Research On Transmit Beamspace Design And Parameter Estimation Algorithm For Bi-static FDA-MIMO Radar

With the increasing complexity of the electromagnetic environment and the continuous development of electronic countermeasure technology,the improvement of the radar technology is also ongoing.In order to improve the degree of freedom of the radar transmitter and obtain higher waveform diversity gain and frequency diversity gain,the frequency diversity array(FDA)radar and Multiple-Input Multiple-Output(MIMO)radar are combined and a new concept of FDA-MIMO radar is proposed.This paper focus on the bi-static FDA-MIMO radar and study the energy focusing transmit waveform design method,the joint estimation of angle,velocity and range unambiguously and the multi-parameter joint estimation algorithm in the impulsive noise environment.The main work and achievements of paper are summarized as follow:1.A transmit waveform design method based on estimation CRB minimization is proposed.In this method,the number of transmit elements,orthogonal waveforms and mixers are considered to be different and the transmit array and mixer array are divided into multiple subarrays to decouple the range and angle response and satisfy the Rotation Invariant Property(RIP)constraint.In order to minimize the CRBs of parameters estimation and satisfy the uniform power distribution constraint,an optimization method to optimize the transmit array,mixer array and transmit waveform is proposed.Then,a hierarchical method is introduced for simplification.Simulation results indicate the method can provide more freedom to the waveform design and focus more energy on the desired direction sectors and the range sectors to improve the performance of radar.2.In order to deal with the problems on the ambiguities of range and velocity estimation,a joint estimation method of angle,velocity and range without ambiguity for bi-static FDA-MIMO radar is proposed.In this method,first,by the deduction of signal model of this radar,the radar echo phase is found not only related to the frequency increment-target range but also related to the frequency increment-target velocity,and it can be used to resolve ambiguity in the range and velocity estimation.Utilizing the ESPRIT algorithm and ambiguity resolve methods based on FDA,the direction-of-departure(DOD),direction-of-arrival(DOA),range and velocity parameters are estimated unambiguously.Additionally,Cramer-Rao bounds(CRB)for these parameters are derived and the performance of this radar is analysed.Simulation results indicate the validity of the joint estimation of angle,range and velocity unambiguously.3.In view of the degradation in performance of traditional subspace-based algorithm in SaS impulsive noise environment for the non-existence of the second-order matrix,two ESPRIT estimation algorithms based on SVD-RPCA and QR-RPCA in bi-static FDA-MIMO radar are proposed in this paper.In these methods,the characteristics of impulsive noise and target signal are studied and the sparsity of the noise and the low-rank property of the target signal matrix are found.After that,according to the characteristics of traditional subspace-based algorithms,the robust principal component analysis(RPCA)is used and a SVD-RPCA algorithm and a QR-RPCA algorithm for coherent target environment are proposed to extract the low-rank target signal matrix from the receive data polluted by impulsive noise and obtain the signal subspace directly.Finally,the angle,range and velocity of targets are estimated based on the ESPRIT algorithm.Simulation results show that the proposed method reduces complexity compared with traditional RPCA algorithm.Meanwhile,the proposed methods perform better than other impulsive noise suppression algorithm in a low characteristic index impulsive noise environment.