Research On The Algorithms Of Adaptive Waveform Design For Target Detection And Parameter Estimation For MIMO Radar

As a new system radar,multi-input-multi-output(MIMO)radar has multiple transmit antennas and multiple receive antennas.Compared with the traditional phased array radar,which can only transmit single waveform,MIMO radar can transmit multiple different waveforms at the same time and has higher degree of freedom.Designing transmitted waveform is one of the important research contents of MIMO radar.Through the joint optimization design of transmitter and receiver and adaptive transmitted waveform design,the performance of MIMO radar can be effectively improved,such as interference suppression,target detection,parameter estimation and target recognition in complex environment.In this dissertation,the adaptive waveform design(AWD)algorithms for target detection and parameter estimation of MIMO radar are studied.The main contents can be summarized as follows:1)The basic principle and key technology of MIMO radar are expounded and the signal models of MIMO radar under extended target and signal-dependent clutter are given.The basic theory of AWD for MIMO radar is introduced.2)The joint design algorithm of MIMO radar constant modulus waveform and receiver filter for target detection is studied.Firstly,the relation between the target detection performance of MIMO radar and the transmitted waveform under determined target impulse response(TIR)and random TIR is given.The common criteria of AWD for target detection are introduced,which are compared and selected.Secondly,the joint design algorithm of MIMO radar constant modulus waveform and receiver filter is given when the prior knowledge is accurate in clutter environment.Based on the signal to clutter and noise ratio(SCNR)criterion,the iterative optimization algorithm is used to decompose the joint design problem into two sub-steps in this algorithm: the optimization problem of receiver filter weights when the transmitted waveform is fixed is modeled as the generalized Rayleigh quotient model,and the corresponding weight vector of the receiver filter is obtained;the transmitted waveform optimization problem of fixed weight of the receiver filter is solved by using positive semi-definite relaxation technique to obtain the corresponding waveform matrix.In the process of solution,lemma 3.1 is introduced to simplify the problem,and the modulus waveform is obtained by Gauss random method according to the waveform matrix obtained.Simulation results show that compared with other waveforms and receiver filter weights,the corresponding SCNR of the constant modulus waveform and receiver filter weights designed by this algorithm is higher,and the detection performance of radar is better.At last,considering the influence of estimation error on prior knowledge,a joint design algorithm of MIMO radar constant modulus robust waveform and receiver filter is proposed when the prior knowledge is inaccurate.The joint design problem when the prior knowledge of the distribution characteristics of TIR and clutter impulse response(CIR)is not accurate is modeled as a maximum minimization problem in this algorithm.The iterative optimization method is used to decompose the problem into two sub-steps,and the two sub-steps are solved by using the solution of generalized Rayleigh quotient model and the convex optimization method respectively to obtain the desired robust waveform and receiver filter weights,improving the lower bound of the target detection performance of system.The simulation results show the effectiveness of the proposed algorithm.3)The adaptive waveform design algorithm of MIMO radar for parameter estimation is studied.Firstly,the relation between the estimation performance of MIMO radar and transmitted waveform under random TIR is analyzed,and the common criteria of AWD for parameter estimation are introduced,which are compared and selected.Secondly,for solving the problem of the constantly changing TIR of the fast moving target,a waveform design algorithm based on MI criterion is proposed.The TIR prediction is derived by the Kalman filter in this algorithm,achieving the accurate estimation of the target,and the maximum energy allocation algorithm is used to solve the model to obtain the desired transmitted waveform matrix.Then,considering the influence of estimation error on prior knowledge,a robust waveform design method for MIMO radar is proposed.In this method,the problem of robust waveform design of MIMO radar is modeled based on MI criterion according to the inaccurate prior knowledge of target and noise.The convex optimization method is used to solve the model and the desired robust transmitted waveform is obtained,improving the lower bound of the parameter estimation performance of radar in case that the prior knowledge of target and noise is inaccurate.At last,considering the fact that the transmitted waveform is often required to be able to simultaneously complete a variety of radar tasks(such as target detection,parameter estimation,tracking and identification,etc.)in the actual scene,a design method of MIMO radar transmitted waveform is proposed,which takes the detection performance into account,so that the radar can not only improve the performance of the parameter estimation,but also meet the basic requirements of the detection performance.