Prediction of Doppler shift for securing GNSS

Abstract

GNSS (Global Navigation Satellite System) is functioned extensively around the whole world for many distinct purposes. At first it was infrastructure for the intention of military function. Nowadays, it also has been used for civilian operations. In recent days it has been developed to its most efficient states and still being acquired further towards speck precision. Accompanying all the improvements, various vulnerabilities have been introduced by researchers and misused by the attackers. Several techniques have been and still being accomplished to secure the GNSS. Previous research exhibit that GNSS-based receivers are still exposed to a very primarily simple, yet operative, attack; known as the replay attack. The replay attack is specifically detrimental since the invader could make the receiver measure an inconsistent position, without even disrupting the encryption or without applying any sophisticated technique. The Doppler shift prediction is a useful and effective way to predict the replay attack. For predicting the Doppler shift at first we have to determine the position of the available satellites. Then through Doppler Shift method we will measure the Doppler shift frequency. Subsequently, identify the attacking signal by comparing the calculated Doppler shift frequency with the original given frequency. The attacker will always try to replay the signal by using the equivalent original given frequency. So, if the Doppler shifted frequency is equivalent to the original received frequency then it will consider as the authentic signal. Otherwise it will be considered as the inconclusive decision and then other test will be initiated. In this study, after the implementation of Doppler shift method, we will predict whether the signal is authentic or not. In this study, we have considered that the satellite has been moving along the straight directional path and the receiver is static. Here, we have used open source data which are available for educational purposes.