  In this paper, we carry-out a study of the Quality of Service (QoS) mechanism
in IEEE802.11e Enhanced Distribution Coordination Function (EDCF) and how it is
achieved by providing traffics with different priorities. It can perform the
access to the radio channel or just simply it can considerably be declined
subsequently to a variation of network dynamicity. The results of the proposed
analysis show that the EDCF scheduler looses the ability of the traffic
differentiation and becomes insensitive to the QoS priority requirements.
Consequently, it goes away from the region of stability and EDCF doesn't offer
better performance than the conventional DCF scheme. Therefore, traffic
specifications are weakly applied only for the channel occupation time
distribution. During the handoff between the Base Stations (BS's), the response
time of the data rate application within the roaming process grows to the
initial throughput level. Performance metrics at the MAC layer, like
throughput, End-2-End delay, and packet loss have been evaluated.
