MASAUM Journal of Basic and Applied Sciences, Vol. 1, No. 3, October 2009 413 Enhanced Variable Channel Allocation Technique for Wireless Local Area Network (WLAN) IEEE802.11 Standard Kazi Md. Abdullah Al Mamun 1 , Gyanendra Prasad Joshi 2 , Maksudur Rahman Jonayed 3 , Sung Won Kim 4 Abstract Vast use and emerging popularity of wireless local area network (WLAN) creates a crisis of bandwidth on allocated channel, and existing fixed channel allocation’s limitation and the variety of the user density, mobility and data transmission requirement caused the degradation on overall throughput of the WLAN. After considering different proposals and existing system of IEEE802.11 network, this paper is to propose an enhanced variable channel allocation technique in two different methods: ‘fixed presumed’ and ‘intelligent variable’, and a simple algorithm based on bandwidth requirement, performance of the network and quality of service (QoS) of the network. According to this paper’s proposal the distributed system (DS) of Wireless LAN (WLAN) will distribute the available frequency band to access points (AP) in such a manner that the maximum possible bandwidth efficiency will be achieved. The proposed technique is simulated and compared with the existing fixed channel allocation’s throughput. Keywords: WLAN, QoS, Channel Allocation, Bandwidth Efficiency, Next Generations Wireless; 1. Introduction On demand of wireless connectivity IEEE 802.11 working group has developed a list of different standard for wireless LAN in different frequency band with the basic standard’s extension, that contain a various versions with different data rate and number of Dept. of Information and Communications EngineeringYeungnam University, Gyeungsan Si, Gyeungsanbuk Do,Korea, Email: kazi@ynu.ac.kr 1 , joshi@ynu.ac.kr 2 , eraesh@ynu.ac.kr 3 , swon@ynu.ac.kr 4 communication channels. Due to the simplicity and cost effectiveness wireless local area network has deployed widely [4]. Now on the maximum data rate 54 Mbps has been achieved in 802.11a standard with 64-QAM modulation technique. This is theoretical, in practice we can achieve at most 20 Mbps. Still because of users’ mobility and frequent change of demand with fixed channel allocation, that having same amount of frequency range, the maximum possible throughput cannot be achieved and the maintenance of QoS requirement become difficult. The equal probability of accessing the wireless medium for all competing nodes has been ensured by the legacy distributed coordination function (DCF). Several research studies have shown the unfairness resulting from this equal access capability of DCF [1]. Many studies refer that users’ service demands have an absolutely dynamic nature, although in the long run certain patterns can be observed, which are particular for every different network [2]. This study stated a comprehensive survey of different load balancing mechanisms and then, it discussed how the future of wireless local area network with version 802.11k’s functionalities could be applied to facilitate the implementation of these load balancing techniques in 802.11 WLANs. To achieve the ultimate throughput one study proposed dynamically changing access point coverage areas [3]. Dynamic channel assignment technique also proposed for IEEE 802.11 wireless networks [4]. The author’s algorithm assigns channels dynamically in a way that minimizes channel interference generated by neighboring access points (APs) on a reference access point, resulting in higher throughput. Still because of allocated channels usability, the ultimate possible achievement of bandwidth is not acquired with the continued growth of WLANs.