Robust Pseudorange and Carrier Phase Multipath Mitigation With Hemispherical Map Considering the Uncertainty

Multipath is a major source of unmodeled errors that will hinder high-precision and high-reliability positioning, navigation, and timing (PNT) in the global navigation satellite system (GNSS). Traditional methods mainly focus on how well to model the multipath effects; little attention has been paid to the reliability of the multipath corrections, which may have abnormal values, especially under complex observation conditions. In this article, a robust pseudorange and carrier phase multipath hemispherical map (MHM) considering the uncertainty based on the least-squares collocation (LSC) is proposed. First, the posterior residuals and the corresponding mean standard deviations (MSTDs) are applied to establish the MHM correction model and its precision model, respectively. Second, the robust MHM approach based on the LSC is deduced, including the real-time differenced (RTD) and real-time kinematic positioning (RTK) modes. The results show that for the designed experiment, the root-mean-square error (RMSE) values of the proposed method are improved by 13.4%, 16.4%, and 13.1% compared to the traditional MHM method in RTD, RTK float, and RTK fixed solutions, respectively. In the field test, accuracy at the decimeter and centimeter levels can be improved by the proposed method in RTD and RTK solutions, respectively. It proves that the proposed method, considering the uncertainty, is robust, especially under complex observation conditions.