By Modifying BEB Algorithm an Optimized MAC 802.11 Protocols for Wireless Network

in wireless ad-hoc network, backoff is traditionally based on the IEEE binary exponential backoff algorithm. As wireless ad-hoc network is usually used in the critical situation, its efficiency and performance is significant. Since MAC is the fundamental layer the design of an efficient and high performance underlying MAC protocol is significant for the overall performance of the ad-hoc network. In the IEEE 802.11standard the network nodes uses Binary Exponential backoff (BEB) is a randomized protocol for regulating transmission on multiple access broadcast channel. BEB is a method in which on each collision on the shared channel, nodes sending collided packets need to backoff for a random period of time, which is uniformly selected from Contention Window (CW), and it is doubled after each collision and immediately reduces to a minimum value after each successful transmission. The problem with original MAC protocol is its static behaviour means at each collision its waiting time increases exponentially and at each successful transmission its waiting time decreases one slot a time. Since the MAC with BEB scheme suffers from low throughput and poor fairness under various network condition, it is not a good choice for adhoc network. In this paper we propose an modified algorithm that is adaptive in nature and changes with time. In our proposed we modify the existing backoff algorithm and proposes an enhanced adaptive MAC protocol for wireless LAN and compare the performance of enhanced 802.11 MAC protocol with conventional 802.11 MAC protocol on different parameters. Keywords— Mobile Ad-hoc Network (MANET), Binary Exponential Back-off (BEB), 802.11 Medium Access Control (MAC),