User's Manual

Designing an LGCell Solution
7-44 LGCell 4.0 Installation, Operation, and Reference Manual PN 8100-40
620004-0 Rev. B
7.5 Connecting a Main Hub to a Base Station
The first consideration when connecting LGCell Main Hubs to a base station is to
ensure there is an equal amount of loss through cables, combiners, etc. 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 will
need to be divided to equilibrate power for each Main Hub. For example, two Main
Hubs will require a 2
×1 combiner/divider; four Main Hubs will require a 4×1 com-
biner/divider; and so on.
Figure 7-2 Connecting LGCell Main Hubs to a Simplex Base Station
When connecting an LGCell 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 7.1, “Maximum Output Power per Carrier at RAU,” on page 7-3.
2. The uplink attenuation should be small enough that the sensitivity of the overall
system is limited by the LGCell, not by the attenuator. However, some base sta-
tions are adversely affected by received signals that are above –50 dBm, for
example. It is therefore helpful to attenuate the uplink in order to retain the maxi-
mum number of received signals.
If, in an area covered by an LGCell, a mobile phone indicates good signal strength
but consistently has difficulty completing calls, it is possible that the attenuation
between the LGCell and base station needs to be adjusted. In other words, it is possi-
ble that if the uplink is over-attenuated, the downlink power will provide good cover-
age, but the uplink coverage distance will be small.
The simplex ports of the Main Hub are usually used for base station connections.
However, there is an exception. In cases where several base stations are combined to
drive the LGCell(s), the loss from the combiners may be high enough to adversely
affect the uplink sensitivity. Since the Cellular and PCS LGCells have gain on the
duplex port, this port can be used as the reverse port to overcome the attenuation.
NOTE: When using the duplex port on Cellular or PCS Main Hubs, reduce the
power out of the base station to accommodate for the gain of the duplex port. For
example, if the power out of the base station is 30 dBm per carrier, and the target
RAU output is 0 dBm per carrier, you must attenuate the base station signal by 60 dB
before going into the Main Hub because the system gain through the duplex port of
the 800 MHz Cellular LGCell is 30 dB. (Refer to Table 7-25 on page 7-28.)
Base Station
2 × 1 combiner/divider
Downlink/Forward
LGCell Main Hub 1
LGCell Main Hub 2
Uplink/Reverse