## 5 Performance Analysis of Proposed Schemes: MRS-ST-BL and MRS-SD-BL
### Schemes Compared  
This section presents the short description of all schemes analyzed in this paper. The schemes we have analyzed are as follows:  
* Direct Communication (Direct): A scheme in which a source device directly transmits to a destination device. This scheme does not use a relay to assist D2D communication between the source and the destination. * Hybrid Relay Selection with Full Battery (HRS-FB): A scheme same as HRS scheme proposed by [PERSON] and [PERSON] [12]. The relay device always has a full battery level and transmits at a power proportional to the social trust. * Hybrid Relay Selection Without Full Battery (HRS-WFB): A modified version of HRS [12]. This scheme is used to analyze the performance of HRS when a relay has varying battery level. In this scheme, a relay device transmits at a power proportional to the social trust only when the battery level on the device is above certain threshold value (\(B_{thres}\)). Otherwise, the relay device transmits at a lowest power (not proportional to the social trust). However, the battery level of devices are not taken into account in the relay selection design. * Hybrid Relay Selection with Different Battery Levels (HRS-BL): A modified version of HRS [12]. This scheme is also used to analyze the performance of HRS when a relay has varying battery level. This scheme is similar to HRS-WFB, except the battery level of devices are taken into account in the relay selection design. \begin{table}
\begin{tabular}{l c} \hline \hline
**Simulation Parameters** & \\ \hline Simulation software & Octave \\ Mobility model & Random waypoint \\ Number of nodes, \(n_{total}\) & 1000 \\ Network width, \(W\) & 100 and 1000 m \\ Speed of nodes, \(S\) & 0–2 m/s \\ Maximum pause time & 5 s \\ Simulation period & 1000 s \\ Channel bandwidth, \(B\) & 1 MHz \\ Pathloss exponent, \(\theta\) & 4 \\ Noise power, \(N\) & \(-114\) dBm \\ Social trust, \(\beta\) & 0–1 \\ Social threshold, \(S_{thres}\) & 0.3 \\ Battery threshold, \(B_{thres}\) & 10, 20, 30, 40 \\ Probe limit, \(l\) & 10 \\ Shape, \(\alpha\) & 1.001, 1.01, 1.1, 2 \\ Scale, \(L\) & 0.001, 0.01, 0.1, 0.2, 0.5 \\ Upper limit, \(H\) & 1 \\ Transmission power, \(P_{s,d}\) & 20 dBm \\ Max. allowable tx power, \(P_{s,j}\) & 20 dBm \\ Time slot duration, \(t\) & 1 s \\ Probe duration, \(\tau\) & 0.01 s \\ Search radius, \(R\) & Upto 700 m \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation setup for analysis of MRS-RP. * Nearest to Midpoint with Full Battery (M-Nearest-FB): A scheme which selects a relay device nearest to the midpoint. The relay device always has a full battery level and transmits at a power proportional to the social trust. * Nearest to Midpoint Without Full Battery (M-Nearest-WFB): A scheme which selects a relay device nearest to the midpoint. It is used to analyze the performance of M-Nearest when a relay has varying battery level. In this scheme, a relay device transmits at a power proportional to the social trust only when battery level on the device is above certain threshold value (\(B_{\textit{thres}}\)). Otherwise, the relay device transmits at a lowest power (not proportional to the social trust). However, the battery level of devices are not taken into account in the relay selection design. * Nearest to Midpoint with Different Battery Levels (M-Nearest-BL): A scheme which selects a relay device nearest to the midpoint. It is used to analyze the performance of M-Nearest when a relay has varying battery level. This scheme is similar to M-Nearest-WFB, except the battery level of devices are taken into account in the relay selection design. * Nearest to Midpoint with Maximum Transmission Power (M-Nearest_MaxTx): A scheme which represents an ideal relay selection (practically not feasible). It is used as a benchmark scheme that provides the upper bound for the throughput of D2D communication. This scheme selects a relay device nearest to the midpoint. The relay device always has a full battery and also transmits at the maximum power.