# Multiparametric Monitoring in Equatorial Tomato Greenhouses (II): Energy Consumption Dynamics
## 4 Experiments and Results
### Energy Consumption Dynamics of WiFi Network  
The analysis of the time series of the ten realizations in the WiFi network at 9600- and 57,600-baud rates showed that, for all cases, consumption continued oscillating around the mean, therefore, there was no trend and the variability was less stable. This allows us to state that the behavior of the signals was mostly homoscedastic. Figure 16 shows the periodicity of the total and partial time signals of the consumption, and the pattern peaks of each node. The values of \(\mu\) and \(\sigma\) at Node 4 indicated that its average energy consumption was higher, due to it having the CO\({}_{2}\) sensor. The Coordinator Node had incorporated the RN-XV wireless communication module and the MeshliumTM router, so that its consumption was higher, because it is a device similar to a router for home wireless networks, and power saving is not a mandatory requirement. The consumption peaks of the sensor nodes occurred when the data sending was generated, and in the Coordinator Node at the moment of data reception and transmission. The event sequence occurred approximately every 1.2 s.  
Table 5 shows the average consumption, as well as its deviation and the transmission duration values of each realization for two speeds. The average power consumption in Sensor Node 4 was the highest and in Node 1 it was the lowest. The average energy consumption of the Coordinator Node was maintained independently of the transmission rate. The standard deviation averages were high, about 20 \(\upmu\)A at sensor nodes and about 11 \(\upmu\)A at coordinator nodes. The transmission duration for both speeds was 1.28 s.  
The differences in the _pdf_ between speeds were not significant. However, the results of the Coordinator Node (MeshliumTM WiFi router) differed considerably with respect to the DigiMesh network, as shown in the example in Figure 17. The signals of WiFi network were very similar in the ten realizations, since this device incorporates its own power system. In comparison to the DigiMesh network, the average consumption was not shifted between realizations, which means that this node was not affected by the load effect. The estimation of the histograms represented in logarithmic scale for the 9600- and 57,600-baud rate is shown in Figure 18. For Nodes 1-3, and Coordinator, we observe that the current ranges with higher probability of occurrence were the same for both speeds. However, in Node 4, this range increased for the lower speed, which reveals the presence of current peaks with amplitudes slightly higher than those generated for 57,600 bauds. This behavior occurred for both speeds, and it was due to the type of sensor installed in this node, but it was more visible at 9600 bauds. In general terms, we conclude that these peaks do not significantly affect the average energy consumption, since their occurrence probability is low. Figure 19 shows the estimated _pdf_, with their respective CI for the WiFi network nodes, at 9600- and 57,600-baud rates. In all cases, the CIs were very narrow, and we conclude that the behavior of the energy consumption process in each node tends to be similar, regardless of the number of repetitions of the data collection experiment. The _pdf_ in the Coordinator Node and in Nodes 1-3 were very similar for both speeds, since they maintained the multi-modal characteristic and the trend to skew to the right. In Node 4, we observe differences for consumption values lower than 0.1 mA, presumably generated by electrical noise. This was more perceptible at 9600-baud rate because the occurrence probability was high there. Besides, the electric current range covered by each _pdf_ was reduced by increasing the speed. The _pdf_ at 9600 bauds showed consumption values higher than 0.6 mA, whose occurrence probability was low, and it was likely caused by random electric current spikes that are typical in the CO\({}_{2}\) sensor operation. Nevertheless, this particularity does not significantly affect the consumption.