Atpc Guidelines - Alcatel-Lucent 9500 MXC User Manual

Chapter 7. Node and Terminal Plug-ins

ATPC Guidelines

Benefits of ATPC
ATPC Operation
Vol. IV-7-20
Automatic Transmit Power Control (ATPC) is an optional setting. It allows radio
links to maintain set thresholds for fade margin, and to maintain overall link
performance at an otherwise lower than maximum transmit power. If path
conditions deteriorate due to fading, ATPC gradually increases the transmitted
power to maintain the remote fade margin. When the condition causing the fade
ens, the TX power level is reduced back to the minimum level.
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 in 9500 MXC is based on two monitored values, Receive Signal Strength
(RSL) and Signal to Noise Ratio (SNR).
Each 9500 MXC 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.
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