Adaptive Interference Suppression Techniques Based On Cyclostationarity In GPS

Global Positioning System (GPS) is the most typical satellite navigation system and has found wide applications in military and civilian fields. Since the satellite is far away from the earth, the power level of GPS signal arriving at the earth is so low that the GPS receiver is vulnerable to various kinds of intentional and unintentional interference and may lose lock to GPS signal. Hence it is necessary to incorporate interference suppression techniques in order to make sure the receiver can work well.Array antenna based adaptive interference suppression algorithms are studied in this thesis. Firstly, several existing algorithms which use adaptive conventional beamforming or blind beamforming methods are overviewed. Secondly, a novel adaptive anti-jamming algorithm is proposed, which combines subspace projection, cyclic adaptive beamforming (CAB) algorithm. In addition, the structure of cyclic conjugate correlation matrix (CCC matrix) is analyzed and Hankel approximation method (HAM) is introduced to process the CCC matrix estimated by finite snapshots. Simulation results show the proposed algorithm can effectively suppress the strong interference, extract the GPS signal and HAM can improve the performance of the proposed algorithm when SNR is relatively low. Finally, the space adaptive processing is extended to space-time adaptive processing by exploiting the cyclostationarity of GPS signal.