# Accurate Energy Consumption Modeling of IEEE 802.15.4e TSCH Using Dual-Band OpenMote Hardware
## 5 Evaluation
### Frequency Band Consumption Comparison
#### 5.4.1 Simulation Setup  
To perform the experiments, the 6 TiSCH simulator is used: an open-source, event-driven Python simulator developed by the 6 TiSCH Working Group (WG) [5]. The simulator supports IEEE 802.15.4e TSCH experimentation with straightforward parameter configuration. The configuration parameters for the simulation experiments discussed in this article, are listed in Table 18. To be able to compare the energy consumption for both \(868\,\mathrm{MHz}\) and \(2.4\,\mathrm{GHz}\), we changed the default propagation model of the simulator (i.e., the so-called Pister-hack) to the International Telecommunication Union - Radiocommunications sector (ITU-R) Rural Macro model, which is applicable to both frequency bands [25]. To have a realistic low-power energy consumption comparison between \(868\,\mathrm{MHz}\) and \(2.4\,\mathrm{GHz}\), we re-calculated the charge consumption values of Table 16, using the device state consumption values of Table 15 and adjusted them to make sure the measured CC2538 PM2 power mode consumption value \(1.56\,\mathrm{\SIUnitSymbolMicro A}\) was used in all states where the CPU was sleeping. When the CPU and radio were sleeping, the Idle state (with the crystal oscillator turned off) consumption value of the CC1200 chip, i.e., the radio Sleep state, was also replaced by the power down Sleep state consumption value of the CC1200 datasheet, which is \(0.5\,\mathrm{\SIUnitSymbolMicro A}\) ([[http://www.ti.com/lit/ds/symlink/cc1200.pdf](http://www.ti.com/lit/ds/symlink/cc1200.pdf)]([http://www.ti.com/lit/ds/symlink/cc1200.pdf](http://www.ti.com/lit/ds/symlink/cc1200.pdf))). The resulting slot consumption values are listed in Table 19. The 6 TiSCH simulator implementation used for these simulation experiments can be found in [26]. In the second TSCH network experiment, the average charge drawn per node per cycle was observed over a period of 300 s. The results are shown in Figure 11, which differentiates between two grid topologies with different sizes: Figure 11a,b shows the Cumulative Distribution Function (CDF) for nine and 25 nodes, respectively. In the network of nine nodes, all eight nodes directly connect to the root node for both 868 MHz and 2.4 GHz. The CDF in Figure 11a shows that almost all of the nodes consume less charge when using 2.4 GHz compared to when using 868 MHz. The difference in consumption is explained by the measured slot consumption values shown in Table 19, which indicates \begin{table}
\begin{tabular}{l c} \hline \hline
**Parameter** & **868 MHz** & **2.4 GHz** \\ \hline Timeslot duration & 15 ms \\ Slot frame size & 101 time slots \\ No. of SHARED cells & 1 \\ Inter-node distance & 70 m \\ No. of stable neighbors & 1 \\ RPL parent set size & 1 \\ Traffic period & 5 s \\ Traffic period variability & 0.05 \\ EB period & 10 s \\ EB probability & 0.15 s \\ DIO period & 30 s \\ DIO probability & 0.15 \\ OIT threshold & 2 \\ OTP housekeeping period & 10 s \\ goto housekeeping & False \\ TX power & 0 dBm \\ No. of channels & 1 & 16 \\ Stable RSSI & \(-\)83 dBm & \(-\)78 dBm \\ \hline \hline \end{tabular}
\end{table} 
Table 18: Parameter configuration in the 6 TiSCH simulator. Figure 10: Total consumed charge per node and average hop count for 868 MHz and 2.4 GHz frequency communication in a random topology as a function of the number of nodes. (**a**) Average hop count; (**b**) total energy consumed per node. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Slot Type** & \multicolumn{2}{c}{**Calculated (\(\mu\)C)**} \\ \cline{2-3}  & **CC2538** & **CC1200** \\ \hline TxDataRxAck & 106.45 & 275.61 \\ RxDataTxAck & 107.66 & 286.76 \\ TxData & 83.07 & 210.32 \\ RxData & 82.97 & 219.8 \\ RxIdle & 47.54 & 81.57 \\ Sleep & 0.82 & 0.89 \\ TxDataRxNodox & 100.32 & 246.98 \\ \hline \hline \end{tabular}
\end{table} 
Table 19: Calculated charge drawn for each slot type, used in the simulator experiments. that 2.4 GHz consumes less energy than 868 MHz. However, when looking at nodes between 0.8 and 0.9, we observe that 868 MHz consumes less.