LoRaWAN "breadcrumbs": Location-Aware Multi-Hop for the Monitoring of Workers in Underground Environments

This paper proposes a novel sensing infrastructure to enhance the safety of workers operating in underground environments, such as mines or railway tunnels. The system combines a wearable sensing platform with an innovative Long Range Wide Area Network (LoRaWAN)-based linear multi-hop network. The sensing platform collects data on environmental parameters, including concentrations of explosive gases and other chemical substances. The LoRaWAN network is supported by a series of portable relays, referred to as "Breadcrumbs", to be deployed by workers at specific intervals before starting their activities. The aim of this deployment is to establish a continuous linear link throughout the underground environment. A network protocol is proposed for the propagation of information from the initial receiving nodes through the intermediate relays. The target of the proposed protocol is also to estimate the worker's approximate position, which is crucial for locating individuals in case of an accident.