## 5 Performance Evaluation and Results Analysis
### Packet Delivery Ratio  
The PDR metric represents the number of data messages that were successfully delivered to the destination node. Thus, a high PDR represents an efficient network that is able to deliver the generated data messages with high reliability. This metric is constantly affected by the quality of the links among the nodes, the radio interference provoked by neighbor devices, and collisions with other data and control messages. In this paper, the Internet messages delivered for a node without an Internet connection were considered lost. The PDR value of the network was obtained according to Equation (2):  
\[PDR=\frac{\sum_{i=1}^{N}Pr_{i}}{\sum_{i=1}^{N}Ps_{i}} \tag{2}\]  
where \(N\) is the number of nodes in the network, \(Pr_{i}\) is the number of data packets received for each node \(i\), and \(Ps_{i}\) is the number of data packets sent by each node \(i\). Figure 6 presents the results obtained for the PDR metric. In all studied scenarios, the proposed LOADng-IoT obtained better results when compared with the other approaches. In the grid scenario, where the network was sparse and the quantity of neighbor nodes was constant, the proposed solution presented satisfactory results, demonstrating its scalability and reaching a PDR of between 75% and 80%. In contrast, the other approaches decreased its performance with the increase in the number of nodes. The reason for this behavior was the dependency on a fixed Internet-connected node to send the Internet messages. In addition, networks using LOADng and LOADng-SmartRREQ were unable to detect an IN's loss of Internet connection. Thus, the Internet messages were continuously forwarded and lost due to the incapacity of the IN to route them to the Internet. With the use of the proposed approach, the INs were able to use the new error code to inform the Internet message originator when its Internet connection was lost. Thus, the message originator was able to start a new process of Internet route discovery to find a new gateway to forward its messages to the Internet. In the random and mobility scenarios, where the network was dense, the same behavior was perceived. However, the obtained PDR values were lower for all the studied networks, mainly in the mobility scenario. The reduction of the network performance is already expected when the network density grows. As the \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline NET\_TRANSVERAL\_TIME & 2 \\ RREQ\_RETRES & 1 \\ RREQ\_MIN\_INTERVAL & 2 \\ R\_HOLD\_TIME & 60 \\ MAX\_DIST & 65,535 \\ B\_HOLD\_TIME & 4 \\ MAX\_HOP\_LIMIT & 255 \\ RREQ\_MAX\_IIITER & 1 \\ RREP\_ACK\_REQUIRED & FALSE \\ USE\_BIDIIRECTIONAL\_LINK\_ONLY & FALSE \\ RREP\_ACK\_TIMEOUT & 2 \\ MAX\_HOP\_COUNT & 255 \\ NUM\_RS\_ENTRIES & 8 \\ NUM\_BLACKLIST\_ENTRIES & 16 \\ METRIC\_TYPE & HOP\_COUNT \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Parameters of LOADng. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline R\_INTERNET\_HOLD\_TIME & 120 \\ USE\_INTERNET\_ROUTE\_CAHCE & TRUE \\ NUM\_ROUTE\_CACHE\_ENTRIES & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Parameters of LOADng-IoT. number of nodes is increased in a fixed area, the probability of packet collisions grows, provoking a high packet loss. However, the proposed solution was able to obtain better results (in some cases, 40% better than default LOADng). The movement of INs also contributes to the packet loss since paths previously constructed can rapidly become unavailable due to the mobility of the nodes. In this case, the nodes that detect a route broken should use RERR messages to inform the data originator about the forwarding incapacity. This behavior provokes the necessity of a new route discovery implying in the transmission of control messages and, consequently, increasing the energy consumption. However, as the mechanism used by LOADng-IoT to find routes requires fewer control messages when compared with the other approaches, the losses provoked by Internet-connected nodes movement are reduced.