Siemens IEEE802.11 Instrukcja Użytkownika Pobierz pdf (Strona 38)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 38 © Siemens, 2002

IEEE802.11e: MAC Enhancements

for Quality of Service (HCF)

– only usable in infrastructure QoS network configurations

– to be used during both the contention period (CP) and the

contention free period (CFP)

– uses a QoS-aware point coordinator („hybrid coordinator“)

• by default collocated with the enhanced access point (QAP)

• uses the point coordinator's higher priority to allocate

transmission opportunities (TxOPs) to stations

– meets predefined service rate, delay and/or jitter

requirements of particular traffic flows.

n HCF (Hybrid coordination function)

–

Caused long delays in standardization process due to its

complexity

–

Recently widely supported „Fast –Track“ proposal to come

to a conclusion in TGe

•

Most complex functions eliminated, streamlined HCF, ...

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Siemens IEEE802.11 Instrukcja Użytkownika Strona 38