# An Autonomous Wireless Device for Real-Time Monitoring of Water Needs
## 1 Introduction  
Some of the main problems that the world population faces today, and on which researchers from all over the world are working, are globalization, global warming, and the supply of food. In order to address the latter, it is necessary to develop modern solutions that allow the optimization of costs and increased yields, such as the smart management of water for precision irrigation in agriculture [1; 2].  
In recent years, many researchers have been integrating the concept of the Internet of Things (IoT) into the field of agriculture, thus helping the development of what is known as precision agriculture. Precision agriculture aims to provide a decision support system that helps farmers to implement efficient agricultural practices, with the aim of increasing profitability, reducing environmental risks, and preserving natural resources [3; 4].  
So-called smart agriculture or digital agriculture uses intelligent networks and data management tools to employ all of the information and experience available in order to enable the automation of sustainable processes in agriculture. This agriculture is based on connected and knowledge-based agricultural production systems and makes great use of information and communication technologies (ICT), both for data collection and for subsequent processing. For this reason, the design and implementation of efficient and economic devices in agriculture are currently an important line of research [5].  
Due to the characteristics of the agricultural sector, the use of wired systems for the collection of information is practically unfeasible, which is why work is currently underway to develop wirelesssensor networks (WSNs) in order to minimize the economic cost and impact of installation in agricultural environments, thus avoiding hindering the work of the farmer [5; 6].  
WSN solutions for establishing different parameters in agriculture should include certain requirements for smaller farmers to implement this type of system on their farms, such as inexpensive devices (i.e., the cost of a radio chipset being less than 2C and an operating cost of 1C per device per year), low energy consumption (i.e., 10+ years of battery lifetime), and a long range of communication (i.e., up to 10-40 km in rural zones)--three areas in which we must work in the future [2; 7; 8].  
Currently, there are some challenges to be overcome that still prevent the use of IoT for irrigation. Firstly, there are still many rural areas that do not have Internet connectivity. Secondly, they do not have electricity either. Thirdly, monitoring with soil sensors requires scalability, but this comes at a price. Finally, the integration of different and advanced sensors requires adequate standards. In order to solve the aforementioned problems, this paper develops and assesses an inexpensive WSN solution based on long-range (LoRa) technology with very low power consumption and high autonomy to control water needs for precision irrigation in agriculture.  
Many additional mechanisms have been proposed to increase the battery life of WSN end-devices and to accomplish energy saving, irrespective of whether the devices are already of low consumption. However, we found it difficult to compare them due to the diversity of the methodologies, end-device components, sensors used, and types of experiment.  
Therefore, the main contribution is that due to the fact that existing WSN systems for precision irrigation are mostly theoretical with limited proof of concept experiences in practice, providing details of devices and equipment as well as irrigation techniques [2; 4], this work compares consumption to show a more energy-efficient end-device configuration.