# Enhancing Heterogeneous Communication for Foggy Highways Using Vehicular Platoons and SDN
## 2 Related Work
In clear weather, the experimental results were carried out, which achieved a high delivery ratio and low latency. Another scheme [14] was proposed to distribute the load of an SDN controller by another sub-layer of controllers in clear weather to enable vehicles moving at high speeds on highways to access multiple services. Similarly, the SDN schemes were used in the literature to select routing paths in vehicular networks during clear weather. A greedy routing based on graph convolutional networks was proposed in the hybrid SDVN [15]. The SDN controller is responsible for training the decision model globally, and vehicles use this model for routing decisions. For high-speed mobile vehicles, an optimal base station was considered in [16] to reduce the cost of route updates and ensure a seamless handover of vehicles in SDVN. Their experimental results demonstrated a significant improvement in network service quality and handover performance. Clear weather scenarios were also considered in this scheme. The propagation delay was estimated in [17] using a novel computationally efficient solution to estimate the parameters of the channel model. The channel characteristics were well-fitted with the theory results, and the model was practical for characterizing beyond 5G V2V communications, as evidenced by the numerical results. Similar to describing the non-stationary nature of multi-mobility V2X channels, a time-varying acceleration model was proposed in [18] to describe the motion of the communication terminals and scattering clusters. The simulation results validated the utility of the model for identifying V2X channels. Thus, the literature shows that the existing schemes do not consider forming an optimal routing path using SDN technology in vehicular networks to overcome the issues of high latency, large overhead, and low successful packet delivery on foggy highways. In addition, none of the schemes discussed above considered visibility less than 20 m to accommodate more challenging scenarios, nor implemented SDN technology to improve network performance during foggy weather. Therefore, we aim to implement a SDVN network to resolve the issue of high latency and large overhead in foggy weather while optimizing safe and stable routing paths. DSRC is a standard band dedicated for vehicular communication that can withstand foggy weather. In addition, the efficiency of communication based on DSRC is greater than that of visual sensors. Thus, in order to capitalize on this, we introduce a novel SDVN architecture for foggy weather using a DSRC band. Hence, the use of heterogeneous communications can lead to an optimal routing path with low latency and low overhead. All the schemes discussed above are compared in Table 1.  
\begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline \multirow{2}{*}{**Protocols**} & **Consider** & \multirow{2}{*}{**Consider** & **Use DSRC** & **Use Hetero-** & **Select** \\  & **Foggy** & **SDN? ** & **Band? ** & **Communication? ** & **Optimal Path? ** \\ \hline [5] & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline [6] & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline [7] & ✓ & \(\times\) &