Abstract
The possibility to harvest energy from ambient radio-frequency (RF) sources has intrigued humankind for the past several decades. In this context, there has been a tremendously growing research interest in the field of wireless power transfer (WPT) using the RF range of the electromagnetic (EM) spectrum. In this paper, we experimentally investigate the aspect of real-time energy harvesting (EH) via different types of waveform designs such as orthogonal frequency division multiplexing (OFDM), square, triangular, sinusoidal, and sawtooth. We make use of a Software Defined Radio (SDR) and a Powercast P21XXCSR-EVB EH module to carry out the experiments on a practical device to assess performance. Specifically, we are interested in obtaining some insights based on the comparison between the aforementioned waveform designs from the perspectives of the separation distance between the USRP and P21XXCSR-EVB EH module, and power emission via USRP. In this vein, we perform additional subsequent experiments after reporting the practical effectiveness of the OFDM waveform, which also follows our intuitive analysis. Correspondingly, we study the effect on WPT with variable USRP transmit power, the separation distance between the USRP and EH antennas, number of OFDM sub-carriers, and multipath setting. As an application of OFDM, the effectiveness of fifth generation-new radio (5G-NR) and long-term evolution (LTE) waveforms are also tested for the WPT mechanism. The demonstration of the EH is provided in terms of the above-mentioned investigation metrics while seeking the best waveform to support WPT.
Highlights
W ITH each passing year, we are inching closer and closer towards realizing a smart and connected society
After having discussed the process of generating 5G-NR and 4G long-term evolution (LTE) waveforms, we present some experimental results based on variable Universal Software Radio Peripheral (USRP) transmit power (τ ) and different modulation schemes, denoted by M
We note that all the considered waveforms perform nearly equal in terms of the wireless power transfer (WPT) process keeping in mind the practical hardware imperfections, where no significant difference is observed in the performance
Summary
W ITH each passing year, we are inching closer and closer towards realizing a smart and connected society. It is important to note the increasing presence of low-power consuming internet-of-things (IoT) devices. These devices primarily serve the purpose of data collection in the form of various types of sensors (e.g., temperature, pressure, etc.), bounded by the strict battery limitations. To address the battery charging issues where the devices are placed at very remote places, while taking into consideration the data exchange process; the possibility to use radio-frequency (RF) signals as a wireless charging means along with the traditional information transmission has gained due attention [1]. While the theoretical findings motivate the use of multi-sine type waveform designs
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