# DYNASTI--Dynamic Multiple RPL Instances for Multiple IoT Applications in Smart City
## 5 Performance Evaluation and Results
### Results
#### 5.5.3 Varying the Application Message Send Intervals  
The main goal of this section is to assess the utilization of adaptative application message send interval for a single application in the DYNASTI approach. The Instance Scheduler enables this adaptation interval in a dynamic way, since each application can have different instances. Each scheduled instance can employ a distinct application message send interval. To reach this, there are two evaluated DYNASTI approaches in this subsection. First, the DYNASTI approach which uses the Instance Scheduler and therefore it enables the dynamic and adaptive message send interval for a single application, called the _Adaptive Interval_. Second, the DYNASTI approach, which does not use the Instance Scheduler, is called _No Variation_. Thus, it is possible to evaluate the impact of the application message send interval, which is a configuration of the traffic class that aims to improve traffic differentiation by adapting the traffic of critical and normal applications in order to gather their requirements. To achieve this purpose, the _Adaptive Interval_ approach appropriately uses two scenarios with two different intervals for each. In the first scenario, _Adaptive Interval_ uses two instances associated with the regular application with the intervals of 5 and 7 min and an instance for sporadic application with three-minute intervals. For the second scenario, _Adaptive Interval_ uses two instances associated with the regular application with the intervals 5 and 15 min and the same interval for sporadic application (three minutes). In total, there are three instances in each _Adaptive Interval_ scenario, but only two run concurrently. When sporadic application appears, the regular instance with shorter message interval (five minutes) is stopped. The second instance of the regular application is then activated, with a higher application message sending interval (7 or 15 min), now representing the regular application. In addition, there is the _No Variation_ approach, which makes use of a single instance for regular application and one instance for sporadic application. In this approach, when the sporadic application comes up, the regular application instance continues to perform with the same traffic class, without adaptation to the regular application. Simulations tests were performed using the information from Table 2 to assess this attribute of the traffic class (send interval). Two applications were used: electricity monitoring, for regular application and normal requirement, and interruption identification, for sporadic application and critical requirement (as described in Section 5.3). Table 6 shows the scheduling for the _Adaptive Interval_ approach, using one message per node in each 7 or 15 min as interval variation. When the scheduling is changed, Application 2 (interruption identification) starts running, Application 1 (electricity monitoring) has its instance changed and now it uses Instance 30, which has a greater application message send interval (one message in each 7 or 15 min). Thus, this switching between the two instances of Application 1 makes it possible to prioritize the traffic of the Application 2, as Application 1 decreases network traffic and therefore frees more resources to sporadic application. The duration time of Application 2 is 20 min. \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 & 5 & 9 \\
1 & 30 & Regular & Normal & 7 or 15 & 10 \\
2 & 20 & Sporadic & Critical & 3 & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Scheduling for DYNASTI for the _Adaptive Interval_ approach.