Localizing GNSS Spoofing Attacks Using Direct Position Determination

Global Navigation Satellite System (GNSS) receivers are vulnerable to all types of interferences due to the inherently low power of GNSS signals. Whereas GNSS jammers aim at denial-of-service attacks, GNSS spoofers bring even more risks, since they can fabricate a fake position and/or time without recognizing it. This paper presents a direct position determination method to improve the localization accuracy of GNSS spoofing attacks, which is called despreading direct position determination (DS-DPD). The localization algorithm utilizes a prior knowledge of the satellites' code sequences, which in turn provides significant gains in localization accuracy. Firstly, the received signal model is established, which takes the time delay, Doppler shift, direction-of-arrival (DOA), and modulation codes into account. Then, the maximum likelihood (ML) criterion is utilized to construct the objective function of DS-DPD. Finally, the location parameters of the spoofers can be obtained through a two-dimensional spectral search of the objective function. Numerical simulations verify the localization performance improvement of the proposed DS-DPD algorithm. Especially when the interference-to-noise ratio (INR) approaches -30dB, the localization accuracy could be improved by more than ten times due to its full utilization of the delay, Doppler shift, DOA, and code sequences information.