I.J. Information Technology and Computer Science, 2017, 2, 30-37 Published Online February 2017 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijitcs.2017.02.04 Copyright © 2017 MECS I.J. Information Technology and Computer Science, 2017, 2, 30-37 On the Selection of MAC Optimised Routing Protocol for VANET Kanu Priya Research Scholar, Department of CSE, Guru Nanak Dev University Regional Campus, Jalandhar, India. E-mail: kanupriya2310@gmail.com Jyoteesh Malhotra Head of CSE & ECE Department, Guru Nanak Dev University Regional Campus, Jalandhar, India. E-mail: jyoteesh@gmail.com Abstract—In today‘s era of modernization, the concept of smart vehicles, smart cities and automated vehicles is trending day by day. VANET (Vehicular Adhoc Network) has also been emerging as a potential applicant to enable these smart applications. Though VANET is very much similar to MANET (Mobile Adhoc Network) but VANET has more severe challenges as compared to MANET due to hostile channel conditions and high degree of mobility. So lot of work related to MAC and Network Layer need attention from the network designers. In this paper MAC Layer has been optimised in terms of Queue Size by using QoS Parameters namely Packet Collision Rate, Packet Drop Rate, Throughput Rate and Broadcast Rate. In doing so, simulative investigations have been done to find out optimum queue size. For this purpose various routing protocols namely DSDV, AODV, ADV and GOD have been considered and optimum queue length for each of these have been obtained. Further the most efficient routing protocol has also been identified. Moreover this paper also compares the performance of most efficient Routing Protocols selected in terms of QoS parameters for different MAC Interfaces. Index Terms—DSDV (Destination Sequenced Distance Vector Routing), ADV (Advanced Distance Vector Routing), GOD (General Operation Directory), ITS (Intelligent Transport System), NCTUns. I. INTRODUCTION In today‘s era VANET (Vehicular Adhoc Network) is one of the emerging technologies that has its usage in specific area of adhoc networks. Several attributes are gaining importance day by day like smart cities, smart vehicles, automated highways and bridges etc. VANET is very well organised and an autonomous wireless adhoc network. Hence this area is gaining momentum in every pulse of time. VANET is prominent area of Intelligent Transport System (ITS) that permits the vehicles to communicate with other vehicles and roadside equipments wirelessly. Whenever an alarming situation like traffic congestion, road accidents, fire incidents etc. are encountered; vehicles wirelessly transmit this crucial information with all the vehicles within its communication range. Hence it permits road safety to the users. But still there is need of optimization in certain key areas of routing layer, physical layer and Mac layer. As the vehicles are increasing on roads and all have varying driving behavior this implies VANET as a very dynamic. In VANET the mobile nodes have to follow some restrictions regarding patterns of movement and traffic conditions. So routing protocols govern the moving behavior of vehicles hence it is the most challenging issue for the researchers to deal with. The routing protocols used in VANET should be highly reliable and must be capable of adapting to network load with minimum delay in data transmission. The main focus of this paper is the optimisation of MAC Layer as well as Routing Layer using IEEE 802.11a Interface. In order to evaluate the performance, extensive simulations have been performed. For doing so, Multi interface car is used by varying queue sizes in various routing protocols. Queues are basically used to store and forward the data packets. Various types of queues are present out of which FIFO queue is used here. Queue size is also an important parameter to measure the performance of routing protocols in VANETs. Queue size may be defined as the length of queue to be used for transferring data packets successfully to the destination. Considering queue size as a key objective this paper aims at selection of optimum queue length for various routing protocols. For achieving this routing protocols namely DSDV, AODV, ADV and GOD have been evaluated at different queue lengths on the basis of QoS parameters i.e. Packet Collision Rate, Packet Drop Rate, Throughput Rate and Broadcast Rate in city scenario. FIFO queue is implemented at five different queue sizes to determine the most appropriate queue length for different protocols. Further these performance parameters have been compared and analysed for finding the most efficient routing protocol for 802.11a interface. The simulations are performed in GUI based tool named as NCTUns (National Chiao Tung University) 6.0 over a simulation time of 400seconds and results have been achieved in the form of graphs presented in IV Section. The rest of the paper is organised as: Section 2 explains Related Work, Section 3 highlights Simulation Methodology and Environment, Section 4 gives Results