A feasibility study of LoRaWAN-based wireless underground sensor networks for underground monitoring

With the continuous expansion of human interaction with the underground space, the observation of underground environment (e.g. soil moisture) and underground infrastructure (e.g. underground pipelines), as well as the monitoring and prevention of geological disasters (e.g., landslide and urban sinkholes) has attracted increasing attention and become a research focus. However, most of the traditional observation technologies are still facing difficulties in dynamic and continuous in-situ observations/monitoring within the complex underground environment. To solve this problem, this study adopts LoRaWAN-based wireless underground sensor networks (WUSNS) to monitor the underground environment or infrastructure. Furthermore, the feasibility of LoRaWAN-based WUSNs for underground monitoring is systematically demonstrated and presented in this article. Based on our recent validation of LoRa-based underground point-to-point channel model, we evaluate its network-level performance in this paper. We firstly develop a network simulator of LoRaWAN-based WUSNs to provide the feasibility analysis and experimental guidance for underground monitoring. Using this simulator, we numerically demonstrate that the LoRaWAN-based WUSNs technology is capable of underground monitoring over a large area and at great depths. We further certify that an appropriate selection of the physical layer parameters in various underground conditions is beneficial for underground observation. Finally, the balance between data receiver rate and network energy consumption can be implemented using different physical layer parameters for various underground monitoring applications. These results successfully demonstrate the efficient protocol development of LoRaWAN-based WUSNs and their applicability for underground monitoring applications.