Spoofing Suppression For GNSS Based On RAIM

The application of Global Navigation Satellite System(GNSS)is more and more widely in the civil and military fields.However,GNSS is vulnerable to all kinds of interferences so that the anti-interference problem becoming the focus in the world.Spoofing has become the one of the major threats to GNSS,whose signal format is just the same as the authentic signals and signal power is at the same level.If spoofing invade the tracking loop of the innocent receiver successfully,the spoofer would take control of the position solution of the receiver output by adjust carrier phase,code phase and Doppler frequency shift.In the condition of that,we proposed an antispoofing algorithm based on RAIM(Receiver Autonomous Integrity Monitoring),which can eliminate the influence of spoofing and ensure the validity of position solution.The main contributions and innovations of this thesis are the following:First,the thesis summarizes the main features which include generation of spoofing,way to invade innocent receiver and method to take control of the output of innocent’s position solution.After that,we introduced spoofing model under linear equation of pseudorange and array antenna when GNSS receiver.Then we introduced the traditional RAIM algorithm and analyzed feasibility of spoofing detection through RAIM.Second,in the case of traditional single antenna receiver,we extend the scale of RAIM detection without any change of the receiver’s structure.We improved extended RAIM algorithm and the proposed algorithm can detect and recognize spoofing effectively in the case of different quantity of spoofing signals.Third,in the case of multiple spoofer in space,we proposed an anti-spoofing algorithm joint with the feature of spread spectrum signal and RAIM algorithm,which does not need to know the array manifold in advance.The algorithm utilizes the RAIM’s advantage of real-time and fast computation to detect error,weights signals from different DOA(direction of arrival)to prevent spoofing from the receiver and ensures receiver’s position solution validly.The effectiveness of the proposed algorithm in this thesis are demonstrated via numerical results with high fidelity data and it does have some practical application value.