Kalman filter-based RAIM for GNSS receivers

A receiver autonomous integrity monitoring (RAIM) algorithm is presented for extended Kalman filter (EKF)-based global navigation satellite system receivers. To this end, a novel method to bound the EKF mean position error is developed under the assumption of step and ascending ramp fault profiles. The calculated mean position error bound is subsequently used to determine EKF protection levels. Simulation results show that the EKF RAIM algorithm offers performance comparable to that of the traditional weighted least squares RAIM. Although performance gains may not be achieved, the proposed approach lays the foundation for efficient, real-time computation of protection levels for range residual-based RAIM with EKF. Thus, it has important extensions to advanced EKF-based navigation algorithms, such as vector tracking receivers.