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Abstract:
The new generation of BDS-3 broadcasted open service signals B1C and B2a, which are compatible and interoperable with GPS and Galileo overlapping frequency signals, are suitable for multi-GNSS PPP-AR. However, multipath errors caused by a complex environment can affect the ability of ambiguity resolution, thereby restricting the positioning performance of multi-GNSS. Due to different orbital repeat periods of GNSS systems, the implementation complexity of a multipath correction based on time-domain is relatively high, while that based on spatial-domain are research hotspot at present. Based on the multipath hemispherical map, four multipath processing schemes, namely, the independent modeling and correction (I-MHM, I-TMHM), together with the joint modeling and correction (C-MHM, C-TMHM) of different GNSS systems are proposed. We find that the residuals of GPS, BDS-3, and Galileo overlapping frequency show a strong correlation at the same spatial position after considering the GNSS inter-system biases, while the multipath joint modeling and correction method can improve the positioning performance more than the independent modeling and correction. This can be attributed to the ability of multi-GNSS to improve the space coverage within grids, making the modeling results more explanatory. Compared to C-MHM, the C-TMHM derived positioning accuracy and convergence time of combined GCE can be improved by up to 29.3% and 40.7%, respectively. The multi-GNSS data modeling time can be shortened by more than half to obtain a correction effect similar to that of full orbit period modeling. This research has significant applicability for mitigating multipath errors in various scenarios to improve positioning reliability.
