User's Manual

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D-620616-0-20 Rev E CONFIDENTIAL
Connecting a Main Hub to a Base Station
Figure 6-2 ALC Operation
6.8.2.1 Using the RAU 10 dB Attenuation Setting
Each RAU band can, independently of the other RAUs in a system, have its uplink or
downlink gain attenuated by 0 or 10 dB for each RAU band (1, 2 or 3). This is accom-
plished by selecting the appropriate UPLINK and/or DOWNLINK attenuation for
each RAU band in the Edit Unit Properties screen of AdminBrowser for the selected
RAU.
• Downlink Attenuation: The downlink attenuator provides a mechanism to reduce
the signal strength from an RAU band. For instance, this could be for an RAU
band 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 sensitiv-
ity is reduced and mobile phones in the area of that RAU band will have to trans-
mit at a higher power. This would increase interference to the outdoor network
from such mobiles.
• Uplink Attenuation: The uplink attenuator attenuates environmental noise picked
up by an RAU band located in an area where heavy electrical machinery is operat-
ing. 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 system. Attenuating the uplink of an RAU band 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 band. The coverage radius will be reduced by roughly a fac-
tor 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 path loss slope (dBm).
Input Signal
Level
Activation
Level
-30dBm
R
e
l
e
a
s
e
L
e
v
e
l
-
4
5
d
B
m
Output Signal
Level
Time
Hold
Phase
Release
Phase
Attack
Phase
1
2
3
4
5
PLSdB
d
d
/10
10
'
=