OFDM Signaling for SWIPT Systems under High Power Amplifier Nonlinearities and Memory Effects

In this paper, we study the employment of conventional orthogonal frequency division multiplexing (OFDM) signals in simultaneous wireless information and power transfer (SWIPT) systems. Specifically, we investigate the impact of high peak-to-average power ratio (PAPR) on OFDM-based information/energy transfer under the nonlinearities and memory effects introduced by high power amplifier (HPA) at the transmitter. A closed-form expression of the symbol error rate (SER) as a function of the PAPR is derived for a Gaussian channel in this context. We notice that even under these realistic non-idealities, PAPR deteriorates the SER performance while facilitating energy transfer efficiency, as expected. To further enlarge the rate-energy (R-E) region, a predistortion scheme that allows the transmission of unclipped high PAPR OFDM signals is also proposed. Numerical simulations based on MATLAB and ADS software validate the impact of PAPR in SWIPT systems, regarding both the information detection and energy harvesting processes