# Energy and Environment-Aware Path Planning in Wireless Sensor Networks with Mobile Sink
## 6 Performance Evaluations
### Simulation Results
#### 6.3.2 Packets Delivery Ratio (PDR) Evaluation  
In this series of tests, the performance of the proposed algorithm is assessed in terms of the packet delivery ratio in comparison to the SEA [18], EGTDA [19], and ACO-based techniques in [22], and EARP [24] for the situations indicated before under varying traffic rates. 1. PDR evaluation under the first scenario  
This experiment studies the variation of the network PDR with respect to the average traffic rate under environmental conditions inside the normal range. This experiment started by varying the average traffic rate \(\lambda\) from three to nine packets per second. Figure 8 shows the variation of the network PDR with the average traffic rate under the first scenario. As shown in Figure 8, it is easily observed that the previous works in [18; 19; 22; 24] with the proposed routing algorithm give the highest PDR compared to that with the PSO-based routing approach in [28] for urgent data collection. The environmental data in this scenario are assumed to be in the normal range; thus the corresponding value of the environmental impact metric is one. This enhancement is because the link quality is considered in selecting the next cluster head forwarder and thus delivering data packets more reliably. Regarding the PSO-based routing approach in [28], it does not consider how to avoid the lossy links, leading to more packet loss. Figure 7: Influence of increasing average traffic rate on network lifetime under the second scenario. Meanwhile, the proposed approach achieves the highest PDR compared to the others, even while increasing the average traffic rate in the network. This is due to three main reasons: The first reason is that the proposed method attempts to avoid urgent messages routing to the mobile basin by considering the zone priority. Data packets are lost during multi-hop wireless transmission due to the dynamic nature of wireless links and unstable channel conditions. Accordingly, avoiding urgent message routing enhances the PDR of the network; it prevents packets from going to possible unreliable paths. The second reason is that the link quality is integrated into the cluster head selection decision, preventing the forwarding of data packets from member nodes to their cluster heads on unreliable links. The third reason is that the proposed routing algorithm reliably forwards the urgent data packet as described above. On the contrary, previous works in [18; 19; 22; 24] did not take into account the zone priority; this leads to more packet loss due to the urgent data transmission to the mobile sink through multi-hop routing processes which negatively affects the network throughput. In addition, the reliable data transmission from the member nodes to their cluster heads is not taken into consideration, which increases the packet loss rate and thus diminishes the network throughput. 2. PDR evaluation under the second scenario  
During this experiment, the PDR of the network was investigated using the second scenario, which included varying traffic rates. Under the second case, Figure 9 illustrates the fluctuation in network PDR that occurs with varied traffic rates. For the purpose of putting this variant through its paces, the typical traffic rate \(\lambda\) is varied from three to nine packets per second. When compared to the earlier efforts in [18; 19; 22; 24], this figure demonstrates that the proposed method produces the greatest PDR possible. In light of the fact that it is presumed that the environmental circumstances were outside of the typical range in this situation, the following explanations are provided to justify such results:  
Figure 8: Influence of increasing average traffic rate on packets delivery ratio under the first scenario. The suggested technique outperforms existing algorithms in the first scenario for the reasons indicated above in addition to the fact that it successfully avoids the hazardous zones and finds safer paths for the mobile sink and urgent data transfer via its improved environmental impact measure.