# 5G V2X Performance Comparison for Different Channel Coding Schemes and Propagation Models
## 2 Proposed V2X Communication System Model
### Large-Scale Fading in V2X System Modelling  
Large-scale fading is a function of two main factors, path loss and shadowing [44; 45; 46]. Path loss models the average power attenuation in V2X channels, is deterministic and it is a function of the three-dimensional (3D) distance \(d\) between the two vehicles in meters and the carrier frequency \(f_{c}\) in GHz. The determination of large-scale modelling for V2X hasbeen of great concern. In [47], they studied the vehicle-induced path loss for millimetre-wave V2V communication. [PERSON] et al. [48] focused on the analysis and modelling of path loss characteristics for V2V communications with vehicle obstructions. In [49], the authors investigated the performance parameters of path loss and shadowing in different 5G NR V2V communication environments. Further, in [50], the authors validated the channel model that 3 GPP proposed for NR-V2X systems and highlighted potential density-based inconsistencies in the model and provided recommendations for future measurement campaigns in vehicular environments. Traffic density, the 3D shape of the vehicles, i.e., length, width and height, and the position of the antennas were taken into account [51] to estimate the path loss in V2V communications and to predict the SNR distribution and the service probability. [PERSON] et al. [52] obtained state transition probabilities for LOS, NLOS and NLOSv channel states that can be used to generate time-evolved V2V channel path loss realisations for representative urban and highway environments. Further, in [53], the authors designed a geometry-based efficient propagation model for V2V communication called GEMV\({}^{2}\) to simulate large-scale signal variations deterministically for city-wide networks based on geometric characteristics of the environment. In [54], the authors analysed and modelled large-scale fading by characterising the influence of common shadowing objects, both regarding the autocorrelation and the joint multilink cross-correlation process for communication at 5.9 GHz. The basis of the aforementioned research lies in the 3 GPP technical reports for 4G-LTE and 5G-NR V2X [7; 8] communications. Accordingly, the path loss in dB is computed by deterministic functions that are summarised in Table 1.  
The second factor, i.e., shadowing, is stochastic and it is implemented as a log-normal random variable that models the variations in power loss due to scattering that exist in the communication system. The shadow fading models for all types of 5G-NR V2X systems are described in [8] and they are adopted from [7] for LTE V2X. Table 2 presents the shadow fading parameters for each possible state and model. When a V2X link is in NLOSv state an additional blockage loss in dB is summed to the path loss, this loss models the possibility that moving vehicles may block the signal between the transmitter and the receiver. This blockage loss \(a\) is modeled according to a log-normal random variable, with mean \(\mu_{a}\) and standard deviation \(\sigma_{a}\), \(\alpha\sim Lognormal\left(\mu_{a},\sigma_{a}^{2}\right)\). Table 3 presents the parameters of the NLOSv additional blockage. In summary, the total path loss of a V2X link is summed up in Table 4. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Channel State** & **Traffic Model** & \multicolumn{2}{c}{**Path Loss (dB)**} \\ \hline \multirow{2}{*}{LOS, NLOSv} & urban & \(PL_{\text{LOS},u}(d,f_{c})=38.77+16.7\text{log}_{10}d+18.2\text{log}_{10}f_{c}\) \\ \cline{2-4}  & highway & \(PL_{\text{LOS},h}(d,f_{c})=32.4+20\text{log}_{10}d+20\text{log}_{10}f_{c}\) \\ \hline NLOS & urban & \(PL_{\text{NLOS},u}(d,f_{c})=36.85+30\text{log}_{10}d+18.9\text{log}_{10}f_{c}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Path loss in dB for V2X system model.