Hybrid Precoding Design for Near-Field Wideband THz Systems With Spatial Non-Stationarity

In this letter, we investigate the hybrid precoding design problem for the near-field wideband terahertz (THz) systems. Due to the large physical size of the whole array, the extremely large-scale antenna array (ELAA) exhibits spatial non-stationarity across the array. Users only effectively communicate with a portion of the antenna elements of ELAA called visibility regions (VRs). To leverage this characteristic for reducing the computational complexity in hybrid precoding design, we initially develop a VR detection algorithm to identify the corresponding VRs for different users. Subsequently, we employ the acquired VR information for true-time delayer (TTD)-based hybrid precoding design to mitigate the beam split effect. Simulation results validate that the proposed algorithm significantly reduces the computational complexity compared to other benchmark schemes while maintaining negligible performance loss.