Multi-hop Vehicular Cloud Construction with Connection Time based Resource Allocation in VANETs

Vehicular cloud computing is a new emerging technology that can provide drivers with cloud services to enable various vehicular applications. A vehicular cloud is defined as a set of vehicles that share their own resources. Since central infrastructures such as roadside units cannot be available always, vehicles should collaborate with each other to construct vehicular clouds through vehicle-to-vehicle communications. Moreover, vehicular cloud might request multi-hop communications to search enough resources to form it. Due to intermittent wireless connectivity and low density of vehicles with the limited resources, the formation of vehicular cloud with multi-hop communications has become challenging in vehicular environments in terms of the service success ratio, the service delay, and the transmitted packet number. However, since the existing protocols do not consider the connectivity of intermediate nodes on multi-hop communications, the neighbor number of vehicles for resource allocations, and the correct reconstruction for the cloud failure of vehicular clouds, they increase cloud service failure and decrease cloud service availability. Thus, we propose a multi-hop vehicular cloud construction protocol that increases the service success ratio and decreases the service delay and the transmitted packet number. The proposed protocol uses a connection time-based intermediate vehicle selection scheme to reduce the cloud failure probability of multi-hop vehicular cloud. To raise service availability, resources for a vehicular cloud are allocated based on the connection time between vehicles and the number of neighbor vehicles. An explicit scheme for the reconstruction of vehicular clouds is provided to handle the connection failure and the leave of vehicular cloud member vehicles. Simulation results conducted in various environments verify that the proposed protocol achieves better performance than the existing protocol.