  The recently ratified IEEE 802.11e standard defines the Enhanced Distributed
Channel Access (EDCA) function for Quality-of-Service (QoS) provisioning in the
Wireless Local Area Networks (WLANs). The EDCA uses Carrier Sense Multiple
Access with Collision Avoidance (CSMA/CA) and slotted Binary Exponential
Backoff (BEB) mechanism. We present a simple mathematical analysis framework
for the EDCA function. Our analysis considers the fact that the distributed
random access systems exhibit cyclic behavior where each station successfully
transmits a packet in a cycle. Our analysis shows that an AC-specific cycle
time exists for the EDCA function. Validating the theoretical results via
simulations, we show that the proposed analysis accurately captures EDCA
saturation performance in terms of average throughput, medium access delay, and
packet loss ratio. The cycle time analysis is a simple and insightful
substitute for previously proposed more complex EDCA models.
