Psion Teklogix 9160 G2, User Manual, Page: 221 / 436

Chapter 19: Quality Of Service (QoS)
Configuring AP EDCA Parameters
Psion Teklogix 9160 G2 Wireless Gateway User Manual 197
AIFS
(Inter-Frame Space)
The Arbitration Inter-Frame Spacing (AIFS) specifies a wait time (in milliseconds) for data frames .
Valid values for AIFS are 1 through 255 .
For more information, see DCF Control of Data Frames and Interframe Spaces.
For more information, see “EDCF Control Of Data Frames And Arbitration Interframe Spaces” on
page 190.
cwMin
(Minimum Conten-
tion 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 doubled. Doubling will continue until the size of the random
backoff value reaches the number defined in the Maximum Contention Window.
Valid values for the “
cwmin
” are 1, 3, 7, 15, 31, 63, 127, 255, 511 , or 1023 .
For more information, see “Random Backoff And Minimum/Maximum Contention Windows” on
page 191.
cwMax
(Maximum Conten-
tion 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 Window size is reached.
Once the Maximum Contention Window size is reached, retries will continue until a maximum number
of retries allowed is reached.
Valid values for the “
cwmax
” are 1, 3, 7, 15, 31, 63, 127, 255, 511 , or 1023 .
For more information, see “Random Backoff And Minimum/Maximum Contention Windows” on
page 191.
Table 19.3 AP EDCA Parameters
Field Description