## 4 Simulation Analysis
### Number of Dead Nodes  
A node is considered dead when its battery is depleted completely and it could not participate in the data forwarding process. Figure 14 shows the average number of dead nodes for different network sizes and fixed transmission ranges. It indicates that the number of dead nodes increases as the network size increases and that is obvious because of a large number of nodes participating in the forwarding process. In all the network scenarios with different network sizes, the number of dead nodes in the EDOVE is less than the WDFAD-DBR. However, at some cases e.g., network of 180 nodes, the number of dead nodes in EDOVE scheme are larger than the conventional WDFAD-DBR. This is because of the EDOVE's fair distribution of data forwarding load on most of the nodes that enable these nodes to be active for a longer time and resulted in the large PDR, refer discussion related to PDR in the previous subsection. The next detailed analysis related to the dead nodes is shown in Figure 15 that shows the total number of dead nodes over the course of the simulation. In the case of WDFAD-DBR, the nodes start dying out immediately after 120 s of the simulation time. On the other hand, the nodes start dying or depleting their batteries between 180 s to 230 s when EDOVE scheme is executed on the same network scenario because it fairly distributes the data forwarding load using their residual energy and the distribution of their second hop potential forwarders. It shows that the network using EDOVE survives for a longer duration than the WDFAD-DBR and forwards more data packets towards the sink(s). Furthermore, we simulated the average number of dead nodes for the varying transmission ranges and different network sizes with a fixed transmission range of 800 m over the course of simulation,  
Figure 14: Number of dead nodes versus different network sizes. Figure 15: Number of dead nodes during simulation duration for the fixed transmission range and different network sizes. as shown in Figures 16 and 17, respectively. Figure 16 shows that the average number of the dead nodes increases as the network size increases, which is only because the data packet traffic drastically increases with the increase in the network size, refer Figure 5. However, it can easily be observed from the figure that EDOVE has slightly less number of dead nodes than the WDFAD-DBR. The number of dead nodes is an important factor. However, the main factor is the time instance when these nodes die out during simulation. If they die out earlier during the simulation, then they can not properly participate in the data packet forwarding process. The number of dead nodes are analyzed for different network sizes and fixed \(t_{r}=800\) m during the simulation course are shown in Figure 17. Due to high data packet traffic for the large network size, it can easily be seen from the figure that nodes start dying earlier during the simulation. For the network of 180, 120 and 60 nodes, the nodes start dying at 80 s, 125 s and 190 s, respectively, during the simulation course for WDFAD-DBR. On the other hand in the case of EDOVE, the nodes start to die out at the time instance of 185 s, 190 s and 220 s, for the network of size 180, 120 and 60, respectively. From the results, we can easily infer that the network using the EDOVE have slowed or delayed battery depletion rate. no further communication can be carried out towards the sink and the time instance when the very last data message is received by the Sink is recorded and compared. Figure 18 shows that the average operational time of EDOVE is larger than the WDFAD-DBR. It is also evident from the figure that EDOVE has almost constant operational time for any size network. On the contrary, WDFAD-DBR's operational time decreases with the increase in the network size. It is only because the WDFAD-DBR generates more data traffic and depletes energy of most of the nodes. Hence, most of the nodes near or between the source and sink node deplete their energy and fail to forward more data toward the sink.