Assessment of Galileo E6B Data Demodulation Performance at High Latitudes: A Norwegian Vessel Case Study

The Galileo High Accuracy Service (HAS) is currently in its testing phase, in which actual corrections are transmitted along with standard dummy messages. The dissemination of Precise Point Positioning (PPP) corrections is performed using an innovative scheme based on a Reed–Solomon code, which allows the reconstruction of the original navigation message from a subset of received pages. This approach introduces robustness to the reception process and aims at reducing the Time-To-Retrieve Data (TTRD); that is, the time to retrieve the HAS message. This study investigated the HAS demodulation performance considering Galileo signals collected at high latitudes. In particular, a Galileo E6-capable receiver was mounted on a vessel sailing from Bergen to Kirkenes, Norway, and reaching up to 71 degrees North. The trajectory of the vessel was at the border of the Galileo HAS service area and high-latitudes impact reception conditions, potentially leading to poor satellite geometries. Three months of data from January to March 2021 were analyzed, considering several metrics including Bit Error Rate (BER), Page Error Rate (PER), and TTRD. The analysis shows that the Reed–Solomon scheme adopted for data dissemination is also effective at high-latitudes, with daily PER below one percent and mean TTRD in the order of eight seconds when three satellites are broadcasting valid HAS corrections. Lower values of the TTRD are achieved with an increased number of satellites. These values are significantly lower than the update rate of the corrections broadcast by the Galileo HAS.

Binary phase hopping based spreading code authentication technique

Civil receivers of Global Navigation Satellite System (GNSS) are vulnerable to spoofing and jamming attacks due to their signal structures. The Spreading Code Authentication (SCA) technique is one of the GNSS message encryption identity authentication techniques. Its robustness and complexity are in between Navigation Message Authentication (NMA) and Navigation Message Encryption (NME)/Spreading Code Encryption (SCE). A commonly used spreading code authentication technique inserts unpredictable chips into the public spreading code. This method changes the signal structure, degrades the correlation of the spreading code, and causes performance loss. This paper proposes a binary phase hopping based spreading code authentication technique, which can achieve identity authentication without changing the existing signal structure. Analysis shows that this method can reduce the performance loss of the original signal and has good compatibility with the existing receiver architecture.

Computational Load Analysis of a Galileo OSNMA-Ready Receiver for ARM-Based Embedded Platforms

Many GNSS applications have been experiencing some constantly growing needs in terms of security and reliability. To address some of them, both GPS and Galileo are proposing evolutions of their legacy civil signals, embedding features of authentication. This paper focuses on the Galileo Open Signal Navigation Message Authentication (OSNMA) and describes its implementation within a real-time software receiver for ARM-based embedded platforms. The innovative contributions of the paper include the software profiling analysis for the OSNMA add on, along with the comparison among performances obtained with different platforms. In addition, specific evaluations on the computational load of the whole receiver complete the analysis. The receiver used for the implementation belongs to the NGene receivers family—real-time fully-software GPS and Galileo receivers, tailored for different platforms and sharing the same core processing. In detail, the paper deals with the introduction of the OSNMA support inside the eNGene, the version of the receiver executable by ARM-based embedded platforms.