An Improved Off-grid Channel Estimation Scheme for Lens Antenna Arrays in mmWave Systems

In this paper, we propose an improved off-grid channel estimation scheme for lens antenna arrays in mmWave systems. This scheme belongs to the spatial domain channel estimation. In the scheme, we first design a two-stage antenna selection algorithm based on the sparsity of mmWave channels as well as the optical focusing characteristic. Next, we exploit off-grid channel estimation to calculate the dimension reduction matrix and the angle of arrival of received signals. Unlike beam domain estimation, our scheme is suitable for wideband and narrowband channel matrix estimation. Simulation results show that our proposed scheme can achieve better estimation accuracy as the existing spatial scheme at much lower hardware overhead.