Energy-Efficient Data Transfer in Delay-Throughput Constrained Small-World LPWAN Using RISs

Abstract

Low power wide area network (LPWAN) is emerging as a recent wireless technology to support the Internet of Things (IoT). However, LPWAN suffers from low device lifetime due to its star topology and heavy data generation by the Internet of Things devices (IoDs). Moreover, the performance of data latency and data throughput degrades due to obstacles present between IoD and gateway. In this work, we address the challenges of energy efficiency, data latency, and data throughput in a mobile LPWAN using active reconfigurable intelligent surfaces (RISs). The proposed method utilizes mobile active RISs to introduce small-world characteristics (SWC) in the network, which results in low average path length and high average clustering coefficient. Subsequently, the proposed RIS-assisted LPWAN method computes the optimal number of RISs required to introduce optimal SWC. An optimization problem is formulated to optimize the data latency, energy consumption, and data throughput, keeping the active RIS's reflection and amplification properties and SWC measures in constraints. Finally, the performance of the proposed method is compared with the existing methods of data routing, taking into account various network parameters such as the optimal number of RIS needed to optimize the network data latency, energy consumption, and data throughput. The results obtained validate the significance of utilization of the proposed method when compared to conventional multi-hop data routing, direct data transmission, LEACH protocol, and passive RIS-based data forwarding scheme.