# Ocean-Current-Motion-Model-Based Routing Protocol for Void-Avoided UASNs
## 5 Performance Simulation and Analysis
### Performance Comparison
#### 5.2.2 Influence of the Node Maximum Moving Velocity  
In this section, we analyze the influence of the maximum node velocity on the performance of these protocols. The number of moving nodes is 800 and the initial energy is 1000 J in this network scenario. The maximum velocity of nodes ranges from 2 to 20 m/s, and the minimum velocity of nodes is 0.2 m/s. A visualization of the simulation results is shown from Figures 11-13.  
Figure 11: Comparison of PDR with different maximum node velocities.  
Figure 12: Comparison of average end-to-end delay with different maximum node velocities.  
Figure 11 demonstrates the comparison of the PDR with different maximum velocities of the nodes. It can be seen from the figure that the performance of the four protocols is basically stable as the maximum moving velocity of the node increases. This is because they are essentially based on the flooding mechanism. The OCMR protocol performs better than the VBF, HH-VBF, and QELAR protocols because the relative velocity component of node is added to the fitness function, which can better reduce the probability of data loss caused by the change in the moving velocity. However, the candidate forwarding set is formed in the OCMR protocol, which improves the forwarding efficiency and increases the PDR.  
Figure 12 represents the comparison of the average end-to-end delay with different maximum node velocities. It is shown in the figure that this performance metric is a little affected by the variation in the maximum moving velocity. This is because the packets of these four protocols are transmitted from the source node to the destination node hop by hop, without an end-to-end communication link. So, they are less affected by the maximum moving velocity of the nodes. The OCMR protocol has the best performance among the four protocols. This is because the relative velocity component of the nodes is added to the fitness function to reduce the effect of the relative moving velocity. However, the OCMR protocol can suppress the problem of a routing void via the voidavoided strategy, which reduces unnecessary data retransmissions.  
Figure 13 shows the comparison of the average energy consumption with different maximum node velocities. It can be seen that the performance of the OCMR, HH-VBF, and QELAR protocols are basically stable, but VBF fluctuates with the increase in the maximum moving velocity. This is because the PDR and the average end-to-end delay of the OCMR, HH-VBF and QELAR protocols remain stable with the increase in the maximum moving velocity of the nodes, as shown in Figures 11 and 12. In addition, the number of nodes forwarding the packets is less affected by the maximum moving velocity of the nodes. However, the VBF protocol is greatly affected by the moving velocity because the PDR is restricted by the routing pipeline. The OCMR protocol performed better in terms of the average energy consumption, compared with the other three protocols. This is because the OCMR protocol takes the effect of relative movement velocity into account, and more packets will be received as the nodes move, which reduces the average energy consumption.  
Figure 13: Comparison of average energy consumption with different maximum node velocities.