## 6 Simulation and Performance Analysis
### Simulation  
Figure 5 shows the network coverage rates of PSA and TVFDA with varying number of nodes. The coverage rates of PSA and TVFDA increase with increasing number of nodes. The coverage rates of PSA and TVFDA are highly similar when the number of nodes is lower than 75, but the coverage rate of PSA is higher than that of TVFDA. When the number of nodes is increased, PSA finds more optimal node deployment locations than TVFDA does. This result may be attributed to the process of PSA of determining the moving directions and distances of the nodes by building the optimization model and solving it using PSOA. When the number of the nodes is extremely low, the difference in the results between the two algorithms is not evident. Therefore, when the goal is to improve network reliability and network connectivity even at the risk of reducing network coverage, PSA can still provide network coverage that is slightly higher than TVFDA. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Length of data packet \(L_{b}\) & 150 bit \\ Carrier frequency \(F_{r}\) & 24 kHZ \\ Energy consumption of data reception \(P_{r}\) & 20 mW \\ Data transmission speed underwater \(V_{t}\) & 1000 bit/s \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameter setting. Figure 6 shows the network connectivity coefficients of PSA and TVFDA with varying number of nodes. The network connectivity coefficients of PSA and TVFDA increase with increasing number of nodes, and PSA can even reach the state of full network connectivity. Moreover, the network connectivity of PSA is higher than TVFDA when the network nodes are sparse. The superiority of PSA can be attributed to the process of optimizing the node positions by first constructing the backbone of the network and subsequently optimizing the positions of the cluster-in nodes on the condition of maintaining network connectivity. When the network nodes are sparse, all the nodes cannot constitute the backbone network, and the unconnected nodes randomly move a certain distance in the direction of the sink node, thereby increasing network connectivity to a certain extent. By contrast, TVFDA determines the moving direction and distance of each node according to the neighbor of the node, which is very easy to cause the original connected network to be divided and consequently reducing the connectivity of the entire network. Figure 7 shows the network deployment energy consumption of PSA and TVFDA with varying number of nodes. As shown, the network deployment energy consumption of both algorithms increase with increasing number of nodes, but the network deployment energy consumption growth  
Figure 5: Network coverage comparison. Figure 6: Network connectivity comparison. of TVFDA is significantly greater than that of PSA. In TVFDA, almost all the nodes in the algorithm have to move corresponding distances several times according to the virtual forces exerted on them; thus, the total distance of the node during the network deployment process significantly increases. In PSA, the nodes only move once during the execution of the algorithm, and the network deployment energy consumption is considered when calculating the deployment locations of the cluster-in nodes. In addition, when the network nodes are sparse, a node has no neighbors with large probability, that is, some nodes may not move when TVFDA runs, thereby reducing the total moving distance to a certain extent. Thus, the deployment energy consumption of TVFDA is approximate to PSA when the number of nodes is low. Figure 8 shows the communication energy consumption of PSA and TVFDA with varying number of nodes. As shown, the communication energy consumption of PSA is lower than that of TVFDA. TVFDA needs to run several iterations in a distributed manner to improve the network coverage and connectivity, and each node in each of the iterations needs to broadcast a message to obtain the environment information.