Research On Target Detection And Interference Suppression Algorithm Of MIMO Radar

Multiple-input multiple-output(MIMO)radar has waveform diversity gain and higher degree of freedom in signal processing,so this radar has advantages in target detection,interference suppression and other aspects.MIMO radar is one of the research hotspots in the current radar field.In the process of target detection,clutter,multipath interference will reduce the detection performance.Therefore,this thesis studies target detection and interference suppression algorithm in MIMO radar.The main research contents are as follows:1.A large number of classic papers in the development of MIMO radar were investigated in the early stage,and the main problems of the current MIMO radar were learned.Based on some current research hotspots in radar field,such as clutter suppression,target detection,target parameter estimation and so on,the research direction of clutter suppression and target detection is clarified.Then,the common interference suppression and target detection methods are studied further for the subsequent improvement.2.Aiming at the problem that clutter would affect the target detection performance,this thesis studied the Sparse Recovery Space-time Adaptive processing(SR-STAP)method for non-homogeneous clutter suppression at the receiving.Orthogonal Matching Pursuit(OMP)algorithm is a typical SR-STAP method,its performance degrades when there are strongly correlated atoms in the sparse dictionary.To solve this problem,an OMP algorithm based on reduced-dimension dictionary is proposed.This method divides the dictionary along the clutter ridge and its vertical direction,and the highly correlated atoms are removed with prior knowledge.Experimental results show that the proposed method can completely cover the clutter ridge and accurately recover the clutter spectrum,thus improving the clutter rejection performance of STAP filter.3.In addition to clutter,the multipath channel interference through the transmitting radar detection waveform will also affect the performance of MIMO radar target detection.In order to solve this problem,this thesis puts forward the optimization of emission frequency waveform of space-time coding method,this scheme is also called STFC.Orthogonal frequency waveforms are used as transmitting waveforms,and the baseband signals of each waveform in orthogonal frequency waveforms are modulated to make the detection signal contain more information of the target in space-time domain,or in frequency domain,or in code domain.At the same time,it also has good range Doppler resolution,which can get more effective energy aggregation,thus reducing the influence of multipath effect on the target.Then,the detection probability of space-time-frequency coded MIMO radar echo signal under Generalized Likelihood Ratio test(GLRT)detector is derived.Using the GLRT detector at the receiving can adjust the pulse duration to obtain higher gain and reduce the impact of multipath interference on target detection.Finally,the simulation results show that the proposed method can effectively suppress multipath interference and improve target detection.