## 6 JCS Sidelink Performance Evaluation Using CCM-SPS
### JCS Sidelike Performances with Dynamic Vehicle Density  
Firstly, the JCS performances of the proposed CCM-SPS have been evaluated, compared with a benchmark scheme in the case of various vehicle densities. The benchmark scheme, FD-enhanced, is proposed in [39]. It detects resource collisions using full-duplex during transmission and then uses aggressive resource reselection by setting \(RC\) to 0 for all vehicles for which access collision occurs. It can quickly break off consecutive collisions to somehow improve communication performance. The proposed CCM-SPS scheme employs Q-learning to optimize the resource reselection process in addition to the FD detection in the resource reservation process. Figure 6 illustrates the empirical CDF of the root CRLB for a range using SB-SPS, FD-enhanced and CCM-SPS in various density scenarios. As the vehicle density increases, the sensing performance of the root CRLB range decreases. And the FD-enhanced significantly improves performance at medium and low vehicle densities, but the improvement is not as obvious at high vehicle densities. However, the proposed CCM-SPS not only further enhances performance in medium to low-density but also effectively improves performance \begin{table}
\begin{tabular}{l c c} \hline \hline
**Parameter** & **Symbol** & **Value** \\ \hline Scenario & & \\ Road layout & \(\,\) -\(\,\) & Highway, 3 + 3 lanes \\ Density & \(\,\) -\(\,\) & 50, 150, 250 vehicles/km \\ Average speed & \(\,\) -\(\,\) & 70 km/h \\ STD of vehicle speed & \(\,\) -\(\,\) & 7 km/h \\ Target RCS & \(\sigma\) & 10 dBm \\ \hline Power and propagation & & \\ Channel model(interference) & \(\,\) -\(\,\) & WINNER+, B1 \\ Available channel bandwidth & \(W_{ch}\) & 40 MHz \\ Transmitted power & \(P_{T}\) & 23 dBm \\ Antenna gain & \(G\) & 3 dBm \\ Noise figure & \(F\) & 6 dB \\ Center frequency & \(f_{c}\) & 5.9 GHz \\ Shadowing & \(\,\) -\(\,\) & Variance 3 dB, decorr.dist. 25 m \\ \hline Physical layer & & \\ SCS & \(\Delta f\) & 15 kHz \\ MCS & \(\,\) -\(\,\) & 5 (QPSK, \(R_{c}=0.3\)) \\ Buchannel size & \(\,\) -\(\,\) & 10 PRBs \\ \hline Access layer & & \\ Keep probability & \(P_{keep}\) & 0.8 \\ Initial reselection counter & \(RC\) & \([5,15]\) \\ RSRP sensing threshold & \(\,\) -\(\,\) & \(-126\,\)dBm \\ \hline Data traffic & & \\ Packet generation interval & \(\,\) -\(\,\) & 100 ms \\ Packet size & \(\,\) -\(\,\) & 350, 1000 bytes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Packet** & **SCS** & **MCS** & \(N_{PRB}^{max}\) & \(N_{sub}\) & \(N_{PRB}\) & **W [MHz]** \\ \hline
350 & 15 & 5 & 216 & 4 & 40 & 7.2 \\ \hline
1000 & 15 & 5 & 216 & 10 & 100 & 18 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Impact of parameters on occupied bandwidth. in high-density scenarios. Figure 7 presents 95% range root CRLB for different algorithms at varying densities. The bar graph provides a more visual representation showing the superior performance of the proposed CCM-SPS across all density scenarios compared to the other two schemes. Similar results also appear in discussions on communication performance. Figure 8 illustrates PRR over a distance using SB-SPS, FD-enhanced and CCM-SPS in different density scenarios. As the vehicle density increases, the PRR of different schemes all show a downward trend. In mid- and low-density scenarios, the FD-enhanced scheme shows some improvements in PRR within a 200 m communication range. However, in high-density scenarios, the improvements are not significant. By examining the maximum distance where PRR exceeds 0.95 under three different schemes at varying densities, as shown in Figure 9, the advantages of the CCM-SPS scheme become more obvious. Compared to the FD-enhanced scheme, the proposed algorithm can further enhance communication  
Figure 6: Empirical CDF of the root CRLB for a range using SB-SPS, FD-enhanced and CCM-SPS. Figure 7: Bar graph of root CRLB (at CCDF = 95-percentile) for a range using different schemes with varying vehicle densities.