Design And Performance Analysis Of Orthogonal Waveform For MIMO Radar

Multiple Input Multiple Output(MIMO)technology has been widely used in fourth and fifth generation mobile communications.Due to the similarity between radar and communication systems,Bliss and Forsythe et al.introduced MIMO technology into the radar field and proposed the concept of MIMO radar.As the battlefield environment becomes more and more complex,stealth fighter technology and jamming combat technology become more and more mature,so anti-stealth and anti-interference become the key indicators to measure radar performance.Compared with phased array radar,MIMO radar has higher target detection accuracy,more accurate target parameter identification,better anti-stealth performance and stronger anti-interference ability.The other type is distributed MIMO radar.The most notable feature is that the transmitting and receiving antennas are fully spatially separated,so that the spatial diversity can be used to improve the detection performance of the target,which can effectively resist the target RCS flicker and improve the anti-stealth performance.Whether it is centralized MIMO radar or distributed MIMO radar,orthogonal waveform design is an important field of MIMO radar research.This paper mainly studies the orthogonal waveform design and optimization of MIMO radar system.The main work is as follows:This paper introduces the research background and significance of MIMO radar,and explains the research status of MIMO radar at home and abroad.Based on the research and analysis of the basic principles and characteristics of MIMO radar,the common MIMO radar waveform optimization criteria and optimization methods are summarized.The matched filtering and digital beamforming techniques in the MIMO radar signal processing flow are discussed.A distributed and centralized MIMO radar signal models are established.Study the design scheme of polarization phase coded orthogonal waveform.In this paper,the polarization information and phase encoding information are combined to construct an orthogonal waveform.Using the idea of phase encoding,the polarization characteristics are introduced into the orthogonal waveform design.First,the discrete phase encoding sequence is optimized,and the influence of the phase encoding phase number and the encoding length on the peak sidelobe level and the cross-correlation peak level is analyzed.Then the signal processing flow of the polarization phase coded waveform design is explained.Finally,the effects of symbol-to-noise ratio(SNR)on the polarization phase-encoded waveform in single-shot and single-receive scenes and the polarization-phase-encoded waveform in multi-shot and multi-receive scenes are analyzed.Based on the analysis of the influence of linear frequency modulation(LFM)signal carrier frequency and pulse duration on the correlation characteristics,this paper proposes a slow time coding segmentation LFM waveform design scheme.The waveform consists of multiple pulses consisting of three LFM signals with different durations.The genetic algorithm is used to optimize the cross-correlation properties based on the minimization of the maximum cross-correlation peak level criterion,thus constructing a good orthogonal waveform.set.Then analyze the effect of bandwidth,segmentation bandwidth and waveform length on the autocorrelation and cross-correlation properties of the orthogonal waveform set and the effect of the segmentation bandwidth and bandwidth ratio on the main lobe width.Finally,the simulation verifies the distance and velocity recognition performance under single and multi-target and the spatial frequency resolution performance under single target.The results show that the waveform has good distance and speed recognition performance.The design of Orthogonal Frequency Division Nonlinear Frequency Modulation(NLFM)signal is studied.Firstly,the phase stay principle and the NLFM signal design based on window function are introduced.On this basis,the phase iterative algorithm and the NLFM signal design method of the mismatch filter iterative algorithm are proposed,and the simulation analysis is given.Finally,the Orthogonal Frequency Division NLFM signal model is proposed,and the Orthogonal Frequency Division NLFM signal set is constructed by using the optimized NLFM signal.The simulation results show that the signal set has good orthogonal characteristics.