Compared with the current ionospheric-free combined PPP, the convergence time of BDS-3 dynamic PPP can reach up to 77%. In addition, the convergence time of GPS+BDS3 dynamic PPP is reduced from 13.51 minutes to 4.45 minutes. Conclusions: High-precision ionospheric model products can significantly shorten the PPP-B2b convergence time.