Long-term performance analysis of BDS-3 precise point positioning (PPP-B2b) service

Since 2020, the BeiDou Navigation Satellite System (BDS) has launched new precise point positioning service which provides precise correction of GPS and BDS-3 satellites to help users realize real-time precise point positioning, known as PPP-B2b service. After being fully operational for more than one year, this contribution comprehensively analyzes the performance of PPP-B2b in terms of correction availability, clock and orbit quality and positioning accuracy with PPP-B2b messages of nearly 48 weeks from 2021 to 2022. The results show that in the PPP-B2b service, the orbit radial differences of BDS-3 MEO, GPS, and BDS-3 IGSO satellites are 0.056 m, 0.069 m, and 0.172 m, respectively, compared to the GFZ final orbit, while the difference of along-track and cross-track is more than three times the radial. For BDS-3 MEO satellites from different manufacturers, the RMS of Satellite Laser Ranging (SLR) residuals is different, with a maximum of 0.11 m. Restricted by the regional tracking network, the correction series of PPP-B2b service are discontinuous, and there are constant satellite-specific clock biases in different arcs of the satellite. Thus, the STD and RMS of satellite clock offset and signal-in-space ranging error (SISRE) are calculated using the method of weighting by arcs. The STD of SISRE for BDS-3 MEO, GPS and BDS-3 IGSO are 0.059 m, 0.092 m and 0.174 m, respectively. A total of 108 days of observation data from 12 MGEX stations of the East Asia region are selected to analyze the positioning performance of PPP-B2b. The results of day-by-day static PPP are stable at the centimeter level, while the average convergence time of GPS-only (61.65 min) is longer than BDS-3-only (45.12 min), which the constant bias in clock offset may cause. To analyze the effect of this bias, the bias is calculated and used as a correction to the PPP-B2b clocks. The convergence time of BDS-3 and GPS positioning is reduced by 48.7% and 65.9%, respectively, after correcting this bias, which confirms the influence of clock constant bias on positioning convergence.