# Quantitative Study on the Impact of Energy Consumption Based Dynamic Selfishness in MANETs +
## 6 Experimental Results
### Impact of Mobility Models  
One of the key characteristics of wireless ad hoc networks is mobility. Mobility does indeed affect the performance of the network. Although the investigation of various mobility models is out of the scope of this paper, it is still worth to carry out some experiments to clarify the impact of mobility in MANETs. Note that the network communication performance is negatively influenced by not only the node selfishness but also the mobility models. In order to assess how the mobility model affects the communication performance of the network, we conducted the simulation with and without mobility. In the experiment, four sets of simulations are conducted. Note that all nodes in this experiment are normal nodes. (1) _Stationary_: All nodes in the network are randomly scattered and immobile at the initial positions. (2) _RWP_: All nodes in the network follow the random waypoint mobility model. (3) _Stationary-battery_: All nodes in the network are _Stationary_ with considering energy consumption. (4) _RWP-battery_: All nodes in the network are _RWP_ with considering energy consumption. The number of nodes varies from 10 to 50 with step size of 10. The results of the experiment are shown in Figure 5.  
It is clear in Figure 4(a) that the packet loss rate is significantly increased by the node mobility. It reflects the fact that in a MANET, link breakages more likely occur because of dynamic topologies caused by the node mobility. In contrast, the packet loss rates in the stationary model keep almost 0% during whole simulation process. It means that there is at least one routing path available in most cases of random node distributions, which makes sure all packets sent by the sender are successfully received by the receiver. In addition, _Stationary-battery_ and _RWP-battery_ lost more packets than _Stationary_ and _RWP_ because  
Figure 4: Comparison of residual energy between altruistic and selfish nodes. Figure 5: Performance impact of random waypoint mobility. some battery-powered nodes could run out of battery and crash during the simulation, which causes unexpected link breakages in the network. The average round-trip delay of the nodes with random waypoint (_RWP_, _RWP-battery_) mobility drastically increases with the increase in number of nodes in Figure 4(b). This is because the greater the number of mobile nodes involved the network operations, the longer the routing path needed to reach the destination. In other words, the routing protocol spends more time on route discovery and route maintenance operations because of the dynamic topology. The increments in hop counts result in long round-trip delays. Additionally, the sum of routing procedure time spent on every node in the route linearly increases with the number of nodes in the route. In the case of stationary nodes (_Stationary_, _Stationary-battery_), with the increasing total number of nodes in the network, the number of neighbors (one-hop distant node) of every node increases, which changes the nearest node in the communication range and slightly affects the round-trip delays. Last but not least, the initial position of nodes is a non-negligible factor to influence the average round-trip delay, especially in stationary networks. These are the reasons of the slight increments in average round-trip delay when the nodes in the network are stationary. However, the average round-trip delay of the stationary nodes is significantly less than that of the nodes with random waypoint mobility. This is because routing table update operations seldom occur in the stationary mobility network, which further saved a large amount of time to discover new routes and constantly update the routing table in every node. From Figure 4(c), we can observe that the average throughput of the stationary network is much higher than that of random waypoint in both networks with and without energy consumption considered. In other words, the bandwidth utilization of the stationary network is more efficient than that of random waypoint.