design and test technologies of a repeater

7/31/2019 Design and Test Technologies of a Repeater

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

Security Level:2012/7/21

Design and TestTechnologies of aRepeater

Internal use only


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

Contents

Introduction to a Repeater

Important Safety Notes

Survey

Installation

Test


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3Page 3


A repeater is an intra-frequency amplification device. It is a relay unit for

amplifying signals during the wireless transmission. The basic function

of a repeater is to amplify the power of RF signals. The donor antenna of

the repeater in the downlink picks up signals from the existing coverage

area of the donor antenna, isolates the signals outside the bandpass with

a bandpass filter, and then transmits the filtered signals to the area to be

covered after the signals are amplified with a power amplifier. With the

same method in the uplink, signals of mobile phones in the mobile

station (MS) within the coverage area are transmitted to the

corresponding BTS; in this way, signals between the BTS and mobile

phones are transmitted.


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Contents



Survey

Installation

Test


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Safety

requirements on

the repeater

features

Safety

requirements on

the repeater in

engineeringapplications


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Important Safety Notes (Continued)

During the repeater power-on, load signals to the repeater if the output port of the master is

connected to an antenna or loaded.

The load voltage standing wave ratio (VSWR) of the output port must be smaller than 1.5.

To prevent electric shocks, do not operate the power supply unit inside the repeater when the power

supply is connected.

The outdoor antenna at the repeater site must be provided with a reliable lightning protection device,

the antenna stand must be provided with lightning rods, and the antenna and feeder must be reliably

grounded.

Make sure that the repeater supports are installed reliably due to the heavy weight of the repeater.

Be cautious when moving and installing the repeater to prevent personnel and the repeater from

being harmed by external factors.

The downlink signal level input by the wireless repeater must be smaller than or equal to -35 dBm.

Otherwise, the repeater is damaged.

The signal level input by an optical fiber repeater must be smaller than or equal to 10 dBm.


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Contents



Survey

Installation

Test


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Survey

I. Signal source selection

CDMA/WCDMA

1. Ec/Io > 6 dB.

2. RxPwr > 70 dBm. The signal strength ranges from 40 dBm to 60 dBm. The best value

is 55 dBm.

3. The Ec/Io of the first pilot is 8 dB higher than that of the second pilot.

GSM

Signal strength: The receiving signal strength meets the requirements of the repeater.

Traffic: Choose the cell with relatively low traffic as the signal source.

Call quality: Lower than level 3.

Direction: See through the BTS to ensure a stable signal source.


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Survey (Continued)

II. Isolation of Receiving and Transmitting Antennas

Common repeater

Ensure that the isolation (I) of receiving and transmitting antennas is at least 15

dB larger than the maximum gain (Gmax), that is, I > Gmax + 15 dB.

ICS

According to the repeater performance, the antenna isolation can be 15 dB

larger than the Gmax.

III. Determine the required coverage area, devices, installation positions of

the antennas, lightning rods, power supply, and grounding.


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Contents



Survey

Installation

Test


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Installation

Install the repeater indoor and in places of good ventilation. Make sure the places are free of the

interference from devices with strong electricity, magnetic field, and corrosion. If the indoor installation

is impossible, install the repeater on an outdoor pole or against the wall. In this case, direct exposure

to the sunlight must be avoided. The installation place must be convenient for cabling, cable

connection, and the subsequent maintenance. The temperature and moisture of the installation place

must be no higher than the normal range of the master unit.

Power supply: Stable AC or DC power input must be provided. When the AC power is 220 V, the

power input voltage must range from 176 V to 266 V, and the frequency must range from 45 Hz to 55

Hz. For the DC power input, the voltage must range from 48 V to5 V. Choose the backup battery

as the power input to ensure the system reliability.

Grounding: The ground cable for the master unit must be at least 16 mm2 and the grounding

resistance must be smaller than 5 ohms.


