Geographic routing protocols for Vehicular Ad hoc NETworks (VANETs): A survey

During the last decade, many routing protocols have been proposed for Vehicular Ad hoc NETworks (VANETs) by taking into account their specific characteristics. The protocols based on the vehicles' positions, named geographic routing protocols (GR) or position-based routing protocols (PBR), were shown to be the most adequate to the VANETs due to their robustness in dealing with the dynamic environment changes and the high mobility of the vehicles. Instead of using the IP addresses, as in the case of Mobile Ah hoc NETworks (MANETs) protocols, position-based routing protocols are based on the geographical position of the vehicles when selecting the best path to forward the data. Further, they do not exchange link state information and do not maintain established routes as in MANET routing protocols. This makes the protocols more robust to the frequent topology changes and the high mobility of the vehicles. In this paper, we present a state-of-art of the routing protocols based on the geographic position of the vehicles. We discuss the pros and the cons of these protocols by exploring the motivations of design of such protocols and we define some possible directions for future research related to the use of this class of protocols.