Psion Teklogix 9160 G2 Wireless Gateway User Manual 195
Chapter 19: Quality of Service (QoS)
Updating Settings
19.3 Updating SettingsTo update QoS settings:
1. Navigate to the QoS tab page.
2. Configure the QoS settings as required.
3. Click the Update button to apply the changes.
cwMin
(Minimum Contention
Window)
This parameter is input to the algorithm that determines the initial random backoff wait time
(“window”) for retry of a tran smission.
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 incre-
mented and the random backoff value (wind ow) is doub led . D oublin g w ill con tinue 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 Contention Windows” on
page187.
cwMax
(Maximum Contention
Window)
The value specified here in the Maximum Contention Window is the upper limit (in millisec-
onds) for the doubling of the random backoff value. This dou bling continu es until e ither 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 Contention Windows” on
page187.
TXOP 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 clie nt 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