Streetcast: An Urban Broadcast Protocol for Vehicular Ad-Hoc Networks

Vehicular Ad-hoc NETworks (VANETs) adopting Dedicated Short-Range Communications (DSRCs) have emerged as a preferred choice of network design for the Intelligent Transportation System (ITS). A possible application of the ITS is to disseminate emergency messages by multihop broadcast. Due to the high density and high mobility of vehicles, it is difficult to design an efficient broadcast protocol for VANETs in urban areas. In this work, we propose a broadcast protocol, named \emph{Streetcast}, to provide efficient broadcast service. Street maps are used to assist the selection of relay nodes, and multicast RTS (Request-To-Send) is adopted to protect wireless communications for providing high reliability. In addition, an adaptive beacon control heuristic is proposed to reduce beacon overheads. At last, we evaluate our broadcast protocol in a real roadmap scenario with real traffic flows. The simulation results show that the proposed broadcast protocol has a superior performance in terms of packet delivery ratio and the number of collisions under various traffic load patterns.