论文标题
可重新配置的智能表面，用于近场通信：光束形成和传感
Reconfigurable Intelligent Surface for Near Field Communications: Beamforming and Sensing
论文作者
论文摘要
可重新配置的智能表面（RIS）可以改善源和目的地之间的通信。最近，事实证明，连续的孔径比离散的光圈具有更好的沟通性能，并且受到了很多关注。但是，常规的连续孔径旨在将传入的平面波转换为传出的平面波，当接收器不是平面阵列并位于RIS的近场时，这不是最佳反射方案。在本文中，我们考虑了RIS的辐射接近磁场中的两种类型的接收器：（1）当接收器配备了均匀的线性阵列（ULA）时，我们设计了RIS系数以将平面波转换为圆柱波； （2）接收器配备了单个天线时，我们设计了RIS系数以将平面波转换为球形波。然后，我们提出最大似然（ML）方法和焦点扫描方法（FS）方法，以根据反射系数的分析表达来感知接收器的位置，并得出相应的位置误差（PEB）。模拟结果表明，与常规方案相比，提出的方案可以减少能量泄漏，从而扩大通道容量。此外，可以通过具有较大的计算复杂性的ML方法准确地检测到接收器的位置，或者通过较小的计算复杂性的FS方法大致感测。
Reconfigurable intelligent surface (RIS) can improve the communications between a source and a destination. Recently, continuous aperture RIS is proved to have better communication performance than discrete aperture RIS and has received much attention. However, the conventional continuous aperture RIS is designed to convert the incoming planar waves into the outgoing planar waves, which is not the optimal reflecting scheme when the receiver is not a planar array and is located in the near field of the RIS. In this paper, we consider two types of receivers in the radiating near field of the RIS: (1) when the receiver is equipped with a uniform linear array (ULA), we design RIS coefficient to convert planar waves into cylindrical waves; (2) when the receiver is equipped with a single antenna, we design RIS coefficient to convert planar waves into spherical waves. We then propose the maximum likelihood (ML) method and the focal scanning (FS) method to sense the location of the receiver based on the analytic expression of the reflection coefficient, and derive the corresponding position error bound (PEB). Simulation results demonstrate that the proposed scheme can reduce energy leakage and thus enlarge the channel capacity compared to the conventional scheme. Moreover, the location of the receiver could be accurately sensed by the ML method with large computation complexity or be roughly sensed by the FS method with small computation complexity.
