Off-grid Compressive Sensing Based Channel Estimation with Non-uniform Grid in Millimeter Wave MIMO System

Channel estimation is challenging for millimeter-wave (mmWave) communications because of the use of hybrid architecture and massive multiple-input multiple-output (MIMO) technology. By utilizing the sparsity in the angular domain, conventional on-grid compressive sensing methods can efficiently recover the channel state information (CSI). However, the channel estimation accuracy is severely affected by the off-grid errors and the selection of grid angles. The off-grid compressive sensing methods and the non-uniform grid angles can improve the channel estimation accuracy. In this paper, we investigate the impact of the non-uniform grid angles for the off-grid compressive sensing methods and the on-grid compressive sensing methods. We propose to employ the orthogonal matching pursuit (OMP) algorithm with interior point (IP) method based off-grid error mitigation to implement the channel estimation using the selected angle design. The simulation results demonstrate the advantages of the proposed off-grid compressive sensing method and show the impact of the non-uniform grid angles.