The resolution is an important performance metric of near-field communication networks. In particular, the resolution of near field beamforming measures how effectively users can be distinguished in the distance-angle domain, which is one of the most significant features of near-field communications. In a comparison, conventional far-field beamforming can distinguish users in the angle domain only, which means that near-field communication yields the full utilization of user spatial resources to improve spectrum efficiency. In the literature of near-field communications, there have been a few studies on whether the resolution of near-field beamforming is perfect. However, each of the existing results suffers its own limitations, e.g., each is accurate for special cases only, and cannot precisely and comprehensively characterize the resolution. In this letter, a general analytical framework is developed to evaluate the resolution of near-field beamforming. Based on this derived expression, the impacts of parameters on the resolution are investigated, which can shed light on the design of the near-field communications, including the designs of beamforming and multiple access tequniques.

翻译：分辨率是近场通信网络的重要性能指标。具体而言，近场波束形成的分辨率衡量了用户在距离-角度域中的可区分程度，这是近场通信最显著的特征之一。相比之下，传统远场波束形成仅能在角度域区分用户，这意味着近场通信能充分利用用户空间资源以提升频谱效率。在近场通信文献中，已有少量研究探讨了近场波束形成分辨率是否完美的问题。然而，现有结果均存在局限性：例如，仅适用于特定场景的精确分析，无法精确且全面地表征分辨率。本文构建了一个通用分析框架以评估近场波束形成的分辨率。基于所推导的表达式，研究了参数对分辨率的影响，为近场通信的波束形成与多址接入技术设计提供了指导。