## 5 Performance Analysis of Proposed Schemes: MRS-ST-BL and MRS-SD-BL
### Results  
#### 5.3.1 Impact of Different Battery Levels of Relays on Throughput  
This section presents the impact analysis of different battery power levels of relays on the throughput of various relay selection schemes in networks. The analysis is done for different social trust scenarios and different node densities. The key observation from our analysis is that the throughput of existing relay selection schemes decrease when the relays have different battery levels. In such scenarios, our proposed schemes MRS-ST-BL and MRS-SD-BL significantly enhance the throughput of D2D communications. Figures 3-6 show the throughput comparison at different social trust scenarios for a high node density network (having width of 100 m). In all these figures, average throughput is on the y-axis and radius of search ring is on the x-axis. The search radius ranges from 2 m up to 60 m and simulation data are recorded at an interval of 2 m. Each scheme analyzed is represented by a line. We also conducted the analysis for different social trust scenarios in a network having width of 1000 m (low node density network). The results are presented in Appendix A.1. Figures A1-A4 show the average throughput variation for all the schemes are similar to that for a network having width of 100 m. The remaining of this section presents the analysis for network having width of 100 m.  
For each of the relay selection schemes, there are three variations analyzed. A line with squares represents throughput of a scheme that has a relay with full battery power. A dashed line represents throughput of the scheme that has a relay with varying battery level. A line with crosses represents throughput of the scheme that has a relay with varying battery level, but we adjust the scheme to take varying battery level of the relay into account. The left graph in each of these figures show the average throughput comparison of each scheme with and without full battery. We analysed the average throughput of MRS-ST and MRS-SD (our previous paper [10]), HRS [12] and M-Nearest schemes using relays with full battery against the schemes using relays with different battery levels. The right graph in each of these figures compares the average throughput of our proposed schemes MRS-ST-BL and MRS-SD-BL, when the relay has different battery power levels. The performance of the proposed schemes are compared against the throughput of MRS-ST, MRS-SD, HRS and other generic schemes without battery awareness in relay selection, but relays have different battery levels. Figure 3: Average throughput of different schemes when Shape = 1.001 and Scale = 0.001 in a network having width of 100 m. (**a**) Different battery power levels not considered in relay selection; (**b**) Different battery power levels considered in relay selection. Figure 3 depicts the average throughput of various schemes as the search radius increases for a very weak social trust scenario (Shape = 1.001, Scale = 0.001) among users in a network with high node density. Each line in the graph represents the average throughput of a scheme. The key result from this figure is that the different battery levels of relays do not impact the performance of any of the relay selection schemes analyzed, when social trust among the users in the network are very weak. Additionally, the proposed schemes MRS-ST-BL and MRS-SD-BL, which take battery level of devices into consideration while selecting a relay, do not show significant improvement in throughput of D2D communications, when social trust among users in the network are very weak. Figure 3a illustrates the average throughput comparison of existing schemes MRS-ST and MRS-SD (our previous paper [10]), HRS [12] and generic schemes, with the increase in radius of search ring. The average throughput of these schemes with relays having full battery are compared against throughput of the schemes with relays having different battery levels.