# Computational Load Analysis of a Galileo OSNMA-Read Receiver for ARM-Based Embedded Platforms +
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1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M.) [PERSON]  
1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M.) [PERSON]  
1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M.) [PERSON]  
1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M.) [PERSON]  
1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M.) [PERSON]  
1 LINKS Foundation, 10138 Turin, Italy; [EMAIL_ADDRESS] (M.N. ); [EMAIL_ADDRESS] (B.M. ); [EMAIL_ADDRESS] (B.M. ); betric. As examples, both GPS and Galileo are proposing evolutions of their legacy signals, embedding features of authentication, intended as the ability of the system to guarantee the user that non-counterfeit navigation data from one of the constellation satellites is used [6]. In particular, GPS is disclosing the Chips-Message Robust Authentication (CHIMERA) solution, suitable for the GPS LIC signal [14]. On the other hand, in 2017 the Galileo program officially announced its intention to offer a free Open Signal Navigation Message Authentication (OSNMA) service [15], designed to be disseminated on the E1 Galileo band. According to [15], the OSNMA signal-in-space transmission is expected to begin in 2020. The new signal will be fully backward compatible: in fact, the performance for users who are not able or not interested in processing the authentication bits will not be affected. On the contrary, users who want to take advantage of the authentication service must update the current Galileo receivers to process the OSNMA bits and verify the authenticity of the transmitted source. Focusing on the OSNMA, this paper describes the implementation of the Galileo authentication scheme in a real-time software receiver for ARM-based embedded platforms, including the comparison among the performance of different platforms. This paper is an extension of the article titled \"Galileo OSNMA: an implementation for ARM-based embedded platforms,\" presented by the same authors at the 2020 International Conference on Localization and GNSS (ICL-GNSS) [16], thereby providing a wider analysis on the compared platforms, along with a dedicated study on the complete OSNMA-ready receiver. Both papers are based in turn on [17], which described the implementation of the software routines able to make a real-time GPS/Galileo software receiver ready for the reception and elaboration of the OSNMA service. In fact, although OSNMA-ready commercial receivers start appearing on the marketplace, e.g., [18], an independent fully-software OSNMA solution allows one to add new features and strategies, as every part of the algorithm can be easily accessed and modified, thereby speeding up the prototyping process. Furthermore, the results achieved with a research tool, such as the one proposed in this paper, provide useful guidelines that might be exploited also for the development of commercial receivers. The receiver used for the implementation in [17] belongs to the NGene receivers family [19], a set of software tools tailored for different platforms and sharing the same core processing. Such tools have been specifically developed for research purposes. While [17] focused on the version of NGene executable by standard PCs running a Linux operating system, both [16] and this paper deal with the introduction of the OSNMA scheme inside eNGene [20], the version of the receiver executable by ARM-based embedded platforms.