On the Design of RIS-UAV Relay-Assisted Hybrid FSO/RF Satellite-Aerial-Ground Integrated Network
On the Design of RIS-UAV Relay-Assisted Hybrid FSO/RF Satellite-Aerial-Ground Integrated Network
复制标题
RIS-UAV中继辅助混合FSO/RF星地天地一体化网络设计
DOI：
10.1109/taes.2022.3189334
复制
发表时间：
2022
影响因子：
4.4
通讯作者：
Pham Anh T.
中科院分区：
文献类型：
--
作者：
Nguyen Thang V.;Le Hoang D.;Pham Anh T.
星空地一体化网络（SAGIN）被广泛认为是一种有前景的 6G 网络架构。在 SAGIN 中，使用混合自由空间光学 (FSO)/射频 (RF) 通信的高空平台 (HAP) 辅助中继卫星系统最近吸引了全世界的研究工作。然而，混合 FSO/RF 系统的主要缺点是 RF 连接的带宽有限，尤其是当 FSO 系统被云覆盖阻挡时。本文探讨了一种在天气和大气条件影响下基于 FSO/RF HAP 的混合 SAGIN 的新颖解决方案。具体来说，部署额外的无人机 (UAV) 将 FSO 链路从 HAP 到地面站进行分流，以避免云阻塞，同时保持 FSO 链路的高速连接。无人机上安装了采用新兴技术可重构智能表面（RIS）构建的反射镜阵列，用于反射来自HAP的信号。 RIS-UAV 的通道模型考虑了大气湍流和悬停引起的指向误差。此外，我们提出了一种新颖的链路交换设计，具有针对不同天气和湍流条件下所提出的网络的多速率自适应方案。数值结果定量地证实了我们建议的有效性。此外，我们还提供了富有洞察力的讨论，有助于使用混合 FSO/RF 链路进行 RIS-UAV 辅助的基于 HAP 的 SAGIN 的实际系统设计。还进行蒙特卡罗模拟以验证理论推导的准确性。
Satellite–aerial–ground integrated network (SAGIN) has been widely envisioned as a promising network architecture for 6G. In the SAGINs, high-altitude platform (HAP)-aided relaying satellite systems using hybrid free-space optics (FSO)/radio-frequency (RF) communications have recently attracted research efforts worldwide. Nevertheless, the main drawback of hybrid FSO/RF systems is the restricted bandwidth of the RF connection, especially when the FSO one is blocked by cloud coverage. This article explores a novel solution for the hybrid FSO/RF HAP-based SAGIN under the impact of weather and atmospheric conditions. Specifically, an additional unmanned aerial vehicle (UAV) is deployed to diverse the FSO link from the HAP-to-ground station to avoid cloud blockage while maintaining a high-speed connection of the FSO link. A mirror array constructed by reconfigurable intelligent surface (RIS), an emerging technology, is mounted on the UAV to reflect the signals from the HAP. The channel model of RIS–UAV takes into account both atmospheric turbulence and hovering-induced pointing errors. Furthermore, we present a novel link switching design with a multirate adaptation scheme for the proposed network under different weather and turbulence conditions. Numerical results quantitatively confirm the effectiveness of our proposal. Additionally, we provide insightful discussions that can be helpful for the practical system design of RIS–UAV-assisted HAP-based SAGIN using hybrid FSO/RF links. Monte Carlo simulations are also performed to validate the accuracy of theoretical derivations.