Aviat Networks ECLIPSE EDGE, User Manual

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260-668080-001 Rev 002 March 2013 41
Eclipse Edge User Manual
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ATPC Operation on page 41
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Interference and ATPC on page 42
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Setting ATPC on page 43
Benefits of ATPC
ATPC supports greater re-use of radio channels in a network. If a given link can still
operate within suitable receive thresholds with a lower transmitted power level, that
link will pose less risk of interference to other links running in co or adjacent
channels. This enables a higher level of channel reuse. For ATPC to be effective, all
links in the same geographic area must be running ATPC.
In areas that have high link densities, a license authority (regulator) may include
within an operating license the requirement for ATPC and the maximum transmit
power permitted under ATPC control.
ATPC Operation
ATPC in Eclipse Edge is based on two monitored values, Receive Signal Strength
(RSL) and Signal to Noise Ratio (SNR).
Each Edge terminal transmits information about its RSL and SNR levels to its partner
terminal. The terminals analyze this information, and each adjusts its Tx power to
maintain the target fade margin settings.
ATPC calculates the remote terminals’ fade margin based on current RSL and
receiver/modulation specifications. If a path fade reduces the fade margin on the
remote terminal, the local transmitter increases its power level to return the remote
fade margin to the target settings. When the fading condition passes and the fade
margin increases, the local transmitter reduces its power level to keep the remote
fade margin at the desired level.
• The ATPC algorithm does not adjust Tx power when a link is running normally, and
the RSL and SNR values are within normal limits.
• If the local terminal determines that RSL at the remote terminal is too low, then it
increases its power level in 0.1 db increments until the RSL is within the specified
range.
• If the RSL value is within range, but the SNR is low, then the transmit power is
increased until the SNR is within the specified range.
• ATPC power changes can occur at a rate of 6 dB/second to provide compensation for
rapid fading conditions.
• ATPC will fail to maintain the remote target threshold settings if the fading condition
is severe enough to require more local transmit power than set as the maximum TX
power, or if the power level required is beyond the capability of the transmitter.