Study On Anti-jamming And Target Detection Approaches Of MIMO Radar Based On Polarization And Frequency Diversity

The main-lobe deception jamming based on the digital radio frequency memory(DRFM)technology has become a serious threat to the modern radar.Because the signal characteristics of the main-lobe deception jamming is very similar to that of the real target,in terms of the time domain,frequency domain and space domain,which is difficult for the conventional radars to identify and suppress it effectively.In addition,with the emergence of low detectable targets and the increasingly complex working environment of the radar,the information acquisition and signal processing methods of the conventional radars are also facing severe challenges in dealing with the problem of target detection.Therefore,maximizing the exploitation and utilization of electromagnetic information obtained from radar sensor system,improving the anti-jamming ability and the target detection ability of the radar,and then adapting to the complex and changeable battlefield environment have become a basic subject and an urgent task in the field of radar information processing.In this dissertation,the anti-main-lobe deception jamming and the target detection of the co-located multiple-input multiple-output(MIMO)radar are studied.The purpose is to further exploit the potential and improve the anti-jamming and target detection performance of the MIMO radar by utilizing the polarization diversity,frequency diversity,phased array,cognitive radar and other techniques and approaches rationally.The main content of this dissertation is summarized as follows.1.The polarization-diversity-based methods for the main-lobe deception jamming suppression in MIMO radar are studied.A new technology of the polarization MIMO(PMIMO)radar is proposed by applying the polarization diversity technology to the MIMO radar.The target parameter estimation method and the target discrimination method for PMIMO radar are studied.In addition,in order to improve the anti-main-lobe deception jamming ability of PMIMO radar,two adaptively designed methods for the radar transmitting polarizations are proposed: one based on the unilateral game for the conventional jammers by which the polarization characteristics of the generated false targets are fixed,and the other based on the strategic game for the smart jammers by which the polarization characteristics of the generated false targets adaptively change according to the battlefield environment.The PMIMO radar has the advantages of both polarization radar and MIMO radar,so it can effectively suppress the main-lobe deception jamming in the space-polarization domain.Furthermore,the optimization design for the transmitting polarizations based on the game theory can further improve the anti-jamming performance.2.The approaches based on the polarization diversity and the phased array technologies for the main-lobe deception jamming suppression in the MIMO radar are studied.To further improve the main-lobe deception jamming suppression capability of the PMIMO radar,a new technology of the phased-polarization MIMO(Phased-PMIMO)radar is proposed by applying the phased array technology to the PMIMO radar.The adaptive beamforming technique is used to suppress the main-lobe deception jamming,and the optimization methods for the transmit sub-array division and the transmitting polarizations of the Phased-PMIMO radar are studied with the maximization of the output signal-to-interference-noise ratio(SINR)as the optimization criterion.For real targets,the Phased-PMIMO radar can obtain both the polarization diversity gain and the coherent processing gain,hence has a better anti-main-lobe deception jamming ability.The joint optimization of the transmit sub-array division and the transmitting polarizations can further improve the anti-jamming performance.3.The approaches based on the polarization diversity and the frequency diversity array(FDA)technologies for main-lobe deception jamming suppression in the MIMO radar are studied.To further improve the main-lobe deception jamming suppression ability of the PMIMO radar,a new technology of the FDA-PMIMO radar is proposed by applying the FDA technology to the PMIMO radar.The target parameter estimation method and the discrimination method for FDA-PMIMO radar are studied.On this basis,the adaptive optimization method of transmitting frequency step and transmitting polarizations are studied respectively,taking the maximization of the SINR as the optimization criterion.The FDA-PMIMO radar can effectively suppress the main-lobe deception jamming in the angle-range-polarization domain,and further improve its anti-jamming performance by optimizing the transmitting frequency step and the transmitting polarizations.4.The target detection approaches based on the polarization diversity technology in the MIMO radar are studied.A technology of the orthogonal polarization MIMO(OP-MIMO)radar is proposed which has the equally simple structure as the traditional dual-channel polarization radar.The target detection algorithm is designed under the Neyman-Pearson criterion,and the analytical expressions for the probability of false alarm and the probability of detection are derived.The OP-MIMO radar can obtain both the waveform diversity gain and the polarization diversity gain,so its detection performance is better than that of the traditional dual-channel polarization radar and it is more robust to the target polarization scattering characteristics.To further improve the detection performance,a new technology of the dual-polarization MIMO(DP-MIMO)radar with adaptive transmitting polarizations is proposed.The estimation and prediction methods of the target polarization scattering vector(PSV)are designed.The adaptive optimization method for the transmitting polarizations is studied with maximizing detection probability and minimizing estimation error as optimization criteria.The transmitting polarizations of the DP-MIMO radar can be adaptively selected according to the polarization scattering characteristics of the target,yielding a better detection performance.5.The target detection approaches based on the polarization diversity and frequency diversity technologies in the MIMO radar are studied.In order to improve the detection performance of the PMIMO radar,a new technology of the frequency diversity polarization MIMO(FD-PMIMO)radar is proposed by applying the frequency diversity to the PMIMO radar.The target detection algorithm is designed and the approximate calculation formulas for the probability of false alarm and the probability of detection are deduced,and the optimization method of the transmitting and receiving polarizations for the purpose of maximizing detection probability is studied.The FD-PMIMO radar technology can obtain the frequency diversity gain,the polarization diversity gain and the waveform diversity gain simultaneously,hence has a better detection performance.Moreover,it can optimize the transmitting and receiving polarizations based on the target polarization scattering characteristics to further improve the detection performance.