Sparse with fast MM superresolution algorithm for radar forward-looking imaging

The problem of low azimuth resolution has restricted the applicability for radar forward-looking imaging in practice. In this paper, a sparse with fast majorization-minimization (SFMM) superresolution algorithm was proposed to realize fast superresolution imaging of sparse targets in radar forward-looking area. Firstly, we analyzed the azimuth signal of radar forward-looking area and modeled the azimuth signal as a convolution of antenna pattern and targets distribution. Secondly, the superresolution problem was converted into a L1 regularization issue by introducing L1 norm to represent the targets distribution under regularization framework. Thirdly, according to the principle of majorization-minimization (MM) algorithm, a simple L2 regularization issue was obtained to replace the difficult L1 one, and the real target distribution was obtained by solving the L2 regularization problem (We named it sparse with MM (SMM) superresolution algorithm for convenience). Then, in order to improve the computational efficiency of the algorithm, we adopted second-order vector extrapolation idea to accelerate the conventional MM algorithm and solve the L2 regularization problem. The simulation and real data verified that the proposed SFMM algorithm not only improves the azimuth resolution in radar forward-looking imaging, but also increases convergence speed on the basis of SMM superresolution algorithm.