SBAS authentication proposals and performance assessment

Satellite Based Augmentation Systems enhance GNSS by increasing accuracy and providing integrity [1]. In the next future, SBAS will evolve to accommodate the new dual frequency multi constellation (DFMC) standard providing messages in two frequencies L1 and L5 [2]. The falsification of the SBAS information can be a concern for many users [3]: SBAS outages can degrade service continuity and in general, SBAS spoofing can lead the receiver to compute a coherently false position and time solution. This can create a risk for many SBAS users, including civil aviation and other safety critical applications. In spite of the amount of references already available concerning GNSS authentication (e.g.: [4], [5], [6], [7], [8] [9]), SBAS authentication is a subject not yet widely analyzed in the literature ([3], [10], [11], [12], [13], [14]). In 2015, the European Commission launched the EAST project (EGNOS Authentication System Test-bed), recently concluded, in order to study if and how authentication services can be added to EGNOS [3]. Specifically, the focus of the project is on the DFMC standard, to be implemented in EGNOS V3 to augment both GPS and Galileo. The project participants include Qascom as prime contractor, GMV and University of Padova, with the advice and support of KU Leuven. This paper summarizes the results obtained during more than one year of design, development and laboratory testing activities of SBAS authentication solutions. The paper is divided in three main sections: first, the authentication protocols are proposed and compared. Then, the SBAS authentication Test Bed used for the experimentation is presented. Finally, the paper shows the results of the experimentation conducted over the selected protocols, and the conclusions derived from the results.