Research On Parameters Estimation And Interference Suppressing For MIMO Radar

In recent years,multiple-input multiple-output(MIMO)radar has been a focus in the field of new radar system.By the most general definition,the existing phased array antenna radar,netted radar,synthetic aperture radar(SAR)can be incorporated into the framework of MIMO radar system.By exploiting the advantages of the diversity system and abundant signal processing algorithms,MIMO radar has great potential in enhancing the target detection resolution and interference Suppressing.The dissertation studies parameter estimation algorithms for MIMO radar,the application in anti-multipath effect and interference suppressing.The main contributions for the dissertation can be summarized as follows:1.For the contradiction between the estimated accuracy and the computational complexity in the joint direction of departure(DOD)and direction of arrival(DOA)measurement for the bistatic MIMO radar,as well as the automatic pairing problem between DOD and DOA,a processing method of multiple signal classification(MUSIC)in semireal-valued domain is proposed.The real-valued domain processing can reduce the computational complexity of angle estimation for MIMO radar with high degree of freedom.The dissertation extends the real-valued processing MUSIC super-resolution algorithm for conventional array to the bistatic MIMO radar with arbitrary array structure.According to the equivalent characteristic between conjugation and image of the steering vector of MIMO radar,the real part of the received signal covariance matrix is first extracted,and an eigendecomposition is performed to obtain the signal subspace with “double targets” and its corresponding noise subspace.Then the characteristic of Kronecker product is employed to achieve one dimensional search MUSIC spectrum in the semi-real-valued domain.The true DODs and its images are substituted into reduced-dimensional Capon spectrum to eliminate the peaks of images.Finally,the eigenvectors are utilized to obtain ambiguous DOAs and the minimum norm of the direction-cosines difference method is used to disambiguate the DOAs.Simulation results demonstrate that the estimation performance of the proposed algorithm is closest to one dimensional search complex domain MUSIC algorithm.Furthermore,the computational complexity can be reduced 50%.Moreover,the proposed algorithm can realize automatic pairing between DOD and DOA.2.The characteristics of polarization diversity and waveform diversity for polarized MIMO radar were studied in the second part of the dissertation,two kinds of joint DOA and polarization parameter estimation schemes for monostatic polarization MIMO radar are proposed.The first scheme is for the separate polarization-MIMO radar,the blockorthogonal matching tracing(BOMP)algorithm is proposed to accomplish the DOA and polarization parameter estimation.The block sparse matrix is first constructed based on the relationship between the polarization parameters and DOA.Then the fast BOMP algorithm is used to estimate the support position.The DOA can be obtained from the support position,and the polarization parameter can be estimated from the amplitude of the support position.The second scheme is for the colocated polarization-MIMO radar,whose receiver is composed of electromagnetic vector sensor.The rotational invariant signal parameter estimation algorithm(ESPRIT)and vector cross-product algorithm are proposed to jointly estimate the two-dimensional DOA and polarization parameters.The filtered vector array is divided into six scalar sub-arrays,jointly polarization-space information is used to construct the rotational invariant equation,and then the electromagnetic vector of incident signal is calculated,DOA is finally estimated by vector cross-product algorithm.Simulation results show the effectiveness of the two proposed schemes.3.In view of the problems existed in direction finding of low-altitude/super low-altitude target with MIMO radar,a new DOA estimation method based on subspace difference reconstruction is proposed.Based on studying the array signal model and the coherence of multipath,a new spatial difference matrix is constructed,and then an iterative scheme is employed to obtain the DOA estimation of low-altitude target.Simulation results show that the method can effectively suppress noise interference and improve estimation accuracy.4.The anti-jamming performance of MIMO radar and MIMO radar network structure were investigated in the last part for the dissertation.By analysing the method against phantom track deception of MIMO radar.A method against deception jamming for radar network with transmit-receive community is proposed.Based on the principle of deceptive track formation,the difference of correlation between the true and deceptive track measurement sequence of the radar nodes is analyzed.When electronic warfare aircraft(ECAV)formation implements track-deception jamming,the correlation of deceptive track measurement sequence is lower than that of the true track measurement sequence.The deceptive track for radar network can be identified based on grey system theory.Simulation results verify the effectiveness of the proposed method.