Fair traffic scheduling algorithm for the roadside unit

To improve the fairness performance of the downlink traffic scheduling algorithm, a network flow based downlink traffic scheduling algorithm is proposed for the roadside unit (RSU) in vehicular networks. In the proposed algorithm, a bipartite graph is constructed firstly, where the node set is composed by the vehicle set and the timeslot set. At any given timeslot if a vehicle can communicate with the RSU, then an edge between the given timeslot and that vehicle is added into the edge set. Next, a flow network graph is constructed based on the bipartite graph by adding a virtual source node and a virtual sink node. By applying the conventional minimum cost maximum flow algorithms, a minimum cost maximum flow can be computed, which is converted to the fair traffic scheduling strategy. Simulation results show that, when the total vehicle requirements are maximized, compared with the existing algorithms, the fairness performance of the proposed algorithm is improved by 116.4% in the offline case, and by 25.9% in the online case.