This paper presents a closed-loop frequency and phase correction technique for distributed beamforming to maximize the wireless radio frequency (RF) power transfer from multiple energy transmitters (TX) to an internet-of-things (IoT) device receiver (RX). A mathematical analysis of the received power loss due to frequency and phase offset that exists between transmitters, is used to establish a design methodology for frequency and phase correction among n-transmitters. Our analysis quantifies the received signal power in the presence of frequency and phase offsets and shows that an optimal frequency and phase correction can boost the combined signal strength by a factor of n2 from n-transmitters. Further, we present optimal conditions which can expedite the phase offset correction implemented using one-shot phase correction algorithm. Finally, we validate our frequency and phase offset correction technique to demonstrate a 9.5 dB improvement in received power from 3 transmitters using Universal Software Radio Peripheral (USRP) devices and commercial rectifier at 2.4 GHz for a distance of 3.3 feet between TX and RX. Our proposed closed-loop correction technique utilizes backscatter communication between TX and RX, which improves the energy efficiency of the distributed beamforming system.

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IEEE 物联网期刊学会信息


本文提出了一种用于分布式波束成形的闭环频率和相位校正技术，以最大限度地提高从多个能量发射器 (TX) 到物联网 (IoT) 设备接收器 (RX) 的无线射频 (RF) 功率传输。对由于发射机之间存在的频率和相位偏移造成的接收功率损耗进行数学分析，用于建立 n 个发射机之间的频率和相位校正的设计方法。我们的分析量化了存在频率和相位偏移的情况下接收到的信号功率，并表明最佳频率和相位校正可以将 n 个发射器的组合信号强度提高 n2 倍。此外，我们提出了可以加速使用一次性相位校正算法实现的相位偏移校正的最佳条件。最后，我们验证了我们的频率和相位偏移校正技术，证明使用通用软件无线电外围设备 (USRP) 设备和商用整流器的 3 个发射器在 2.4 GHz 频率下，TX 和 RX 之间距离 3.3 英尺的接收功率提高了 9.5 dB。我们提出的闭环校正技术利用 TX 和 RX 之间的反向散射通信，提高了分布式波束形成系统的能源效率。