User Manual

AXELL MBF MULI-BAND FIBRE REPEATER
PRODUCT DESCRIPTION AND USER’S MANUAL
20 © Axell Wireless Ltd
3-2. Dual band repeater for E-GSM and UMTS
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The OMU will usually be fed from the donor BTS via an attenuator or coupling network. The
electrical configuration of this OMU Point of Interface (POI) will be system specific depending on
the presentation of the BTS RF ports, the power class of the BTS and whether the BTS itself provides
coverage via antennas/radiating cable infrastructure or if coverage is only via the MBF repeaters.
The important consideration for commissioning is that the correct attenuation exists between BTS
and OMU in order that
 input power limits of OMU ports are not exceeded
 operating levels can be brought into the correct range using the OMU internal attenuators
 isolation is preserved between ports and bands
OMU damage levels are 10dBm RF in to the fibre optic converter.
For some systems the commissioning adjustments may be completely independent (e.g. an MBF Tri
Band repeater fed by separate OMUs, one per frequency band). For other systems (e.g. an MBF Tri
Band repeater fed a by a single OMU carrying all three bands) one adjustment may affect all bands
simultaneously. In such cases certain commissioning actions e.g. optical link adjustment only need to
be carried out once for all bands but the POI must include some means to level the different
frequency bands at the OMU interface ports.
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The critical aspect for the correct system operating level is the composite power presented at the
input of the fibre optic converter in the OMU (UFO-M). The illustration below shows the simplest
possible arrangement for a single Tri Band repeater fed by three BTSs - one per band. It is assumed
that the BTS for GSM900 and GSM1800 produce two carriers each of +43dBm and that the UMTS
BTS produces a single carrier of +43dBm.
MCPA UMTS
2 x
Duplex
Filter
RF
O
Optical
In/Out
Downlink
Uplink
RF in/out
Fiber Optic
Converter
Radio Module
UMTS
Radio Module
GSM
MCPA GSM
Downlink
Uplink
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