# C-V2X Centralized Resource Allocation with Spectrum Re-Partitioning in Highway Scenario
## 5 Simulation Results  
The system performance in terms of interference ratio IR and packet reception ratio PRR for the FFR technique for different vehicle densities are shown in Figure 4a and Figure 5, respectively. The reference curve in Figure 5 (and Figure 6) indicates the PRR for a system without interference effects--\(REF_{\textit{val}}\). We observe excellent performance with more than 95% of the packets delivered correctly for vehicles in the distance ranging from 100 to 300 m and good performance for those vehicles which are within 300 to 400 m range between the broadcasters and the receivers. Such a distance usually corresponds to the transmission carried out in the inner part of the RSU coverage area, so the impact of interference or collisions in BCZ is minimal, as it is also shown in Figure 4a. \begin{table}
\begin{tabular}{c c c c c c} \hline \(\alpha\) & 0.6 & 0.7 & 0.8 & 0.9 & 1 \\ \hline \(Coll_{\textit{perc}}\) & 1.32\% & 1.02\% & 0.80\% & 0.78\% & 0.72\% \\ \hline \end{tabular}
\end{table} 
Table 2: Percentage of the total vehicles that are located inside \(BCZ\) with FFR technique. \begin{table}
\begin{tabular}{c c c c c c} \hline \(\alpha\) & 0.6 & 0.7 & 0.8 & 0.9 & 1 \\ \hline \(Coll_{\textit{perc}}\) & 35.5\% & 33.4\% & 31.8\% & 29.5\% & 26.7\% \\ \hline \end{tabular}
\end{table} 
Table 3: Percentage of the total vehicles that are located inside \(BCZ\) with the SB technique. Figure 4: The interference impact of the system in partitioning techniques: **(a)** FRR and **(b)** PRR. **(c)** is the interference impact of SB when the system is without any partitioning technique. According to the FFR technique, the repetition of _RSU-bands_ has been defined for the distance equal to the doubled radius of the RSU coverage area (effectively specifying the frequency reuse factor of 2). Despite the excellent performance at low distances, when the spacing between the transmitter and the receiver increases above 400 m, the probability that BCZ appears is high when two or more vehicles are using the same resources, and the distances between them are smaller than the minimum allowed frequency reuse distance \(h_{\textit{reuse}}\). We observed a fast degradation in PRR, with unacceptable values of around 65-73%, and fast slope in IR between 18% and 27% for all vehicles' densities and for the distance of 600 m.  
With the PFR technique, the possibility of a receiver being in the BCZ zone, which is a common case with FFR, does not exist, because the re-partitioning band distance is higher than \(h_{\textit{reuse}}\). Furthermore, the interfering devices are located at a greater distance compared to the other two. Figure 5: The Packet Reception Ratio (PRR) of vehicles’ CAM messages broadcast for different vehicle density factors with bandwidth partitioning using the Full Frequency Reuse (FFR) technique. Figure 6: The Packet Reception Ratio (PRR) of CAM messages broadcast for different vehicle density factors bandwidth partitioning using the Partial Frequency Reuse (PFR) technique. with the FFR technique. Thus, for the PRR of PFR, and IR shown in Figures 4b and 6, we observed higher performance and lower interference impact with inter-vehicle distances below 400 m for all vehicles densities. Moreover, PRR and IR observed at 600 m vary between 72% and 89%, and between 3% and 18%, respectively. Hence, an improvement can be observed compared to the FFR case, especially with the lower number of served vehicles. The gains resulting from using frequency-domain partitioning are clearly highlighted when we compare the PRR obtained with FFR and PFR, shown in Figures 5 and 6, with the outcomes of the system performance evaluation with SB operation without any resources split, presented in Figure 7. One can clearly note that the successful reception ratio increases with partitioning, compared to the SB case, at the distance of 400 m is about 15%.