GNSS Spoofing Detection and Mitigation Based on Maximum Likelihood Estimation

Abstract

Spoofing attacks are threatening the global navigation satellite system (GNSS). The maximum likelihood estimation (MLE)-based positioning technique is a direct positioning method originally developed for multipath rejection and weak signal processing. We find this method also has a potential ability for GNSS anti-spoofing since a spoofing attack that misleads the positioning and timing result will cause distortion to the MLE cost function. Based on the method, an estimation-cancellation approach is presented to detect spoofing attacks and recover the navigation solution. A statistic is derived for spoofing detection with the principle of the generalized likelihood ratio test (GLRT). Then, the MLE cost function is decomposed to further validate whether the navigation solution obtained by MLE-based positioning is formed by consistent signals. Both formulae and simulations are provided to evaluate the anti-spoofing performance. Experiments with recordings in real GNSS spoofing scenarios are also performed to validate the practicability of the approach. Results show that the method works even when the code phase differences between the spoofing and authentic signals are much less than one code chip, which can improve the availability of GNSS service greatly under spoofing attacks.

Performance Analysis of Direct GPS Spoofing Detection Method with AHRS/Accelerometer

“…, where z 1n ∼ N f s,n , σ 2 n and z 1e ∼ N f s,e , σ 2 e with σ 2 n and σ 2 e being defined in (10) and (11).…”

“…Some experiments tried to implement the spoofer itself [5][6][7]. A variety of approaches have been studied about spoofing detection of the GNSS [7][8][9][10][11][12][13][14][15][16][17][18] such as using received signal strength [9], signal quality monitoring at code and carrier levels [7], phase-only analysis of variance (PANOVA) method with generalized likelihood ratio test (GLRT) by employing dual antenna system [10], and using maximum likelihood estimator…”

“…The performance of the two decision variables is compared by calculating the probability of spoofing detection and the detectable minimum spoofing acceleration (DMSA), given a pre-defined false alarm probability and a pre-defined detection probability. It turns out that both decision variables need to be used together to obtain the best spoofing detection performance.Sensors 2020, 20, 954 2 of 22 (MLE) [11]. Prior studies [7,12] summarize various spoofing detection techniques, among which low complexity spoofing detection techniques include C/N 0 monitoring, absolute power monitoring, power variation versus receiver movement, code and phase rate consistency check, and GPS clock consistency check, while high complexity spoofing detection techniques include Direction Of Arrival (DOA) comparison [14] and consistency check with other solutions [15][16][17][18].Among the effective high complexity spoofing detection techniques mentioned in the prior study [12], the DOA comparison approach uses the DOA measurements to assess the direction of the spoofing source and mitigates the interference by placing the spatial null in the antenna reception pattern [14].…”

“…Sensors 2020, 20, 954 2 of 22 (MLE) [11]. Prior studies [7,12] summarize various spoofing detection techniques, among which low complexity spoofing detection techniques include C/N 0 monitoring, absolute power monitoring, power variation versus receiver movement, code and phase rate consistency check, and GPS clock consistency check, while high complexity spoofing detection techniques include Direction Of Arrival (DOA) comparison [14] and consistency check with other solutions [15][16][17][18].…”

Spoofing Detection Algorithm Based on Pseudorange Differences

“…Current research focuses on using the antenna array method [ 10 ], the receiver pseudorange or carrier phase difference [ 11 , 12 ], the correlation method [ 13 , 14 ], the inertial aided method [ 15 , 16 ] or the hypothesis testing method [ 17 , 18 ]. The antenna array method needs more than one antenna.…”