# HCLE: Hybrid Clustering Approach for Extending WBAN Lifetime
## 5 Simulation Results and Analysis
### Node Deployment  
In our simulation setup, we strategically positioned sensors on the human body, as shown in Figure 6. Among these sensors, one-hop nodes, such as sensor 3 and sensor 7, are crucial in monitoring tasks that require immediate action (e.g., ECG and glucose). Due to their critical nature and time-sensitive requirements, these sensors transmit their data to the sink (node 0) using single-hop communication, as illustrated in Figure 6 (e.g., direct packet transmission from node 3 to node 0). These critical sensors are positioned near the sink node to ensure efficiency and prompt data delivery. Figure 5: QQ–plot. Figure 6: Node deployment. On the other hand, the two-hop sensor nodes are responsible for normal monitoring functions, encompassing all other deployed sensor nodes shown in Figure 6. These nodes adopt a two-hop communication approach, transmitting their data through the intermediate parent node to reach the sink. The transmission path of packets from some two-hop sensor nodes to the sink is showcased in Figure 6 (e.g., packet transmission from sensor node 1 to node 4, the selected parent node, and then to node 0, the sink node). Using a two-hop communication extends the network lifetime by distributing the energy consumption among nodes, reducing the distance to the sink, and mitigating the energy drain on any single sensor. This design choice ensures a balance between critical monitoring requirements and the efficient utilization of network resources for normal monitoring tasks. In the experiment depicted in Figures 7 and 8, we compared the network lifetime and stability period of our proposed routing protocol (HCEL) with both SIMPLE and ERRS protocols. The results demonstrate the superiority of the HCEL protocol in extending both the stability period and the overall network lifetime. The effectiveness of our proposed protocol stems from selecting parent nodes based on residual energy (i.e., not exceeding the threshold value \(Th\)), ensuring that the energy load is evenly distributed across the network and providing the chance for every sensor node to become a parent node. In contrast, the low performance of the SIMPLE protocol arises from the repeated selection of nodes closer to the sink as parent nodes, leading to their quick energy depletion and subsequent death of other sensor nodes. While the ERRS protocol does improve network lifetime compared to SIMPLE, it still falls short of the performance achieved by our HCEL protocol. ERRS achieves this improvement by balancing the load and selecting a new parent node after a set number of transmission rounds. Moreover, ERRS considers both distance and residual energy when selecting parent nodes. However, our HCEL protocol takes it a step further by considering an additional parameter, RSSI from the node to the sink, to make better parent node selections. This additional refinement helps optimize energy usage and contributes to the high performance of our protocol. We observed the number of dead nodes over different rounds to evaluate the network lifetime, as shown in Figure 7. The results indicate the higher performance of our proposed routing protocols compared to both the SIMPLE and ERRS protocols. Our protocol increases the stability period, with the HCEL protocol achieving approximately 7300 rounds, surpassing the 6383 rounds attained by the SIMPLE protocol and the 6425 rounds achieved by  
Figure 7: Analysis of network lifetime. the ERRS protocol. Additionally, in both HCEL and ERRS protocols, two-hop sensor nodes exhibit extended lifetimes due to the balanced distribution of traffic load. This achievement is made possible by combining static and dynamic clustering during the parent node selection process; thus, the stability period and network lifetime increase. Notably, nodes 3 and 7 in all protocols, which do not participate in data forwarding or routing, exhibit longer lifetimes, as their communication is direct to the sink (i.e., the last two dead nodes).