Fast Multiple Fault Detection and Exclusion (FM-FDE) Algorithm for Standalone GNSS Receivers

Abstract

Numerous applications and devices use Global Navigation Satellite System (GNSS)-provided position, velocity and time (PVT) information. However, unintentional interference and malicious attacks render GNSS-provided information unreliable. Receiver Autonomous Integrity Monitoring (RAIM) is considered an effective and lightweight protection method when a subset of the available satellite measurements is affected. However, conventional RAIM Fault Detection and Exclusion (FDE) can be computationally expensive, due to iterative search to exclude faulty signals, in case of many faults and more so for multi-constellation GNSS receivers. Therefore, we propose a fast multiple fault detection and exclusion (FM-FDE) algorithm, to detect and exclude multiple faults for both single and multi-constellation receivers. The novelty is that FM-FDE can effectively exclude faults without an iterative search for faulty signals. FM-FDE calculates position distances of any subset pairs with max{3 + P, 2P} measurements, where P is the number of constellations. Then, the algorithm utilizes statistical testing to examine the distances and identify faulty measurements to exclude from the computation of the resultant PVT solution. We evaluate FM-FDE with synthesized faulty measurements in a collected data set; it shows that FM-FDE is practically equally effective as the conventional Solution Separation (SS) FDE in a single constellation receiver. The computational advantage of FM-FDE is more pronounced in a multi-constellation setting, e.g., being more efficient for GPS-Galileo receivers facing more than 2 faults across both constellations. The trade-off is that FM-FDE slightly degrades performance in terms of detection and false alarm probabilities with small errors, compared to the conventional SS FDE.

Keywords

• Hypothesis testing
• chi-square test
• solution separation
• FDE
• multi-constellation