Hybrid-field Beam-split Pattern Detection-based Channel Estimation for THz XL-MIMO Systems

In this letter, we delve into the uplink channel estimation for terahertz extremely large-scale multiple-input multiple-output (XL-MIMO) communication systems, focusing on both the polar and the angle domains. Specifically, we explore the pervasive implementation of hybrid-field communication in XL-MIMO scenarios, addressing challenges such as the beam-split and power interference effects caused by bandwidth expansion and dense scatterer environments. As a solution, we present a hybrid-field channel estimation approach that utilizes the beam-split pattern detection method. Furthermore, to enhance the estimation accuracy, we prioritize the near-field channel estimation and minimize its impact on the far-field path components as much as possible. Simulation results validate that the proposed hybrid-field scheme outperforms benchmark algorithms in normalized mean square error (NMSE) performance.