Specifications
Chapter 4 - Operation and Administration Menus and Parameters
BreezeACCESS 4900 127 System Manual
4.2.6.2.9.5 Show Cell Distance Parameters
Select Show Cell Distance Parameters to view the Cell Distance parameters. In
addition, the Measured Maximum Cell Distance and the MAC address of the unit
that the mechanism found to be the farthest from the AU are displayed.
4.2.6.2.10 Arbitration Inter-Frame Spacing (AIFS)
The time interval between two consecutive transmissions of frames is called
Inter-Frame Spacing (IFS). This is the time during which the unit determines
whether the medium is idle using the carrier sense mechanism. The IFS depends
on the type of the next frame to be transmitted, as follows:
SIFS (Short Inter-Frame Spacing) is used for certain frames that should be
transmitted immediately, such as ACK and CTS frames. The value of SIFS is
16 microseconds.
DIFS (Distributed coordination function Inter-Frame Spacing) is typically used
for other frame types when the medium is free. If the unit decides that the
medium is not free, it will defer transmission by DIFS plus a number of time
slots as determined by the Contention Window back-off algorithm (see
“Minimum Contention Window” on page 164) after reaching a decision that the
medium has become free.
DIFS equals SIFS plus AIFS, where AIFS can be configured to a value from 1 to 50
time slots. A unit with a lower AIFS has an advantage over units with a higher
AIFS, since it has a better chance to gain access to limited wireless link resources.
Typically, AIFS should be configured to two time slots. A value of 1 should only be
used in one of the two units in a point-to-point link, where in the other unit the
AIFS remains configured to two time slots. This ensures that the unit with AIFS
configured to one has an advantage over the other unit, provided that the
Minimum Contention Window (see “Minimum Contention Window” on page 164)
parameter in both units is configured to 0 to disable the contention window
back-off algorithm.
The available range is from 1 to 50 (time slots).
The default is 2 time slots.
NOTE
The AIFS parameter is not applicable when the Wireless Link Prioritization Option is enabled.