SDN-based offloading policy to reduce the delay in fog-vehicular networks

Integrating fog computing with vehicular networks led to the rapidly growing demands of vehicle applications regarding computation-intensive and low response time with meeting the request deadline. The limited resources of the fog node have made it unable to meet the demands of such applications. Offloading the requests to other Off-Load Destination (OLD) is a suitable solution for the fog node to deal with these demands. Nonetheless, this simultaneously faces two challenges. The first challenge is the offloading to a nearby fog node which stills not the fully efficient choice when this nearby fog node is busy. The second challenge is the selection decision of the optimal OLD where the fog node incurs additional burden through getting status information of all neighboring fog nodes, affecting the selection decision, which is why it may not fulfill the request deadline. To solve the first challenge, a new hybrid offloading architecture has been proposed, where the underutilized resources of Vehicular Fog Computing (VFC) are joined with the cloud to be an OLD, thus increase the processing chance of the offloaded requests. The second challenge has been solved by optimizing the selection decision of the fog node via taking the global network resources benefit of Software Defined Network (SDN) in the proposed offloading architecture to design an SDN-based offloading policy. The selection decision problem is formulated as a Binary-Linear Programming and solved by CPLEX software. The simulation results show that our proposed improves the performance of the fog node by providing less response time and significantly outperforming other offloading policies.