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D-620003-0-20 Rev J
CONFIDENTIAL
Connecting a Main Hub to a Base Station
6.6
Connecting a Main Hub to a Base Station
The first consideration when connecting Unison Main Hubs to a base station is to
ensure there is an equal amount of loss through cables, combiners, and so on from the
base station to the Main Hubs. For this example, assume that the base station will
have simplex connections, one uplink and one downlink. Each of these connections
needs to be divided to equilibrate power for each Main Hub. For example, two Main
Hubs require a 2×1 combiner/divider; four Main Hubs require a 4×1 com-
biner/divider; and so on.
Figure 6-2
Connecting Main Hubs to a Simplex Base Station
When connecting a Unison Main Hub to a base station, also consider the following:
1.
The downlink power from the base station must be attenuated enough so that the
power radiated by the RAU does not exceed the maximum power per carrier listed
in Section 6.1, “Maximum Output Power Per Carrier at RAU,” on page 6-3.
2.
The uplink attenuation should be small enough that the sensitivity of the overall
system is limited by Unison, not by the attenuator. However, some base stations
trigger alarms if the noise or signal levels are too high. In this case the attenuation
has to be large enough to prevent this from happening.
NOTE:
The UPLINK and DOWNLINK ports cannot handle a DC power
feed from the base station. If DC power is present, a DC block must be used
or the hub may be damaged.
If, in an area covered by Unison, a mobile phone indicates good signal strength but
consistently has difficulty completing calls, it is possible that the attenuation between
Unison and the base station needs to be adjusted. In other words, it is possible that if
the uplink is over-attenuated, the downlink power will provide good coverage, but the
uplink coverage distance will be small.
When there is an excessive amount of loss between the Main Hub uplink and the base
station, the uplink system gain can be increased to as much as 15 dB to prevent a
reduction in the overall system sensitivity.
Base Station
2 × 1 combiner/divider
Downlink/Forward
Main Hub 1
Main Hub 2
Uplink/Reverse
