Environmental monitoring of coastal waters with a collaborative underwater acoustic and above water LoRaWAN sensor network

Climate changes are transforming the world as we know it and have a devastating impact on frail areas, such as coasts, afflicted by catastrophic events (rise in seawater temperature, floods) deteriorating the local biodiversity. Between the strategies undertaken to mitigate these effects, the EU Biodiversity Strategy for 2030 is one of the most ambitious. In particular, a relevant point is the inclusion of new solutions to monitor the conditions of the water, measuring specific parameters and polluting agents. However, up to today, there is no common ground when dealing with low-cost and low-power devices to collect data related to the quality of the water in coastal areas: a dense deployment of sensors would be the best option, but the technology used for long-range underwater acoustic communication is indeed extremely expensive. Nonetheless, in the last few years researchers have been investigating the possibilities given by low-cost and low-power acoustic modems, in the attempt to provide a way to employ dense deployment of underwater nodes. Another major turn in long-range low-power communications is the introduction of Low-Power Wide-Area Networks (LPWAN), which can be regarded as one of the most crucial entries in Internet of Things (IoT) applications. With this dissertation, we propose a network infrastructure for the tracking and the study of water quality parameters, to understand the impact they have on biodiversity. Specifically, we envision a system where there are two types of sensor nodes; one underwater and another on the water surface, forwarding the data they aggregate to one or more gateways. The gateways are connected to the Internet so that the data can be saved in a database for further processing. Underwater nodes use a part of the surface nodes as relays basing on an acoustic communication protocol, while the remaining surface nodes generate sensor data themselves; LoRa (together with LoRaWAN) has been chosen as the core LPWAN, enabling the long-range communication between the surface nodes and the gateways. Finally, the gateways are connected to the Internet with LTE standard. Simulations have been run to estimate the traffic requirements of the network as well as the feasibility of the system and a functioning prototype of a surface node has been developed. We selected a section of the Venice lagoon as reference area where our network could eventually be put in place, thus the simulations have been set according to this scenario. Also, the low-cost prototype has been tested and proved its full operativity.