This letter studies an unmanned aerial vehicle (UAV) aided multicasting (MC) system, which is enabled by simultaneous free space optics (FSO) backhaul and power transfer. The UAV applies the power-splitting technique to harvest wireless power and decode backhaul information simultaneously over the FSO link, while at the same time using the harvested power to multicast the backhauled information over the radio frequency (RF) links to multiple ground users (GUs). We derive the UAV's achievable MC rate under the Poisson point process (PPP) based GU distribution. By jointly designing the FSO and RF links and the UAV altitude, we maximize the system-level energy efficiency (EE), which can be equivalently expressed as the ratio of the UAV's MC rate over the optics base station (OBS) transmit power, subject to the UAV's sustainable operation and reliable backhauling constraints. Due to the non-convexity of this problem, we propose suboptimal solutions with low complexity. Numerical results show the close-to-optimal EE performance by properly balancing the power-rate tradeoff between the FSO power and the MC data transmissions.

中文翻译：

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具有同步 FSO 回程和电力传输功能的节能无人机组播


这封信研究了一种无人机 (UAV) 辅助多播 (MC) 系统，该系统通过同步自由空间光学 (FSO) 回程和电力传输来实现。无人机应用功率分割技术通过 FSO 链路同时收集无线功率和解码回程信息，同时使用收集到的功率通过射频 (RF) 链路将回程信息多播到多个地面用户 (GU) ）。我们推导出基于泊松点过程 (PPP) 的 GU 分布下无人机可实现的 MC 速率。通过联合设计FSO和RF链路以及无人机高度，我们最大限度地提高了系统级能效（EE），它可以等效地表示为无人机的MC速率与光学基站（OBS）发射功率的比率，无人机的可持续运行和可靠的回程约束。由于该问题的非凸性，我们提出了低复杂度的次优解决方案。数值结果显示，通过适当平衡 FSO 功率和 MC 数据传输之间的功率速率权衡，可实现接近最佳的 EE 性能。