Menus and Parameters
Operation and Administration
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the link establishment time. This is achieved by using shorter dwell periods,
transmitting a Probe Request at each frequency. This reduces the time spent at
each frequency as well as the disassociation period.
When DFS is supported by the Country Code being used by the SU, Scanning
Mode is forced to Passive.
The default selection is Passive.
4.2.6.2.8 Power Control Parameters The Automatic Transmit Power Control (ATPC) algorithm simplifies the
installation process and ensures optimal performance while minimizing
interference to other units. This is achieved by automatically adjusting the power
level transmitted by each SU according to the actual level at which it is received
by the AU. To support proper operation of the system with optimal performance
and minimum interference between neighboring sectors, the ATPC algorithm
should be enabled in all units.
The algorithm is controlled by the AU that calculates for each received frame the
average SNR at which it receives transmissions from the specific SU. The average
calculation takes into account the previous calculated average, thus reducing the
effect of short temporary changes in link conditions. The weight of history (the
previous value) in the formula used for calculating the average SNR is determined
by a configurable parameter. In addition, the higher the time that has passed
since the last calculation, the lower the impact of history on the calculated
average. If the average SNR is not in the configured target range, the AU
transmits to the SU a power-up or a power-down message. The target is that each
SU will be received at an optimal level, or as high (or low) as possible if the
optimal range cannot be reached because of specific link conditions.
Each time that the SU tries to associate with the AU (following either a reset or
loss of synchronization), it will initiate transmissions using its Transmit Power
parameters. If after a certain time the SU does not succeed to synchronize with
the AU, it will start increasing the transmit power level.
In an AU the maximum supported transmit power is typically used to provide
maximum coverage. However, there may be a need to decrease the transmitted
power level in order to support relatively small cells and to minimize the
interference with the operation of neighboring cells, or for compliance with local
regulatory requirements.
In some cases the maximum transmit power of the SU should be limited to
ensure compliance with applicable regulations or for other reasons.
Different power levels may be used for different modulation levels by taking into
account possible HW limitations or regulatory restrictions.