Near-Field Beam Management with Ring-type Codebook

The sixth generation (6G) wireless communication system requires extreme capacity and coverage, which can be achieved through the introduction of higher frequency and ultralarge-scale reconfigurable intelligent surface (RIS) array. This also enables the expansion of the near-field range to tens or even hundreds of meters. However, near-field beamforming presents different challenges than far-field beamforming, as it involves two parameters (angle and distance) rather than just angle. This requires a larger number of codewords for near-field beams and frequent beam switching due to the narrow beamwidth. To address these challenges, we propose an enhancement to the ringtype codebook (RTC) using non-uniform quantization of focal length and beamwidth control methods. Our proposed methods effectively reduce the beam management overhead and SNR fluctuation by 34% and 4dB respectively, while also improving the robustness of the beams. Overall, our proposed enhancement to the RTC can significantly improve the performance of near-field beamforming in the 6G wireless communication systems, enabling them to satisfy the extreme capacity and coverage requirements of the future.