By Rigas Themistoklis Ioannides, Thomas Pany, and Glen Gibbons
Global navigation satellite systems (GNSS) provide position and timing for numerous applications, but GNSS vulnerabilities can have technical, political, and socioeconomic consequences. Jamming, interference, and spoofing are among the main threats that the GNSS community is currently seeking to resolve by providing countermeasures at the user and GNSS signal/system levels.
Global navigation satellite systems (GNSS) like global positioning systems (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. Different types of interference attacks result in different effects at the target receiver. Disruption of the GNSS service can have a large, negative impact on critical infrastructure.
“Known Vulnerabilities of Global Navigation Satellite Systems, Status, and Potential Mitigation Techniques” – published in the Proceeding of the IEEE special issue on “Vulnerabilities, Threats, and Authentication in Satellite-Based Navigation Systems” – discusses GNSS vulnerabilities and their potential impact, as well as categories of attacks and state-of-the-art countermeasures. (Read the full paper, published in the Proceedings of the IEEE | Vol. 104, No. 6, June 2016, online at http://ieeexplore.ieee.org/document/7442783/.)
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 a 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. With GNSS entering more in the core of many other systems and user applications (as shown in Fig. 1) the disruption of GNSS services can have a high economic impact. .
GPS technology will create $122.4 billion benefits per year and will directly affect more than 5.8 million jobs in the downstream commercial GPS-intensive industries when penetration of GPS technology reaches 100 percent. Based on a survey from the European Commission (EC), it is reported that the estimated assets depending on GNSS are at the 800 billion Euros level. As such governmental organizations and the whole GNSS community is investing in the infrastructure, awareness, and research to provide the appropriate countermeasures against interference threats at system and user level.
About the authors
R. T. Ioannides is with ESA-ESTEC, TEC-ETN/RF Payload Systems Division, Noordwijk, The Netherlands.
T. Pany is with IFEN GmbH, Receiver Technology, Poing 85586, Germany.
G. Gibbons is with Gibbons Media & Research LLC, Inside GNSS, Eugene, OR 97401 USA.
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