On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer With Nonlinear Energy Harvesting
On the Beneficial Roles of Fading and Transmit Diversity in Wireless Power Transfer With Nonlinear Energy Harvesting
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DOI：
10.1109/twc.2018.2870377
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发表时间：
2018-09
影响因子：
10.4
通讯作者：
B. Clerckx;Junghoon Kim
中科院分区：
文献类型：
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作者：
B. Clerckx;Junghoon Kim
研究了信道衰落对无线功率传输(WPT)的影响，表明衰落提高了非线性射频能量采集器的射频-直流转换效率。然后，我们提出了一种新的WPT信号设计形式，称为发射分集，它依赖于发射端的多个哑天线来诱导无线信道的快速波动。这些波动提高了RF-DC转换效率，这要归功于能量采集器的非线性。与(能量)波束形成相比，发射分集不依赖于发射机(CSIT)的信道状态信息，并且不增加能量收集器输入的平均功率，即使它仍然提高了整体端到端的功率传输效率。发射分集还与最近开发的(能量)波形和调制相结合，以提供进一步的增强。基于物理模型和基于曲线拟合的非线性模型对该方案的有效性进行了分析，并通过电路仿真、样机和实验验证了该方案的有效性。用两个发射天线进行的测量表明，在单个发射天线设置下，收获的直流功率可获得50%的增益。这项工作(再次)突出了收割机非线性所起的关键作用，并证明了即使在没有CSIT的情况下，多个发射天线也可以对WPT有利。
We study the effect of channel fading in wireless power transfer (WPT) and show that fading enhances the RF-to-DC conversion efficiency of nonlinear RF energy harvesters. We then develop a new form of signal design for WPT, denoted as transmit diversity, that relies on multiple dumb antennas at the transmitter to induce fast fluctuations of the wireless channel. Those fluctuations boost the RF-to-DC conversion efficiency thanks to the energy harvester nonlinearity. In contrast with (energy) beamforming, transmit diversity does not rely on channel state information at the transmitter (CSIT) and does not increase the average power at the energy harvester input, even though it still enhances the overall end-to-end power transfer efficiency. Transmit diversity is also combined with recently developed (energy) waveform and modulation to provide further enhancements. The efficacy of the scheme is analyzed using physics-based and curve fitting-based nonlinear models of the energy harvester and demonstrated using circuit simulations, prototyping and experimentation. Measurements with two transmit antennas reveal gains of 50% in harvested DC power over a single transmit antenna setup. The work (again) highlights the crucial role played by the harvester nonlinearity and demonstrates that multiple transmit antennas can be beneficial to WPT even in the absence of CSIT.