Robust mitigation of multipath and ionospheric delays in multi-GNSS real-time kinematic (RTK) receivers

In this paper, we develop a new scheme for RTK positioning using multi-constellation GNSS measurements in presence of multipath and ionospheric delays. The proposed procedure for multi-frequency ambiguity resolution is based on four steps: 1) at each epoch, a Gaussian sum particle filter is used to track the user position and the float ambiguity solution adaptively to the dynamic environment by minimizing the noise level and estimating the ionospheric errors ; 2) we utilize a new carrier phase multipath indicator to reject integers candidates that are affected by multipath errors, 3) we apply LAMBDA method to search the integer ambiguities; and finally 4) validate the fixed solution using a robust statistical test. Real-data test results show the effectiveness of the overall developed procedure for long-baseline RTK positioning.