Nowadays, Global Navigation Satellite Systems (GNSS) are essential in our daily lives. These systems are used in many different sectors, including critical missions, such as transportation, telecommunications, and finances — not just for positioning ourselves or navigating in an unknown town.
Due to its gain in popularity, GNSS have become the objective of many attacks of diverse nature. For example, according to the Finnish Transport and Communications Agency Traficom, several GNSS signal interference observed by aircrafts have been reported in the eastern border of Finland.
Another example can be found in Ukraine, most likely due to the current situation in the area. The European Union Aviation Safety Agency (EASA) issued a safety information bulletin warning of a GNSS outage leading to navigation degradation in the area.
Typically, deliberated attacks against GNSS come from two ends: full denial of the GNSS service, which is easier to perform, and/or impersonating GNSS real satellites transmissions and forging signals, which is more advance as the signal should mimic the real satellite movement. Attacks against GNSS service could end up in disastrous consequences, such as an economical loss or even putting lives at risk, since many critical services rely on GNSS for their correct functioning.
“In my thesis, I have investigated and proposed new procedures for detecting, localizing, mitigating, and classifying the interferences affecting GNSS transmissions. The proposed methods try to quickly detect interferences, in order to provide a prompt countermeasure,” Rubén Morales Ferré explains.
“Besides the interference management procedures, I have also proposed an alternative system based on satellites placed in lower orbits compared to the current GNSS. This alternative/complementary system is thought as a backup in a case that, for example, the current GNSS is not available due to interferences. By diversifying the satellite-based positioning service makes it less prone to global failure and blockage. In addition, putting in orbit satellites closer to the Earth, provides additional benefits such as they can be smaller, less costly to build and put in orbit, and more power efficient,” he continues.
The solutions provided in this work have shown accuracies of more than 90% in terms of correct detection and interference signal classification even at low interference powers. In addition, the proposed alternative system will enhance the positioning accuracy, as the additional satellites will increase the geometrical distribution in the sky, critical for increasing the positioning precision of the provided solution.
The doctoral dissertation of MSc. Ruben Morales Ferré in the field of Wireless Positioning entitled Interference Management and System Optimization with GNSS and non-GNSS Signals for Enhanced Navigation will be publicly examined in the Faculty of Information Technology and Communication Sciences of Tampere University at Hervanta Campus, in the auditorium TB109 of Tietotalo building (Korkeakoulunkatu 3, Tampere) on Tuesday 15th of November 2022 at 09:00. The opponents will be Professor Christophe Macabiau, Doctor Beatrice Motella, and Professor Paul Groves, from Ecole Nationale de l’Aviation Civile (France), LINKS Foundation (Italy), and University College London (UK), respectively. The Custos will be Professor Elena Simona Lohan from Tampere University, Finland. The work has been done under a double doctoral degree agreement between Tampere University and Universitat Autonòma de Barcelona. It has been supervised by Professor Elena Simona Lohan and Professor Gonzalo Seco Granados, from Tampere University and Universitat Autonòma de Barcelona, respectively.