ARAIM protection level calculation method for BeiDou decimeter level single epoch point positioning

Precision positioning quality control and integrity assessment is an integral part of real-time Global Navigation Satellite System (GNSS) navigation applications, especially in GNSS vulnerable urban canyon scenarios. Wide-area precise point positioning (PPP) instantaneous decimeter level positioning can be realized by using the observation values of two wide lanes formed by GNSS three-frequency signal. However, in the complex urban environment, the impact of reflected signals, serious multipath and other signal interference on positioning cannot be accurately evaluated and identified, which limits the application of PPP instantaneous decimeter-level point positioning. advanced receiver autonomous integrity monitoring (ARAIM) in the concept of integrity can calculate the upper limit protection level (PL) of the minimum confidence interval of user positioning error to evaluate the positioning effectiveness, which can be used for quality control of PPP instantaneous positioning after some improvement. Aiming at the problem that the error model used to calculate the PL in ARAIM is difficult to meet the requirements of high-precision positioning, an improved ARAIM PL algorithm which is called B-ARAIM is proposed in this paper. The residual of PPP three-frequency combination observation value is used to modify the ARAIM weight and error model to calculate the PL. This paper verifies the algorithm based on on-board data collected in environments with different complexity levels, and evaluates the improvement of PL and the improvement of navigation availability. The results show that the PL obtained by the improved B-ARAIM algorithm is more in line with the needs of city positioning than that obtained by the traditional method, and the PL is reduced by 30% to 70% in different environments. This method is helpful to the application of ARAIM algorithm in GNSS positioning.