Performance Analysis of Pulse Modulation Schemes for SWIPT in Non-Linear Terahertz Channel

The next-generation wireless networks operating in the Terahertz (THz) band have the potential to satisfy the diverse demands of their always-connected devices. Recent advances in device electronics and antenna design in the THz band herald the massive deployment of millimeter-scale Internet-of-Things (IoT) that often have limited battery capacity due to physical constraints. Consequently, the potential employment of simultaneous wireless information and power transfer (SWIPT) in the THz band emerges as a transformative paradigm shift, albeit complicated by challenges like molecular absorption loss and spectrum-efficient waveform design. In this paper, we demonstrate the applicability of low-complexity signal modulation schemes to achieve SWIPT to battery-less IoT devices in the THz band. Specifically, the comparative performances of two pulse-based THz signal modulation schemes, return-to-zero on-off keying (RZ-OOK) modulation and pulse position modulation (PPM), are analyzed for SWIPT from a transmitter to a rectenna-based receiver (RRx). To this end, tractable models are proposed for both wireless power transfer (WPT) and wireless information transfer (WIT) between the transmitter and RRx through a non-linear THz channel. The theoretical models are validated with circuit simulations comprising THz band GaAs Schottky diode to showcase the novel performance analysis of both pulse modulation schemes in terms of WPT and WIT metrics in the THz band.