| As a new radar system,MIMO(multiple input multiple output)radar has higher design freedom and better potential performance,and has attracted great attention from researchers.Generally,the main research contents of MIMO radar include MIMO array design,transmit beampattern design,waveform design,parameter estimation and application research of MIMO radar.With the maturity of MIMO radar theory,how to realize MIMO radar or how to combine with traditional radar with MIMO radar is an urgent problem.Based on MIMO radar,this paper studies the beampattern design of subarrayed MIMO radar,proposes a method of integration of MIMO radar and communication,and discusses the application of1-bit sampling technology in MIMO radar,which is a low-cost and low-power technology.The main content of this dissertation can be summarized as follows.(1)We establish the signal model of the phased-MIMO radar,analyze the beampattern composition of the phased-MIMO radar,and compare phased-MIMO radar with phased array radar and MIMO radar in terms of transmit beampattern,beamforming,signal processing method and parameter estimation performance.In order to reduce the high side lobes caused by regular subarrays,we propose a design method that uses irregular subarrays in the transmitting and receiving arrays.(2)The subarray conversion matrix in the phased-MIMO radar is extended to a generalized weight matrix.By optimizing this weight matrix,we design the transmit beampattern.On this basis,for a two-dimensional planar array with a large number of elements,we propose a FFT(Fast Fourier Transform)-based beampattern design method.For multi-target multibeam pattern,we propose an effective multi-beam design method based on target detection.And at the same time,we propose an iterative algorithm to approximate the ideal waveform with a constant modulus waveform.In order to improve the parameter estimation performance of the MIMO radar,a dynamic waveform optimization method is proposed.Each waveform design is based on the previous parameter estimation results to radiate the emitted energy to the target direction of interest.(3)The application of 1-bit technology in MIMO radar has been studied.The existing literatures lack a unified theoretical basis for 1-bit sampling,and always qualitatively describes the application conditions of 1-bit technology.First,we abstractly analyze the signal after 1-bit sampling,and then discuss the application conditions of 1-bit technology,the loss of signal-to-noise ratio(SNR)after using 1-bit technology,and the possible negative effects.After understanding the application conditions of the 1-bit technology,we put the 1-bit technology in Coast-ship bistatic high-frequency surface-wave MIMO radar and monostatic high-frequency radar for detailed theoretical analysis and actual data verification.It is found that 1-bit can be used in these radars,and the performance is in line with theoretical expectations.Finally,the 1-bit technology is extended to general MIMO radar,some parameter estimation methods are proposed.The corresponding Cramér-Rao Bound(CRB)of MIMO radar parameters under 1-bit sampling is derived.Our analysis shows that1-bit will bring 2/ ? times the loss of SNR at low SNR,but not affect signal processing and parameter estimation.(4)A method of integration of MIMO radar and communication is proposed.Based on Orthogonal Frequency Division Multiplexing Linear Frequency Modulated(OFDM-LFM)signals,communication method is achieved by changing the carrier frequency of the signal transmitted on each antenna.In this paper,the signal processing procedures of the radar and communication are described separately.Then the communication performance and the selection criteria of the carrier frequency are discussed.Finally,the influence of this method on the original radar performance is discussed.Analysis shows that the proposed method can complete data transmission without affecting radar performance,and realize the integration of radar communication. |
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