BDS-3 B1I Signal Tracking Error Characteristic and Its Advantage in PPP Under Ionospheric Scintillation at Low Latitudes.

Ionospheric scintillation affects the tracking performance of GNSS code delay-locked loop (DLL) and phase-locked loop (PLL), thus degrading GNSS precise positioning accuracy. To investigate the third phase of BeiDou Navigation Satellite System (BDS-3) signal tracking error characteristic under ionospheric scintillation, this study comprehensively analyzes the standard deviation of tracking error of DLL (sDLL) and PLL (sPLL) for BDS-3 B1I signal by using the data (from July 15, 2021 to August 9, 2022) collected by a newly ionospheric scintillation monitoring receiver (ISMR) station installed with the Septentrio PolaRx5S GNSS receiver at Le Dong of China (18.4(?)N, 108.9(?)E; geomagnetic latitude: 11.6?N). The analysis suggests that under scintillation activity, the sDLL and sPLL points of BDS-3 B1I show more stable and concentrated distribution than those of GPS L1C/A, GLONASS G1C/A, and Galileo E1C. Statistics indicate that the average values of sDLL for BDS-3 B1I, GPS L1C/A, GLONASS G1C/A, and Galileo E1C are 0.089, 0.117, 0.100, and 0.126 m, respectively, and those of sPLL are 0.563, 0.732, 0.623, and 0.789 mm, respectively. Furthermore, based on sDLL and sPLL of BDS-3 B1I, the receiver tracking error stochastic (RTES) model for BDS-3 B1I precise point positioning (PPP) is established in this study. The root-mean square (rms) statistics show that compared with the elevation angle stochastic (EAS) model, the RTES model can improve BDS-3 single-frequency PPP by approximately 32.0%, 23.5%, and 24.3% in September-October of 2021 and by 33.2%, 31.8%, and 31.8% in March-April of 2022 in the east, north, and up directions, respectively.