Alvarion BreezeACCESS EZ AU-EZ, System Manual

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Chapter 4 - Operation and Administration Menus and Parameters
BreezeACCESS EZ AU-EZ 83 System Manual
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
Section 4.2.6.5.2 ) after reaching a decision that the medium has become free.
DIFS equal 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 ( Section 4.2.6.5.2 ) parameter in both units is
configured to 0 to disable the contention window back-off algorithm.
The available options are 1 to 50 (time slots).
The default is 2 time slots.
4.2.6.2.9 Maximum Number of Associations
The Maximum Number of Associations parameter defines the maximum number
of Subscriber Units that can be associated with the selected AU, while still
guaranteeing the required quality of service to customers.
Available values range from 0 to 512.
CAUTION
An AIFS value of 1 should only be used in point-to-point applications. Otherwise the default value of
2 must always be used. In a point-to-point link, only one unit should be configured to an AIFS value
of 1. When both units need to transmit, the unit with an AIFS value of 1 will have an advantage over
the unit with AIFS of 2.