A Framework for Analyzing Architectures that Support ARAIM

Advanced Receiver Autonomous Integrity Monitoring (ARAIM) has been studied in recent years as method of providing vertical guidance for aircraft [1]. The aircraft compares the various ranging measurements that it makes to different satellites to ensure that they are consistent with each other. However, for the aircraft to meet its integrity requirement, the satellites must perform within a certain set of expectations. While the satellite providers might be able to guarantee this performance, in order to meet aviation integrity requirements and to retain sovereign control, it is more likely that individual aviation authorities will independently perform monitoring of satellite performance. This paper examines important components for different architectural choice such as monitoring network size and density, the method for getting information to the aircraft including latency of information, the handling of consistent faults, and the methodology for demonstrating integrity. We examine two extreme architectures to better explore the trades between these and other important performance parameters. One architecture is based on Space Based Augmentation System (SBAS) assets and relies very heavily on ground monitoring. Another architecture minimizes the ground requirements and is more similar to today’s Receiver Autonomous Integrity Monitoring (RAIM). By examining these architectures, we will better understand the impact of possible choices and determine which are most important to lock down early and which can be left open to flexibility. Ultimately, this allows us to characterize other architectures that exist between the two extremes.