Validation of GNSS ARAIM Algorithm Using Real Data

Abstract

This paper presents the research results on validation of the GNSS ARAIM (Advanced RAIM) algorithm, which is required in extending GNSS applications to areas demanding high integrity and safety, such as precision approach of LPV-200 phase before landing. In the ARAIM algorithm, the integrity risk of the GNSS systems is quantified by applying theory of multiple-hypothesis (MH). The multiple hypotheses are tested individually by using the method of solution separation (SS). Depending on different scenarios of the potential risks in the GNSS system, the given total tolerated integrity risk is allocated among the satellite-failure cases. For each case, the user’s XPL (including HPL, and VPL which is more concerned in this paper), accuracy and EMT, are predicted. In this paper, the ARAIM algorithm is studied using real GNSS observation data from a number of IGS stations at different locations, and then the availability levels of the GPS and GPS/GLONASS systems are evaluated based on the navigation performance requirements of LPV-200. Results show that: (1) VPE calculated using GNSS observation data are consistent with the results of the predicted VPL, accuracy and EMT, which validates the ARAIM algorithm. (2) Under the ARAIM, the highest availability achieved in the GPS system is only 63.04 %, while availability in the GPS/GLONASS system achieves more than 99.0 %, which fully meets the navigation performance requirements of LPV-200.