Performance Analysis of Spoofing Signal Ratio for Receiver-Spoofer

Global Navigation Satellite System (GNSS) is able to provide real-time, all-weather, continuous, global coverage of high precision positioning and timing services. However, since navigation signals are very weak and the interfaces of GNSS to users are open, GNSS is vulnerability to spoofing attacks. As a spoofing attack, receiver-spoofer can complete attacking without interrupting the tracking loops of a receiver, and it is difficult to be detected. In this paper, the signal model of the receiver-spoofer is built and the process of the receiver-spoofer taking over the Delay Locked Loop (DLL) of the target receiver is carefully studied. It is found that the key of the spoofing is the alignment of the spoofing and authentic signals. If the receiver-spoofer is not able to accurately estimate the position of the target receiver and makes the spoofing and authentic signals align in code phase, it should increase the power of spoofing signal for a possible successful spoofing. In the paper the following situations are analyzed. (1) the carrier phases of spoofing and authentic signals are aligned; (2) the carrier frequencies of spoofing and authentic signals are the same, but the carrier phases of them are different; (3) both the carrier phases and carrier frequencies of them are different. Under the three cases, the lower threshold of the SSR, which is the ratio of the amplitudes of the spoofing and authentic signals, will be changed due to the imprecise alignment of the code phases. The performance curves of the SSR on the three cases are obtained. The mathematical derivation of the lower bound of the SSR in the first case is given, and the numerical solutions for the other two cases are provided as well. Finally, in order to evaluate the analysis above, a serial of experiments are performed in a simulation environment. The simulation results verify the above analysis results.