BDS receiver autonomous integrity monitoring algorithm assisted by baseband domain parameters

Abstract The vulnerability of the BeiDou satellite navigation signal and the complexity of its transmission environment lead to abnormal events when it reaches the baseband domain, such as ‘evil waveform (EWF)’ and multipath (MP) effects caused by diffuse reflections. These abnormal events lead to code phase errors in the receiver tracking loop, which ultimately result in tiny pseudo-range biases. The traditional receiver autonomous integrity monitoring (RAIM) algorithm detects faults in receiver terminals (measurement domain), but it is difficult to detect tiny pseudo-range biases caused by distorted signals in the baseband domain. This study proposed a baseband domain parameter assisted RAIM algorithm to solve the limitations of traditional RAIM. Firstly, a baseband domain faults detection and exclusion (BDDE) method is constructed, which integrates baseband domain monitoring parameters such as the squared distance of the sample set vectors, carrier-to-noise ratio, and position-velocity-time solution time for detecting the two types of distorted signals, MP and EWF. Secondly, the fault exclusion weights of the measurement domain and baseband domain modules are reasonably assigned by designing the weight factors of the fusion of BDDE and RAIM. The simulation and real experiment results show that the BDDE method is able to detect the occurrence time and duration of BeiDou B1I distorted signals in the baseband domain. Compared with the RAIM and the extended Kalman filter based RAIM algorithm, simulation experiments show that the position accuracy of BDDE assisted RAIM algorithm can be improved by 16.33% and 8.48%, respectively, and real experimental results in a MP environment show that the position accuracy of BDDE assisted RAIM algorithm is improved by 36.48% and 20.35%, respectively.