## 4 Simulations
### Simulation Result Analysis  
#### 4.2.1 Performance Evaluation of the FCNS Algorithm  
This section mainly describes the performance of the FCNS algorithm with various warming-up times. During the warming-up phase, all nodes in the communication area move randomly and use the meeting opportunity to exchange state sequence information between them. Therefore, the length of the warming-up time determines the node's understanding of the network state, which has a significant influence on the transmission performance of the FCNS algorithm. According to the simulation results, when the total experimental time is set to 2-6 h and the warming-up time is at 35-45 min, the FCNS algorithm shows the optimal performance in the transmission environment. Firstly, we explore the impact of warming-up time on delivery ratio. As shown in Figure 6, the broken line first rises sharply, and then falls rapidly. In other words, when the value of the warming-up time is increasing, the delivery ratio rises at first and then decreases, and reaches the maximum value 0.95 when the length of the warming-up phase is 40 min. As the warming-up time increases, all nodes in the network may obtain more information about the state of the network. Accurate calculation results of node similarity will be acquired by the message carrier, and the source node can select suitable and reliable relay nodes through these precise transmission statistics. However, a long warming-up phase means each node in the network needs to carry, transport, and process more irrelevant information in the data transmission process. Meanwhile, frequent communication of information between nodes will consume a lot of the energy of mobile devices in the network, and a severe lack of energy may result in the slow movement of users. Additionally, both information collection and message forwarding require some computing tasks, so these computing tasks executed by nodes also have to consume the cache spaces and energy of users, which may cause large resource consumption and reduced delivery ratios in the network. Figure 6: Delivery ratio with various warming-up times. Secondly, the influence of the warming-up time on average end-to-end delay is demonstrated in Figure 7. As presented, the broken line first declines rapidly and then rises slowly. When the value of the warming-up time is 35 min, the average end-to-end delay of the FCNS algorithm achieves the minimum value of 80. With the increase of the warming-up time, frequent information exchanges between nodes can establish sufficient statistics about the attribute characteristics of the node in the network. Moreover, the message carrier is able to choose the optimal two-hop nodes and less time is spent on successful data transmission. However, for an overly long warming-up time, excessive information carried by nodes in the network may lead to the lack of energy and memory of nodes, implying that it takes more time to route and transmit messages in the data transmission process, and the average end-to-end delay then begins to go up. Finally, Figure 8 shows the impact of the warming-up time on the overhead on average. When the value of the warming-up time increases constantly, the corresponding value of the overhead on average continues to decline and never exceeds 300. The later the warming-up time occurs, the deeper the understanding of the network state obtained by the node will be. Meanwhile, more nodes participate in the routing and forwarding of messages. It is efficient and stable to transmit data packages between nodes through the feedback mechanism, and the number of hops decreases significantly in successful data transmission. Consequently, less time is spent and shorter distances are experienced in complete end-to-end communication between nodes. Moreover, the computing resources and cache spaces of nodes can be utilized effectively, and the overhand on average in the network continues to decrease from 300 to 140. Figure 8: Overhead on average with various warming-up times.