Subband-based wideband beamforming design for RIS-aided sensing system

The reconfigurable intelligent surface (RIS) has become a promising technology for enhancing the communication and sensing systems with low complexity and energy consumption. This paper addresses a wideband beamforming challenge, presenting a novel beamforming scheme within an RIS-aided sensing system to rectify the pointing deviation issues. Different from the existing narrow subband-based beamformer, we divide the RIS into multiple sub -blocks, with each block responsible for beamforming at distinct frequency components. Meanwhile, the characteristic of RIS that the frequency -dependent variations of amplitude and phase -shift across a wideband range is considered. Based on this model, the optimization problem is formulated, and the reflection coefficient is determined through solving it. Simulation results demonstrate a significant performance improvement in wideband scenarios, affirming the effectiveness of the proposed beamforming scheme.