User's Manual

Horizon Compact Plus Release 1.0.1 Wireless Ethernet Product User Manual – Volume 2
11.0 Adaptive Transmit Power Control (ATPC)
Adaptive Transmit Power Control (ATPC) allows a Horizon Compact Plus system to adjust its transmit
power to compensate for far end signal loss caused by changes in atmospheric conditions e.g. heavy
rain. ATPC maintains the RSL at the ATPC threshold, which is system mode dependant, and adjusts
the transmit power as necessary in order to maintain the ATPC threshold during fade conditions.
RSL threshold levels that trigger power changes, the maximum power change allowed is preset at
values which optimize the operation of the Horizon Compact Plus system. A fade factor of 60dB/second
can be handled.
The Horizon Compact Plus system is able to discriminate between RSL levels that are reduced as a
result of interference and those as a result of genuine path loss, so that ATPC is not invoked
unnecessarily. An ATPC log is available for debugging the system. Use the CLI command get atpc log.
The log can be cleared using the CLI command clear atpc log.
Some jurisdictions require the use of ATPC so that power levels are kept as low as possible when
wireless communication conditions are good.
When ATPC is to be used, if it can be shown that the maximum power of the system would be used only
on infrequent occasions, some jurisdictions will allow a lower power level to be used in the calculations
that determine interference criteria. This offers some advantage to the installation. This lower power is
termed the “coordinated power”. The DragonWave ATPC feature supports a coordinated power
parameter called the coordinated power “offset”. This offset value represents the offset from the
maximum transmit power level of the radio.
There are two situations when ATPC can be used. The first is when a link is engineered to prevent
receiver saturation (normal link installation). The second is when, due to extreme rain conditions, a link
is engineered to have receiver saturation during clear weather (short range between systems). This
allows more margin for ATPC to operate and thus maintain a link operational during severe rain. The
configuration of ATPC is different for each case.
11.1 Normal Link
Procedure 11-1
Configure Horizon Compact Plus Adaptive Transmit Power Control – Normal Installation
Required Action
Steps
login
Log in as a NOC user.
View atpc status
Returns the current status of the atpc
Sequence:
get atpc status press Enter
System responds (example):
ATPC STATUS
------------------------
State : Running
Transmit Power (Actual) : 6.9 dBm
Transmit Power Range : (-0.6 - 19.4) dBm
RSL (Peer) : -52.0 dBm
RSL Target : -52.0 dBm