# DYNASTI--Dynamic Multiple RPL Instances for Multiple IoT Applications in Smart City
## 5 Performance Evaluation and Results
### Results
#### 5.5.2 Varying the Number of Applications  
In this subsection, DYNASTI and _Static Instances_ are evaluated with different quantities of application. Different numbers of applications are used to assess the approaches. Two scenarios were selected--the first with two applications and the second with three applications. To generate the obtained results, we employed the information from Table 2 and 25 nodes (one sink node and 24 sensor nodes). Figure 8: The average number of control messages and average delay for critical instance. Figure 9: Average of lost application messages and average energy consumption. It is possible to find four different types of scheduling of instances for the scenario with three applications of the DYNASTI solution. The possibilities and characteristics of each applications are described below. Two other possibilities of scheduling of instances emerged in the second scenario with two applications, when employed the DYNASTI solution. Table 4 presents the scheduling for DYNASTI solution with three applications. Application 1 (electricity monitoring) is active on Scheduling 3, 4, 5, and 6. It uses all the necessary resources to transmit data on the network as long as it is active. Application 2 (interruption identification) is active in Scheduling 4 and 6. Application 3 (voltage monitoring) is active in Scheduling 5 and 6--all applications are active in Scheduling 6. Scheduling 4 differentiates from Scheduling 5 in the application message interval of the sporadic applications. The duration time of 20 min remains for both sporadic applications; however, these applications can be started at different times. Table 5 shows the scheduling for the DYNASTI solution with two applications. Only Application 1 is active in Scheduling 7 and 8. Both applications are active in the Scheduling 8; Application 2 appears sporadically and lasts 20 min. Figure 9(a) shows the average number of control messages for scenarios with two and three applications between the DYNASTI and _Static Instances_ approaches. The control message transmissions occur throughout the simulation in _Static Instances_ approach, thus the average number of control message is higher for both scenarios when _Static Instances_ are employed. In the 2-application scenario, _Static Instances_ result in an average of 77.58% more control messages than DYNASTI. In the 3-application scenario, _Static Instances_ approach reach 143.31% more control messages than DYNASTI on average (more than double). Hence, the total number of control messages increases much more when _Static Instances_ approach are used as the number of applications increases. This is explained by the fact that the DYNASTI solution employs the message controller mechanism that makes it possible to stop control messages from instances of sporadic applications that do not need to be activated all the time. Figure 9(b) shows a comparison between the average number of lost application messages. _Static Instances_ approach results in a loss 93.09% more than the DYNASTI solution in the 2-application scenario. The _Static Instances_ approach results in a lost application messages of 138.09% more than DYNASTI in the 3-application scenario (more than double). The message controller mechanism of the DYNASTI solution also assists with reducing the number of lost application messages, since there are much less control and application messages in the network than the _Static Instances_ approach. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Application** & **Instance** & \begin{tabular}{c} **Traffic** \\ **Pattern** \\ \end{tabular} & \begin{tabular}{c} **Traffic** \\ **Type** \\ \end{tabular} & \
\begin{tabular}{c} **Messages** \\ **Interval** \\ \end{tabular} &
\begin{tabular}{c} **Scheduling** \\ \end{tabular} \\ \hline
1 & 10 & Regular & Normal & 7 & 3,4,5,6 \\
2 & 20 & Sporadic & Critical & 5 & 4,6 \\
3 & 30 & Sporadic & Critical & 3 & 5,6 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Scheduling of DYNASTI with three applications.