User Manual
Table Of Contents
- MBF, Multi Band Repeater
- Contact Information
- About This Manual
- For whom it is Intended
- Notice
- Confidential - Authorized Customer Use
- Disclaimer of Liability
- Warrantee
- Table of Contents
- 1 Introduction
- 2 Installation
- 3 Commissioning Advice
- 4 Setup
- 5 Troubleshooting
- 6 Maintenance
- 7 Modem Communication
- 8 Specifications
AXELL MBF MULI-BAND FIBRE REPEATER
PRODUCT DESCRIPTION AND USER’S MANUAL
24 © Axell Wireless Ltd
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The UMTS signal carries wideband and complex modulation and its properties vary depending on the
level of traffic carried.
3.6.1 Bandwidth
The first issue is the wideband nature of the signal. It occupies around 3.8MHz and measurements
through a narrower filter will reduce the apparent power level since only a portion of the signal
reaches the detector in the test equipment.
Equipment that includes a UMTS/3G measurement personality simplifies the task considerably.
Usually a stored configuration for power measurement will integrate many samples taken using a
narrower filter to display the correct power level for the bandwidth of the signal. Settings can easily
become corrupted however leading to erroneous results. In such cases following the manufacturers
instructions in detail is advised.
Measuring with a simple spectrum analyzer must use a wider resolution bandwidth than 3.8MHz or
else a bandwidth correction factor has to be applied to the observed result. E.g. if measuring with a
300kHz RBW the power level in the centre of the signal would appear to be around 11dB lower than
actual (10Log 3.84/0.3).
3.6.2 Traffic
A further complication is that the power level of a UMTS signal depends on the traffic level being
carried. UMTS carrier power is usually quoted as average values e.g. a 5Watt or 37dBm signal can
contain peaks up to 10dB greater when traffic is high. An idling base station carrying no traffic
radiates only a Pilot in which case the power observed is around 10dB below the average value with
traffic.
Advanced test equipment that can measure the different code power components in the UMTS signal
avoids this problem but more often in the field repeater commissioning must be done when only
simple test equipment is available. This leads to the need to know and allow for the state of traffic
when making repeater setup and diagnostic measurements. It is obvious that adjusting a repeater to
maximum rated output power by using BTSs that are idling radiating only the pilot will lead to
overloading when they are in traffic.