Research on Optimization Design Method of MIMO Radar Waveform Based on Frequency-Orthogonal LFM

In the field of Multiple Input Multiple Output(MIMO) radar waveform design, how to design an orthogonal waveform with high performance is one of the current hot topics. The Orthogonal Frequency Division Multiplexing - Linear Frequency Modulation(OFDM-LFM) waveform has been widely studied due to its excellent characteristics in many aspects. However, the spatial synthesized signal autocorrelation function of the traditional OFDM-LFM waveform design method has the disadvantage of high grating sidelobes. Based on a detailed analysis of the factors contributing to the high grating sidelobes in traditional OFDM-LFM waveform design methods, in order to meet the requirement that the waveform in the radar system has good properties of correlation, an innovative and effective algorithm for optimizing waveforms has been introduced in this paper. It uses the initial phase and frequency modulation bandwidth as optimization variables simultaneously, with the integrated sidelobe level (ISL) of the waveform as the optimization target. This algorithm aims to solve the waveform optimization problem of the spatial synthesized signals of the traditional frequency-orthogonal linear frequency modulation waveform design method. For the proposed objective function, the alternating direction method of multipliers integrates with the gradient descent algorithm is used to alternately optimize the objective function and the iteration factor is dynamically adjusted based on the gradient descent method. Multiple numerical simulations have verified that the proposed method is superior to the traditional waveform design method in terms of correlation performance while ensuring the orthogonality between signals.