An Evaluation of "Quality of Service" Schemes for IEEE 802.11 Wireless LANs Using OPNET Modeler

In the era of information and communication technology, WLANs are being used for military, multimedia and health application, where high system performance and the ability to stay in link is extremely required. WLAN supports best-effort service at lower investment and cost. Apart from low cost ,IEEE 802.11 technology is relatively easy, quick to install , and operating on a unlicensed frequency of 2.4 GHz which can be built independently by the individual or organization without reliance on operator. With the increasing demand and penetration of wireless services, users now expect good Quality of Services (QoS), in terms of delay; media access delay, throughput, and retransmission attempts. In this Paper, the performance optimization methods have been presented using a networks simulator, OPNET modeler 14.5. Various physical parameter such as Number of Nodes, Data Rates, Transmission Technology, Buffer Size etc. have been varied for the infrastructure wireless network. The effects of these variation on QoS characteristics like delay, media access delay, throughput, etc have been studied. It was found that there is trade off among the QoS parameters. Thus for a particular application the QoS requirements change and accordingly those parameters are being selected.