## 3 Performance Evaluation Results and Discussion
### Impacts of Maximum Speed of Nodes  
Figure 20 shows the trend of the packet delivery rate of different protocols when the maximum movement speed of a node changes. During the simulation process, the most fundamental problem introduced by node movement is the fluctuation in the number of candidate nodes within the forwarding area. Because the forwarding area is relatively fixed, some nodes may move out of the original area due to the randomly assigned positions. However, because of the variability in movement speed, the number of nodes in the forwarding area remains relatively stable in actual simulations. For example, when the number of nodes in the entire network is set to 400, the number of nodes in a single-hop forwarding area is about 10. Therefore, due to the introduction of the mobility model, there may be an increase or decrease in the number of nodes in the actual forwarding area. The impact of node mobility on network performance is equivalent to the variation in network parameters when the number of nodes ranges from 200 to 500. Thus, node movement has a minimal effect on the packet reception success rate, showing only minor fluctuations.  
Figure 21 shows the trend of network average end-to-end delay of different protocols as the maximum movement speed of nodes changes. Except for the VBF protocol, which is sensitive to node movement due to the use of a single pipeline forwarding area, the other four protocols show a slightly increasing trend. The reason is also that the two-dimensional movement model of random walks superimposes movement speed and direction, which causes fluctuations in the number of nodes within the forwarding region. Therefore, the number of nodes at the optimal forwarding position or the edge of the transmission range will decrease, thus reducing the effective advance distance of one-hop transmission and increasing the number of end-to-end transmission hops, thereby increasing the overall end-to-end delay.  
Figure 22 shows the trend of network average energy consumption across different protocols as the maximum node movement speed varies. When a node joins or escapes from the original forwarding area due to mobility, node density within the forwarding region changes, which in turn affects the number of nodes involved in receiving the data packets from the previous forwarding node, which will impact the overall energy consumption performance of the network. As shown in Figure 20, the number of successfully received data packets is also fluctuating, so the average energy consumption of the network will also show slight fluctuations. This is jointly determined by the trend of total energy consumption and the number of successfully received data packets in the network.  
Figure 20: Effects of maximum speed of nodes on packet delivery rate.  
Figure 23 shows the trend of the network lifetime across different protocols as the maximum node movement speed varies. Similarly, when node density within the forwarding area changes due to node movement, for example, if a new node joins the forwarding area, the time interval for the node to take turns serving as a forwarding node in one-hop transmission will increase. When the node's initial energy is constant, the time interval for the node to act twice as a forwarding node will increase. This is because there are more nodes participating in the \"rotation\" process. Therefore, for a single node, its survival time will be extended. Conversely, when a node escapes from the original forwarding area, the network survival time will correspondingly decrease. Due to the random superposition of node movement speed, the overall trend of network survival time also fluctuates.  
Figure 21: Effects of maximum speed of nodes on end-to-end delay.  
Figure 22: Effects of maximum speed of nodes on average energy consumption.