Research On MIMO Radar Based On OFDM Signal

With the advancement of technology,radar technology has been rapidly developed.In order to improve the radar resolution and the recognition ability of target parameters,the research on MIMO radar has become a development trend.Because MIMO radar has multiple transmit antennas and multiple receive antennas,it can obtain good waveform diversity,which makes the radar more freedom and can better resist the cross-sectional area flicker,which improves the radar detection performance.In addition,the introduction of OFDM technology into MIMO radar can effectively combat the problem of frequency selective fading and multipath fading,and improve the reliability of the received signal.Therefore,this paper combines OFDM signals to construct a MIMO radar system model for target parameter estimation and waveform design.The feasibility of the method in signal processing and waveform design is verified by simulation.The main work in this thesis contains:1.The basic principle of MIMO radar and the key technology of OFDM are analyzed,and the echo signal model of distributed MIMO radar is constructed.The relevant performance parameters of MIMO radar are explored.The OFDM signal is selected as the transmission signal of MIMO radar.The OFDM technology is elaborated.The advantages of OFDM technology are analyzed.Then the basic principle of OFDM is summarized.The modulation and demodulation process is described in detail.The reason for adding the guard interval and the necessity of adding the cyclic prefix are described.Finally,the fuzzy function of the OFDM signal is analyzed.2.To design the OFDM MIMO radar waveform,First,analyze the influencing factors of the waveform design.For example,factors such as signal-to-noise ratio and peak-to-average power ratio,through the analysis of the influencing factors,four design criteria are proposed,and the radar waveform is designed according to the design criteria.In this paper,the other three standards are independent of the transmitting antenna when the first standard is met.Therefore,after the waveform design meets the first design standard,it is only necessary to design an OFDM pulse for one of the transmitting antennas.The frequency domain orthogonality of the first design standard utilizes the structural characteristics of the orthogonal space-time block code,and the improved iterative limiting and filtering algorithm is used to jointly design the OFDM pulse to meet the other three design criteria.Finally,the performance of the algorithm is verified by simulation experiments.3.The target parameters of OFDM MIMO radar are estimated,and the MIMO radar echo signal model is established.The OFDM signal is applied to the MIMO radar.In order to obtain the channel response including the target delay and Doppler information,this paper proposes to perform pulse compression in the frequency domain.For each subcarrier in the discrete frequency domain,the orthogonality does not affect the transmitter time delay.After obtaining the channel response,two high-resolution algorithms are proposed to estimate the delay and Doppler of the target: using two-dimensional MUSIC algorithm to achieve spectral estimation;using compressed sensing theory to identify the target,thus delaying and Puller estimates the feasibility of the proposed method for target parameter estimation by simulation.