Countermeasures for GPS Signal Spoofing

Hengqing Wen, Peter Yih-Ru Huang, John Dyer, Andy Archinal and John Fagan

Abstract:	The strength of the GPS signal on the earth’s surface averages -160 dBw [5]. While many GPS receivers leave large space for signal dynamics, enough power space is left for the GPS signals to be overridden (spoofed). Spoofing is completely different from jamming. The objective of jamming is to simply interrupt the availability of the signal in space at the receiver. The effect is to cause the signal at the receiver to be corrupted so that no valid GPS signal can be decoded by the receiver. The goal of spoofing, on the other hand, is to provide the receiver with a misleading signal, fooling the receiver to use fake signals in space for positioning calculations. The receiver will produce a misleading position solution. While the GPS P-code is heavily encrypted and thus, is hard to spoof, the civilian GPS signal, the C/A code, is easy to spoof because the signal structure, the spread spectrum codes, and modulation methods are open to the public. The purpose of this paper is to analyze the vulnerability of the satellite signal and GPS system to spoof attacks, propose the anti-spoofing algorithms and illustrate the simulations of spoofing impact and anti-spoofing results. It is believed by the authors of this paper that GPS can be spoofed in theory and producing a spoofing satellite signal is possible. However, practical spoofing that provides misleading navigation results at the receiver is difficult to conduct due to the signal infrastructure, and by applying trivial anti-spoofing algorithms in GPS receivers, spoofing attack can be easily detected.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	1285 - 1290
Cite this article:	Wen, Hengqing, Huang, Peter Yih-Ru, Dyer, John, Archinal, Andy, Fagan, John, "Countermeasures for GPS Signal Spoofing," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 1285-1290.
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