Waveforms and End-to-End Efficiency in RF Wireless Power Transfer Using Digital Radio Transmitter

Abstract

We study radio frequency (RF) wireless power transfer (WPT) using a digital radio transmitter for applications where alternative analog transmit circuits are impractical. An important parameter for assessing the viability of an RF WPT system is its end-to-end efficiency. In this regard, we present a prototype test bed comprising a software-defined radio (SDR) transmitter and an energy-harvesting receiver with a low resistive load; employing an SDR makes our research meaningful for simultaneous wireless information and power transfer (SWIPT). We analyze the effect of clipping and nonlinear amplification at the SDR on multisine waveforms. Our experiments suggest that when the direct current (dc) input power at the transmitter is constant, high peak-to-average power ratio (PAPR) multisines are unsuitable for RF WPT over a flat-fading channel, due to their low average radiated power. The results indicate that the end-to-end efficiency is positively correlated with the average RF power of the waveform and that it reduces with increasing PAPR. Consequently, digital modulations, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), yield better end-to-end efficiency than multisines. Moreover, the end-to-end efficiency of PSK and QAM signals is invariant to the transmission bit rate. An in-depth analysis of the end-toend efficiency of WPT reveals that the transmitter efficiency is lower than the receiver efficiency. Furthermore, we study the impact of a reflecting surface on the end-to-end efficiency of WPT and assess the transmission quality of the information signals by evaluating their error vector magnitude (EVM) for SWIPT. Overall, the experimental observations of end-to-end efficiency and EVM suggest that, while employing an SDR transmitter with fixed dc input power, a baseband quadrature PSK signal is most suitable for SWIPT at large, among PSK and QAM signals.Index Terms-Nonlinear distortion, radio frequency (RF) energy harvesting (EH), simultaneous wireless information and power transfer (SWIPT), software-defined radio (SDR), wireless power transfer (WPT).

UAV-aided data and energy integrated network: System design and prototype development

“…There are also some existing works focusing on prototyping a link-level SWIPT system [23][24][25][26][27][28]. Specifically, a multi-band rectifier was presented in [23], which can be used for MIMO energy harvesting system.…”

“…Khemar et al [25] designed a rectifier achieving the RF-DC conversion efficiency of 45%, which can be used for ambient RF energy harvesting. Ayir et al [28] study the waveforms and end-to-end efficiency in RF WET using a digital radio transmitter(DAT). Their experiments suggest that when the direct current (DC) input power at the transmitter is constant, high peak-to-average power ratio (PAPR) multi-sines are unsuitable for RF WET over a flat-fading channel, due to their low average radiated power.…”

Uniform and constant long-time wireless power transmission of multi-targets in local space based on time reversal

“…在智慧医疗、智能工厂以及智慧家 居等场景应用中, 输能非均匀将会导致场景中部分 传感器处于电压过高或过低的不健康工作状态, 长 期工作将会导致传感器的损坏甚至物联网设备的 故障. 此外, 输能非均匀还会导致能源不合理的低 效分配, 造成电能浪费的问题 [20,21] . 因此, 研究解 决输能非均匀问题至关重要.…”

Wireless Charging Constant Power Output System Based on LCC/S-S Self-Switching

“…The driving signal of the inverter circuit issued by the MCU is not only sent to the half-bridge driver module IR2014S through the HCPL optocoupler isolation module to drive the full-bridge inverter circuit; but also regulates the input voltage by controlling the conduction of MOSFET. The topology switching control signal sent by it controls the switching action of the relay [24,25]. The relay module adopts electromagnetic mode, and its control characteristics of low voltage and low current make it have low power loss, which can realize effective switch of topology structure.…”