User Manual

User Reference and Installation Manual 2-16
MDS 5800 II
• Network Management options described in Section 2.9.
2.8 Power Management
RF power management is a radio design feature that controls the power level (typically expressed
in dBm) of the RF signal received from a transmitter by a receiver. The traditional goal of power
management is to ensure that the RF signal at a receiver is strong enough to maintain the radio
link under changing weather and link conditions.
Traditional power management techniques such as Constant Transmit Power Control (CTPC)
and Automatic Transmit Power Control (ATPC) transmit at a high power level to overcome the
effects of fading and interference. However, these techniques continue to operate at a higher
power level than needed to maintain the link in clear weather. Because transmit power remains
high when the weather clears, the level of system interference increases.
Radios operating at high transmit power will interfere with other radios, even if the interfering
source is miles away from the victim. High interference levels can degrade signal quality to the
point that wireless radio links become unreliable and network availability suffers. The traditional
solution to system interference is to increase the distance between radios. However, the resulting
sparse deployment model is inappropriate for metropolitan areas.
In response to the need for a high-density deployment model the MDS 5800 II use a unique
power control technique called A
d
TPC. A
d
TPC enables MDS 5800 II units to transmit at the
minimum power level necessary to maintain a link regardless of the prevailing weather and
interference conditions. The MDS 5800 II is designed and manufactured to not exceed the +30
dBm maximum power allowed. The purpose of power management is to minimize transmit power
level when lower power levels are sufficient. A
d
TPC also extends the concept of power
management by controlling not only the power (dBm) of the RF signal, but its quality (signal-to-
noise ratio) as well.
In contrast to ATPC, the A
d
TPC technique dynamically adjusts the output power based on both
the actual strength and quality of the signal. Networked MDS 5800 II units constantly monitor
receive power and maintain 10
-12
BER performance under varying interference and climate
conditions. Each MDS 5800 II unit can detect when there is a degradation in the received signal
level of quality and adjust the transmit power level of the far-end MDS 5800 II unit to correct for it.
A
d
TPC provides maximum power in periods of heavy interference and fading and minimum power
when conditions are clear. Minimal transmit power reduces potential for co-channel and adjacent
channel interference with other RF devices in the service area, thereby ensuring maximum
frequency re-use. The resulting benefit is that operators are able to deploy more MDS 5800 II
units in a smaller area.