Energy-efficient roadside unit scheduling for maintaining connectivity in vehicle ad-hoc network

Vehicle Ad-hoc Network (VANET) is a type of mobile ad-hoc networks with highly dynamic topology. To address its frequent network partition issue, recently a special kind of infrastructure called the Roadside Unit (RSU) is proposed to be deployed along the road to improve the VANET connectivity. In this paper, we study the energy saving problem in RSU scheduling. Given a set of deployed RSUs, our objective is to find the optimal schedule of turning them on and off within a given time period so that the overall energy consumption of RSUs in the system is minimized while the network connectivity is still maintained. We divide this problem into two subproblems called the snapshot scheduling problem and the snapshot selection problem. The snapshot scheduling problem decides the minimum number of active RSUs needed for a snapshot of the VANET at a given time point, while the snapshot selection problem decides a sequence of time points on which the snapshot must be updated. By addressing these two subproblems, we present a complete solution for our energy-efficient RSU scheduling. We present our theoretical analysis and experimental results to show that our algorithms can achieve a significant energy saving while still maintaining the VANET connectivity.