Resilient Ambiguity Resolution Strategy in GNSS Real-Time Kinematic Positioning for Urban Environments

Global navigation satellite system (GNSS) real-time kinematic (RTK) positioning is highly appreciated for realizing high-accuracy navigation and positioning in many fields. Noteworthily, correct and reliable ambiguity resolution is a prerequisite of high-accuracy RTK positioning. However, refining the delicate handling of ambiguity resolution estimator and resolution form is still a tough issue, especially in urban environments. We proposed a new resilient ambiguity resolution strategy driven by batch best integer equivariant (BIE) estimator. The proposed strategy can resiliently adopt the integer rounding, bootstrapping, integer least squares (ILS), and BIE, which are paired with full ambiguity resolution (FAR) or partial ambiguity resolution. To validate the effectiveness of the proposed strategy, deformation monitoring and vehicle-borne experiments are carried out, including in typical urban scenarios. The results show that, in the monitoring experiment, the 3-D positioning accuracy of the proposed strategy is improved by 84.9% compared to the commonly used ILS of FAR. For the vehicle-borne experiment in urban environments, the positioning solutions of the proposed strategy perform the best with a decimeter-level positioning accuracy, which coincide well with the reference trajectory. The proposed strategy has the highest positioning availability with 83.3% and 91.9% epochs of positioning errors smaller than 0.2 and 0.5 m in horizontal direction, respectively, which is promising for autonomous driving at Level 3 and high-accuracy lane-level navigation applications in urban environments. In conclusion, our proposed strategy exhibits the best positioning accuracy and availability, which is especially suitable for urban environments.