USRobotics Instant802 APSDK - Manual (Page 149)

Professional Access Point
Administrator Guide
Quality of Service - 149
Enabling/Disabling Wi-Fi Multimedia
By default, Wi-Fi MultiMedia (WMM) is enabled on the access point. With WMM enabled, QoS prioritisation
and coordination of wireless medium access is on. With WMM enabled, QoS settings on the Professional
Access Point control downstream traffic flowing from the access point to client station (access point EDCA
parameters) and the upstream traffic flowing from the station to the access point (station EDCA
parameters).
Disabling WMM will deactivate QoS control of station EDCA parameters on upstream traffic flowing from
the station to the access point
With WMM disabled, you can still set some parameters on the downstream traffic flowing from the access
cwMin
(Minimum Contention Window)
This parameter is input to the algorithm that determines the initial random
backoff wait time for retry of a transmission.
Select a value from the list. The value selected for cwMin 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 in
cwMin .
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)
Select a value that is higher than cwMin .
The value specified for cwMax is the upper limit, in milliseconds, for the dou-
bling of the random backoff value. This doubling continues until either the data
frame is sent or the Maximum Contention Window 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.
Max. Burst
(Maximum Burst Length)
AP EDCA Parameter Only. The Max. Burst Length applies only to traffic flowing
from the access point to the client station.
This value specifies, in milliseconds, the Maximum Burst Length allowed for
packet bursts on the wireless network. A packet burst is a collection of multiple
frames transmitted without header information. The decreased overhead
results in higher throughput and better performance.
Valid values for maximum burst length are 0.0 through 999.9.
For more information, see “Packet Bursting for Better Performance” on
page 147.
Field Description