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Contents



Survey

Installation

Test


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Test

Test tools

Local test software for the repeater (the version number must match the producttype)

One laptop and one piece of connection cable

One spectrum analyzer

One optical power meter and two optical pig tails (at the site of optical fiber

repeater)

One attenuator of 30 dB and one attenuator of 20 dB

Several feeder connectors

Two soft jumpers

Tool kit

One telescope, directional antenna, and GPS (at the site of wireless repeater)


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Test (Continued)

Test process for the RF repeater

(1) To avoid the large fluctuation of the loss on the radio wave propagation path

between the repeater and the donor BTS, both the repeater and the donor BTS must be

within the light of sight (LOS).

(2) The receiving signal level must range from

50 dBm to

80 dBm for the repeater atthe site.

(3) Site selection: The repeater site must be between the donor BTS and the coverage

hole to ensure that the azimuth between the donor antenna and the service antenna is

at least 90.

Figure 6 Appropriate site Figure 7 Inappropriate site

BTS Repeater BTS Repeater


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Test (Continued)

Test process for the RF repeater

(4) Output power test

(5) If the power within the coverage area cannot meet the requirements, adjust the

antennas so that the output power meets the design requirements.

(6) The sum of the uplink output noise and the path loss from the repeater to the donor

BTS must comply with the repeater specifications.

Wireless

repeaterSpectrum

analyzer

Attenuator


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Test (Continued)

Test process for the optical fiber

repeater

Run the local test software

Connect RU and set site

Set online the MU site and networkmanagement parameters and

register the RU No.

Measure the received BTS signal leveland check the optical power on the

direct coupling MU

Set the uplink gain to theminimum

Check the MU state

Normal

Faulty

Faulty

Faulty

Normal

Normal

Check and repair

Check and repair

Check and repair

Check the RU state

Test whether the downlinkoutput power meets the

design requirements

Test signal strength andadjust antenna coverage

Fine tune the MU and RU uplinkgains to ensure a balance

between uplink and downlink

Recheck interference from BTS

End


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Test (Continued)

Test process for the optical fiber repeater

(1) Measure the input signal strength of the source cell

Testing relevant parameters is a prerequisite to site test. Parameters suchas receiving power of the selected cell are obtained from the test. Make

sure the signal from the signal source meet the input requirements of the

repeater.

Test of receiving power: Check that the devices are connected correctly,

disconnect the downlink input port of the MU of the optical fiber repeater,

and then connect the signal input port of the spectrum analyzer.

BTS Spectrum

analyzer


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Test (Continued)


I. Measure the input signal strength of the source cell

Note that whether the input signal is strong enough to cause the input saturation

of the previous components in the spectrum analyzer or even the damage of thespectrum analyzer. The BTS power output usually ranges from 33 dBm to 43

dBm. The input RF signal power of the MU of the optical fiber repeater ranges

from 0 dBm to 10 dBm. Select a proper attenuator based on the coupling degree

so that the signal input to the spectrum analyzer meets the requirements.


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Test (Continued)


II. Test the optical path parameters

Procedure:

1. Test the optical transmitting and receiving of the MU.

2. Test the optical transmitting and receiving of the RU.The goal is to check whether the optical path is smooth and check the optical path

attenuation. If the optical path is not smooth, choose another optical fiber. If the attenuation

of the optical path is too low, it will cause a saturation of the optical module input and affect

the demodulation; in this case, attenuators must be added. If the attenuation of the optical

path is too high, the input power of the optical module cannot meet the demodulation

requirements; in this case, a new optical path must be selected.The input power and output power of the optical module in the optical fiber repeater are as

follows:

Optical transmitting: 4 dBm to1.5 dBm Optical receiving: 0 dBm to 10 dBm

The optical path test is performed together with the RF test to reduce the round-trips

between the MU and the RU.


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Test (Continued)


(2) Test the optical path parameters

Connector type for the optical fiber repeater:

FC/APC or UPC

Ensure that the connector types match the optical

pig tail and jumper.


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Test (Continued)


(3) Adjust the uplink output noise level of the MU

BTS

Spectrumanalyzer

The sum of the uplink output noise level of the repeater MU and the coupling degree of the

BTS coupler must comply with the output noise specifications of the repeater.


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design and test technologies of a repeater

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