## 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
The throughput of M-Nearest is not affected by battery level of a relay. Figure 4b illustrates the average throughput comparison of different relay selection schemes with a relay having different battery levels. Our proposed schemes MRS-ST-BL and MRS-SD-BL, which take battery level of devices into consideration for selection of a relay are compared against existing schemes MRS-ST, MRS-SD, HRS and generic schemes with a relay having different battery power levels. We also analyzed the performance of modified version of HRS, HRS-RP, in which relay selection is done considering battery level of devices. The main result from Figure 4b is that the throughput of our proposed scheme MRS-ST-BL is highest among all others. For small radius, the throughput of MRS-ST-BL is same as that for MRS-ST-WFB when search radius is small. However, with the increase in search radius, the throughput of the proposed scheme MRS-ST-BL is significantly higher than that of MRS-ST-WFB. When the search radius is very large, the difference in throughput is reduced. This is because when search radius is large, the link length from source to relay and that from the relay to destination affects more on SNR values than transmission power of relay. All other schemes attains lower throughput than that of MRS-ST-WFB. The throughput of our proposed scheme MRS-SD-BL is not improved compared to that of MRS-SD-WFB. This is because of the way MRS-SD-BL filters devices to select a relay. Figure 5 shows the same scenario as Figure 4, except the social trust scenario is stronger with Shape = 1.1 and Scale = 0.1. The results are almost the same as in Figure 4.  
Figure 6 depicts average throughput comparison of different schemes for a strong social trust scenario (Shape = 2, Scale = 0.5) among users in a network with high node density. The key result from this figure is that network with strong social trust between users have no significant difference in the performance of all relay selection schemes, when the relays have different battery power levels. Additionally, the figure shows that when social trust between the users are strong, our proposed scheme MRS-SD-BL is better than others, but it does not outperform M-Nearest scheme. Figure 6a illustrates the average throughput comparison of existing schemes MRS-ST and MRS-SD (our previous work [10]), HRS [12] and generic schemes, with the increase in radius of search ring. The average throughput of these schemes with relay having full battery power are compared against throughput of the schemes with relay having different battery power levels. The key observation in Figure 6a is that choosing a relay node nearest to midpoint results in higher throughput among all others, in a network having strong social trust among network users. In addition to that, battery power on a relay device does not significantly affect the average throughput of different relay selection schemes analyzed, except for MRS-ST. The throughput of MRS-ST with varying battery power (the blue dashed line) is reduced for larger value of search radius compared to the scheme with full battery power (the blue line with squares). Figure 6b illustrates the average throughput comparison of different relay selection schemes with a relay having varying battery power levels. Our proposed schemes MRS-ST-BL and MRS-SD-BL, which takes battery power of devices into consideration for selection of a relay, are compared against existing schemes MRS-ST, MRS-SD, HRS and M-Nearest scheme with a relay having different battery levels. We also analyze the performance of modified version of HRS, HRS-BL, in which relay selection is done considering battery power of devices.