USRobotics Instant802 APSDK - Manual (Page 151)

Professional Access Point
Administrator Guide
Quality of Service - 151
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cwMin
(Minimum Contention Window)
This parameter is input to the algorithm that determines the initial random
backoff wait time (window) for retry of a transmission.
The value specified here in the Minimum Contention Window is the upper limit
(in milliseconds) of a range from which the initial random backoff wait time is
determined.
The first random number generated will be a number between 0 and the
number specified here.
If the first random backoff wait time expires before the data frame is sent, a
retry counter is incremented and the random backoff value (window) is dou-
bled. Doubling will continue until the size of the random backoff value reaches
the number defined in the Maximum Contention Window.
For more information, see “Random Backoff and Minimum / Maximum Conten-
tion Windows” on page 146.
cwMax
(Maximum Contention Window)
The value specified here in the Maximum Contention Window is the upper limit
(in milliseconds) for the doubling of the random backoff value. This doubling
continues until either the data frame is sent or the Maximum Contention Win-
dow size is reached.
Once the Maximum Contention Window size is reached, retries will continue
until a maximum number of retries allowed is reached.
For more information, see “Random Backoff and Minimum / Maximum Conten-
tion Windows” on page 146.
TXOP Limit
(Transmission Opportunity Limit)
Station EDCA Parameter Only (The TXOP Limit applies only to traffic flowing
from the client station to the access point.)
The Transmission Opportunity (TXOP) is an interval of time when a WME
client station has the right to initiate transmissions onto the wireless medium
(WM).
This value specifies (in milliseconds) the Transmission Opportunity (TXOP) for
client stations; that is, the interval of time when a WMM client station has the
right to initiate transmissions on the wireless network.
Field Description