An Optimized Navigation Method Integrating Fixed-Lag Smoothing and Integrity Monitoring for Shipborne GNSS Receivers in High-Latitude Challenging Environments

Arctic-specific limitations, including a limited number of visible satellites with unfavorable distribution, and the fact that during Arctic navigation, Global Navigation Satellite System (GNSS) signals suffer from significant multipath interference caused by sea ice, icebergs, ship superstructures, and low-elevation satellite signals reflected off the sea surface, have rendered conventional positioning solutions inadequate for maritime navigation safety requirements. To address these challenges, this paper implements a vector tracking loop (VTL) architecture incorporating forward–backward Kalman filtering to improve the estimation accuracy of carrier and code phase errors while proposing a scalar sequential integrity monitoring algorithm that enables identification and exclusion of faulty satellite signals to further enhance position estimation accuracy. The faulty satellite signals refer to satellite signals containing significant deviations that cannot be corrected by conventional models. The experiment uses a navigation scheme with commercial receivers as a reference. To verify the effectiveness of the proposed method at different latitudes, it was tested with real-world data from the Arctic; two sets of tests were conducted at latitudes between 70 and 80° and above 80°. The results show that the optimized navigation method improved positioning accuracy by 65.9% and 56.8% compared with existing methods in the two test groups, respectively, effectively enhancing positioning accuracy in the Arctic environment.