-10-
If a CSI repeater is installed in an area with very strong desired and/or undesired signals, it is important to ensure that the overall signal
levels are optimized to be within the best operating range of the repeater. Additionally, de-sensing of a nearby base station site must be
avoided. These goals can be accomplished by properly attenuating the antenna port(s) in the path of the donor antenna(s). In effect,
one can imagine that the particular repeater deployment is electrically moved farther from the base station using attenuators that are
equivalent to increasing the path loss from the donor antenna to the base station. The following potential outcomes result from the use
of attenuators on the donor port(s) of the unit: Uplink output power, as reported by the repeater, is reduced by the value of the attenua-
tion, protecting nearby base stations. Downlink signal to noise ratio is high at the point of the attenuator, resulting in slight but negligible
reduction in downlink performance. Other performance is essentially unchanged.
Donor Port
Server port attenuation may also be necessary, particularly where a powered DAS is present. The selection guidelines below apply to
both server and donor ports. In order to properly measure uplink signal strength, a signal generator should be used. If a signal generator
is not available, placing a test call while under the server antenna with the least path loss to the repeater should provide reasonable data.
The following potential outcomes result from the use of attenuators on the server port(s) of the CSI repeater: Downlink output power, as
reported by the unit, is reduced by the value of the attenuation. Uplink incoming power from the DAS is reduced, along with potentially
strong and/or harmful out-of-band signals (including noise) that are generated by the DAS.
Server Port
Attenuator Selection Guidelines
Accurate attenuator values need to be chosen to ensure that the maximum total power (higher of Composite or In-Band Input) applied to
the donor and server port(s) does not exceed the following thresholds:
Input Signal
Max Gain Input Signal
Max Gain
<-45 dBm
85 dB
-32.2 dBm
69 dB
-44.3 dBm
84 dB
-31.4 dBm
68 dB
-43.6 dBm
83 dB
-30.6 dBm
67 dB
-42.9 dBm
82 dB
-29.8 dBm 66 dB
-42.2 dBm
81 dB
-29 dBm
65 dB
-41.5 dBm
80 dB
-28.2 dBm
64 dB
-40.6 dBm
79 dB
-27.4 dBm
63 dB
-39.7 dBm
78 dB
-26.6 dBm
62 dB
-38.8 dBm
77 dB
-25.8 dBm
61 dB
-37.9 dBm
76 dB
-25 dBm
60 dB
-37 dBm
75 dB
-24.4 dBm 59 dB*
-36.2 dBm
74 dB
-23.8 dBm 58 dB*
-35.4 dBm
73 dB
-23.2 dBm 57 dB*
-34.6 dBm
72 dB
-22.6 dBm 56 dB*
-33.8 dBm
71 dB
-22 dBm
< 55 dB*
-33 dBm
70 dB
*We recommend padding this level due to potential for fl uctuating signal.
-25 dBm is the maximum input signal level that should be applied to the repeater, even if the gain is lower than 55 dB.
Input signals exceeding these thresholds will result in composite input attenuation, called
“ADC Protect”
(
A
nalog to
D
igital
C
onverter
P
rotection). Output power is reduced whenever the above thresholds are exceeded by reducing the gain by 1dB for each 1 dB that the
threshold is exceeded. ADC Protect should not be confused with
AGC
(
A
utomatic
G
ain
C
ontrol), which reduces gain to prevent
In-Band
(measured) output power from exceeding the
specifi ed maximum output level. To determine the total power applied to the donor and
server ports, please reference the “Composite Input” values as reported in the Web (“System Status”) or Menu (“Link Status”) interfaces
(depicted and explained later in this manual).
Large delta’s between in-band and composite input signals:
Care should be taken to isolate the best donor site to ensure the least possible delta between in-band and composite downlink signals. If
the (downlink) composite input exceeds the in-band input by more than 3 dB for the LTE band the maximum output power will be reduced.
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