Signal Conditioning for Selective OFDM SWIPT Systems

The conversion efficiency of a harvesting component can hinder device self-sustainability. Countering this inefficiency can be a rigorous task that requires either a modified input waveform at the harvesting component or an improved design of the harvesting component itself. This paper considers a selective orthogonal frequency division multiplexing (OFDM) system that is designed for simultaneous wireless information and power transfer (SWIPT). This paper introduces an enhanced transmitter architecture designed to condition the transmit signal for improved conversion efficiency. Leveraging the structure of the OFDM signal, the cyclic prefix plus a portion of the information signal are conditioned and used for harvesting. Then, a rectifier model and prototypes are designed to further improve conversion efficiency. System performance is evaluated with the analytical derivation of the rate-energy (R-E) tradeoff and an optimized transmission strategy for system self-sustainability. Monte Carlo simulations show increased energy gains and full self-sustainability with the introduction of signal conditioning.