Ground Subsystem Error Contribution of a Multi-Constellation GBAS Based on a CORS Network in the Vicinity of Airport Areas

The use of multi-constellations in the Ground Based Augmentation Systems (GBAS) brings new scenarios to the modeling and certification path in comparison to a single constellation configuration. Previous studies have employed Continuously Operating Reference Stations (CORS) to achieve the Ionospheric modeling for GBAS, meanwhile, local conditions such as terrain-induced errors, multipath, receiver correlation characteristics, antenna-induced errors, radio frequency interference and other noise, are also critical for GBAS, therefore it is important to assess the modeling of the ground subsystem error contribution that accounts for all of them. In recent years, as satellite constellations grew, also the ground stations and CORS Networks increased in capacity and number, representing an opportunity for GBAS, however, multi-constellation signals with different coding schemes, receivers with their own correlator spacing specifications and different antennas may influence the performance of the overall system. This study investigates the ground subsystem error contribution of a multi-constellation GBAS based on selected receivers from the National CORS Data Center (NCDC) of Thailand, located in the vicinity of Suvarnabhumi International Airport. The NCDC is a growing GNSS Network with capacity to process multi-constellation and multi-frequency signals. By the use of GPS L1 C/A and BDS B1I, this study employs the novel two-dimensional modeling technique to analyze the ground subsystem error contribution of a GBAS implementation. The experimental results demonstrate that both signals satisfy the Ground Accuracy Designator (GAD) requirements for CAT-I precision approach, in the case of GPS L1 C/A the results show similarity with the standard deviation of the multipath, noise and antenna-induced error of the Dual Frequency Multipath Models for Aviation (DUFMAN) project, while highlighting the potential of employing CORS Networks in the implementation of main or backup GBAS, emphasizing the need for further research to optimize the system performance by managing the ground subsystem error contribution in critical zones.