Through field experiments, we observed a varying instantaneous charging capacity of the energy buffer with respect to the dynamic intensity of the incident RF signal in the RF energy harvesting system (RF-EHS). The dependency of charging capacity on the incident power of RF signal challenges existing RF energy harvesting models that assume constant charging capacity. In order to accurately describe the energy harvesting process in the real system, we propose a new energy clamp model. The new model reveals that RF intensity higher than the sensitivity of the harvester circuit cannot always guarantee successful energy reception, especially when the energy level of energy buffer is high while the intensity of the incident power is relatively weak. In order to improve the efficiencies of energy harvest and energy utilization in an RF-EHS, we develop new offline (i.e., non-causal) optimal and online (i.e., causal) suboptimal data transmission strategies based on the energy clamp model. Simulation results show that the new strategy can considerably improve the throughput after taking into account the varying instantaneous charging capacity caused by the dynamic RF power density in the air.

中文翻译：

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不同无线电功率密度对射频能量收集系统无线通信的影响


通过现场实验，我们观察到射频能量采集系统 (RF-EHS) 中能量缓冲器的瞬时充电容量随入射射频信号动态强度的变化。充电容量对射频信号入射功率的依赖性对假设充电容量恒定的现有射频能量收集模型提出了挑战。为了准确描述实际系统中的能量收集过程，我们提出了一种新的能量钳模型。新模型表明，高于采集器电路灵敏度的射频强度并不总是能保证成功的能量接收，特别是当能量缓冲器的能级较高而入射功率的强度相对较弱时。为了提高 RF-EHS 中能量收集和能量利用的效率，我们基于能量钳模型开发了新的离线（即非因果）最优和在线（即因果）次优数据传输策略。仿真结果表明，考虑到空气中动态射频功率密度引起的瞬时充电容量变化，新策略可以显着提高吞吐量。