# Stability-Aware Geographic Routing in Energy Harvesting Wireless Sensor Networks
## 5 Performance Evaluations
### The Impact of Radio Range on PDR, Hop Count, and Energy Consumption between EHWA and SAGREH  
Figure 6 shows the PDR, average hop count, and average energy consumption as functions of the radio range with 100 nodes. Radio range varied from 50 m to 100 m.  
From Figure 6a, radio range influences the packet delivery ratios for both the EHWA and SAGREH. As the nodes' radio range increases, the number of neighboring nodes increases, and the possibility that data packets traveled through a shorter route path was higher, which increases the reliability of the path between a source node and a sink node. SAGREH provides a significantly higher \(PDR\) than the EHWA when the path loss exponent, represented as \(\beta\), degrades from 4 to 2 because the  
Figure 5: Accumulated routing path corresponding to (**a**) EHWA and (**b**) SAGREH after transmitting 15 packets.  
Figure 6: (**a**) The Packet delivery ratio (PDR), (**b**) average hop count, and (**c**) average energy consumption as functions of radio range.  
\(PDR\) closely depends on the \(PRR\) of each route path. Based on Equation (15), SAGREH tends to select the path that supports the highest \(PRR\), while EHWA tends to selects the routes that maximize the residual energy of the network. Therefore, SAGREH provides a path having higher \(PRR\) than EHWA, leading to the EHWA providing a significantly lower \(PDR\) than SAGREH.  
As shown in Figure 6b, in regards to the average number of hop counts, the higher the radio range is, the lower the average obtained hop count. This is because a node can have more neighbors if it has a longer transmission range. When the radio range increases, SAGREH improves the average hop count compared to the EHWA; for example, with a \(\beta=2\), SAGREH improves the count by 20% compared to EHWA's average hop count at the 50 m radio range, and it improves by 32% at the 100 m radio range because in a small radio range (_i.e._, 50 m), a specific node does not have many neighbors to select from. This leads to less hop count variances for the paths selected by the EHWA and SAGREH and can explain why EHWA's and SAGREG's \(PDR\)s were proportional to the radio range, as shown in Figure 6a. The difference is proportional because the hop count was inversely proportional to the \(PRR\) of the route path. We can see that the EHWA tends to select longer routes formed by nodes with the highest residual energy, and the SAGREH selects a shorter route formed by nodes that not only satisfied the energy condition and \(PRR\) condition but were also closer to the sink node.  
From Figure 6c, decreasing the average hop count leads to decreased average energy consumption in each route. The higher \(\overline{HC_{i}}\) in the EHWA led to higher \(\overline{CE_{i}}\). The degree of change in the average energy consumption of the EHWA was larger than that of SAGREH when the \(\beta\) degraded from 4 to 2 because the average energy consumption depends on the hop count and \(PDR\). Moreover, the degree of changes to the \(PDR\) of the EHWA was much larger than that of the SAGREH, as the \(\beta\) decreased from 4 to 2, and the degree of changes in average hop count for the SAGREH was lower than that for the EHWA. Therefore, the SAGREH provides better average consumption energy than the EHWA.