Support Quality of Services (QoS) to enhancement of MAC in Vehicular Ad-Hoc Network

A Vehicular Ad-Hoc Network VANET is a form of Mobile Ad-Hoc Network or MANET which provides communication between the vehicles and the road-side base stations. A vehicle in VANET is considered to be an intellectual Vehicular node competent of communicating with its neighbors and other vehicles in the network. [1], [2], [3], [4], [5], [6]. QoS (Quality of Service) is the proposal that communication rates, fault rates, and other uniqueness can be painstaking, improved, and to some assured level in advance in VANET nevertheless in particular concern for the continuous communication of high bandwidth video and multimedia information this kind of content habitually communicating is complex in unrestricted networks using common "best effort” protocols [1,2,3,4,7,8] MACA (Multiple Accesses with Collision Avoidance) Protocol is a conflict based Sender initiated Protocol which uses Three way handshaking means that RTS—CTS—Data packet exchange [2]. It used in network congestion prevention to help in decisive the accurate sending rate by binary exponential back off (BEB) Algorithm in which if a packet communicated by a node is lost, the node uses the binary exponential back-off (BEB) algorithm to back off a uninformed period of time before retrying which is then also inadequate dependable because of data sending acknowledgement is not received, hence Enhancement of Multiple Accesses with Collision Avoidance (EMACA) Protocol based on MACA with some modifications over it have been proposed. Instead of three way handshaking in MACA, EMACA protocol proposes five way handshaking RTS – CTS – DSSI – DSSI_ACK – DATA Sending -ACK. A comparative study done on QualNet 5.0 Version simulator [9], [10] over MACA & EMACA. AODV routing protocol is used to evaluate the MACA and EMACA performance [4], [5], [11]. Results shows that the EMACA simulation performs well as compared to MACA in sense of Throughput, Total Packet Received and Drop Packet Ratio under varying circumstances of no. of nodes and pause time.