# V2X Communication over Cellular Networks: Capabilities and Challenges
## 5 5G Capacity Analysis for V2X Communications
To introduce stochastic analysis in our evaluation, we used a program in MATLAB that resulted in circa 5% of all available vehicles being active in each V2X UC, apart from \"Lane Merging\" and \"Emergency Trajectory Alignment\" (3%) and \"See Through for Passing\" (1%), and we have only considered one vehicle per sector to be remotely operated. The estimated spectrum needs per gNB sector for the UCs examined in this section are summarized in Table 13.  
From the above table, it is clear that most of the UCs have limited bandwidth needs. Only a few of them require the transmission of a significant amount of information (i.e., \"Remote Driving\", \"Infrastructure-Based Perception of Environment\", \"Collective Information Sharing\", and \"See Through for Passing\"). It is exactly these UCs that dominate the \begin{table}
\begin{tabular}{c c c c}  & \multicolumn{3}{c}{**Spectrum Needs (MHz)**} \\ \cline{2-4}
**UC** & **30 km/h** & **15 km/h** & **5 km/h** \\ \hline Platooning & 0.24(SL) & 0.40(SL) & 0.76(SL) \\ Sensor and State Map Sharing & 2.88(DL) 7.2(UL) & 4.9(DL) 12.24(UL) & 9.21(DL) 23.04(UL) \\ Remote Driving & 0.1(DL) 30(UL) & 0.1(DL) 30(UL) & 0.1(DL) 30(UL) \\ Lane Change & 0.59(SL) & 1.01(SL) & 1.90(SL) \\ Infrastructure-Based Perception of Environment (multicast on the DL is assumed and one group of sensors on the uplink) & 1(DL) 91.67(UL) & 1(DL) 91.67(UL) \\ Collision Avoidance & 3.97(SL) & 6.74(SL) & 12.69(SL) \\ Collective Information Sharing & 25.79(SL) & 43.85(SL) & 82.54(SL) \\ See Through for Passing & 39.68(SL) & 39.68(SL) & 39.68(SL) \\ Emergency Trajectory Alignment & 2.38(SL) & 4.05(SL) & 7.62(SL) \\ Intersection Crossing & 1.24(SL) & 2.10(SL) & 3.97(SL) \\ Cooperative Driving & 19.04(SL) & 32.38(SL) & 60.95(SL) \\ \hline
**Total (MHz):** & **225.78** & **270.12** & **365.13** \\ \end{tabular}
\end{table} 
Table 13: Spectrum needs per gNB sector (2 gNBs) in the urban grid environment. spectrum needs. It is important to note that these UCs mainly use the SL or the UL, where the spectral efficiency is much lower compared to that of the DL's. The above results consider the urban grid environment with the deployment of 2 gNBs, as shown in Figure 3. To visualize the spectrum needs in an ultra-dense environment, we have also evaluated the case where 3 and 4 gNBs have been deployed to cover the same area. Figures 4-6 present these results for the DL, UL, and sidelink, respectively. Since only a few vehicles are involved in V2N UCs and the DL data rate requirements are low, the resulting DL spectrum requirements are also notably low. As mentioned above, the DL has a good spectral efficiency value. Figure 4: Downlink (DL) spectrum needs per gNB sector in the urban grid environment. Figure 5: Uplink (UL) spectrum needs per gNB sector in the urban grid environment. The UL spectrum needs are heavily dominated by two UCs, namely \"Remote Driving\" and \"Infrastructure-based Perception of Environment\". For these two UCs, we have adopted the evaluation assumption of [20], that only a small number of vehicles will execute such services in this area (i.e., one vehicle for \"Remote Driving\" per sector) and only a single group of sensors will be transmitting on the UL for the \"Infrastructure-based Perception of Environment\". The spectrum needs for each of these two UCs were 30 and 91.67 MHz, respectively. The contribution of the \"State and Sensor Map Sharing\" depends on the number of vehicles using the service in the area. It is worth noting that V2V communication is expected to be used for most of the considered advanced UCs. The spectrum needs for UCs 1, 4, 6, 9, and 10 are relatively modest, due to low data rate requirements, and can be more or less addressed via about 10 MHz in an urban environment. On the other hand, UCs such as \"Collective Information Sharing\", \"See Through for Passing\", and \"Cooperative Driving\" dominate the sidelink spectrum needs and raise the system's needs to 210 MHz in the case of 2 gNBs combined with a high traffic urban environment.