International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 02 Issue: 02 | May-2015 www.irjet.net p-ISSN: 2395-0072 © 2015, IRJET.NET- All Rights Reserved Page 432 EFFICIENT DATA TRANSMISSION AND SECURE COMMUNICATION IN VANETS USING NODE-PRIORITY AND CERTIFICATE REVOCATION MECHANISM D.Yamini 1 , J. Jayavel 2 1 III-M.tech(IT) , Department of Information technology, Regional Centre, Anna University, Coimbatore, India 2 Teaching Assistant, Department of Information technology, Regional Centre, Anna University, Coimbatore, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Vehicular Adhoc NETwork (VANET) is a technology that uses moving vehicles as nodes in a network, to create a mobile network on roads. Greedy Perimeter Stateless Routing (GPSR) is one of the best position-based protocols, where each node needs to know only its neighbors' positions. Major drawback of GPSR is void routing problem. An Improved GPSR provides better performance in handling void routing problem with the help of a Node-Priority forwarding strategy. Security issue plays a major role in VANETs. Accuracy and integrity of the information should be guaranteed in vehicles. The Certificate Revocation mechanism is proposed for efficient security framework. NS2 simulator is used to show the results, that the proposed strategy have realized better packet forwarding and efficient packet transmission in VANETs in terms of packet delivery success ratio and end-to-end delay together with more secured communication between vehicles. Key Words: VANET , GPS , Node Priority, Certificate Revocation 1. Introduction The greedy forwarding method is based on the position based routing scheme. In this method neighbor nodes which is closest to the destination is selected as the forwarder. For void routing, different algorithms has been approached. All those approaches are simple solution, which is not suitable for VANETs. Even though GPSR[6] protocol appears to be comprehensive solution for VANETs it suffers from the following drawbacks.1)Greedy forwarding is often restricted because direct communications between vehicles may not exist due to obstacles such as truck and trees, which leads to routing loop and too many hops.2)If building first the routing topology by the planarized graph and then return greedy of face routing on it, the routing performance will degrade. Especially, in a sparse network condition where a packet reach a node that does not have any neighbors closer to the destination than itself, the performance decreases. This condition is called void routing. Existing methods deals with the void routing, but most of the methods are perimeter forwarding-based . In Improved Greedy Perimeter Stateless Routing[3] , along with greedy perimeter the node priority mechanism has been proposed. Every vehicle is capable of determining its own position and mobility by data fusion and using existing technologies such as GPS, map matching and accelerator meters. Vehicles are able to verify direct neighbors with direct line of sight using radio strength signal and share a table of neighboring. Every vehicle has a unique identity. Based on the analysis above, for position- based routing, the conventional strategy handled the void routing is blindness, thus the Node-priority mechanism based opportunistic routing is proposed. The overview of the Improved GPSR scheme is followed: on the perimeter of void region, the neighbor node competes by those advantages to be selected as the next-hop, which is able to refrain from the blindly forwarding that resulted in excessive routing ,further, the proposed scheme makes the overhead. At first, the packet is transfer by the greedy forwarding model, assume that the intermediate node receives the packet, that intermediate node is not capable of searching a node that is closer to destination than itself due to the void routing. In this situation, the node broadcasts the beacon which includes the address of the destination of the packet, the beacon was marked as ADP (Address- Destination-Packet), which is available to all nodes, and the priority-parameters for every node were calculated, respectively. The higher the priority, the more likely it is that the node is considered as the next-hop. Certificate Revocation[2] happens when problematic certificate encountered. Road Side Units(RSU) checks message for correctness, if the message is correct then RSU assi gns Valid Certificate(VC) vehicle or else assigns as Invalid Certificate(IC) and adds that particular vehicle to Certificate Revocation List(CRL).