## 6 Simulation and Analysis
### Performance of the Proposed Transport Scheme
That is why the mean round-trip delay of the RTS was smaller than that of the RTS-MV when \(p\geq 70\%\) (the delay of RTS was reduced by 17% compared to that of RTS-MV when \(p=80\%\)). The mean energy consumption to deliver a file of the RTS was significantly lower than that of the RTS-MV. For instance, when \(p=30\%\), RTS had a 26% lower energy consumption than that of RTS-MV. In order to prevent that the residual power of relays going down to the level that could trigger selfish  
Figure 11: The energy consumption of both RTS and RTS-MV under different \(p\). Figure 12: The number of files successfully delivered in the simulation time of both RTS and RTS-MV under different \(p\). behavior, the RTS reduced the relay's energy consumption by periodically injecting a small number of coded packets into the network and limiting the time for the dissemination of packets, according to the latest ACK received by the source in the last cycle. However, RTS-MV spent a lot of energy to reduce the delay, and some of the energy was consumed in inefficient replication/forwarding. Therefore, RTS used much less energy consumption than that of RTS-MV. The number of files successfully delivered in the simulation time of the RTS was remarkably larger than that of the RTS-MV. For example, when \(p=30\%\), RTS had a 26% more delivered files than did RTS-MV. Since it was less likely for relays in the RTS to behave selfishly than in the energy-consuming RTS-MV, RTS could keep high efficiency for a longer time. In addition, the RTS could avoid network congestion by controlling the redundancy injected to the network, which prevented performance degradation caused by heavy consumption of network resources. As a contrast, RTS-MV consumed the limited cache of nodes quickly, resulting in a reduction of transmission efficiency. Therefore, RTS could deliver more files than RTS-MV under the given time and energy constraints. We also plotted the ratio of nodes with selfish behavior and the number of files delivered successfully versus the simulation time \(t\), shown as Figures 13 and 14, respectively. \(p\) was set to 30% for both experiments. It can be observed from Figure 13 that the ratio of nodes with selfish behavior in the RTS-MV went up fast, and then reached saturation. Because the energy of nodes that were willing to provide for forwarding was quickly exhausted to get a low delay, more and more nodes became selfish, as the simulation proceeded. What is more, it also can be seen that the RTS outperformed the RTS-MV most of time. Specifically, the curve showed that the ratio of nodes with selfish behavior rose slowly, and it took much longer to reach its saturation. Based on the analysis, we can conclude that in the RTS, limited energy was efficiently used and the network could provide longer effective communication time compared with the RTS-MV. Figure 14: Number of successfully delivered files versus simulation time. Figure 13: Ratio of nodes with selfish behavior versus simulation time. Figure 14 shows the comparison result of the two schemes in terms of the number of successfully delivered files. For the RTS-MV, the number of delivered files grew rapidly to its maximum, and then remained unchanged with no more files delivered successfully. This is because that the network had relatively sufficient energy at the beginning of the simulation, relays were highly active in forwarding, and could deliver files within a short delay by consuming a lot of energy. However, after the energy of relays was exhausted, the number of selfish nodes increased greatly. Since the number of nodes that could participate in communication decreased fast, the delivery probability of files became very low. As for the RTS, the number of files delivered grew slower but more steadily as t increased, and finally the maximum number far exceeded that of the RTS-MV.