RlS-empowered self-sustainable Internet of Things (loT) networks

Abstract

With the rapid development of the Internet of Things (IoT), there is an increasing demand for wireless communication networks that can support power-constrained devices with improved performance and energy sustainability. Reconfigurable Intelligent Surfaces (RIS) have recently attracted considerable attention due to their capability of reconfiguring wireless propagation environments, providing additional degrees of freedom for enhancing wireless transmission. Recent studies on RIS-assisted Wireless Powered Communication Networks (WPCNs) have demonstrated their potential in improving system throughput through techniques such as joint phase-shift and time allocation optimization. However, existing works often face challenges including high computational complexity, reliance on accurate channel state information (CSI), or limited investigation of practical system configurations.

This thesis aims to investigate how RIS can be effectively integrated with WPCNs to enhance system throughput by jointly optimizing the RIS phase-shift matrix and the time allocation between Wireless Energy Transfer (WET) and Wireless Information Transfer (WIT). The optimization objective is to maximize the uplink sum throughput subject to users’ energy harvesting constraints, ensuring that sufficient harvested energy is available for reliable data transmission.

To address this problem, an optimization framework is developed to coordinate the RIS configuration and transmission time allocation in RIS-assisted WPCNs. By jointly designing the RISphaseshiftsandtheWET/WITtimeallocation,theproposedframeworkenablesmoreefficient utilization of the wireless propagation environment and harvested energy. The formulation is further solved using appropriate optimization techniques to obtain efficient solutions with manageable computational complexity.

The proposed framework is evaluated through numerical simulations under various system configurations. The results demonstrate that RIS-assisted WPCNs can achieve higher uplink sum throughput compared with benchmark schemes without RIS or without joint optimization. In particular, the results indicate that proper RIS phase-shift design combined with effective time allocation plays a key role in improving throughput performance in wireless powered IoT networks.

Date of Award	15 Jan 2026
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Zheng Chu (Supervisor) & David Chieng (Supervisor)