## 6 Performance Evaluation
### Simulation Results
#### 6.4.4 Transient Node Failure Test (Fourth Simulated Scenario)  
In this scenario, we consider a sensor network of size equal to 600 nodes. In order to simulate the transient node failure rate, we fixed the permanent node failure rate to 20% and varied the transient node failure rate from 10% to 60% in step of 10% in order to obtain routing protocol performance at different percentages of the transient node failure rate. We performed three sets of experiments with a different  
Figure 6: Sensor network density test (third simulated scenario) with source node = 40: (**a**) Average packet delivery rate (success rate); (**b**) End-to-end delay; (**c**) Energy consumption; (**d**) Transmitted MAC layer packets; (**e**) Packet error rate. From Figure 7a-d, we can observe that the three routing protocols perform very well with a higher percentage of the packet delivery ratio. The three protocols achieve above 90% success rate because of less traffic congestion in the network. The ASAART performance drops to nearly 94% at 20% of the transient node failure rate. However, it slightly outperforms the SHR protocol when the transient node failure rate is between 30% and 60%, and the SSR protocol is between 50% and 60%. We observe that the ASAART protocol end-to-end delay is slightly higher than the SSR and SHR protocols. Nonetheless, this is negotiated by having the least number of MAC layer transmissions and energy consumption. ASAART attempts to minimize the retransmission of packets caused by flooding at the MAC layer, which makes it an energy efficient protocol. Figure 8: _Cont._  
Figure 7: Transient node failure rate test (fourth simulated scenario) with source node = 10: (**a**) Average packet delivery rate (success rate); (**b**) End-to-end delay; (**c**) Energy consumption; (**d**) Transmitted MAC layer packets. Figure 8: Transient node failure rate test (fourth simulated scenario) with source node = 20: (**a**) Average packet delivery rate (success rate); (**b**) End-to-end delay; (**c**) Energy consumption; (**d**) Transmitted MAC layer packets. Figure 8a-d show the performance of the three protocols with 20 nodes as the source communicating node under different transient node failure rates. We can observe that there is high routing performance in terms of the success rate exhibited by ASAART. The ASAART protocol achieves a success rate above 90% when the transient node failure rate is between 20% and 40%. However, when the failure rate is between 50% and 60%, the success rate drops to 87%. This is at the expense of slightly higher end-to-end delay compared with the SHR and SSR protocols. We can also observe that the SSR protocol success rate slightly outperforms the SHR protocol. This is because of its prioritized continuous back-off delay strategy. However, SSR shows slightly higher MAC layer packet transmission because of flooding compared with the SHR and ASAART protocols. It is interesting to observe that the SSR protocol shows better reduction in the end-to-end delay compared with the ASAART and SHR protocols. From Figure 9a-d, we can observe that the ASAART protocol outperforms both the SHR and SSR protocols at a transient node failure rate from 10% to 50%, respectively. The SHR protocol success rate drops to 69% when the transient node failure rate is 40%. However, at 50%, it increases to 70%. The SSR protocol end-to-end packet delivery drops to 67% at 50% of the transient node failure rate. Surprisingly, however, it outperforms both the ASAART and SHR protocols when the transient node failure rate is 60%. From Figure 9b, we can observe that ASAART end-to-end delay outperforms both the SHR and SSR protocols at a different percentage of the transient node failure rate. However, the SSR protocol outperforms ASAART at a transient node failure rate between 50% and 60%. The SHR protocol has the highest delay because of its route repairing mechanism. Too much time is spent repairing and retransmitting network packets.