HCCA- A QOS SUPPORT STANDARD IN IEEE 802.11e WIRELESS LANS

Abstract

The most popularly and widely used Wireless LAN standard all over the world today is IEEE 802.11. It is likely to play a major role in the next generation wireless communication networks. In the present 802.11 Wireless LANs two basic co-ordination functions exists such as DCF (Distributed Coordination function) and PCF (Point Coordination Function). DCF is responsible for asynchronous data services and the PCF was developed for time bounded services. Unlike traditional best effort data applications, multimedia applications require quality of service (QoS) support such as guaranteed bandwidth and bounded delay/jitter. Providing such QoS support in 802.11 is challenging and thus a number of IEEE 802.11 QoS enhancement schemes have been proposed. In this present work we analyze the QoS limitations of IEEE 802.11 wireless MAC layers with present protocol PCF. And we suggest the QoS Enhancement techniques for IEEE 802.11 WLAN which is Reference Scheduler of the HCF Controlled Channel Access (HCCA) Protocol referred in IEEE 802.11e standard. The Simulation and thus Performance of the HCCA protocol with Reference Scheduler is realized using Network Simulator 2 (ns2). The basic structure of ns-2 and the networking protocols are realized in the programming language C++. The script language Tcl is used for easy control and assembly of new simulations. The generated trace files are to be analyzed using perl script and the graphs are plotted using xgraph/gnu plot. i