Time-Differenced Carrier Phase Based Integrity Monitoring for Urban Air Mobility Using 3D City Model

Hojoon Jeong, Changdon Kee, Junesol Song

Abstract:	In this study, we propose an integrity monitoring method for Urban Air Mobility operations in urban areas using TDCP (TimeDifferenced Carrier Phase) measurements. Carrier-based measurements possess the advantage of being robust against multipath error in urban environments. Additionally, since TDCP utilizes a time differencing technique, there is no need to resolve the carrier’s integer ambiguities. There is an existing technique called RRAIM that uses carrier phase differencing as a conventional method. TDCP maintains a fixed time differencing period of 1 second, increasing it potential usability compared to conventional method RRAIM. To practically leverage carrier-based measurements, addressing cycle slip issues with in the carrier phase measurement is crucial. Previous research has shown that cycle slip can be detected using short-term differenced carrier signals. To evaluate the proposed TDCP/RAIM method and compare it with the existing RRAIM method, we conducted simulations of UAM landing operations in an urban environment. To create a more realistic urban environment model, we utilized a 3D city model, incorporating building data from Gangnam area in Seoul. We employed ray tracing techniques to simulate signal blockage caused by buildings. Based on the simulation results, it has been confirmed that TDCP/RAIM can maintain integrity monitoring performance even in urban scenarios where the visibility of satellites changes rapidly. This is achieved without the need for external correction information like SBAS, relying solely on the initially received correction data.
Published in:	Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) September 11 - 15, 2023 Hyatt Regency Denver Denver, Colorado
Pages:	2977 - 2989
Cite this article:	Jeong, Hojoon, Kee, Changdon, Song, Junesol, "Time-Differenced Carrier Phase Based Integrity Monitoring for Urban Air Mobility Using 3D City Model," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 2977-2989. https://doi.org/10.33012/2023.19357
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