Intelligent reflecting surfaces (IRSs) are gaining attention as a low-cost solution to the coverage reduction in high-frequency bands used in next-generation communications. IRSs achieve low costs by controlling only the reflection of radio waves. However, to improve further the propagation environment, larger IRS sizes are required owing to their inability to amplify and retransmit signals. As the IRS size increases, the near-field region expands, requiring beamfocusing instead of beamforming, which is extensively used in existing research. This results in considerable overhead for IRS control decisions. To address this, constructing a codebook that achieves high communication quality with fewer IRS control patterns is effective. This article presents experimental results demonstrating the effectiveness of beamfocusing, construction policy for nonuniform three-dimensional codebooks, and simulation evaluation results of communication performance when operating IRSs with various codebooks. We believe these insights will foster further value for IRSs in next-generation communications.

翻译：智能反射表面（IRS）作为解决下一代通信高频段覆盖范围缩减的低成本方案正受到关注。IRS通过仅控制无线电波的反射实现低成本。然而，为进一步改善传播环境，由于其无法放大和重传信号，需要更大尺寸的IRS。随着IRS尺寸增大，近场区域扩展，需要采用波束聚焦而非现有研究中广泛使用的波束赋形。这导致IRS控制决策产生显著开销。为解决此问题，构建能以较少IRS控制模式实现高通信质量的码本是有效方法。本文展示了验证波束聚焦有效性的实验结果、非均匀三维码本的构建策略，以及使用不同码本操作IRS时通信性能的仿真评估结果。我们相信这些见解将为IRS在下一代通信中创造更大价值。