Communications system with analog or hybrid analog/digital architectures usually relies on a pre-defined codebook to perform beamforming. With the increase in the size of the antenna array, the characteristics of the spherical wavefront in the near-field situation are not negligible. Therefore, it is necessary to design a codebook that is adaptive to near-field scenarios. In this letter, we investigate the hierarchical codebook design method in the near-field situation. We develop a steering beam gain calculation method and design the lower-layer codebook to satisfy the coverage of the Fresnel region. For the upper-layer codebook, we propose beam rotation and beam relocation methods to place an arbitrary beam pattern at target locations. The simulation results show the superiority of the proposed near-field hierarchical codebook design.
翻译:具有模拟或混合模拟/数字结构的通信系统通常依赖预先定义的代码簿来进行波形成形。随着天线阵列的大小的增加,近地情况中球形波浪的特性不容忽视。因此,有必要设计一个适合近地情况的代码册。在本信中,我们调查近地情况中的等级代码册设计方法。我们开发了方向波束增益计算方法,设计了低层代码册以满足Fresneel区域的覆盖范围。对于上层代码册,我们建议采用光束旋转和波浪迁移方法,以便在目标地点放置任意的波束图案。模拟结果显示拟议的近地级代码册设计的优越性。