RSU-Assisted Geocast in Vehicular Ad Hoc Networks

Geocast, delivering a message to nodes within a geographical region, is an important issue in VANETs. In this article, we address the geocast problem in VANETs. Given a piece of a message, we must find the minimal cost to relay the message to a specific vehicle in a given geographical area. To solve this problem, we propose an RSU RAG approach for VANETs. We use a quadtree model that represents a hierarchical decomposition of the global region. Then we propose a tree trimming approach to search the intersection between the destination area and the quadtree. Based on the quadtree model, we propose an election approach that selects an optimal RSU to forward the message to the destination area. Theoretical analysis is given about the complexity to search the quadtree. Extensive simulations show that the performance of our proposed method is superior to other approaches.