# Energy-Efficient Opportunistic Routing Algorithm for Post-Disaster Mine Internet of Things Networks
## 5 Performance Evaluation
### Performance for Varying Communication Ranges  
According to Formula (3), it can be seen that for a given sensing area, the network density \(D\) is determined by the number of nodes \(N\) and the communication range \(r\). The more network nodes there are or the larger the communication range, the higher \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Network topology & Random \\ Deployment area & 300 m \(\times\) 50 m \\ Generate rate & 1 packet/0.1 s \\ Number of nodes & 200–300 \\ Sink & 1 static sink (edge) \\ Source node & 1 static node (random) \\ Transmission rate & 1 Mbps \\ Communication range & 40 m \\ Simulation time & 2000 s \\ RF channels & 2.4 GHz \\ Packet size & 1024 bits \\ Initial energy & 0.5 J \\ Sleep power & 0.78 mW \\ \(E_{\text{elec}}\) & 50 nJ/bit \\ \(\epsilon_{\text{amp}}\) & 0.0013 pJ/bit/m\({}^{4}\) \\ \(\epsilon_{\text{E}_{\text{R}}}\) & 10 pJ/bit/m\({}^{2}\) \\ \(\alpha_{\theta},\alpha_{d},\alpha_{c}\) & 1,1,1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation Parameters. Figure 9 illustrates the influence of the communication range on the energy consumption. From Figure 9, we can see that the energy consumption of all four routing algorithms decreases with the increase in communication range \(r\). This is because as the communication range \(r\) increases, the number of hops for packet forwarding to the sink will correspondingly decrease, which means that the number of nodes involved in forwarding decreases, and therefore the total energy consumption of the network is reduced. The network energy consumption in ORR is the highest because ORR is a centralized routing algorithm that utilizes a large number of control packets to transmit node information to the sink when calculating routing metrics, resulting in significant energy consumption. Compared with OBRN and ECSOR, DEOR has the least energy consumption. This is because, in DEOR, the number of forwarding nodes is restricted by the directional forwarding zone; see Formula (6). The sender will dynamically adjust the number of candidate forwarders based on the current communication range \(r\), thereby reducing the number of packet replicas. In addition, based on Formula (17), DEOR balances the load of nodes close to the sink and improves the energy utilization efficiency of nodes. Therefore, DEOR has better energy efficiency than ORR, OBRN, and ECSOR. Figure 10 illustrates the influence of the communication range on the average hop count of delivered packets. It can be clearly seen that as the communication range \(r\) increases, the number of routing hops decreases for all four algorithms. This is because the larger the communication range \(r\), the greater the transmission distance of nodes, which means that the packet's routing path from the source node to the sink is shortened, and therefore fewer nodes are involved in forwarding. Compared with ORR, OBRN, and ECSOR, DEOR has the least number of hops because the DEOR can adjust the density  
Figure 11: Packet delivery ratio varying with communication range. Figure 12: Network lifetime varying with communication range. of candidate nodes in the target area based on the communication range \(r\) and thus dynamically select the appropriate number of forwarders. In addition, DEOR considers the relationship between link length and transmission range, thus ensuring a lower number of hops in the routing path. Figure 11 illustrates the influence of the communication range on the packet delivery ratio. It is obvious from Figure 11 that DEOR is better than ORR, OBRN, and ECSOR, because the PDR of the network is related to the link quality and the number of forwarding nodes. The DEOR algorithm takes into account the effect of transmission distance \(d_{i,j}\) on routing when selecting relay nodes, ensuring better path quality of packets throughout the entire routing process.