Implementation of the Reference Advanced RAIM User Algorithm

Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is a proposed evolution of Receiver Autonomous Integrity Monitoring (RAIM) to multi-constellation and dual frequency implementations. Six different groups have coded the ARAIM Algorithm Description Document (ADD)’s reference receiver algorithm in their GNSS availability simulation tools, including ARTEX by the Joint Research Centre (JRC) of the European Commission, Global Navigation Satellite System (GNSS) Performance Analysis Tool (GPAT) by MITRE, MATLAB Algorithm Availability Simulation Tool (MAAST) by Stanford University, PEGASUS by EUROCONTROL, Service Volume Simulator (SVS) by GMV, and AVA (Assured Vehicle Autonomy laboratory) Tool for ARAIM Analysis (ATAA) by Virginia Tech. This paper describes their implementations of the baseline ARAIM user algorithm. First, the paper provides flowcharts of the ARAIM algorithm: it explains the ARAIM algorithm’s input, processes, and output with practical considerations relevant to different algorithm implementations. Next, the paper describes the lessons learned from cross-checking the tools among the six groups. Finally, a worldwide ARAIM evaluation with complete numerical value description is given to illustrate the implementation of the ARAIM algorithm, which can serve as a practical verification methodology for other ARAIM algorithm implementations. With the flowcharts, practical observations and findings from collaborative groups that have been working together for years, and an illustrative ARAIM numerical example, this paper can be seen as a companion to the ARAIM ADD.