## 4 Conclusions  
In this study, through the GNSS multifunctional precision positioning software Net_Diff, 20-day data for 17 stations in global were assessed to analyze the BDS-3 (B1 cB2a) static and kinematic PPP performance. The BDS-2+3 (B1 IB3I), GPS, GPS+BDS-3 (B1 cB2a), and GPS + BDS-2+3 (B1 IB3I) positioning error, static and kinematic convergence, and convergence efficiency between different receiver models were compared. The conclusions are summarized as follows.  
1. In terms of PPP error, the results show that the RMS accuracies of BDS (B1 cB2a) static PPP are 6.9 mm, 5.2 mm, and 27.2 mm, and of kinematic PPP are 2.6 cm, 6.0 cm, and 8.5 cm in the North, East and Upward directions, respectively. Whether it is static PPP or kinematic PPP, the positioning accuracy of BDS (B1 CB2a) and BDS (B1 IB3I) PPP are worse than that of GPS. The main reason is that the accuracy of BeiDou's precise orbit and clock difference provided by GBM is worse than that of GPS, and the BeiDou PCO correction model uses GPS correction parameters. In static PPP, BDS (B1 cB2a) and BDS (B1 IB3I) have obvious inter-system bias, which is mainly reflected in the upward. Kinematic PPP has a greater impact on the number of satellites.
2. In terms of Convergency, for static PPP or kinematic PPP, BDS + GPS has better convergence than GPS only or BDS only. The main reason is the increase in the number of satellites involved in positioning. For BDS (B1 CB2a) PPP, there is no obvious difference in convergence between different antenna models (high-end receiver), though the number of satellites observed has a great impact on convergence. Because the observation noise of BDS (B1 IB3I) is larger than that of BDS (B1 CB2a), when the number of satellites is the same, the convergence of BDS (B1 IB3I) is worse than that of BDS (B1 CB2a). When the number of satellites participating in static PPP is less than five satellites and there are too many epochs of the total epochs in a day, the static PPP convergence does not reach 0.1 m within 60 min.  
To sum up, BDS (B1 CB2a) PPP can meet the PPP needs of BeiDou users in the global range, but compared with GPS, the elevation direction BDS (B1 CB2a) PPP performs poorly. With the advancement of algorithms, these gaps will gradually narrow. BDS (B1 CB2a) is equivalent to GPS in terms of convergence.  
[PERSON] researched the performance evaluation method. [PERSON] validated the results and undertook the writing. [PERSON] researched the model and undertook the writing. [PERSON] revised the written work. [PERSON] investigated the related work. [PERSON] researched Kalman filtering. [PERSON] analyzed the experimental results. All authors have read and agreed to the published version of the manuscript.  
Figure 14: Fewer than five satellites participating in static PPP at PIE1 station accounted for the total epoch (20 days).  
**Funding:** This study was supported by the National Natural Science Foundation of China (62173237, 71731001); the Zhejiang Key laboratory of General Aviation Operation technology (JDGA2020-7); the Talent Project of Revitalization Liaoning (XLYC1907022), the Key R & D projects of Liaoning Province (2020 JHz/10100045), the Natural Science Foundation of Liaoning Province (2019-MS-251), the Scientific Research Project of Liaoning Provincial Department of Education (JYT2020142), The High-Level Innovation Talent Project of Shenyang (RC190030).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** All data can be available from Multi-GNSS Experiment (MGEX) or by contacting the primary author.  
**Conflicts of Interest:** The authors declare no conflict of interest.