# C-V2X Centralized Resource Allocation with Spectrum Re-Partitioning in Highway Scenario
## 4 System Model and Settings
#### System Performance  
Simulations were executed for different vehicle densities. This comparison was made with the following metrics:  
* _Packet Reception Ratio (PRR)_: The ratio of the number of successfully received packets to the total number of broadcast packets in a CAM message interval. Additional PRR values have been calculated as a reference PRR without interference impact for all vehicles with different vehicle densities and they have been denoted by \(REF_{val}\). The purpose of \(REF_{val}\) is to analyze the performance with and without interference effects.  
\begin{table}
\begin{tabular}{l c} \hline \hline
**Common Parameters and Settings** & **Values** \\ \hline Carrier frequency & 5.9 GHz \\ \hline MCS & 8 \\ \hline Broadcasting power by vehicles & 23 dBm \\ \hline Bandwidth & 10 MHz \\ \hline Shadowing & log-normal \\ \hline Std. dev. & 3 dB \\ \hline Road length \(\times\) road width & 5000 m \(\times\) 4 m \\ \hline No. of lanes in each direction & 3 \\ \hline Number of RSUs & 5 \\ \hline Radius of RSU coverage & 500 m \\ \hline Distance between RSUs & 1000 m \\ \hline Radius of vehicle broadcasting coverage area & 600 m \\ \hline Radius of inner RSU coverage & 250 m \\ \hline Distance of RSUs to the highway & 3 m \\ \hline Vehicles speed in each direction & 70, 100, 140 kmph \\ \hline Antenna gain & 3 dBi \\ \hline Path loss at 1 m & 37.02 dB \\ \hline Loss exponent & 2.75 \\ \hline Noise power over 10 MHz & \(-\)95 dBm \\ \hline CAM interval & 100 ms \\ \hline Packet size & 190 bytes \\ \hline Simulation time & 5 s \\ \hline Simulation time step & 100 ms \\ \hline Vehicle density factor & [0.6–1] \\ \hline Number of sub-channels in a sub-frame & 4 \\ \hline Number of RBs in a sub-channel & 12 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Common settings.  
* _Difference of Packet Reception Ratio (D-PRR)_: The difference between the PFR and FFR packet reception ratios for each vehicle density.
* _Minimum Frequency Reuse Distance \((MFRD)\)_: The smallest distance between two broadcasters using the same resources in coverage of different RSUs. \(MFRD\) can be described as follows: \[MFRD=\min[D_{\textit{reused}}]\] (26) where \([D_{\textit{reused}}]\) is a vector of all frequency reused distances expressed in meters.
* _Average Frequency Reuse Distance (AFRD)_: The average of all frequency reused distances applied for a specific scalar factor \(\alpha\) determining the number of vehicles in the modeled network. \(AFRD\) has been calculated by gathering all reused frequency distances throughout the simulation time for each vehicle density, and then dividing them by their number. The following formula expresses \(AFRD\): \[AFRD=\frac{\sum D_{\textit{reused}}}{Number\ of\ D_{\textit{reused}}}\] (27)
* The percentage of vehicles located inside BCZ areas to the total number of vehicles in the network \(Coll_{\textit{perc}}\) is the percentage of the total number of receivers receiving two or more non-decodable packets \(Pack_{\textit{col}}\) from transmitters using the same resource allocation to the number of all broadcast packets \(Pack_{\textit{Total}}\). \(Coll_{\textit{perc}}\) can be calculated as follows: \[Coll_{\textit{perc}}=\frac{Pack_{\textit{col}}}{Pack_{\textit{Total}}}100\%\] (28) Because in the PFR technique the distance \(h\) between two frequency reused bands is larger than \(h_{\textit{reuse}}\), \(Coll_{\textit{perc}}\) is equal to zero. Furthermore, in the FFR technique, some of the frequency reuse distances are lower than \(h_{\textit{reuse}}\), creating BCZ. Table 2 shows the percentage of vehicles that are located inside the BCZ zone \(BCZ_{\textit{rebliches}}\) with the FFR technique whereas Table 3 shows the percentage of vehicles located inside the BCZ zone when the standard SB technique is applied.
* _Interference Ratio (IR)_: The interference impact on the system has been defined as the difference between PRR system performance without interference effects (defined as the reference values \(REF_{\textit{val}}\)) and the observed PRR with interference impact.