FTN-Assisted SWIPT-NOMA Design for IoT Wireless Networks: A Paradigm in Wireless Efficiency and Energy Utilization

In the next-generation wireless Internet-of-Things (IoT) networks empowered by modern communication technology, nonorthogonal multiple access (NOMA) and faster-than-Nyquist (FTN) signaling are purportedly two enabling technologies that enhance spectral efficiency (SE) without requiring additional spectrum resources. In addition, simultaneous wireless information and power transfer (SWIPT) technology enables IoT sensors and devices to harvest energy from radio frequency (RF) signals, effectively mitigating power supply limitations. This article proposes and investigates a novel SWIPT-NOMA system based on FTN technology, referred to as FTN-assisted SWIPT-NOMA, for IoT relay networks over Rayleigh fading channels. We provide a comprehensive analysis of the ergodic capacity and achievable rate of the FTN-assisted SWIPT-NOMA system applied in IoT relay networks. Specifically, we explore two distinct relaying architectures geared toward augmenting SE and energy utilization, i.e., power-splitting (PS) and time-switching (TS). We derive approximated expressions for the ergodic capacity and analyze high- signal-to-noise radio (SNR) slopes for sensor users in both architectures. Simulation results show that the ergodic capacity of the proposed system surpasses that of the conventional Nyquist SWIPT-NOMA system, with greater capacity improvements as the FTN acceleration factor τ decreases. This highlights the substantial potential of FTN-assisted SWIPT-NOMA systems in enhancing the performance of IoT relay networks, particularly with respect to SE.