Coalition Formation of Vehicular Users for Bandwidth Sharing in Vehicle-to-Roadside Communications

In vehicular-to-roadside (V2R) communications of vehicular network, the bandwidth from roadside unit (RSU) can be shared among vehicular users to improve the utilization and reduce the cost. In this paper, the coalition game is formulated to model the situation in which multiple vehicular users can cooperate to share the bandwidth to RSU. First, the rational coalition formation is considered in which each vehicular user has self-interest to form coalitions so that the individual utility is maximized. The dynamic model of such a formation is presented to obtain the stable coalition collection. The distributed algorithm based on split and merge mechanisms is also proposed. Then, the optimal coalition formation is considered in which the coalitions is formed so that the social welfare of all vehicular users is maximized. The performance evaluation shows that the optimal coalition formation yields higher utility than that of rational coalition due to the group-interest of all vehicular users. Also, both optimal and rational coalition formations achieve much higher utility than that without bandwidth sharing. Keywords-Intelligent Transportation Systems (ITS), vehicleto-roadside (V2R) communications, coalition game.