13. 802.11e QoS Performance Evaluation

Wireless networks have become a tremendous network solution for home and enterprise users, without worrying about wire, and mobility. With IEEE 802.11e Wireless Local Area Networks (WLAN), we have implemented Quality of Service (QoS) to our wireless network that provides significant improvements for high-priority QoS traffic. However, these improvements have a negative performance impact to lower-priority traffic, such as HTTP, FTP etc. In this paper, we examine two IEEE 802.11e QoS functions which are Point Coordination Function (PCF), and Hybrid Coordination Function (HCF). We also examine their negative effects on performance of lower-priority traffic in two different WLAN infrastructures which are Basic Service Set (BSS) and Extended Service Set (ESS), using OPNET Modeler software. We evaluate the impact of high-priority traffic (with QoS enabled) on low-priority-traffic when they use the same access point. All of the simulation results proved that it has a significant detrimental impact to low-priority-traffic. Performance of HTTP, FTP, and database traffic drops when VoIP and video applications are using same access point.