Mohammadreza Pourkiani - Department of Information Technology, Science and Research Branch, Islamic Azad University
Sepideh Adabi - Department of Computer Engineering, Tehran North Branch, Islamic Azad University
Sam Jabbehdari - Department of Computer Engineering, Tehran North Branch, Islamic Azad University
Ahmad Khademzadeh - Department of International Collaboration, Research Institute for ITC

The systems in which information and communication technologies and systems engineering concepts are utilized to develop and improve transportation systems of all kinds are called The Intelligent Transportation Systems (ITS) . ITS integrates information, communications, computers and other technologies and uses them in the field of transportation to build an integrated system of people, roads and vehicles by utilizing advanced data communication technologies. Vehicular Ad-hoc Networks which is a subset of Mobile Ad-hoc Networks, provide Vehicle to Vehicle (V2V), Vehicle to Roadside (V2R) and Vehicle to Infrastructure (V2I) communications and plays an important role in Intelligent Transportation System. Due to special characteristics of VANETs, QoS (Quality of Service) provisioning in these networks is a challenging task. QoS is the capability of a network for providing superior service to a selected network traffic over various heterogeneous technologies. In this paper we present an overview of Vehicular Networks, QoS Concepts, QoS challenges in VANETs and approaches which aim to enhance the Quality of Service in Vehicular Networks

VANET, Quality of Service (QoS), Delay, Packet loss, Throughput