## 3 Methodology
### Energy Consumption Model of Lora Sensor Node
The transceivers feature three different RF power amplifiers [54]. Two of these, connected to RFO_LF and RFO_HF, can deliver up to +14 dBm and are not regulated for high power efficiency [65]. The third, PA, connected to the PA_BOOST pin, can deliver up to +20 dBm via a dedicated matching network [58]. The low-frequency PA_LF covers the lower bands (up to 525 MHz), while the high-frequency PA_HF covers the upper bands (from 860 MHz). Finally, the high-power PA_HP, connected to the PA_BOOST pin, covers all frequency bands the transceiver addresses. 3. Listen mode of operation of the transceiver In this mode, the circuit spends most of the time in an idle state, during which only the RC oscillator is on. Then, periodically, the receiver wakes up and looks for an incoming signal. If a signal is detected, the receiver is kept on, and the data are analyzed. Otherwise, if there is no signal for a defined period of time, the receiver is switched off until the following receive period [64]. The radio stays mainly in a low-power mode during the listen mode. This fact results in very low average power consumption. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Transceiver**} & \multicolumn{8}{c}{**Current Consumption**} \\ \cline{2-9}  & \multicolumn{4}{c}{**Transmit**} & \multicolumn{2}{c}{**Receive**} & \multirow{2}{*}{**Sleep**} & \multirow{2}{*}{**References**} \\ \cline{2-9}  & **20 dBm** & **14 dBm** & **13 dBm** & & & & & 11.5 mA \\  & & & & & & & (min. 10.8 mA, & 0.2 \(\mu\)A (max. 1 \(\mu\)A) & [54] \\ \hline HopeRF RFM95/96/97/98(W) & 120 mA & - & 29 mA & 20 mA & - & (min. 10.8 mA, & 0.2 \(\mu\)A (max. 1 \(\mu\)A) & [54] \\  & & & & & & max. 12.1 mA) & \\ \hline HopeRF & 120 mA & - & 35 mA & - & - & 16 mA (min. 15 mA, & 2 \(\mu\)A (max. 3 \(\mu\)A) & [59] \\ HM-TRLR-LF/HFS & 133 mA & - & - & - & - & 16.3 mA & 7.7 \(\mu\)A & [60] \\ \hline Semtech SX1276 & 120 mA & - & - & 20 mA & - & (min. 10.8 mA, & 0.2 \(\mu\)A (max. 1 \(\mu\)A) & [61] \\ \cline{2-9}  & & & & & & max. 12.0 mA) & \\ \cline{2-9}  & - & - & - & - & - & 14 mA & 0.17 mA & [34] \\ \hline  & - & - & - & - & - & 16.6 mA & 3.7 mA & [35,62] \\ \hline  & 124 mA & - & - & 18 mA & - & 10.5 mA or 11.2 mA & 0.1 \(\mu\)A (max. 1 \(\mu\)A) & [63] \\ \cline{2-9}  & - & - & - & - & - & 11 mA & 2 \(\mu\)A (max. 1 \(\mu\)A) & [63] \\ \cline{2-9} Semtech SX1272 & - & - & - & - & 26 mA & 12 mA & 40 mA & [32,64] \\ \cline{2-9}  & - & - & - & - & 20 mA & 70 \(\mu\)A & [33,65] \\ \hline  & - & 38.9 mA & - & - & - & 14.2 mA & up to 100–150 \(\mu\)A & [58,60,66,67] \\ \cline{2-9}  & - & 48 mA & - & - & - & 17.2 mA & 3.4 mA & [62,66] \\ \cline{2-9} Microchirp RN2482 & - & 38.5 mA & - & - & 23.9 mA & - & - & [68] \\ \cline{2-9}  & - & - & - & - & - & 46 mA & 34 mA & [69] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Transceiver current consumption. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Transceiver**} & \multirow{2}{*}{**Transmit Mode**} & \multirow{2}{*}{**RFO = +7 dBm**} & \multirow{2}{*}{**RFO = +13 dBm**} & \multirow{2}{*}{**RFO = +17**} & \multirow{2}{*}{**RFO = +20**} & \multirow{2}{*}{**Reference**} \\  & & & **on RFO\_LF/HF Pin** & & & **dBm, on RFO\_LF/HF Pin** & & **dBm, on PA\_BOOST** & \\ \hline SX1272 & Power consumption & 95.4 & 95.4 & 297 & 412 & [15] \\ RFM95/96/97/98(W) & (mW) & 66 & 95.7 & 287 & 396 & [54] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Transceiver power consumption. 3. Receive mode of operation of the transceiver The receiver automatically restarts after a packet collision or after receiving a valid packet. In receive mode, the transceiver can detect packet collisions and restart the receiver. Collisions are detected by a sudden rise in received signal strength. This functionality can be useful in network configurations where many asynchronous slave nodes attempt periodic communication with a single master node [64].