User's Manual

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D-620610-0-20 Rev F CONFIDENTIAL
Connecting a Main Hub to a Base Station
6.8 Connecting a Main Hub to a Base Station
The Fusion system supports up to three RF sources: one for Band 1, one for Band 2,
and one for Band 3. This section explains how each band can be connected to its asso-
ciated base station.
Each Fusion Main Hub band has separate system gain parameters. For example, Band
1 can be set for +5 dB of downlink system gain while Band 2 can have +15 dB of
downlink system gain. Thus, each band can be configured as a separate system to
allow for full integration to its associated base station.
When connecting each of the Fusion Main Hub bands to its base station, the follow-
ing equipment may be required: circulators, filter diplexers, directional couplers,
combiner/splitters, attenuators, coax cables, and connectors. In addition, use the fol-
lowing considerations to achieve optimal performance:
1. The downlink power from the base stations must be attenuated enough so that the
power radiated by the RAU does not exceed the maximum power per carrier listed
in Section 6.3, “Maximum Output Power per Carrier,” on page 6-4.
2. The uplink attenuation should be small enough that the sensitivity of the overall
system is limited by Fusion, not by the attenuator. However, some base stations
trigger alarms if the noise or signal levels are too high. In this case the attenuation
must be large enough to prevent this from happening.
CAUTION:The UPLINK and DOWNLINK ports cannot handle a DC power
feed from a BTS. If DC power is present, a DC block must be used or the
Fusion main hub may be damaged.
If, in an area covered by Fusion, a mobile phone indicates good signal strength but
consistently has difficulty completing calls, it is possible that the attenuation between
Fusion 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 Fusion Main Hub uplink and
its associated band’s base station, the uplink system gain can be increased to as much
as 15 dB to prevent a reduction in the overall system sensitivity.
6.8.1 Uplink Attenuation
The attenuation between the Main Hub’s uplink port and the associated band’s base
station reduces both the noise level and the desired signals out of Fusion. Setting the
attenuation on the uplink is a trade-off between keeping the noise and maximum sig-
nal levels transmitted from Fusion to the base station receiver low while not reducing
the SNR (signal-to-noise ratio) of the path from the RAU inputs to the base station