Spoofing Mitigation of GPS Receiver using Least Mean Squares-Based Adaptive Filter

The Global Positioning System (GPS) signals are very weak signal over wireless channels, so they are vulnerable to in-band interferences. Therefore, even a low-power interference can easily spoof GPS receivers. Among the variety of GPS signal interference, spoofing is considered as the most dangerous intentional interference. The spoofing effects can mitigate with an appropriate strategy in the receiver. In this paper, we use methods of adaptive filter based on Least Mean Squares (LMS) and Normalized Least Mean Squares (NLMS) algorithms in order to defense against spoofing. The new approaches based on LMS and NLMS are applied in the acquisition stage of the receiver. The new approaches are operated to mitigate effect of spoofing from the received signal in GPS valid receiver. LMS-based algorithm is a class of adaptive filter that modify the filter coefficients to minimize the error signal. NLMS algorithm is a modified form of the normal LMS algorithm that solves the LMS problem by normalizing with the power of the input signal. The proposed methods have been implemented on real dataset. The results explain that the suggested algorithms significantly decrease spoofing. Also, they improve Position Dilution of Precision (PDOP) parameter. Based on the results, NLMS algorithm has better performance than LMS algorithm.