ISSN: 2277-9655 [Jain * et al., 7(9): September, 2018] Impact Factor: 5.164 IC™ Value: 3.00 CODEN: IJESS7 http: // www.ijesrt.com© International Journal of Engineering Sciences & Research Technology [43] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY IMPROVED GPSR USING COGNITIVE RADIO IN VANET FOR SAFETY MESSAGE TRANSMISSION Jyoti Jain *1 & Nidhi Chahal 2 *1 Dept of Electronics & Communication Engineering, Chandigarh Engineering College, Landran, Punjab, India 2 Assistant Professor of Dept of Electronics & Communication Engineering, Chandigarh Engineering College, Landran, Punjab, India DOI: 10.5281/zenodo.1409472 ABSTRACT VANET is vehicular Ad-hoc network which is used for intelligent transport system for the drivers the ad-hoc network is used to transmit various types of message over the network. Safety message has to transmit for the security reasons on the vehicle and road transportation various routing protocols have been utilized for the purpose of message transmission. GPSR, AODV, DSR, PUMA these are various routing protocol utilizes for message transmission VANET scenario is used for mainly V2V and V2R purposes. In various scenarios message transmission is done according to vehicle density available on the road. The main issue of road density is due to high load on road message communication get overhead due to less amount of network bandwidth to overcome this issue cognitive radio bandwidth can be utilize for data transmission by channel sensing and message can be transmit through cognitive radio channels. Keywords: VANET, Cognitive Radio, Spectrum Sensing, GPSR, AODV, DSR. 1. INRTODUCTION 1.1 VANET A VANET uses cars as mobile nodes in a MANET to create a mobile network. A VANET turns turn participating car into a wireless router or node which allowing cars 100 to 300 meters of each other to connect and create a network with a wide range. As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another so that a mobile network is created. It is estimated that the first systems that will be this technology are police and fire vehicles to communicate with each other for the purpose of security. Figure 1.1 VANET The connectivity is done among one vehicle to other vehicle and vehicle to road side infrastructure and vehicle or road side infrastructures to the central authority responsible for the network maintenance. The basic tool for message transfer is the short range radios that are being installed in any of the nodes. The short transmission node is used by vehicular node. RSU’s are spread sporadically or regularly depending on the deployment of the network in any particular region. In reality spread sporadically. They act as an intermediary node between the Central Authority (CA) and Vehicular Node (VN). VANET-Vehicular Ad-Hoc Network is the network in which communication has been done between road side units to cars, car to car in a short range of 100 to 300 m. Existing authentication protocols to secure vehicular ad hoc networks raise challenges like as certificate