## 4 System-Level Simulation  
The simulation process takes into account resource allocation according to the LTE prioritization gates model already described. As shown in Table 2, the traffic model assumes train control data for LTE-R and PS-LTE voice calls. Train control data are essential for safe operation and control of trains, and should be guaranteed a higher QCI priority than PS-LTE voice calls. The main simulation parameters are listed in Table 3.  
We do not consider applying access class barring, which is the access priority step distinguishing between public safety and non-public safety users, because there are only public safety users, not users of commercial networks. Also, the second admission priority step is not applied, leaving only the third step for scheduling priority to be applied in the simulation process. Our main concern of presenting the priority gates model in order to practically follow the procedures in the proposed work. In our proposed frame work, we practically employed the Step 3 (scheduling priority) according to the assumed scenario because we are managing resource allocation using scheduling. The Step 1 and Step 2 will be considered in our future work. In present work, Step 1 (access priority) is not considered, because it is used to distinguish between public safety and non-public safety users, and we consider only public safety users. Since we do not consider the other users of commercial networks, Step 2 (admission priority) is not applied.  
Figure 3 shows the network layout with the mPC deployed in coexisting PS-LTE and LTE-R networks. There is one PS-LTE base station at the center of the region of interest (ROI), which consists of three sectors, and PS-LTE users are represented by the blue circles. On the left side of the simulation layout are four LTE-R base stations that consist of two sectors each, represented by red circles. LTE-R users are marked by blue squares. The only mPC that exists in the measuring area is represented by a red circle, and the mPC user located near the mPC is represented by a black circle.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Traffic Model** & \multicolumn{3}{c}{**ARP**} & **QCI** & **QCI Priority** \\ \cline{3-5}  & & **Preemption Capability** & **Preemption Vulnerability** & **QCI** & **QCI Priority** \\ \hline LTE-R & Control Data & Yes & No & 0 & 1 \\ PS-LTE & Voice Call & Yes & Yes & 1 & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: QoS class identifier (QCI) priority under the traffic model.  
Figure 3: Network layout.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ Carrier Frequency & 723 MHz \\ System Bandwidth, No. of PRBs & 10 MHz uplink, 50 PRBs \\ No. of PS-LTE eNBs & 21 Sectors (1-tier, 7 Sites) [Only 3 Inner Sectors in the ROI] \\ No. of LTE-R eNBs & Maximum 2 eNBs/Sector beside the Railway \\ Inter-eNB Distance & PS-LTE eNBs: 4 km / LTE-R eNBs: 1 km \\ No. of mPCs & 21 mPCs/Inner Sector in the ROI \\ mPC Mobility Pattern, Speed & mPC Random Walking Model, 3 km/h \\ No. of UEs/Sector & mPC UEs: 4/mPC / PS-LTE UEs: 8 \\ LTE-R UEs: 1 (Control Signal) \\ UE Mobility & LTE-R UEs: 250 km/h \\ UE RF Parameters & Max Tx Power: 23 dBm / Noise Figure: 9 dB \\ Path Loss Model & Rural Macro (3 GPP TR 36.837) \\ Shadowing & Log-normal Distribution (Mean: 0 dB, SD: 6 dB) \\ \multicolumn{2}{c}{mPC: Winner II (D1-Rural Macro)} \\ Fast Fading & LTE-R: Winner II (D2a-Rural Macro) \\ MCS & MCS 0 - MCS 28 \\ Transmission Mode & SISO (\(1\times 1\)) \\ Thermal Noise Density & 174 dBm/Hz \\ Scheduling & Proportional Fair Traffic \\ \hline \hline \end{tabular}
\end{table}
Table 3: System-level simulation parameters.