Reconfigurable Intelligent Surfaces (RIS) or Intelligent Reflecting Surfaces (IRS) are metasurfaces that can be deployed in various places in wireless environments to make these environments controllable and reconfigurable. In this paper, we investigate the problem of using 3D beamforming in RIS-empowered wireless networks and propose a new scheme that provides more degrees of freedom in designing and deploying the RIS-based networks. In the proposed scheme, a base station (BS) equipped with a full dimensional array of antennas optimizes its radiation pattern in the three-dimensional space to maximize the received signal to noise ratio at a target user. We also study the effect of angle of incidence of the received signal by the RIS on its reflecting properties and find a relation between this angle and the BS antenna array's tilt and elevation angles. The user receives the signal from a reflected path from the RIS as well as from a direct path from the BS which both depend on the BS antenna array's tilt and elevation angles. These angles and also the RIS element's phase shifts are jointly numerically optimized. Our simulation results show that using RIS-assisted 3D beamforming with optimized phase shifts and radiation angles can considerably improve the performance of wireless networks.

中文翻译：

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可重构智能表面辅助无线通信网络中的 3D 波束成形

可重构智能表面 (RIS) 或智能反射表面 (IRS) 是超表面，可以部署在无线环境中的各个位置，使这些环境可控和可重构。在本文中，我们研究了在基于 RIS 的无线网络中使用 3D 波束成形的问题，并提出了一种新方案，该方案为设计和部署基于 RIS 的网络提供了更多的自由度。在所提出的方案中，配备全维天线阵列的基站 (BS) 在三维空间优化其辐射模式，以最大化目标用户的接收信噪比。我们还研究了 RIS 接收信号的入射角对其反射特性的影响，并找到了该角度与 BS 天线阵列之间的关系 s 倾斜角和仰角。用户从 RIS 的反射路径以及来自 BS 的直接路径接收信号，这两者都取决于 BS 天线阵列的倾斜角和仰角。这些角度以及 RIS 元件的相移都经过联合数值优化。我们的仿真结果表明，使用具有优化相移和辐射角的 RIS 辅助 3D 波束成形可以显着提高无线网络的性能。