Performance Evaluation of Priority based ContentionMAC in Mobile AdHoc Networks

The communication through wireless media is in very much demand because of high mobility of the users and establishing ad hoc network in emergency situations, which requires the designing of an efficient and priority based MAC (Medium Access Protocol) to support quality of service in MANET (Mobile Ad hoc Networks) adequately. MAC is the base layer, which is required to catch up the system performance especially in mobile ad hoc wireless network. There are various MAC standards used in MANET. The IEEE 802.11 is one of them and most frequently applied to such networks presently. We found that the IEEE 802.11 MAC standard is not very much suitable into wireless network scenario because its poor performance and not satisfactorily addressing the critical issues of networking like priority based transmission across the nodes results in lower throughput, higher delay and poor fair access of cannels. In this paper, we propose a dynamic PBC-MAC protocol for wireless ad hoc networks named as Priority Based Contention-MAC protocolin which after the collision, contention window size increases or decreases dynamically and non-uniformly depending upon the priority levels of nodes in the network. It decides its lower Backoff time as per higher priority level of the nodes to access channel adequately. The simulation result show that PBC-MAC scheme is outperform than the Binary Exponential Backoff (BEB) scheme in the IEEE 802.11 MAC.