**5. Conclusions**

This paper focused on the performance of multi-GNSS in the Asia-Pacific region. Oneweek period observation data from 10 MGEX stations, precise satellite orbit and clock offset products, and broadcast ephemeris were used to investigate the performance of C/N0, pseudorange multipath, broadcast ephemeris clock offset accuracy, broadcast ephemeris orbit accuracy, SISRE, static PPP, and kinematic PPP in the Asia-Pacific region, and the conclusions are as follows:

(1) The C/N0 and pseudorange multipath among GPS, BDS-2, BDS-3, QZSS, GLONASS, and Galileo were investigated and compared; the C/N0 of GPS and Galileo shows the best performance, and the C/N0 for BDS and GLONASS are worse, and the C/N0 of QZSS is the poorest. The pseudorange multipath error of Galileo has the smallest, about 0.2 m, GPS and QZSS are comparable at about 0.3 m, and GLONASS is around 0.4 m.

(2) The broadcast ephemeris orbit and broadcast ephemeris clock offset of GPS, BDS-2, BDS-3, QZSS, GLONASS, and Galileo were analyzed, and the results show that the broadcast ephemeris clock offset accuracy of Galileo is the best, followed by GPS, QZSS, BDS-3, BDS-2, and GLONASS, respectively. For the broadcast ephemeris orbit, the accuracy of BDS-3 is the best, followed by GPS, Galileo, QZSS, GLONASS, and BDS-2, respectively. The SISRE of BDS-3 is better than BDS-2 for both MEO and IGSO satellites, and by comparing the observation data quality and SISRE, it can be found that when the observation data quality is better, the broadcast ephemeris SISRE is also better, and vice versa, indicating that the magnitude of SISRE has a certain correlation with the observation data quality results.

(3) The static PPP and kinematic PPP performance were analyzed in terms of GPS, GPS/QZSS combination, BDS, BDS/QZSS combination, GLONASS, and Galileo. For static PPP, the positioning accuracy of GPS and GLONASS present the best and worst performance, respectively. In terms of kinematic PPP, the positioning accuracy in the east and north direction of GPS is better than that of Galileo. For up direction, the positioning accuracy of BDS is better than that of Galileo, the GLONASS shows the worst positioning performance in the east, north, and up component. Compared to the GPS-only and BDS-only solutions, the positioning accuracy of GPS/QZSS and BDS/QZSS solutions is improved, and the improvement rate of kinematic is larger than static PPP.

**Author Contributions:** M.L. and G.H. conceived and designed these experiments and wrote the paper; M.L., G.H., L.W. and W.X. performed the experiments, analyzed the data, drew pictures, and wrote the paper; F.Y. reviewed the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Programs of the National Natural Science Foundation of China (42127802), the Key R&D Program of Shaanxi Province (2022ZDLSF07-12), the Special Fund for Basic Scientific Research of Central Colleges (Grant No. CHD300102269305, CHD300102268305, Chang'an University).

**Data Availability Statement:** The observation data and precise products used in the research are available on the FTP of Wuhan University (ftp://igs.gnsswhu.cn/pub/ accessed from 10 to 16 October 2021).

**Acknowledgments:** The IGS and WHU are greatly acknowledged for providing the multi-GNSS tracking data, SINEX coordinates, and satellite orbit and clock offset products. We would also like to thank Zhongyang Zhao, an employee of Xi'an Honor Device Co., Ltd. for his suggestions on this paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
