  We first propose a simple mathematical analysis framework for the Enhanced
Distributed Channel Access (EDCA) function of the recently ratified IEEE
802.11e standard. Our analysis considers the fact that the distributed random
access systems exhibit cyclic behavior. The proposed model is valid for
arbitrary assignments of AC-specific Arbitration Interframe Space (AIFS) values
and Contention Window (CW) sizes and is the first that considers an arbitrary
distribution of active Access Categories (ACs) at the stations. Validating the
theoretical results via extensive simulations, we show that the proposed
analysis accurately captures the EDCA saturation performance. Next, we propose
a framework for multimedia capacity analysis of the EDCA function. We calculate
an accurate station- and AC-specific queue utilization ratio by appropriately
weighing the service time predictions of the cycle time model for different
number of active stations. Based on the calculated queue utilization ratio, we
design a simple model-based admission control scheme. We show that the proposed
call admission control algorithm maintains satisfactory user-perceived quality
for coexisting voice and video connections in an infrastructure BSS and does
not present over- or under-admission problems of previously proposed models in
the literature.
