## 1 Introduction  
In arid and semi-arid zones, such as the southeast of Spain, the agriculture yield is conditioned by limiting factors, the main one being the available irrigation water. Regulated deficit irrigation (RDI) techniques allow controlling the water applied to the crop in critical and non-critical phenological stages, determining periods where the crop can be irrigated with much less water. Therefore, these techniques have been widely used in these areas where water is a scarce resource [1, 2, 3]. However, the application of RDI strategies is conditioned by crop and climatic conditions. The development of irrigation models specifically designed for a crop would allow the application of RDI for water optimization purposes. In order to develop these models, it is necessary to carry out several comparative tests on different areas of the same crop, where the conditions of the applied RDI are modified. By studying the production and soil and plant water relations on trees subjected to the different treatments, it is possible to determine the most appropriate models for optimal irrigation management. In order to establish these RDI models, sensors that report on the state of the soil, plant and atmosphere are required. In addition, to achieve sufficient precision, it is important to have several repetitions of the measurements deploying different deficit irrigation regimes to obtain relations among the agronomic results and the water stress indicators studied [4, 5, 6]. Sensor networks are widely used when a high density of instrumentation is required on test plots. In the particular case of wireless sensor networks (WSN), their usefulness hasbeen demonstrated in different papers [7; 8; 9; 10], where the absence of wiring has resulted in a very important improvement in terms of installation flexibility and time savings in installation and maintenance. Several protocols have been described in the bibliography for the deployment of WSN in precision agriculture (PA) [11; 12]. Zigbee is one of the most commonly used technologies in recent years with positive results [13; 14; 15; 16; 17; 18], although it is claimed that ZigBee communication has the problem of short distance, complicated networking and high communication frequency [19]. From the experience of our research group in previous installations, in which we deployed WSNs with Zigbee nodes [20; 21; 22; 23], we found significant drawbacks such as the high maintenance required by the nodes, the difficulty of programming the Zigbee stack, the high price of the software licenses and the limited availability of microcontrollers that supported this stack. Some authors such as [11], who conducted a comprehensive review of WSN technologies and their applications in PA, claim that the most suitable technology for this type of applications is narrowband internet of things (NB-IoT). A well-known example is long-range radio (LoRa), which allows very low energy consumption and long life (i.e., 10 years with battery), low cost, wide coverage and large networks (52,000 devices/channel/cell). This is why LoRa is being used extensively in IoT applications in all fields, including PA [19; 24; 25; 26; 27; 28; 29; 30; 31; 32]. However, there are numerous WSN deployments in PA that use 802.11 wireless fidelity (Wi-Fi) [33; 34; 35; 36; 37; 18]. It is important to highlight that the suitability of each technology in terms of range, robustness and, above all, in terms of instrumentation capacity, must be analyzed and studied to use it properly. Wi-Fi networks have also been used previously in other disciplines such as post-harvest for monitoring perishable products in transport and conservation [39]. The sensor network described in this article aims to support agronomic trials to relate criteria of deficit irrigation in almond trees with measured values of soil-plant-atmosphere. To this end, it is necessary to study different deficit irrigation treatments.