Async-Hop: Energy-Efficient Multihop LoRaWAN With On-Demand Event Transmissions

Abstract

Recently, the need for monitoring industrial and agricultural areas has led to the increased adoption of low power wide area network (LPWAN) sensor networks, which utilize a primary group of data transmission technologies. Long Range Wide Area Network (LoRaWAN) networks, which operate using a specific transmission protocol within the LPWAN framework, have gained significant importance in these applications due to their energy efficiency and cost-effectiveness. As monitored areas grow and become more remote, the traditional LoRaWAN protocol faces challenges in scalability and wide-area coverage. This issue is typically managed by adding additional gateways, though this solution increases both infrastructure costs and gateway-to-server connectivity complexity. Recent research has explored multihop schemes to address these limitations; however, these schemes currently support only periodic transmissions, as relay nodes require prior knowledge of transmission times to wake up and forward packets. This reliance on periodic transmissions limits the protocol’s flexibility, making it less responsive to non-periodic or event-driven data needs. This work introduces a novel approach that leverages wake-up radio (WuR), supporting not only periodic but also asynchronous and event-based data retransmissions while maintaining high energy efficiency. Therefore, this work overcomes the limitations of asynchronous and event-driven transmissions without requiring continuously active receivers, achieving high energy efficiency and supporting a theoretically unlimited number of hops. Extensive simulations demonstrate that the network capacity of the proposed LoRa multihop protocol outperforms that of a three-gateway topology, while also achieving higher energy efficiency than an Adaptive Data Rate (ADR)-enabled single-gateway LoRaWAN setup.