This paper examines the number of communication modes, that is, the degrees of freedom (DoF), in a wireless setup comprising a small continuous linear intelligent antenna array in the near field of a large one. The framework allows for any orientations between the arrays and any positions in a two-dimensional space assuming that the transmitting array is placed at the origin. Therefore, apart from the length of the two continuous arrays, four key parameters determine the DoF and are hence considered in the analysis: the Cartesian coordinates of the center of the receiving array and two angles that model the rotation of each array around its center. The paper starts with the calculation of the deterministic DoF for a generic geometric setting, which extends beyond the widely studied paraxial case. Subsequently, a stochastic geometry framework is proposed to study the statistical DoF, as a first step towards the investigation of the system-level performance in near field networks. Numerical results applied to millimeter wave networks reveal the large number of DoF provided by near-field communications and unveiled key system-level insights.

翻译：本文研究了一种无线通信场景中的通信模式数量，即自由度（DoF），该场景包含一个位于大型连续线性智能天线阵列近场中的小型连续线性智能天线阵列。该框架允许阵列间存在任意朝向，并假设发射阵列位于原点，接收阵列可位于二维空间中的任意位置。因此，除了两个连续阵列的长度外，还有四个关键参数决定了自由度，并在分析中予以考虑：接收阵列中心的笛卡尔坐标，以及分别建模每个阵列绕其中心旋转的两个角度。本文首先计算了通用几何设置下的确定性自由度，其研究范围超越了广泛研究的近轴情况。随后，提出了一个随机几何框架来研究统计自由度，这是研究近场网络系统级性能的第一步。应用于毫米波网络的数值结果揭示了近场通信所能提供的巨大自由度，并揭示了关键的系统级见解。