## 4 Performance Evaluation
### Simulation Result
The lesser the number of working nodes selected, the lesser the number of paths created, which saves the network energy considerably, so the energy consumption of ERG-NCS is minimized. At first, the energy consumption of ERG is higher than RTG and AMSG, but ERG is able to save the energy of broken links and when a certain number of rounds is reached, the energy consumption of the network is a little bit smaller, of course, this energy saving mechanism is not apparent after considering coverage. There is a turning point when the curve reaches a certain number of rounds in the considered coverage algorithms, this is because the networks are no longer able to meet the coverage rate threshold at this point, thus mobilizing all the nodes to work. The amount of energy consumption deeply affects the lifetime of the network, and the ERG-NCS has the lowest energy consumption so that it can continuously run for the maximum number of rounds. Figure 11: Lifetime with different communication radius. In Figure 13, the number of alive nodes is closely related to the energy consumption of the network, when all the nodes are selected to work, the network energy consumption is high and the nodes die faster. ERG-NCS makes full use of spatial correlation among the nodes, which enables the coverage rate threshold to be reached with fewer sensing nodes, and thus the nodes' death rate is the slowest. The sink in the AMSG is able to move to the area where the nodes are burdened heavily, thus effectively prolong the nodes' lifetime around the sink, so the lifetime of AMSG is a little longer than RTG. The nodes' death is categorized into two trends, the first slower trend is the nodes that die in the inner area, which are close to the sink and are more likely to die due to energy depletion. The second trend is mainly caused by the nodes in the outer area, and the nodes in the outer area start to die centrally when they reach a critical point due to balanced energy consumption, from this aspect it can also be seen that the above algorithms especially ERG-NCS make full use of the nodes' energy. Figure 14 illustrates the graph of network coverage rate with the number of rounds, and it can be clearly seen that with a coverage rate threshold of 0.9, ERG-NCS needs to sacrifice little coverage rate at the beginning in exchange for high coverage rate for the longest period of time, this is because in a network with a large number of sensor nodes, there is a large amount of redundancy and duplication of data, which will degrade the performance of the network, and scheduling algorithms can be a good way to avoid this risk. Allowing the coverage range to be relatively independent of the sensor nodes to work, especially after taking into account the collaboration between the nodes, the network can  
Figure 12: Total energy consumption with different number of rounds. Figure 13: Alive nodes with different number of rounds. use fewer working nodes and also have a better coverage effect, which indicates that this nodes' scheduling approach is very efficient. In contrast, RTG, AMSG, and ERG all use all nodes for their work which generate a large amount of redundant data. In addition, the initial coverage rate of ERG-NCS is also higher than that of the DGS, which gives the algorithm some room for error tolerance, further reflecting the superiority of the NCS method compared to the DGS method. Figure 15 reveals the network throughput with different numbers of rounds. ERG has the highest throughput due to its efficient energy management method and high PDR. After considering the coverage algorithms, the throughput of the networks decreases a bit compared to the original algorithms which is due to the fact that there are fewer sensing nodes after the nodes' scheduling, which leads to a reduction in the number of packets generated. However, the throughput of the ERG-NCS is still higher than that of RTG and AMSG.