To deeply discuss the mathematics model for EDCF (enhanced distributed coordination
function), the performances of two access mechanisms, 802.11 DCF (distributed coordination function)
and 802.11e EDCF, were analyzed and compared through simulation. The differences between 802.11 DCF
and 802.11e EDCFwere discussed, and the principle of EDCF providing the quality of service (QoS) was
investigated. Simulation result shows that EDCF can provide the guarantee of QoS forwireless LANs (local
area network), but systemperformance deteriorates if there are many data streamswith high priority contend
for a channel.