Range-Angle Coupling in Linear Sparse Array: Far-Field Model With Narrow-Band FMCW Signal

The linear sparse array (LSA) can enlarge the array aperture and significantly enhance the angle accuracy. However, if the array aperture of the LSA is comparable to the range resolution, a phenomenon known as range-angle coupling (RAC) will be generated. It will lead to biased estimates of range and angle. In this article, we investigate the RAC in LSA under the far-field and narrow-band model. We employ the frequency-modulated continuous wave signal and highlight how the RAC exists in our model. In particular, we analytically elaborate on the impact of the RAC on system performance in terms of resolution and accuracy. Two challenging problems are effectively resolved in this article for parameter estimation. One is to separate the RAC from the range term to achieve the decoupling, and we propose a modified reduced-dimension multiple signal classification algorithm. The second critical problem is to identify the true angles from a great number of false peaks in the presence of the RAC. We propose an eigenvalue-based algorithm and construct a function whose peaks only point to the true angles, successfully eliminating the impact of false peaks. Simulation results demonstrate the effectiveness of the proposed algorithm.