Long-range radio-frequency wireless charging has received more and more attention in recent years. Unlike the literature that focuses on the mobile charging scenario, which is formulated as a path-planning problem, we consider a static network that consists of a power beacon (PB) and multiple wireless powered user nodes. Each user node is equipped with a rechargeable battery and harvests energy only from the PB. We assume that all user nodes are either in charge or work mode. Under this assumption, we first propose a charge scheduling scheme that achieves the system’s maximal energy efficiency. We then further investigate the system’s improvement with a multiantenna PB using the energy beamforming technique. Next, we extend our scheduling scheme to a two-tier network architecture, where a first-tier PB first transfers energy to the second-tier sub-PBs, and then those sub-PBs deliver energy to the user nodes which belong to their clusters. It is shown that energy beamforming with multiple antennas brings a significant improvement to the system’s performance. Moreover, the two-tier architecture is shown to be superior to the one-tier architecture in terms of the energy transfer efficiency and the system’s realization complexity. Finally, the simulation results demonstrate our theoretical findings.

中文翻译：

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两层无线供电网络的面向能效的充电调度和波束成形


远距离射频无线充电近年来受到越来越多的关注。与关注移动充电场景（被表述为路径规划问题）的文献不同，我们考虑由电源信标（PB）和多个无线供电用户节点组成的静态网络。每个用户节点都配备了可充电电池，并且仅从 PB 获取能量。我们假设所有用户节点要么处于负责模式，要么处于工作模式。在此假设下，我们首先提出一种实现系统最大能源效率的充电调度方案。然后，我们使用能量波束成形技术进一步研究多天线 PB 系统的改进。接下来，我们将调度方案扩展到双层网络架构，其中第一层 PB 首先将能量传输到第二层子 PB，然后这些子 PB 将能量传输到属于其集群的用户节点。结果表明，多天线能量波束赋形对系统性能带来显着提升。此外，两层架构在能量传输效率和系统实现复杂度方面均优于一层架构。最后，模拟结果证明了我们的理论发现。