Advanced Receiver Autonomous Integrity Monitoring for Multi-Constellation GNSS and LEO-Augmented GNSS

Abstract

Global Navigation Satellite Systems (GNSS), including the U.S. Global Positioning System (GPS), the European Galileo, Russia's GLONASS, and China's BeiDou, have become essential for modern positioning, navigation, and timing (PNT) services, from driving directions to timing in telecommunications. In safety-critical areas such as aviation, it is not enough for these systems to be accurate, they must also be high integrity, the ability of the system to provide timely warnings when positioning errors exceed acceptable limits. Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is a key framework developed to meet these demanding integrity requirements by leveraging multi-constellation, dual-frequency GNSS signals alongside integrity support data. Central to ARAIM's ability to provide navigation guarantees are protection levels, i.e., high confidence bounds on the positioning error, including the horizontal protection level (HPL) and the vertical protection level (VPL).

This dissertation advances the state of ARAIM and complementary satellite navigation technologies through two main contributions. First, it introduces two new formulations of the HPL that reduce computational complexity by only requiring a single-step iterative solution, in contrast to the baseline HPL algorithm which sequentially solves for East and North bounds. One formulation offers a more compact expression, while the other provides a tighter bound. Additionally, a generalized chi-square horizontal reference boundary is derived by direct integration of a bivariate Gaussian distribution, serving as a theoretical reference for bounding horizontal positioning error (HPE). Through analytical examples and global availability simulations, these new bounds are shown to maintain equivalent or improved performance compared to the baseline, with strong improvement when the HPE characteristics vary across different fault hypotheses.

Second, this work investigates Xona Space Systems' Pulsar, a 258-satellite low Earth orbit (LEO) constellation, as a standalone high-integrity alternative to traditional GNSS. System-level assumptions and time-correlated measurement error models are developed and implemented to enable rigorous integrity analysis. Navigation accuracy, integrity, continuity and availability performance is evaluated using both snapshot and sequential ARAIM algorithms with dual-frequency code and carrier-phase measurements for an example application of aircraft navigation with vertical guidance down to 200 feet above the runway. This analysis highlights Pulsar's potential to complement or serve as a reliable backup to GNSS for integrity-critical applications across the continental United States.