Integrity-Bounds Computation for SBAS Multi-Domain Users

Alejandro Rodriguez-Veiga, Leslie Montloin

Abstract: Satellite-Based Augmentation Systems (SBAS) provide Global Navigation Satellite Systems (GNSS) users over a given service area with satellite differential corrections and confidence bounds to meet the tight safety-of-life (SoL) requirements imposed by their target operations. Dual-Frequency Multi-Constellation (DFMC) SBAS systems for aviation and maritime users currently under development (such as EGNOS-V3 in Europe) are constrained to broadcast simplistic confidence bound models containing just a few quantized parameters per monitored satellite, so that all data can be fitted in the 250 bits-long SBAS message described in the EUROCAE, (2022) standard. To do so, the SBAS satellite range (orbit and clock) residual errors are overbounded by zeromean Gaussian distributions whose standard deviations have been inflated before-hand in order to ensure integrity for every user. This strategy is way overpessimistic and may penalize both availability and continuity performances for some users. With the arrival of new users demanding higher levels of availability and continuity, as well as new dissemination means with higher data rate capabilities (terrestrial and/or Signal-In-Space on new frequency bands), next generation SBAS systems can take advantage from the possibility to disseminate additional integrity information to come up with more performing overbounding strategies. Within this context, and following the work of previous publications, several alternatives aiming to enhance the SBAS performances for DFMC users are quantitatively assessed in this paper. With the aid of different numerical simulations, it has been demonstrated that a substantial reduction of the range integrity bound and vertical protection level for SBAS DFMC users could be achieved by increasing the size of integrity-related messages by 122 bits and deporting on the end users some stages of the integrity bound estimation process which are currently carried out at SBAS ground system level.
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: 1163 - 1181
Cite this article: Rodriguez-Veiga, Alejandro, Montloin, Leslie, "Integrity-Bounds Computation for SBAS Multi-Domain Users," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 1163-1181.
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