Galileo H-ARAIM: Update on Performance Characterization and Integrity Support Message

This paper provides an update on three essential aspects related to the future support of Galileo to Advanced Receiver Autonomous Integrity Monitoring (ARAIM) service: performance assessment, system reactivity against SIS faults and Integrity Support Message (ISM) message type definition. The first part of this paper gives a detailed measurement characterization of the Galileo performance parameters relevant for ARAIM users, with particular view on URA and Broadcast Group Delay (BGD) error overbound. This work is one of the important outcomes of the Integrity Failure Mode and Effect Analysis (IFMEA) that has been established for Galileo in the frame of the Galileo Open Service Safety of Life (GoSoL) work plan set up by the European Commission. The work presented in this paper has been conducted by ESA, EUSPA and EC together with industry partners. These results are an extension of the prior work presented on [1][2][3][4][5], considering an enlargement of the observation period for Galileo of approximately 1, 2, 3, 4 and 5 years respectively. The additional monitoring period has corroborated the good performance on the SoL relevant parameters and the fulfillment of the target Psat, Pconst and URA as per Galileo SARPs [6]. This work also focuses on the effective and rapid system reaction against one event that occurred in July 2024. The second part of this paper addresses the Galileo ISM that will be disseminated through the Galileo Signal-in-Space and that has been recently included in the latest version of the Galileo OS SIS-ICD [12]. This document describes the final design of the Galileo ISM message type to support H-ARAIM and along with the test ISM. Additionally, this work details how the E1B I/NAV message stream broadcast by Galileo satellites, at a rate of one I/NAV word (128 bits) per 30-seconds sub-frame, can also accommodate ISM from other constellations.