Progress on Working Group-C Activities on Advanced RAIM

Abstract : Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is a concept that extends RAIM to other constellations beyond GPS. ARAIM will enable theintegration in the position solution of the newer GNSS core constellations that may have different properties (in particular with higher failure rates than GPS). This inclusionwill provide better levels of performance of horizontal guidance than RAIM with GPS alone. In addition, when sufficient satellites have dual frequency (L1-L5) signals,ARAIM could enable aviation safety of life operations, including approaches with vertical guidance.The European Union (EU) and the United States (US) have an agreement establishing cooperation between GPS and Europe's Galileo system. As part of this cooperativeagreement a technical subgroup was formed to investigate the benefits of Advanced Receiver Autonomous Integrity Monitoring (ARAIM) [1]. This EU-US ARAIMsubgroup has developed a reference airborne algorithm [2] and two potential ARAIM architectures [3, 4, 5]:Offline ARAIM to support horizontal and vertical navigation based on a low latency (days to months) ISM.Online ARAIM to support horizontal and vertical navigation based on an hourly ISM from the ground, which would include clock and ephemeris corrections.We will describe the current status of ARAIM as a concept. We will start by discussing the relationships between SBAS and ARAIM, and among the different architectures.This is important, as ARAIM aims to provide globally the services that SBAS already provides regionally. Then, we will present preliminary Integrity Support Messageformats adapted for a GNSS broadcast, both for the offline architecture (which are the same for horizontal and vertical), and the online architecture (which include clock andephemeris corrections). Finally, we will describe a notional ARAIM roadmap for the deployment of a global ARAIM service.