Research On Waveform Optimization Design Of MIMO Radar Based On Phase Coding

With the complex changes in the electromagnetic environment of modern communications,improving the detection capability of radar for weak target information is becoming a hot topic of research in the field of radar communications today.The optimized design of the transmit waveform and the optimized processing of the return waveform are key to ensuring the detection performance of radar systems.Waveform optimization techniques for phase coding can ensure low side flap performance.At the same time,the full integration of phase coding with Multiple Input Multiple Output(MIMO)radar,the diversity gain capability of MIMO radar ensures that the transmit signal waveform can detect weak target information more efficiently and accurately.This paper discusses issues related to the optimal design of MIMO radar waveforms based on phase coding,focusing on the optimal design of low side-lobe waveforms for phase coded signals,the optimal design of mismatch filter weights,the optimal design of MIMO radar quadrature waveforms and the extension of complete complementary sequence construction for MIMO radars.The specific work is as follows:1.For the problem of phase coding signal waveform side-lobe suppression,two methods,low side-lobe waveform optimization and mismatch filter weight optimization,are used for the study.Based on the traditional optimization algorithm,an improved butterfly optimization algorithm is proposed for side-lobe suppression.In the low-bypass waveform optimization design,this paper establishes the low side-lobe waveform optimization function with the peak side-lobe level ratio and side-lobe energy as the criteria,introduces the logistic mapping to generate the initial coding matrix,and proposes the nonlinear variation convergence coefficient and nonlinear inertia weights to improve the butterfly algorithm for waveform optimization design.In the mismatch filter design,this paper incorporates the improved butterfly algorithm for mismatch filter optimization design with the criteria of reducing the integral and peak side-lobe levels and the mismatch filter loss as a constraint.The performance advantages of the waveform’s side-lobe characteristics and mismatch filter are verified through experimental simulations.It is shown that the improved butterfly algorithm has better performance in the direction of waveform optimization design.2.The orthogonal performance of MIMO radar waveform design is a key issue in the transmit performance of radar systems.To address the problem of poor orthogonal performance of MIMO radar transmit waveform,this paper optimizes the design of MIMO radar transmit waveform by improving the genetic-sooty tern algorithm.The superiority of the update sequence is enhanced by fusing the genetic algorithm and the sooty tern algorithm.The average adaptation function is introduced to adjudicate the optimization process.The orthogonal waveform optimization objective function is designed with the peak side-lobe level,integral side-lobe energy and inter-correlation peak as criteria.The effectiveness and generalizability of the improved genetic-sooty tern algorithm for MIMO radar quadrature waveform optimization design is confirmed by comparison experiments under the same conditions.The algorithm can effectively improve the problem of mutual influence of MIMO radar orthogonal phase coding signals.Theoretical analysis and simulations show that the method is able to satisfy the requirements of mutual orthogonality and low peak side-lobe of the transmitting signal and effectively reduce the problem of mutual interference between different sequences.3.For the application of complete complementary sequences in MIMO radar systems,the complete complementary sequences are extended by three methods:cross transformation,matrix cycle and inverse transformation,so that the complete complementary sequences break the bound of sequence length and ensure the orthogonal performance of the complete complementary sequences in MIMO radar systems.And the simulations of the three methods are compared.The theoretical analysis and simulations show that the inverse transformation method constructs a clear and computationally simple complete complementary sequence,and the resulting complete complementary sequence has excellent orthogonal performance,including autocorrelation parameters and completely zero correlation properties,which can be further applied to the field of MIMO radar.