# Multiparametric Monitoring in Equatorial Tomato Greenhouses (II): Energy Consumption Dynamics
## 4 Experiments and Results
### Energy Consumption Dynamics of ZigBee Networks  
The analysis of the time series in the ZigBee network at 9600, 19,200 and 57,600 bauds showed that, for the ten realizations, consumption fluctuated around the mean, there was no defined trend, and the variability remained stable. This also indicates that the behavior of the signals is homoscedastic. The cyclo-stationarity of the total and partial temporal signals for the 9600-baud rate is shown in Figure 8, together with the time signals for 19,200 and 57,600 bauds, which did not exhibit any periodicity. The \(\mu\) and \(\sigma\) values of the Sensor Nodes indicate that the average energy consumption was the highest. The Coordinator Node had lower consumption, because it has the XBEE ZB S2 PRO communication module incorporated, and it is a low-power consumption module. Figure 9 shows at a closer scale the consumption peaks of two realizations for the speed of 9600 bauds, in which the signal periodicity can be identified. The peak pattern indicates that Node 2 initiates the communication, then Node 3, and later Node 1. The peaks of the Coordinator Node are present in the entire transmission sequence, whose duration is approximately 0.33 s. Five additional  
Figure 6: SAFs with different characteristics for DigiMesh network at 19,200 bauds. From left to right: Coordinator Node, Node 2, and Node 4. Figure 7: CI for SAF with distinctive characteristics for DigiMesh network: (**Left**) at 19,200 bauds; (**Right**) at 57,600 bauds; (**Top**) Coordinator Node; and (**Bottom**) Sensor Node 4.  
experimental tests were realized with the modification of the NPLC to characterize the periodicity for speeds of 19,200 and 57,600 bands, however, it was not possible to visualize the presence of periodicity in any of them. The duration of the experiment was directly proportional to the resolution of the multimeter expressed in NPLC, for its highest value, and the acquisition of measurements lasted approximately 4 h per realization. In Figure 10, we observe that the increase of this parameter did not improve the perception of periodicity, on the contrary, the current in the Coordinator Node noticeably decreased. For this reason, we decided to maintain the NPLC to perform the energy consumption analysis for the ZigBee network. Table 4 summarizes the average consumption and deviation of each realization for the three analyzed baud rates. The standard deviations were high, being above 12 uA at the Sensor Nodes and above 22 uA at the Coordinator Nodes. The transmission duration at 9600 bauds was to 0.33 s. This value was determined by taking the mode of the samples in each realization, and then calculating the average for all realizations. Figure 8: Time signals for ZigBee network. From left to right: at 9600, 19,200, and 57,600 bauds. (**Top**) Complete time signal; and (**Bottom**) time detail of the same signal. Figure 9: Complete time signals for ZigBee network at 9600 bauds in two example realizations: (**Left**) Realization 4; and (**Right**) Realization 7. \begin{table}
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The similarity of the _pdf_ signals obtained in ten realizations for the Coordinator Nodes was high between the speeds of 9600 and 19,200 bauds, but it was different by the slight displacement in Realization 10 at 57,600 bauds, as shown in Figure 11. In the case of the Sensor Nodes, the similarity was greater among the three baud rates. Then, we can say that the increase in the transmission speed does not significantly affect the behavior of the energy consumption. Figure 12 shows the estimated _pdf_, with their CI for the ZigBee network nodes, at the three speeds. The widest CIs were produced in the Coordinator Nodes, whereas the Sensor Nodes have narrow CI. The empirical _pdf_ of the elements in the ZigBee network was multimodal, and it was skewed to the right. The _pdf_ of the Coordinator Nodes were similar for the three speeds.