# Dynamic Allocation of SDN Controllers in NFV-Based MEC for the Internet of Vehicles
## 2 Related Work
### Mobile Networks
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Reference** & **Pros** & **Cons** \\ \hline [PERSON] et al. [36] & The first work using Integer Linear Program to optimal controller provisioning problem. & The switches may be assigned randomly among the activated controllers. \\ \hline [PERSON] et al. [37] & Since the proposal relies on the controller’s worst response time, it will be possible to check if the designation choice meets the latency restrictions of the applications. & After matching, the strategy is that no switch will change its controller, which may not be useful in a contest of high variability. \\ \hline [PERSON] et al. [38] & Consider the configuration time of switches with several controllers. & The proposal was not designed to be executed in real-time. \\ \hline [PERSON] et al. [39] & Two different approaches are proposed that aim to guarantee resilience considering the flow setup time. & It is assumed that all controllers have the same capacity. \\ \hline [PERSON] et al. [40] & It considers different imbalance metrics to maximize the use of resources. & It does not consider the change in the number of controllers. \\ \hline [PERSON] et al. [41] & Assume that when using different types of controllers, there is an increase in security. & Dispersands the consequences of employing different controllers in the same architecture, such as increasing management complexity and limiting communication between controllers. \\ \hline [PERSON] et al. [42] & The proposal aims to divide the network into several parts with each part assigned to a controller. & Each part of the network is not necessarily balanced and the task of reconfiguration is complex. \\ \hline [PERSON] et al. [43] & Employed heuristics to achieve an approximate optimal solution with acceptable time duration. & Did not compare the idealized model with the proposed heuristic. \\ \hline [PERSON] et al. [55] & When employing fog, the latency between device and controller is reduced. & The vehicle relay communications ignore interference. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparative of pros and cons between this proposal and previous works. \begin{table}
\begin{tabular}{c c c} \hline
**Reference** & **Pros** & **Cons** \\ \hline [PERSON] et al. [46] & It uses bio-inspired computing for making of dynamic & It does not consider controllers with different capacities. \\  & dynamic allocation of controllers. & \\  & & \\  & & \\  & & \\  & & \\  & & \\  & & \\  & & \\ \end{tabular}
\end{table} 
Table 3: _Cont._The work in [50] aims at maximizing bandwidth efficiency and enhancing system scalability by an SDN-based service architecture for heterogeneous vehicular communication environments.They formulate a novel problem of Coding-assisted Broadcast Scheduling (CBS) considering vehicular caching and network coding. In [51] is proposed an SDN-based architecture to enable unified management on heterogeneous network resources, formulated the cooperative temporal data dissemination problem and heuristic algorithm, which synthesizes dynamic task assignment, broadcast efficiency, and service deadline into priority design.