Performance study of a new crosslink-aided User Range Accuracy (URA) integrity monitor algorithm for LPV-200

A new algorithm for the GPS satellite User Range Accuracy (URA) integrity monitor that incorporates the satellite ranging measurements taken at ground monitor stations, aided by the crosslink ranging measurements taken between the GPS satellites, is presented. The new algorithm provides improved performance and eliminates the need for a key assumption of a previous algorithm that used ground and crosslink measurements. The performance of the new algorithm is analyzed and measured by the values of the minimum monitorable URA (MMU) for the satellites in the constellation. The availability of LPV-200 operations for an aviation GPS receiver that uses the MMU values as URAs to derive its integrity assured navigation position solution is also analyzed. The LPV- 200 availabilities at representative US and worldwide airport locations are presented. Improved performance of the new algorithm is shown as a reduction of the MMU value and an increase of the LPV-200 availability.