Analysis of HAS Performance in Pedestrian Navigation with Different Grade Devices

With the growing complexity and population density of urban areas, efficient and safe navigation is increasingly vital for people's everyday lives. Precise navigation enables pedestrians to steer clear of dangerous spots, like busy streets, construction areas, or neighborhoods with safety concerns. In such contexts, the enhancement of global navigation satellite system (GNSS)-based navigation through corrections is essential. One such service that provides corrections at no cost is the Galileo High Accuracy Service (HAS). HAS aims to offer real-time precise point positioning (PPP) corrections to achieve a horizontal positioning error of fewer than 20 centimeters under standard conditions. The signal processing and positioning accuracy of HAS have piqued the interest of both researchers and industry professionals. However, the literature falls short when it comes to the use of HAS by pedestrians, especially when they are on the move and using affordable devices. To bridge this research gap, evaluations were conducted using receivers of different grades in different scenarios, comparing the performance of data corrected by HAS against solutions that rely solely on broadcast parameters and against final SP3 products. Several tests have been carried out including static and kinematic conditions, tests aimed to assess solution availability and position accuracy. The challenging scenarios and the target accuracy required a very accurate and stable reference trajectory. For the study, a topographical approach using a total station was used, with this approach the reference solution has cm level accuracy. Results indicate that the HAS-refined broadcast ephemeris improves positioning accuracy and enables the obtaining of more reliable solutions, particularly when employing the dual-constellation Galileo/GPS modality. In obstructed environments, both static and kinematic tests faced greater challenges due to outliers and difficult PPP conditions, resulting in larger errors.