## 4 Simulations
### Simulation Result Analysis
#### 4.2.2 Comparison Result Analysis between Algorithms  
This section mainly focuses on the comparison and analysis between the five different algorithms above. For the algorithms based on contextual information in opportunistic social networks, nodes in the network have to carry, transport, and forward large amounts of text information about the routing state, but the insufficient cache space of nodes is a big limitation in the data transmission process. Therefore, in the experiment, we reasonably set the cache space as a variable to explore the transmission performance of each algorithm. Additionally, the comparison results show that the FCNS algorithm always performs better than the other four algorithms in the delivery ratio, average end-to-end delay, and network overhead. More specifically, in the FCNS algorithm, the delivery ratio is 0.85 on average, and the average end-to-end on delay and the overhead on average are the lowest among these algorithms. Above all, we evaluated the delivery ratio of each algorithm with various cache spaces, and the comparison results between the five different algorithms in terms of delivery ratio are shown in Figure 9. On the whole, where the cache space of nodes continues to increase, the delivery ratio of all algorithms is growing constantly. This is because the node in the network is able to operate complex computing tasks and to carry more information. In addition, the delivery ratio in the FCNS algorithm is always the highest among these algorithms, because successful data transmission in the proposed scheme can be implemented by node similarity and contextual information. In the FCNS strategy, nodes in the network are divided into different communities through social similarity, and a pair of nodes in the same community with a high mobile similarity may communicate with each other frequently. Meanwhile, the message carrier executes the fuzzy routing and forwarding operation for messages, which is an efficient method to synthetically consider the mobile and social similarities of nodes, so the delivery ratio of the FCNS algorithm is the highest all the time. As for the Epidemic algorithm and the Spray and Wait algorithm, they are all typical flooding methods in opportunistic social networks and a large number of message group copies cause a low transmission efficiency in the network, so the delivery ratios of the two algorithms are relatively low. Moreover, the EIMST and ICMT algorithms perform the transmission operation of messages through the cooperation of multiple nodes, but this is not an efficient transmission scheme when the cache space of nodes is limited. Consequently, it can be concluded that the delivery ratios of the EIMST and ICMT algorithms are inferior to the FCNS algorithm. Figure 9: Delivery ratio with various cache spaces. Next, Figure 10 exhibits the comparison results between the five different algorithms in terms of average end-to-end delay. As shown in the figure, the average end-to-end delay of each algorithm is rising with the increase of the cache space of nodes. Clearly, when the cache space of the node rises from 10 Mb to 40 Mb, the average end-to-end delay of the FCNS algorithm remains relatively stable and is always the lowest among these algorithms. This is due to the fact that the FCNS algorithm makes message delivery decisions by determining and comparing the similarity degree of the node, and the transmission preference plays a decisive role in the data transmission process. Additionally, an increase in the cache space does not have a significant effect on the mobile information and social attributes of nodes--thus, the delay of routing selections, of relay nodes waiting for messages, and of message forwarding are only a slight change. Comparatively speaking, the Epidemic algorithm manufactures a large number of message group copies in the network, which causes a sharp increase in the routing and forwarding delays of the message.