## 5 Performance Evaluation
### Simulation Results
#### 5.3.1 Impact of Traffic Load  
Figure 4 illustrates the performance of the protocols varying traffic load. In this study, we vary the traffic load by varying data generation rate in terms of packets generated per second. The bit error rate varies randomly ranging from \(10^{-6}\) to \(10^{-2}\). Here, the impact of traffic load is investigated on the performance metrics for the related traffic classes. Although TARA and ALTR do not support traffic differentiation, however, the data related to the corresponding traffic class was collected exploiting the node-ID that generates traffic of a particular type. We evaluate the average end-to-end delay only for delay sensitive packets. As the traffic load increases, the average end-to-end delay increases for all the protocols as depicted in Figure 4a. TARA exhibits the worst performance in high traffic load due to its withdrawal strategy while a hotspot is encountered. Compared to TARA, ALTR shows better performance in this regard, as it avoids unnecessary hop traversal applying the shortest path algorithm for packet routing after a hop-count threshold is reached. Considering delay parameter in route selection, both TMQoS and TLQoS achieve the significantly lower end-to-end delay compared to the non-QoS aware protocols. During low traffic load, TLQoS and TMQoS show almost similar performance in end-to-end delay, however, TLQoS excels the delay performance than TMQoS in high traffic load. The reason behind is that, TMQoS adopts end-to-end approach in taking routing decision which delays the propagation of routing information from BC to the source at high traffic load due to the increased contention, in other words, the convergence time is prolonged resulting stale information during high traffic load. In contrast, TLQoS employs local selection for choosing the least delay node from its neighbors. Despite the greedy approach, TLQoS avoids the unnecessary packet transmission along the network, and tends to follow less hop-count path to the \(BC\) due to hybrid potential field and routing loop avoidance mechanism. The impact of traffic load on on-time delivery ratio is depicted in Figure 4b. This metric considers the effective reliability for delay sensitive packets, in particular, it takes into account the number of successful delivery of delay sensitive packets within the specified deadline. Considering \(300\) ms as a deadline for delay sensitive packets, TLQoS demonstrates the best performance regarding on-time delivery ratio among all the protocols because of its localized QoS provisioning approach. Due to the high latency at high traffic load, and higher packet losses, TMQoS shows poor performance in on-time delivery ratio compared to TLQoS. TARA, because of its poor delay performance even in moderate traffic load, the on-time delivery ratio drops significantly as the traffic load increases. The poor reliability performance also influences this result as to be discussed later. ALTR, however, achieves much higher on-time delivery ratio than TARA in all traffic loads. Still, this performance does not exceed the performance of QoS-aware protocols like TMQoS and TLQoS due to the lack of exploiting QoS parameters as routing metric. Figure 4: Performance Comparison for different traffic loads. (**a**) Average End-to-End delay varying data generation rate; (**b**) On Time Packet Packet Delivery Ratio varying data generation rate; (**c**) Reliability varying data generation rate; (**d**) Average Temperature Rise varying data generation rate; (**e**) Average Energy Consumption varying data generation rate. The reliability performance for reliability sensitive packets (Cr and Rc) varying traffic load is shown in Figure 4c. With the increasing traffic load, the reliability drops for all the protocols. This is because, at high traffic load, the media contention and node congestion increases, resulting higher packet drops. Because of the excessive packet transmission, the reliability of TARA drops sharply as the traffic load increases.