Receiving ASK-OFDM in Low Power SWIPT Nodes without Local Oscillators

In this work we propose a method that enables utilizing (biased) amplitude modulated OFDM (bASK-OFDM) signals for low power Simultaneous Wireless Information and Power Transfer (SWIPT) receivers. This is a first step towards utilizing full OFDM signals for low power SWIPT applications. SWIPT emerged as a viable technology to realize the world of internet of things (IoT), SWIPT IoT receiver nodes should be small, power efficient and harvest both information as well as energy from the received RF signal. To make power and spectrum efficient SWIPT signals, multi-carrier waveforms should be used, ideally, with integrated information receiver architectures without a power consuming local oscillator. Receiving the proposed SWIPT modulation method is based on the intermodulations caused by the rectifier's diode, and allows to construct a bASK-OFDM signal that can be received and downconverted without LO. Our results show that adding a constant tone to the bASK-OFDM waveform suffices. The amplitude and phase of that tone can easily be tuned at design time. Measurement results validate the feasibility of the proposed technique and the general simulation results.