Connecting a Main Hub to a Base Station
6-42
InterReach Unison Installation, Operation, and Reference Manual
CONFIDENTIAL
D-620003-0-20 Rev J
6.6.3.1
Using the RAU 10 dB Attenuation Setting
Each RAU can, independently of the other RAUs in a system, have its uplink or
downlink gain attenuated by 10dB.
1
This is accomplished by selecting the check
boxes in the Advanced RAU Settings dialog box. There are two check boxes: one for
setting the downlink attenuation and another for setting the uplink attenuation.
• Downlink Attenuation
The purpose of the downlink attenuator is to provide a mechanism to reduce the
signal strength from an RAU. For instance, this could be for an RAU located near
a window in a tall building that is causing excessive leakage to the macro-network.
In such a case it is important to attenuate the downlink only. The uplink should not
be attenuated. If the uplink is attenuated, the uplink sensitivity is reduced and
mobile phones in the area of that RAU will have to transmit at a higher power.
This would increase interference to the outdoor network from such mobiles.
• Uplink Attenuation
The purpose of the uplink attenuator is to attenuate environmental noise picked up
by an RAU located in an area where heavy electrical machinery is operating. In
such environments the electrical noise can be quite high and it is useful to reduce
the amount of such noise that gets propagated through the distributed antenna sys-
tem. Attenuating the uplink of an RAU located in areas of high electrical noise
helps preserve the sensitivity of the rest of the system.
The effect of activating the uplink or downlink attenuators is to reduce the coverage
area of the adjusted RAU. The coverage radius will be reduced by roughly a factor of
2. More specifically, if
d
is the coverage distance without attenuation and
d’
is the
coverage radius with the attenuation, then
where
PLS
is the path loss slope.
1. With UMTS-2 RAU, a higher granularity of gain control is provided in 1dB increments, giving a better gain control and
fine-tuning capability.
PLS
dB
d
d
/
10
10
'
=
