## 4 Simulation Analysis
### Simulation Results in the Mobile Sink Scenario  
In the previous section, we critically analyzed and reasoned about the performance gain of the ESEVBF in the network scenario with the static Sink. However, the literature suggests that introduction of the Sink mobility enhances the network performance in terms of small end-to-end delay, reduces the broadcast of the number of Data packets, minimizes energy consumption and increases the network lifetime, and so on. Although the AHH-VBF has not been tested in the mobile Sink network scenario, however, we extensively simulated AHH-VBF as well as our proposed ESEVBF in the mobile Sink paradigm and the results are discussed below. Figure 19 shows the total number of copies processed within the network of varying size and transmission range. It is evident from the figure that the Sink mobility minimizes the broadcast of the number of data packet copies in the network. The reason behind this phenomenon is that Sink moves within the network and passes near the data generating and forwarding nodes. Hence, these nodes  
Figure 17: Average packet delivery ratio versus the network size. Figure 18: Average packet delivery ration versus the transmission range. just have to forward data packet at fewer hops to reach the Sink that is within the close proximity of these nodes, refer Figure 20 that shows average number of hops the data packet traverses in the network to reach the Sink. Figure 19a,b explicitly show that the ESEVBF and AHH-VBF forward far more less copies of data packet in the mobile Sink scenario as compared to the one with static Sink. The analysis shows that ESEVBF for any network size in a mobile Sink scenario processes 12.6%, 24.4%, 32.5%,..., and 34.0% less number of data messages in the network compared to static Sink scenario for \(T_{r}\) of 500 m, 600 m, 700 m,..., and 900 m, respectively. Similar data packet gain is also achieved by the AHH-VBF in the network with Sink mobility. Additionally, it is also obvious from the figure that ESEVBF outperforms the AHH-VBF in any network scenario. The mobility enables the Sink to vary its proximity respective to the data packet source and the forwarder nodes. Hence, the number of hops traversed by the data packet is far more less in the mobile Sink network than the static Sink network scenario, refer Figure 20.  
Figure 19: Total copies of data message forwarded in the network with and without Sink mobilty for different (**a**) network size (**b**) transmission range. Above analysis shows that the Sink mobility in the underwater network scenario significantly reduces the number of data message copies and the number hops the message traverses in the network. In result, it can easily be predicted that the end-to-end delay must also be alleviated in this network setting. Figure 21 shows the end-to-end delay experienced by the data message in a network with static and mobile Sink for varying (a) network size (b) transmission range. A notable difference in the end-to-end delay can be observed in the figure. On average, the ESEVBF lessens about 28.5%, 31.0%, 31.4%,..., and 34.0% of end-to-end delay in the network with mobile sink than the network without sink mobility for the size of 200, 250, 300,..., and 450 nodes and all \(T_{r}\). Notwithstanding, the AHH-VBF achieves 28.3%, 29.0%, 29.9%,..., and 33.1% less end-to-end delay for the network of 200, 250, 300,..., and 450 nodes, which is closer to ESEVBF's performance gain. Figure 20: Average number of hops the data message needs to traverse in network to reach static and mobile Sink (**a**) Network with varying size (**b**) Network with varying transmission range. Next, the influence of Sink mobility on the overall network energy consumption is shown in Figure 22. Results in that figure show the similar impact on the energy conservation as it has on the data copies processed in the network. It also verifies the claims in the literature that Sink mobility achieves energy efficiency in the network, which is about 36% more energy conserved than the static Sink scenario.