In this paper, we propose a novel beamforming codebook (CB) design for wireless communications with recon-figurable intelligent surface (RIS) in both near-field and far-field scenarios. To this end, we first develop a generic model to analyze spherical waves and explore the boundary between the near-field and far-field regions. Based on this model, we propose a novel beamforming design for both the near-field and far-field areas. We prove that near-field beamforming can be mathematically decomposed into two parts: directional beamforming which is similar to far-field beamforming, and distance beamforming within the near field region. In addition, we propose an algorithm to decide the beamforming CB, taking into account the practical constraint of quantized phase shifts in RIS implementation. Finally, we implement the proposed beamforming CB design in a network scenario, considering both cases with and without the location information of the user equipment (UE). Extensive simulations validate the superior performance of the proposed beamforming design.
Near-Field and Far-Field Beamforming Design for RIS-enabled Millimeter Wave Systems
2024-06-24
744091 byte
Conference paper
Electronic Resource
English