# LoRaWAN Network for Fire Monitoring in Rural Environments
## 6 Test Bench and Results
### Data from Sensors
Table 3 shows a summary of the states for each module  
We can estimate the current consumed by each module in each stage, according to the information collected in the data sheets (see Table 4). With this data, we add the consumptions in each operating mode according to the states indicated above (see Table 5). As can be seen, the mode that consumes more current is the state where the sensors are collecting the data from the environment, which is almost four times higher than the process of wirelessly transmitting the message with the information. To estimate the amount of battery required to power a node for one year, the diagram of the operating time of the device in each state was obtained (see Figure 25). It should be noted that the schedule is not made to scale since the time spent in states 1 and 2 is very short compared to the sleep mode or state 3. As we commented before, the node sends data every 28 min. Therefore, 1,680,000 ms remain in an inactive state. The time remaining in state two, which is transmitting, correlates to the estimation of the air-time (107.78 ms) corresponding to a 55-byte payload with SF7 and 125 BW. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Device** & **Consumption in ON (mA)** & **Consumption in OFF (mA)** \\ \hline DHT11 & 2.5 & 0.15 \\ MQ135 & 150 & - \\ Arduino UNO & 46 & 0.058 \\ Dragino & 10.3 & 0.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Consumption for each device. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Stage** & **MCU** & **Sensors** & **LoRa Tx** \\ \hline Preheating phase of & ON & Only MQ135 & OFF \\ MQ135 & ON & ON & OFF \\ Measurement of sensors & ON & OFF & ON \\ LoRa Tx & ON & OFF & ON \\ Sleep Mode & OFF & OFF & OFF \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Stages of modules in each state. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Status** & **Arduino UNO** & **Sensors** & **LoRa Tx** & **Total** \\ \hline Preheating phase of MQ135 & 46 mA & 150 mA & 0.2 mA & 196.2 mA \\ Measurement of sensors & 46 mA & 152.5 mA & 0.2 mA & 198.7 mA \\ LoRa Tx & 46 mA & 0.15 mA & 10.3 mA & 46.45 mA \\ Sleep Mode & 0.058 mA & 0.15 mA & 0.2 mA & 0.408 mA \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Consumption for each device. Finally, it is possible to calculate the capacity (in mAh) the node needs in a cycle by using expressions (7)-(10):  
\[196.2\;\mathrm{mA}\times 20000\mathrm{ms}=3924000\;\mathrm{mA}\mathrm{ms} \times\frac{1\mathrm{h}}{3600000\mathrm{ms}}=1.09\mathrm{mAh} \tag{6}\]  
\[198.7\;\mathrm{mA}\times 1000\mathrm{ms}=198700\;\mathrm{mA}\mathrm{ms}\times \frac{1\mathrm{h}}{3600000\mathrm{ms}}=0.552\mathrm{mAh} \tag{7}\]  
\[46.45\;\mathrm{mA}\times 107.78\mathrm{ms}=5006,381\;\mathrm{mA}\mathrm{ms} \times\frac{1\mathrm{h}}{3600000\mathrm{ms}}=0.00139\mathrm{mAh} \tag{8}\]  
\[0.408\;\mathrm{mA}\times 1680000\mathrm{ms}=685440\;\mathrm{mA}\mathrm{ms} \times\frac{1\mathrm{h}}{3600000\mathrm{ms}}=0.1904\mathrm{mAh} \tag{9}\]  
Table 6 shows a summary of these results. Therefore, to perform a full cycle, our node uses 1.833 mAh of energy. If we had a battery of 20,000 mAh of capacity, we could perform 10,911 transmissions, i.e., performing 52 transmissions per day (one transmission each 28-min intervals). Therefore, we could maintain the node active for 210 days (without taking into account the self-discharge. In this sense, the battery lifetime will be slightly lower). Furthermore, the number of gateways we need to have full coverage of a wooded area can be defined. According to the results shown in Figure 18, considering the use of a gateway with an omnidirectional antenna [48], a single gateway is capable of covering a circular area of 4 km of radius. This implies that we can cover an area of approximately 50 km\({}^{2}\). We can, for example, consider some rural areas declared as protected natural parks in Spain and their total areas (see Table 7). Furthermore, to ensure that no place in the area is without connectivity, we can consider an overlapping of coverage of 30%.