Software-defined networking-based cognitive routing protocol for vehicular ad hoc networks

Cognitive routing for software-defined vehicular networks is proposed in this paper to find a stable path between source and destination. The protocol has two phases: registering phase and route prediction phase. The main controller is responsible for global view of the network whereas several local controllers are defined to reduce the burden of main controller by keeping a localized global view of the network. Local controllers are selected in the registering phase. Once all the local controllers are selected, the protocol switches to route prediction phase. With the aid of main controller and local controllers, the proposed algorithm aims to reduce end-to end delay by selecting the best route which maximizes the path duration. A route is established by selecting both channel and relay simultaneously for each link, thereby making a stable path between source and destination. Two vehicles can only form a link if they both have consensus on common idle channel. Therefore, spectrum sensing is the primary task of this algorithm to find a stable route by keeping licensed users safe. We apply belief propagation (BP) algorithm to compute a final belief about existence of primary user (PU). Our simulation results report a significant improvement in end-to-end delay.