## 5 Results
### Coverage Analysis  
In this subsection, we first calculate the time during which a node has coverage from the gateway. Then, we calculate from those cases and with different bandwidth the amount of exchanged information  
Figure 8: Message exchange between the elements of the architecture. Figure 7: Algorithm of the node. between the node and the gateway and evaluate if this is enough to send the data stored in the node during the day. Before starting to analyze the theoretical results, some assumptions must be made related to the connection and the density of nodes on the soil. * First, we must consider the time required to establish the connection. We performed tests in real environments to determine the time required by Arduino nodes to establish the connection between each other. The results showed connection establishment times ranging between 2 and 4 s. To ensure the connection of the nodes, we will consider the worst-case scenario of connection time of 4 s. Since the data are forwarded after the connection establishment, we will consider 5 s of total required time for connection establishment and data transmission. Therefore, all the combinations of _dc_ and _fh_ that give, as a result, a time in coverage equal to or less than 5 s are considered as unfeasible scenarios for connection. Since the current velocities in WiFi have increased in the last years and the gathered data by the sensors are small, we can consider that all the information can be sent in this period of 5 s.
* Moreover, all the coverage areas do not have the same properties in terms of signal strength. The further points have lower Received Signal Strength Indicator (RSSI) values, and the connection will be difficult in those situations. Nonetheless, the estimation of the effects of RSSI on the establishment of the connection is not the purpose of this paper. * Finally, regarding the density of nodes, we must consider the number of nodes that will be able to connect to the drone at the same moment and that have to share their time in coverage. There is a different type of scenario regarding node density in precision agriculture. The densest cases are related to the intensive agriculture of fruit-bearing trees such as orchards. The farmers used to grow their trees in a density of one tree each 16 to 20 m\({}^{2}\). In the case that we have one node per tree, the node density will be one node each 16 to 20 m\({}^{2}\). Nonetheless, this is not usual, since the conditions of the soil and irrigation techniques are relatively homogeneous. Therefore, we can expect that in the densest networks, we have one node every three or four trees, having a density of one node each 60 m\({}^{2}\). Other scenarios can include cereal or energetic crops. In these cases, the crops create a uniform soil coverage, and it is not possible to differentiate the individual plants. Moreover, as the outcomes of these crops are much lower than in the case of fruit-bearing trees, the investment in precision agriculture is lower. In addition, if we consider that most of the cereals and energetic crops do not need irrigation, the node density can be further lower. It is no exaggeration to say that in these cases, we can have only one node in each field having node densities of one each 5000 m\({}^{2}\) or even more. In between both cases, we can find another example of fruit-bearing trees as olive trees. The density of trees in the field is lower than in the case of orchards. Moreover, since no irrigation systems are used in the culture of olive trees, the monitoring requirements are lower. Thus, we can expect densities of one node each 750 m\({}^{2}\) in the cropping of this type of crop. Nevertheless, the final density will be a factor that the farmer will define.