## 5 Results
### Coverage Analysis
With this _fv_, the maximum _fh_ for different _dc_ values increases significantly compared with previous velocities; for _dc_ = 25, 5 m, the maximum _fh_ are 14, 44 m. Nonetheless, for _dc_ values of 75 and 100 m, the maximum _fh_ is the same as in the previous velocities, and for _dc_ values higher than 100 m, the communication is feasible at all the _fh_. Following, in Figure 12, we can see the theoretical values of time in coverage for _fv_ = 5 m/s. The maximum time in coverage increases to 80 s with _dc_ of 200 m and _fh_ of 4 m. For the _dc_ of 25 m, the maximum _fv_ where it is possible to establish a communication with a single node is 19 m. For other _dc_ in all the cases where there is coverage for the sensor, the time in coverage is high enough to establish the connection and communicate the data. In Figures 2-12, we presented the time in coverage of a single node and evaluated if this node will be able to transmit the information or not according to the required time to establish the connection and send data, which has been set in 5 s. Next, we are going to analyze for each combination of _dc_ and _fh_ the area in the soil which has coverage. Then, according to the aforementioned node densities in Table 3, we calculate the number of nodes that will have coverage in a certain period and need to send their data to the gateway. According to the time in coverage, the minimum required time to establish a connection, send the data, and close the connection, and the number of nodes, we estimate if the drone can be used to receive all the data of the WSN or not. The summary of different considered  
Figure 11: Time in coverage when a drone flies at 10 m/s and different _dc_. Figure 10: Time in coverage when a drone flies at 15 m/s and different _dc_. scenarios and the results in terms of the success or not of the connection are presented in Figure 13. In Figure 13, we can identify in different rectangles the different scenarios, which combine different node densities and _fv_. In each scenario, we can consider the combination of _dc_ and _fh_ in the x and y-axis. Thus, we cover all the parameters that affect the success or not of the gathering of all data stored in the nodes placed in the soil. The success of the connection is indicated in colors; the area colored in gray indicates that there is no coverage (NC) for this combination of _fh_ and _dc_. This is found when the _fh_ is higher than the _dc_. The areas in red represent combinations of _dc_ and _fh_ when even that we have coverage, the time in coverage is too short for ensuring the transmission of data from all the nodes. It means that the time in coverage of the nodes contained in the area in coverage is lower than 5 s for each one and the gathering of data contained in the nodes cannot be attained. Combinations colored in yellow represent the combination of _dc_ and _fh_ that can be used to receive the data but with very adjusted time. Therefore, if an unexpected problem such as punctual loss of connection appears during the communications, it can endanger the collection of the data of certain nodes. In green, we present the optimal combination of _dc_ and _fh_ that ensure the data gathering. According to Figure 13, we can determine for a given _fv_, _fh_, and node density if we will be able to communicate and receive the data from all of our nodes or not with different types of _dc_. Now, we are going to analyze the different scenarios; for the scenario with the maximum node density (1 node each 60 m\({}^{2}\)), there is only one combination that allows the communication. This combination is found for the lowest _fv_ (1 m/s) at _fh_ = 24 m and _dc_ = 25 m. The result of this combination of parameters is good coverage (yellow). For the other node densities, we can find more combinations. For node densities of one node every 750 m\({}^{2}\) and the maximum _fv_, no combination allows the communication. For other _fh_ of 15 and 10 m/s, few combinations allow a good connection.