Improved Multipath Mitigation Using Multiple Trend-Surface Hemispherical Map in GNSS Precise Point Positioning

Global navigation satellite system (GNSS) precise point positioning (PPP) is highly appreciated as a positioning technology; however, multipath restricts its accuracy and reliability. In this study, we proposed a multiple trend-surface multipath hemispherical map (MT-MHM), where discrepant multipath fading frequency or orbit orientation of each satellite in each azimuth and elevation grid is considered. In a typical static scenario, consecutive eight-day observations are collected to extract multipath and conduct PPP experiments. Compared with traditional multipath hemispherical map (MHM) based on trend-surface fitting, MT-MHM has better modeling performance of residuals and improves standard deviations (STDs) of residuals for all satellites. Besides, the positioning errors and required convergence epochs of PPP are reduced by using MT-MHM. For the positioning accuracy of all solutions, MT-MHM exhibits 50.8%, 15.2%, and 27.9% improvements compared with that without multipath correction in the east, north, and up directions, respectively. In conclusion, our proposed MT-MHM exhibits better performance in terms of residual reduction, convergence time, and positioning accuracy in PPP.