User Manual

MBF, Multi Band Repeater
PRODUCT DESCRIPTION AND USER'S MANUAL
© Axell Wireless Ltd A 200 93 00, rev E 64 (105)
5 Installation
5.1 Commissioning Advice
5.1.1 Introduction
To set the proper operating RF levels on the repeaters in the MBF family during commissioning there are six
steps to be carried out for each band of operation.
 Set OMU DL attenuation to adjust the RF level from the BTS to suit the fibre optic converter in the
OMU (UFO-M)
 Run the OLA (Optical Link Adjustment) command for each band to correct for DL optical fibre loss
 Set the DL attenuation in the repeater to adjust gain following fibre optic converter in the repeater
(UFO-S)
 Set the UL attenuation in the repeater to adjust gain before the fibre optic converter in the repeater
(UFO-S)
 Run the OLA (Optical Link Adjustment) command for each band to correct for DL optical fibre loss
 Set OMU UL attenuation to adjust the OMU output level to suit the BTS
5.1.2 OMU Point of Interface (POI)
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.
5.1.3 Downlink POI / OMU DL Attenuator Adjustment
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.
The correct interface level at the optical fibre converter is -5dBm/carrier in 900MHz and -7dBm/carrier in
both GSM1800 and UMTS bands. An attenuation of 48dB in 900MHz and 50dB in 1800/UMTS is therefore
required between them.