Introducing Countermeasure Approach against Delay Spoof Attack in GPS using Adaptive Filtering

The civilian GPS signals are unencrypted, predictable and low power ones. Therefore, they are vulnerable to destroyer interfaces such as spoofing. In this paper, in order to reduce spoofing effect and achieve time series without interface, an adaptive filter with finite impulse response based on Least Mean Square (LMS) algorithm has been used for the first time. Contrary to the previous methods, proposed approach needs no extra hardware and structural change in GPS receiver. Input signal of utilized adaptive filter is pseudo-range data in navigation section. The principle of using adaptive filter to eliminate interference is obtaining an estimate of interfering signal and subtracting that from the corrupted signal. Therefore, what remains at final output is the authentic signal. In this paper, root mean square (RMS) criteria is used to validate the proposed method. Simulation results show that the proposed approach can neutralize laboratory interface effects average up to 95 percent and measurement spoofing effect in average of 81 percent.