# Adaptive Energy Balanced Routing Strategy for Wireless Reschargeable Sensor Networks
## 6 Simulation and Evaluation
### The Impact of Charging Duration on Network Performances  
In order to analyze the impact of the charging duration on the network performance, the network size was set to 200, the charging cycle was changed from 0 to 20 with step size of 2 and the number of charging points on \(r_{\mathrm{v}}\) was \(4v\), \(5v\), \(6v\), \(7v\), \(8v\). Figure 3a,b and c are the graphs of network time, network balance and average hops under different charging cycle \(T_{c}\), respectively.  
When the charging cycle is longer, nodes can get more energy, which makes their energy closer to the average level. Furthermore, with the energy of the nodes sufficient, the hop distance can be longer and the average hop can be less; thus, the network lifetime is longer. At the same time, with the increase of the number of charging points, those performance indicators gradually become better then weaken after the number of charging points increases to a certain value. When the number of charging points increases from \(4v\) to \(6v\), the WCV charges nodes more frequently, and the average distance between the charging points and nodes becomes closer. Therefore, average charging efficiency gets improved and nodes gain more energy during the charging stage; thereby, nodes survive longer. While the number of charging points increases from \(6v\) to \(8v\), increasing the number of charging points can hardly make sensor nodes be charged more times. Besides, as the charging cycle is fixed, the average charging time allocated to each charging point decrease rapidly since the number of points per charging route increases greatly. Nodes obtain less energy and die quicker.  
Similarly, in Figure 3b, when the number of charging points increases from \(4v\) to \(6v\), nodes that consume more energy get more supplement and their residual energy is closer to the average energy level of the network. Thus, the balance is better. From the formula of charging time allocation, the charging time associates with the energy consumption of nodes and the number of charging points per charging paths obtained. When the number of charging points continues to increase, the number of points in the outer paths increases faster than that in the inner paths. The charging time allocated to the nodes with more energy consumption in the inner rings decreases greatly. Thus, the residual energy of the nodes with higher energy consumption is at a lower level and nodes with less energy consumption at a higher level; thus, the network balance decreases.  
In Figure 3c, in the process of increasing the number of charging points from \(4v\) to \(6v\), the routing formula shows that nodes closer to the paths are more likely to be the transfer nodes. And they are more likely to get more energy in charging stage, so their hop distance is farther, which can effectively reduce the average hop of the network. Similarly, in the process of increasing the number of charging points from \(6v\) to \(8v\), the high energy-consuming nodes obtain relatively less energy, and the average hop count is reduced.