Known Vulnerabilities of Global Navigation Satellite Systems, Status, and Potential Mitigation Techniques

Global navigation satellite systems (GNSS) like GPS but also Galileo, GLONASS, and Beidou represent an important infrastructure to our society. They provide position and timing for numerous applications. A GNSS is a rather complex system consisting of around 30 satellites, a number of monitor stations, plus a control center. Billions of GNSS receivers represent the user segment. The receivers and the monitor stations receive a weak satellite radio signal and thus are susceptible to interference like jamming or spoofing. This paper outlines the core operation principles of satellite navigation to describe those kind of interference and to analyze the impacts. Different types of interference attacks result in different effects at the target receiver. The attack schemes are categorized within this paper. Reported incidents are summarized as well as the potential impact of GNSS vulnerability on critical infrastructure. Well known countermeasures at user receiver level or at system level are outlined and discussed for their suitability. The political and socioeconomic context of GNSS vulnerability is described emphasizing the large impact of a potential disruption of the GNSS service.

I. INTRODUCTION

Global navigation satellite systems (GNSS) utilize the time difference of arrival (TDOA) principle to provide position and time information to a multitude of users. The satellites are equipped with synchronized atomic clocks and broadcast a signal containing the satellite clock reading plus information of the satellite location. The user receives these signals. After decoding, the receiver is able to compare the broadcast satellite clock reading with its own clock. If signals from four or more satellites are received, the receiver is able to solve for its 3-dimensional (3-D) position plus the user clock offset compared to the satellite's time scale. Satellite navigation is an one-way ranging system, serving many users in different applications. Due to the large distances between monitor stations, satellites and users, the system may be compromised if suitable signals are broadcast on the same frequencies as used by the GNSS.