International Journal of Engineering and Technical Research (IJETR) ISSN: 2321-0869 (O) 2454-4698 (P), Volume-6, Issue-4, December 2016 10 www.erpublication.org Abstract— Vehicular ad hoc networks (VANETS) have been appeared as a new area of data dissemination. Vehicular Ad hoc network is regarded as intelligent agent, in which vehicles provide aid to the end users. Vehicles in vehicular ad hoc networks are very unstable due to dynamic topology. Therefore to provide efficient data delivery from source node to destination node, clustering is one of the best panaceas (way out) for the above issue. In this paper we mainly emphasize on the process of clustering how the cluster head is elected and re-scheduled and what are the problems in stable clustering which leads to the betterment of clustering process in VANETS. Index Terms— Vehicular Ad Hoc network (VANETS), Clustering, Cluster head (CH), Gateway node (GW). I. INTRODUCTION The question arises why there is great need for traffic control management system to provide aid to end users. As we all are familiar with roadside condition which results in high traffic jams and high possibility of accidents so there is great concern for high alerts. The way out for above issue is traffic control. Imperial liquid measure of fuel is wasted everyday when vehicle gets stuck in traffic congestion therefore to conserve the resources as well as to provide the safety to the passengers VANETS emerged as intelligent transportation system (ITS) in which mobile/vehicle node is capable of communicating with neighbouring mobile/vehicle node. Traffic control systems provide the assurance that the atmosphere is accident free. With the advancement in wireless communication, Federal communication commission (FCC) provide various standards to boost the communication among the vehicles in traffic control system [3]. Wireless access in vehicular environment (WAVE) and Dedicated Short Range Communication (DSRC) are the two standards defined by FCC in IEEE 1609.14 and 802.11p [3]. For inter-vehicle and roadside to vehicle type of communication domain, 75MHZ frequency spectrum is dedicated by FCC. DSRC standard was invented by USA [4].DSRC is allocated 802.11 MAC Layer plus IEEE 802.11a physical layer [4].As we all know in Vehicular Ad hoc network vehicles topology is highly dynamic thereby it require a high data transfer rate. IEEE 802.11 MAC suffers from high overhead rate [4]. So there is immense need to enhance the feature of DSRC standard. American society for testing and materials (ASTM) improved the DSRC standard to 802.11p which is regarded as WAVE [4]. Navneet Kaur, Computer Science & Engineering Amritsar College of Engineering & Technology, Amritsar, India Er. Sandeep Kad, Computer Science & Engineering Amritsar College of Engineering & Technology, Amritsar, India A. Architecture The main components of Vehicular Ad hoc networks vehicles, roadside unit, on board unit (OBU). Vehicles are equipped with OBU and sensors to gather the information from roadside unit (infrastructure unit) or neighboring vehicles by broadcasting alert messages [8]. Wireless communication in traffic control system is of two type’s inter-vehicle and roadside-vehicle type of communication Fig 1: Generalized view of VANETs [6] The inter-vehicle communication is also known as cooperative communication because the group of vehicles communicates with one another thus forming the cooperative driving atmosphere [1]. Further the inter-vehicle communication is of two types’ naïve broadcasting and intelligent broadcasting. Naïve broadcasting broadcasts messages or beacons periodically which results in collision of messages whereas the intelligent broadcasting generates beacons on demand hence result in less collision of messages and efficient communication without delay. The vehicle-roadside type of communication is regarded as single hop broadcast where the roadside unit sends the broadcast message to all equipped vehicles in the vicinity [1]. It provides the high bandwidth link as well as the high mobility link between vehicles and roadside units. B. Routing Protocols in VANETs Main hindrances in VANETs scenario which leads to requirement of routing are dynamic topology changes, fast data rate, overhead issue, quality of Data Dissemination In VANETS- A Review Navneet Kaur, Er. Sandeep Kad