High Efficiency Distributed Beamforming RF Energy Transfer using a Closed-loop Energy Receiver

由于物联网(IoT)设备在我们的环境中扩散，环境射频(RF)能量(如来自Wi-Fi和蓝牙发射器的能量)的数量正在继续增加。然而，潜在的技术挑战阻碍了通过使用分布式波束成形为远程物联网设备收集有用的射频能量来有效组合来自多个发射机的能量。该项目旨在克服这些技术挑战，开发一种高效的分布式波束形成技术，将来自多个射频发射机的能量组合起来，并将其引导到远程物联网能量接收器。该项目还旨在开发一种高效率的RF-DC转换电路。它将使一种收集射频能量的新技术成为可能，这将对物联网、生物医学和遥感应用有用。这些技术对于在超低功率水平下收集具有波束形成能力的射频能量具有变革性。该项目的研究成果将与研究生水平的课程--电源管理集成电路(PMIC)课程整合在一起。本项目的所有设计和成果将在项目网站上公布。该项目还将通过高中暑期实习计划和东北大学未来转型领导者本科计划(Uplift)吸引本科生和高中生。该项目团队将与工程学院的多元文化工程项目合作，以增加参与NSF本科生研究体验(REU)项目的学生的多样性。参与该项目的研究生和本科生将接受半导体芯片设计方面的培训。该项目旨在开发一种基于分布式波束形成的高效射频能量采集技术，该技术将来自多个射频能量发射器的能量组合在一起，并将其引导到远程能量接收器。有效的分布式波束形成需要能量发送器和能量接收器之间的闭环优化。然而，实现闭环优化所需的感知和通信开销导致传统的分布式波束形成技术效率低下。为了克服通信的开销功耗，本项目将开发一种新的后向散射通信方法。后向散射通信系统将实现用于闭环优化的超低功率反馈技术。为了检测能量发射器之间的相位和频率偏差，还将开发一种基于超低功耗能量检测的新型传感平台。该项目还旨在开发一种新的RF-DC整流器拓扑结构，以在广泛的接收功率级别上实现高效的RF能量收集。伴随着RF-DC转换器的设计，将有一个最大功率跟踪方案，该方案将提供输出阻抗匹配，以实现整流器的最高效率工作点。波束成形、高效RF-DC转换、超低功率传感和后向散射通信的组合将使射频能量收集显著增加。该项目还包括开发一种将在无线网络中实施的射频能量传输协议。建议的解决方案的硬件演示将使用能源收集系统的测试芯片进行。该奖项反映了NSF的法定使命，并已通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The amount of ambient radio frequency (RF) energy, such as those from Wi-Fi and Bluetooth transmitters, is continuing to increase due to the proliferation of internet-of-things (IoT) devices in our environment. However, the underlying technological challenges have hindered the effective combination of energy from multiple transmitters by using distributed beamforming to harvest useful RF energy for a remote IoT device. This project aims to overcome these technological challenges to develop a high-efficiency distributed beamforming technique to combine energy from multiple RF transmitters and direct it to a remote IoT energy receiver. The project also aims to develop a high-efficiency RF-to-DC converter circuit. It will enable a new technique for harvesting RF energy which will be useful for IoT, biomedical, and remote sensing applications. These techniques are transformative for harvesting RF energy with beamforming capability at ultra-low power levels. The research outcomes from this project will be integrated with a graduate-level curriculum offering, a power management integrated circuits (PMIC) course. All designs and results of this project will be made public on the project website. This project will also engage undergraduate and high school students through a high school summer internship program and the Northeastern University’s Undergraduate Program for Leaders In Future Transformation (UPLIFT) program. The project team will work with the College of Engineering Multi-Cultural Engineering program to increase the diversity of students engaged in NSF Research Experiences for Undergraduates (REU) program. The graduate and undergraduate students participating in this project will be trained on semiconductor chip design. This project aims to develop a high-efficiency distributed beamforming-based RF energy harvesting technique that combines energy from multiple RF energy transmitters and directs it toward a remotely located energy receiver. Effective distributed beamforming requires closed-loop optimization between energy transmitters and the energy receiver. However, the overhead power consumption of sensing and communication needed to realize closed-loop optimization render conventional distributed beamforming techniques inefficient. To overcome the overhead power consumption of communication, this project will develop a new backscatter communication method. The backscatter communication system will enable an ultra-low-power feedback technique for closed-loop optimization. For sensing phase and frequency offset among energy transmitters, a new ultra-low-power energy detection-based sensing platform will also be developed. The project also aims to develop a new RF-to-DC rectifier topology to enable high-efficiency RF energy harvesting across a wide range of received power levels. Accompanying the RF-to-DC converter design will be a maximum power tracking scheme that will provide output impedance matching to realize maximum efficiency operating point for the rectifier. The combination of beamforming, high-efficiency RF-to-DC conversion, ultra-low-power sensing, and backscattering communication will enable a significant increase in RF energy harvesting. The project also includes development of an RF energy transfer protocol to be implemented in wireless networks. A hardware demonstration of the proposed solutions will be carried out using test chips of the energy harvesting system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.