TE Connectivity InterReach Fusion ADCP-77-044, Руководство пользователя, Страница: 103 / 236

Help Hot Line (U.S. only): 1-800-530-9960 6-37
D-620616-0-20 Rev F
CONFIDENTIAL
Connecting a Main Hub to a Base Station
6.8 Connecting a Main Hub to a Base Station
The Fusion Wideband 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 associated 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 Wideband Main Hub bands to its base station,
the following equipment may be required: circulators, filter diplexers, directional
couplers, combiner/splitters, attenuators, coax cables, and connectors. In addition, use
the following 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 Wideband, 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 Wideband Main Hub may be damaged.
If, in an area covered by Fusion Wideband, a mobile phone indicates good signal
strength but consistently has difficulty completing calls, it is possible that the attenua-
tion between Fusion Wideband 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 pro-
vide good coverage, but the uplink coverage distance will be small.
When there is an excessive amount of loss between the Fusion Wideband 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 Wideband.
Setting the attenuation on the uplink is a trade-off between keeping the noise and
maximum signal levels transmitted from Fusion Wideband to the base station
receiver low while not reducing the SNR (signal-to-noise ratio) of the path from the