A Study on OFDM Modulation Suitable for Wireless Power Transfer

The number of IoT devices is expected to increase enormously toward the realization of Society 5.0. There is a major issue in supplying power to these devices. We study the wireless power transfer (WPT) to these devices using existing communication base stations. We also consider creating a modulation signal for WPT using resource blocks that are not used for communication. For this purpose, we will study what kind of modulation signal is suitable for WPT, assuming Orthogonal Frequency Division Multiplexing (OFDM) modulation. We propose to use a Zadoff-Chu sequences with low Peak to Average Power Ratio (PAPR) as the modulating signal for WPT. This proposed modulation signal has a lower PAPR than the 64Quadrature Amplitude Modulation (QAM) signal used in communications. Therefore, the backoff can be reduced in the transmitter, and higher power can be output when the proposed signal is output. Furthermore, we evaluate that the proposed modulation signal provides higher rectification efficiency than 64QAM in the region where the input power of the rectifier circuit is high.