Efficiency-Throughput Trade-off of Pulsed RF Waveforms in Simultaneous Wireless Information and Power Transfer

We study the receiver efficiency-throughput trade-off in a realistic radio frequency (RF) simultaneous wireless information and power transfer (SWIPT) system. Based on the energy harvesting receiver characteristics, we propose a continuously phase-modulated pulsed RF waveform to achieve maximum receiver efficiency at any input RF power level. We study the impact of varying the duty cycle of a pulsed RF waveform on the receiver efficiency of wireless power transfer along with the throughput of information transfer, and the trade-off thereof. The experiments confirm that a phase-shift keying (PSK) modulated pulsed RF waveform yields superior receiver efficiency than other digital baseband modulations as well as multisine signals despite they are designed particularly for power transfer. However, the optimal efficiency is attained at the expense of a significant loss in throughput due to pulsed transmission, depending on the average input RF power level.