• Hi just wondering,
    Are the default values for the AIF and Contention window Min and Max in HCF the same as they would be in normal DCF with DIF and contention window values?

    tks Rico

  • Hi Rico,

    AIFS values are per AC and built on SIFS, not DIFS (like in DCF).

    The Contention Window value is an integer range (CWmin/CWmax).

    "Normal" and "Default" have no meaning in the 802.11 standard that I can discern, but rather CWmin/CWmax values are based on the short/long retry count and the modulation in use - obviously starting at the min and incrementing to the max.

    hope this helps,


  • Thanks Devin,

    When learning new things i get lost inbetween the trees before i can make it out to see the forest.

    On page 143 of the 802.11 handbook states

    --The parameters defining EDCA operation , such as minimum idle delay before contention and min and max CW, are stored locally at the QSTA. These parameters will be different for each AC and can be dynamically updated by the QoS AP for each AC through EDCA parameter sets.--

    The minimum idle delay time is that the AIF? and does this statement also mean that CW min and max values are changing as a result of a change in short/ long retry count and modulation, or would there be some other reason that they would change?

    I guess what i am wondering is if adjusting the CWmin/CWmax, between ACs, can be used to give weight to the chance that one AC will access the medium before another.

    I appreciate you help and patience

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