Alvarion BreezeACCESS II System Manual page 177

Menus and Parameters
Best AU Selection Parameters
In BreezeACCESS systems with software version 3.0 and below an SU
can associate with any AU it can communicate with, provided they both
use the same ESSID. An SU that can communicate with more than one
AU using the same ESSID becomes associated with the first AU it
"finds", not necessarily the best choice in terms of quality of
communication or other factors such as number of SUs serviced by
each AU. The same limitation also exists if only one AU in the
neighborhood has an ESSID identical to the one used by the SU, since it
is not always necessarily the best choice.
The topology of a fixed access network is constantly changing. Changes
in base station deployment and subscriber density can accumulate to
create substantial changes in SU performance. The quest for load
sharing together with the desire to create best throughput conditions for
the SU created the need for the Best AU feature, to enable a SU to
connect to the best AU in its neighborhood.
When the Best AU feature is used, each of the AUs are given a quality
mark based on the level at which it is received by the SU. The SU scans
for a configured number of cycles, gathering information from all the
AUs it can communicate with. At the end of the scanning period, the SU
reaches a Best AU decision according to the information gathered. The
AU with the highest quality mark is selected as the Best AU, and the SU
will immediately try to associate with it.
The quality mark given to each AU depends on the level at which it is
received by the SU., as follows:
The Best AU selection mechanism can be overridden by defining a
specific AU as the preferred AU.
NOTE:
Although the SU selects the Best AU based on long-term conditions prior to the decision
time, it may not always be connected to the instantaneous Best AU at any given time.
Note also that the decision is done only once during the scanning interval. The decision
may not remain the optimal one for ever. If there are significant changes in deployment
of neighboring AUs and the SUs served by them, overall performance may be improved
if the applicable SUs are reset intentionally so as to re-initiate the Best AU decision
process.
Best AU Parameters in SU
Best AU Support – Enables or disables the Best AU selection
feature.
The default is Disable.
NOTE:
If the Best AU feature is not used, the SU associates with the first AU it finds
whose ESSID or Operator ESSID is identical to its own ESSID.
Number of Scanning Attempts – Defines the number of
scanning cycles to be used for gathering information on
BreezeACCESS Version 4.3 System Manual
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