RAIM availability analysis: LEO-enhanced multi-frequency GPS/BDS/Galileo

GNSS is vital for safety-critical positioning but vulnerable to space-environment disruptions. LEO navigation signals enhance integrity and reliability. This study investigates LEO’s impact on Receiver Autonomous Integrity Monitoring availability for single/dual-frequency GPS, BDS, and Galileo. Using real GNSS data from 18 MGEX stations and simulated LEO data on 10 January 2022, we demonstrate that LEO integration improves availability under degraded GNSS. Horizontal/Vertical Protection Level decrease by 10–45 m and 17–85 m. Non-Precision Approach availability rises to 10%, with dual-frequency Galileo from 86.54% to 96.27%. Approach Procedure with Vertical Guidance-I availability rises to 21%, with single-frequency GPS from 5.49% to 27.4%.