Elimination of amplify-and-forward relay spoofing signal for global positioning system receiver

Abstract

The Global Positioning System (GPS) provides positioning and timing information for various civil and military devices like the fifth generation (5G) smartphones, aviation systems, autonomous vehicles, drones, and other navigation systems. There have been multiple incident reports that a fake GPS spoofing signal interferes the received GPS signal with a fake pseudo-noise (PN) sequence code and guides a victim’s device to an undesired location. Several solutions have been available on the market against the GPS spoofing threat. The existing methods either need major modifications to current GPS devices, require specific hardware (i.e., high deployment costs), or are not resistant to sophisticated attackers. In this thesis, the GPS spoofing signal is generated by a simple amplify-and-forward (AF) relay near a victim device. The existing anti-spoofing solutions on the market are not effective against this type of an AF relay GPS spoofing signal. In this thesis, a simple method of how to estimate and eliminate the AF relay GPS spoofing signal from the received signal, and obtain an estimate of the true GPS signal. The key steps of the proposed method consist of simple six steps: (1) Take cyclic cross-correlation between the received signal and the available PN sequence used by the GPS; (2) Find the peak correlation position and peak value of the cyclic cross-correlation; (3) Estimate the fake AF relay GPS spoofing signal; (4) Eliminate the fake spoofing signal from the received signal; (5) Take cyclic cross-correlation with the same PN sequence; (6) Estimate the true time delays and the true position. An example is shown to demonstrate these steps and the effectiveness of the proposed method.