Vehicular Ad-Hoc Networks: Introduction, Standards, Routing Protocols and Challenges

The development in the field of Intelligent Transportation System (ITS) is growing exponentially with the advancement of Vehicular Ad-hoc NETworks (VANETs). Vehicular networks have gained notable attention among the researchers from both industry and academia due to major research going in the era of smart cities. There exist many standards for wireless access in VANETs such as 2G, 2.5G, 3G, 4G, DSRC, WAVE and WiMAX. Further existing topological and geographical MANET routing protocols are also used to help the vehicles in making the routing decision for dynamic and highly mobile environment. There also exist some routing protocols specifically designed for the vehicular environment. The paper discusses existing routing protocols that are most commonly used by VANETs as per best of our knowledge, with their details and the problems associated with these protocols. Some open challenges and possible direction for future research in the field of VANETs are also included in the paper.