Siemens IEEE802.11 - Manual (Page 36)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 36 © Siemens, 2002
IEEE802.11e: MAC Enhancements
for Quality of Service (EDCF)
– differentiated DCF access to the wireless medium for
prioritized traffic categories (4 different traffic categories)
– output queue competes for TxOPs using EDCF wherein
• the minimum specified idle duration time is a distinct value
• the contention window is a variable window
• lower priority queues defer to higher priority queues
n
EDCF (Enhanced Distributed Coordination Function)
Mapping to
Access Category
Transmit Queues
Per-queue
channel access
functions with
internal collision
resolution