| As new system radar,MIMO radar has the advantages of high precision detection performance,anti-stealth target and anti-jamming ability.Therefore,MIMO radar has aroused extensive attention from many domestic and foreign scholars as soon as it is proposed.It has become a new research topic in recent years,and a large number of research achievements on target positioning have appeared.But for target tracking problem of MIMO radar,there are relatively few studies and published literature.The target in real battlefield is usually moving.Therefore,the target tracking of MIMO radar is a problem that must be solved.In this paper,the bistatic MIMO radar that can be practically applied in engineering is studied.The urgent problems in target tracking are researched as well.The main contents are as follows:1.The angle tracking problem for target in bistatic MIMO radar under ideal conditionsTo track high angular rate targets,an improved adaptive asymmetric joint diagonalization(AAJD)algorithm is proposed for angle tracking.The reason for the low tracking performance of AAJD algorithm is that the estimated angle at the previous time is reused for angle estimation.Therefore,it was first proved that each column of the feature vector obtained by the AAJD algorithm corresponds to a steering vector.The improved AAJD algorithm directly uses eigenvectors estimate the DOD and DOA directly,which improves tracking performance and can solve high maneuvering target tracking problems.And the ESPRIT algorithm is improved for automatic pairing and association of DOD and DOA.To track low angular rate targets,an angle tracking algorithm for target based on the difference of covariance matrix is proposed.First,the linear relationship between the difference of covariance matrix and the difference of angle between the adjacent moments is obtained through three first order approximates.Then,the proposed algorithm obtains the relationship among the elements in the difference of covariance matrix.On this basis,the information of the difference of the covariance matrix is fully utilized by averaging the elements,which improves the performance of the algorithm.Finally,the least square method is used to estimate the DOD and DOA.At the same time,the automatic matching and association of target angles is achieved.The algorithm provides better performance when compared with the AAJD algorithm.2.The angle tracking problem for target in bistatic MIMO radar when the number of targets is unknownNo variable,which can directly represent the eigenvalue,exists in AAJD algorithm.A joint tracking algorithm,which combines the number of target and angle,is proposed with adaptive asymmetric joint diagonalization deflation.First,the idea of principal component sequence estimation is introduced to the AAJD algorithm,and the eigenvalue variables are iteratively evaluated.Second,the number of target is estimated by using the improved information theory criterion algorithm.Then the joint tracking of the number and angle of the target is completed.Finally,the anti-dithering algorithm for target number is proposed,which improves the robustness.The simulation results show that the improved AAJD algorithm can successfully track the number of target and angle trajectories.The efficiency of the proposed method is verified.3.The angle tracking problem for target of bistatic MIMO radar in low signal to noise ratio levelWhen signal to noise ratio is low,the AAJDd algorithm has the problem of signal subspace expansion.An angle tracking algorithm for target based on improved MUSIC is proposed.First,the eigenvalues obtained by the AAJDd algorithm are used to get the extended signal subspace through the decision criterion.Second,the relationship between the extended signal subspace and the noise subspace is derived,and the correct noise subspace is estimated.Finally,in order to reduce the amount of calculation,the MUSIC algorithm is divided into two steps depending on the tracking status.The first step is to scan the whole airspace with large step length,corresponding to tracking the unsteady state.The second step is to scan the small-space with small step length,corresponding to tracking the steady state.The peak search process is changed to find the maximum value which further reduces the amount of calculation.Because the signal subspace expansion problem is solved at low SNR,the tracking performance is improved.The algorithm uses improved MUSIC algorithm which has higher performance and lower calculation complexity.Aiming at the problem of large amount of computation in the improved MUSIC algorithm,an angle tracking algorithm for target based on improved ESPRIT is proposed.First,the eigenvalue variables are sorted by descending order and the eigenvectors corresponding to the large eigenvalue variables are found.The signal subspace is obtained from the extended signal subspace.Second,the influence of the accumulation of the eigenvalue variables error is eliminated in the unsteady tracking state.The obtained signal subspace is more accurate.Finally,the ESPRIT algorithm is improved to achieve the automatic pairing and association of angle.The simulation results show that the algorithm can achieve angle tracking in low SNR,and the convergence speed and stability are better than that of the AAJDd algorithm.4.The joint tracking problem of angle and Doppler frequency in bistatic MIMO radarTo track high angular rate targets,a joint tracking algorithm of angle and Doppler frequency based on space-time structure is proposed.First,the signal model of the bistatic MIMO radar is improved.According to the phase shifts of the adjacent array elements,the received signal after matched filtering is sampled by the delay tap to obtain the phase shift of the adjacent delays in the time domain.The extended joint guidance vector is formed at the same time.Second,in order to estimate the extended joint guidance vector,the PASTd algorithm is improved,which can solve the problem that PASTd cannot track the target with the same angle.Finally,the ESPRIT algorithm is improved to obtain the extended rotation invariant factor,which is used to estimate the angle and Doppler frequency.The automatic pairing and association of the target parameters are accomplished at the time.The simulation results show that the algorithm can realize the joint tracking of the angle and Doppler frequency.To track low angular rate targets,a joint tracking algorithm of angle and Doppler frequency based on improved covariance matrix is proposed.First,in order to make the improved covariance matrix structure contain Doppler frequency information,the received signals are sampled by the delay tap.Second,the linear relation between the difference of improved covariance matrix and the difference of angle is presented by there first order approximations.The angle and Doppler frequency of targets are estimated via least squares method.Finally,it is proved that some elements on the diagonals of the improved covariance matrix are equal.By taking the average operation,the tracking accuracy of the target parameters is improved.The simulation results verify the efficiency of the proposed algorithm... |
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