# 3 GPP 5G V2X Scenarios: Performance of QoS Parameters Using Turbo Codes
## 4 Conclusions  
The C-V2X approach corresponds to collaboration of existing cellular technology (e.g., LTE) with V2X communication. 3 GPP 5G V2X Release 16 has specified six application scenarios considering the following four parameters: end-to-end latency, data rate, reliability and communication range. Additionally, according to published literature, throughput and vehicle density represent critical QoS issues. In this work we investigate all six of the above parameters and apply the LTE turbo coding scheme to these 5G V2X scenarios. Our approach considers nine realistic simulation scenarios with two short frame length values \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Related** \\ **References** \\ \end{tabular} } & **3 GPP 5G V2X** & \
\begin{tabular}{c} **QoS** \\ **Optimization/Parameters** \\ **Taken into Account** \\ \end{tabular} &
\begin{tabular}{c} **Channel Coding** \\ **Consideration** \\ \end{tabular} \\ \hline
[15] & 16 & Vehicle speed, density & \\ \hline
[16] & 16 & Vehicle density & \\ \hline
[20] & 16 & & ✓ \\ \hline
[21] & 16 & Message size & ✓ \\ \hline
[22] & 16 &
\begin{tabular}{c} Message size, vehicle speed, \\ data rate \\ \end{tabular} & ✓ \\ \hline
[23] & & & ✓ \\ \hline Proposed & 16 &
\begin{tabular}{c} Message size, vehicle speed, \\ data rate, vehicle density \\ \end{tabular} & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of our proposed approach with published literature. (256 and 512 bits), two mobile terminal speeds (60 and 100 km/h) and three data rates (6, 12 and 18 Mbps). We examine 6 QoS parameters in this work, starting from data rate per vehicle and mobile terminal speed QoS parameter, where we found that doubling the data rate results in up to 1.85 dB performance losses (in [20] for a short frame length of 128 bits the corresponding loss is 2 dB). Tripling the data rate results in a 1 dB loss, which means that when we increase the data rate, we observe that the performance losses decrease. For link reliability QoS parameter, data rate and frame length are important mainly for medium SNR values. On the other hand, mobile terminal speed's effect on reliability is negligible. For small SNR values only scenario 5 from Table 1 can be established. For medium SNR values the choice of the suitable Table 1 scenario depends on data rate and on the decoding algorithm. For high SNR values, scenarios 2, 3, 6 from Table 1 are recommended. The influence of traffic density in QoS performance is evident only in the medium SNR values for the corresponding traffic density values between 85 and 105. Considering throughput QoS parameter, for a frame length of 512 bits and simulated scenarios 5, 6 of Table 2 (speed value of 60 km/h), the minimum SNR value of 3 dB can be satisfied to achieve non--zero throughput values. For end-to-end latency QoS parameter and scenarios 1, 3, 6 and 8 of Table 2, the scenarios of Table 1 depend on turbo decoding algorithm while for communication range QoS parameter, mainly Table 1 scenarios 1, 3 (communication range short to medium) can be implemented and probably scenarios 2, 4 (communication range short). The V2V communication model (with turbo coding and GEMV mobile channel) proposed in this work can be established because it satisfies the QoS limitations (considering all six of the above QoS parameters). The cooperative sensing 3 GPP implementation scenario meets these QoS limitations for medium and large SNR values. Finally, the above analysis justifies the need for a dynamic physical layer channel coding selection scheme (which emphasizes on turbo coding). As a future work, we intend to implement a fully dynamic scheme that will do the selections on a multi--level QoS parameter indicator depending on the observed traffic conditions (considering simulation results) with the use of a ML procedure. Conceptualization, D.K. and C.C. ; methodology, D.K. and C.C. ; software, D.K. and C.C. ; validation, D.K. and C.C. ; formal analysis, D.K. and C.C. ; investigation, D.K. and C.C.