User's Manual

94 Operation
Chapter 4 - Operation
4.6 BST/AU ID Parameters Menu
Each AU/Micro Base Station (logical sector) in the network is configured with a
unique ID comprising an Operator ID, Cell ID and Sector ID. The BST/AU ID
parameters in the SU define the Base Station(s)/AU(s) that can synchronize with
the SU. These parameters include the base BST/AU ID and the BST/AU ID Mask.
The SU can synchronize only with AUs/Micro Base Stations whose Base Station
ID is included in the IDs range defined by the applicable parameters in the SU.
When the Best BST/AU Support is disabled, the SU will start searching for
available AUs/Micro Base Stations in the range defined by the BST/AU ID and
BST/AU ID Mask, and will try to connect to the first found AU/Micro Base Station
whose Base Station ID is in the defined range.
An SU that can communicate with more than one BST/AU may become
associated with the first BST/AU it "finds", not necessarily the best choice in
terms of quality of communication. 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 BST/AU feature,
to enable an SU to connect to the best BST/AU in its neighborhood.
When the Best BST/AU feature is enabled, the SU scans all BSTs/AUs in a
predefined range, using all defined scanning frequencies (see “Frequency
Scanning Parameters” on page 98). Each of the BSTs/AUs with which the SU can
communicate (perform initial phase of network entry) is given a quality mark
based on the quality of the signal at which it is received by the SU. At the end of
the scanning period, the SU reaches a Best BST/AU decision according to the
information gathered. The BST/AU with the highest quality mark is selected as
the Best BST/AU, and the SU will immediately try to associate with it at the
relevant frequency.
The range used for scanning is defined by the BST/AU ID and BST/AU ID Mask
parameters. The initial range can be limited by defining a preferred range of
BST/AUs, and selecting the best BST/AU in the preferred range. If no BST/AU is
found in the preferred range, the SU will scan the entire range.
If the SU loses communication with the Best BST/AU, it will continue searhing for
it for 5 minutes. If not found within 5 minutes, the SU will try to associate with
the second BST/AU in the of Best BSTs/AUs Table. If not found immediately, the
SU will initiate a short scan, checking all the BSTs/AUs in the table, and trying to
associate with the best one. If no BST/AU from the is found, the Best BSTs/AUs