# 5G V2X Performance Comparison for Different Channel Coding Schemes and Propagation Models
## 2 Proposed V2X Communication System Model
### Small-Scale Fading in V2X System Modelling  
Extensive research has been conducted lately in order to determine small-scale fading parameters. [PERSON] et al. [55] used the Akaike Information Criterion, which aims to solve the problem of the optimal model selection and to select the best fading distribution for vehicle radio channel between Rayleigh and Rician distributions in a highway environment. They showed that the Rician distribution has the best fitting for the V2V radio channel in a highway communication environment and found that the vehicles, as obstacles have the largest influence on the small-scale fading of V2V channels by modelling the time-varying nature of the K factor. In [56], a small-scale fading analysis of the V2V channel inside tunnels was presented, driven from narrowband channel measurements, and it was collected in four different tunnels under real road traffic conditions. The Rice distribution has been proven to provide a reasonable fit to the measured small-scale fading, whereas the measured time-varying K-factor estimation inside tunnels is between 3 and 6.4 dB and outside tunnels is between 4.9 and 8.6 dB. In [57], K-factor estimation in Urban Terrain for Gdansk city (base station to vehicle) was presented. The authors proposed a Gaussian mixture for K-factor distribution in urban terrain after measuring the data. In [58], the authors studied V2V channel characteristics at the 5.9 GHz band based on measurement under a ramp, with a soundproof wall on the urban viaduct and an urban intersection scenario. The authors concluded that for the NLOS case, a Weibull distribution more appropriately describes the propagation medium, and a Rician distribution is the best for describing the LOS case. In [59], data captured from typical urban, suburban and rural areas were analysed and the Rician K factor was approximated for each scenario to give an insight into the V2V channel behaviour. For all three areas, most K values were found to be within a range of \(-10\) to \(+10\) dB, concluding that the logistic distribution provided a somewhat better fit, with very similar mean and standard deviation. The aforementioned results are mainly based on experimental measurements with real data or geometry-based simulations. 3 GPP technical reports for 4G-LTE and 5G-NR V2X communications [7; 8] provide a stochastic approach to small-scale fading. The channel state characterises the type \(\kappa\alpha\) conditions of data transmission. LOS and NLOSv states are types of data transmission where there is a dominant LOS signal between the transmitter and the receiver, although in the second case, the dominant path is partially obscured by other vehicles. For this purpose, the channel in LOS and NLOSv cases is modelled as a Rician channel [7; 8]. Due to the randomness and high mobility in the communication \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Channel State** & **Traffic Model** & **Path Loss (dB) + Shadow Fading + Blockage Loss** & **Random Loss Terms** \\ \hline \multirow{3}{*}{LOS, NLOSv} & urban & \(PL_{LOS,u}(d,f_{c})=\) & \multirow{3}{*}{\(\chi_{sf}\sim\)\(Lognormal(0,9)\)} \\  & & \(38.77+16.7\text{log}_{10}d^{+}+18.2\text{log}_{10}f_{c}+\chi_{sf}+max(0,\alpha)\) & & and \\ \cline{1-1} \cline{2-4}  & highway & \(PL_{LOS,h}(d,f_{c})=32.4+20\text{log}_{10}d+20\text{log}_{10}f_{c}\) & \(\alpha\sim\)\(Lognormal(\mu_{a},\sigma_{a}^{2})\), according \\ \cline{1-1} \cline{2-4}  & & \(+\chi_{sf}+max(0,\alpha)\) & to Table 3 \\ \hline \multirow{2}{*}{NLOS} & \multirow{2}{*}{urban} & \(PL_{NLOS,u}(d,f_{c})=36.85+30\text{log}_{10}d+18.9\text{log}_{10}f_{c}\) & \multirow{2}{*}{\(\chi_{sf}\sim\)\(Lognormal(0,16)\)} \\  & & \(+\chi_{sf}\) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Large-scale fading in V2X communication models.