## 5 Performance Study
### Simulation Results
#### (3) Number of data flows  
We also analyze the effect of the number of data flows on the network performance. The number of data flows is varied from 1 to 5 while keeping the node load as 900 Kbps. Recall that there are 5 RNs with the speed of 20 m/s. The maximum speeds of the group's movement and nodes inside the group are also set to 20 m/s. Figure 10: Effects of network traffic on average end-to-end delay. Figure 9: Effects of network traffic on average throughput. As shown Figure 11, RoCoMAR also achieves a higher throughput than other routing protocols. For example, when the number of data flows is 2, RoCoMAR has throughput higher than 650 Kbps, while other protocols show less than 450 Kbps. As shown in Figure 11, the gap between throughput values of RoCoMAR and other protocols tend to decrease as the number of data flows grows. It is because there are only 5 RNs in the network, which implies that the ratio of the number of RNs per a route decreases from 5 to 2.5, 1.7, 1.25 and 1. As a result, it is possible that the poorest link is selected to be reinforced but the available RNs could not be found. Figure 12 shows the average end-to-end delay of protocols. As seen in Figure 12, RoCoMAR also shows the consistently low average end-to-end delay, while the delay of DSR, OLSR, and GFR becomes long as the number of data flow increases. The reason of low performance of those routing protocols is as following: the frequency of route discovery of those routing protocols is high because the quality of links varies unpredictably over time and space due to the fading channel and network topology changes. As a result, data delivery delay as well as the routing overhead are increased. Figure 11: Effects of the number of data flows on average throughput. Figure 12: Effects of the number of data flows on average end-to-end delay. RoCoMAR alleviates the problem of low quality links and frequent route discovery. More specifically, when the quality of links on the route becomes poor, RoCoMAR detects this and places RNs until the quality of route meets the specific requirements, which makes the route more reliable and stable. _(4) Transmission ranges of nodes_  
In order to analyze the effect of the transmission range on the network performance, the radii of transmission range are varied from 200 m to 300 m. The maximum speed of group and member movements are set to 20 m/s. Each source transmits data at the rate of 900 Kbps. The terrain dimension is 1,000 m \(\times\) 1,000 m and 25 nodes are randomly deployed in a circular group area with the radius of 400 m.  
Figure 13 shows the average throughput of routing protocols over different transmission ranges of nodes. As shown in Figure 13, the average throughput of all routing protocols increases as the transmission range of nodes grows. The reason is that, given the same distance between two communicating peers, a longer transmission distance leads to a good link quality due to a higher RSSI and SNR. Also, with a longer transmission distance, the possibility of link breakage becomes lower. The results in Figure 13 also indicate that RoCoMAR achieves the highest throughput among routing protocols over different transmission ranges. Moreover, RoCoMAR's throughput gain tends to decrease as the transmission range of nodes grows, since nodes can find a good quality link without link reinforcement _i.e_., the quality of links in the network becomes higher as the transmission range of nodes increases. Figure 14 shows the average end-to-end delay of routing protocols over variation of transmission ranges. As shown in Figure 14, the end-to-end delay of routing protocols decreases as the transmission range of nodes becomes larger. It is because the routing protocol can establish a shorter route in terms of the number of hops when the transmission range is large. RoCoMAR and AODV show a low end-to-end delay compared with other routing protocols as shown in Figure 14.  
Figure 13: Effects of transmission range on average throughput.