QoS Performances of IEEE 802.11 EDCA and DCF: A Testbed Approach

There has been considerable research into the performance of the enhanced IEEE 802.11e standard in recent years. Majority of the performance analysis has been based on simulations and analytical models, with little testing done in a real-world environment. We investigate the behaviors of the enhanced distributed channel access (EDCA) and legacy distributed coordination function (DCF) based on a testbed operating in a realistic working environment. Both TCP/UDP streams representing traffic types such as FTP and VoIP are tested. Quality of service (QoS) metrics such as throughput and delay are calculated directly from a passive capture of the channel. These metrics can also be converted into physical layer requirements such as signal to noise ratio. EDCA and DCF are shown to have similar performances with single streams of traffic, which are contributed directly by the loss effect at the MAC layer.