## 4 Design and Method
### System Performance Comparison
From Figure 15, we can observe that the data flow rate in three algorithms increases with the number of nodes increasing in three different scenarios, with our algorithm performing a little better than the Dlex and Edat. As the number of nodes increases in the area, it affects the node density and delivery ratio. The overall raw data rate is proportional to the number of nodes in the network. More packets were generated in the network and the data aggregation rate improved greatly. At the same time, the nodes' density increased, which also drives the network topology from sparse to dense and the data correlation between neighboring nodes becomes higher, so more redundant information can be removed through data aggregation. compressed with high ratio and data collection rate increases due to a decrease in the power being used for data forwarding. While \(\alpha=0.01\), the data correlation coefficient is low, which indicates that the packets are very different to each other and data is hard to compress. Therefore, original raw data will be forwarded to the sink and there will be more power expenditure for this procedure, which causes low data generation rate. To further illustrate the performance of data collection based on the topology controlling for our scheme we introduce a new algorithm that uses a cooperative repeater to improve data collection in low power generation for solar-powered wireless sensor networks [72]. In [72], the authors propose a repeater role to some nodes for improving the data collection performance, which only relays data from the other nodes without transmitting its own data. The reason for selecting the methods for performance comparison is that high data collection rate is the purpose and the scene is also subject to solar-powered WSNs. At the same time, the selected method is recognized and widely used for improving data collection rate in WSNs. Figure 17: Data generation rate with number of nodes increasing when data correlation \(\alpha=0.01\). Figure 18: Comparison of the average data collection rate for a day when the probability of sunny day. Figure 18 shows the comparison of the average data collection rate for a day when the probability of a sunny day is high in our scheme and in [72], which can be abbreviated as Cplp (Cooperative repeater for low power WSNs). We can see that the average data collection rate of the scheme sustains a high lever compared to Cply on a sunny day. This is because the topology controlling techniques are utilized for adjusting its communication paths continually, while this method has been considered in Cplp. We analyze the total energy depletion for all sensors with the number of nodes increasing when the duty cycle is \(1\%,10\%,30\%\), as shown in Figures 19-21, respectively. From Figure 19, we can observe that the energy depletion increases gradually when more sensors are added to the scenario, and our algorithm will consume more energy than other methods for any number of sensors. This does not mean that energy is wasted and there is a network lifetime reduction, which is the point of traditional WSNs. On the contrary, it demonstrates an outstanding performance for our algorithm because the power of each node can be replenished continually, which is significantly different to traditional WSNs, where saving energy is considered prior to routing design, e.g., the Edat scheme obtains better performance with respect to saving energy. Comparing Figure 19 with Figure 21, when the duty cycles are raised 30 times in Figure 21 compared to Figure 19, we can see that the total energy expenditure increases significantly, i.e., about 20 times. When the duty cycles improved due to data collection rate increases, the total energy consumption will improved, which indicates that more energy is extracted from the environment. From another point of view, when more energy is supplied for a sensor, it will be more lively in the active state and undertake more tasks, such as, increased packet generation.