Repeater Doc

7/30/2019 Repeater Doc

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Repeaters

Topics

1. Introduction to Repeaters

2. Repeater Setup Considerations3. Procedure in Repeater Cell Setup

4. Repeater Block Diagrams

5. Frequency Shift Repeater

6. Optical Repeater

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IntroductiontoRepeaters

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RadioRepeaters

Radio repeaters, or Bi-Directional Amplifiers (BDA)

Works as a bi-directional amplifier to increase the signalbetweenmobiles and base stations, in uplink and downlink direction.

Used for an area with poor coverage in outdoor and indoorenvironment, or for coverage enhancements in areas

blocked byobstacles.

Uses a pick up (donor) antenna to receive and amplify theradio

signal from a donor cell, and then retransmit from anantenna

mounted near the area to be covered.

Complete local monitor function and powerful remoterepeater

network administration (OMC).

Typical applications include

Indoor : conference centre, shopping mall, office building.

Radio shadow areas : underground car parks, tunnels,

valleys. Coverage extension : motorways.


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TypicalRepeaterSetup

BTS

Donar antenna

Repeater

Service area antenna

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Off-AirRepeaterApplication

DonorANT

ServiceANT

BTSRepeater

RepeaterBTS Coverage Coverage

Extension of BTS Coverage

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BenefitsofaRepeater

Fast rollout and fast coverage leads to fast return on investment

Low build out costs

No microwave link and No 2 Mbit- connection needed Less antennas and cable usage, and smaller space required

for equipment.

Easy to locate site for installation & coverage

Expands coverage areas in: rural, tunnels, in-building, canyons and

highways

Platform for subscriber growth

Acts just like base station

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TypesofRepeater

Band Selective / Broadband

Pico repeater - Good forproviding indoor coverage

such as office, meeting room,

function room and stairway

etc.

In-line Booster - Boost signal

power in feeder cables.

Bandwidth Adjustable

Suitable for Inbuilding

coverage. Outdoor coverage in rural and

sub-urban areas.

dB Typical7 MHz Typical 25 MHz

0 -3

-40

Centrefrequency

dB 390kHz Operator's band

0-3

-40

Centrefrequency

Typical7 MHz

Frequency

390kHz

Frequency

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TypesofRepeater

Channel Selective

Suitable for providing

coverage in high rise

buildings.

Outdoor coverage in urban

areas where frequencies

reuse is tight.

Hybrid Repeater

Suitable for use in

synthesize frequency

hopping network.

dB

0 -3

-40

dB

0-3

-40

approx200 kHz

190

approx200 kHz

190 190 FrequencykHz kHz

390 Operator's 390kHz TCH band kHz

Centre Frequency

190kHz kHz

frequency

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RepeaterSystemComponents

BDA

To BTSYagi Panel

antenna antenna

To MSservice area

coaxial coaxial

Batterybackup

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DonorAntennas

Donor antenna must be directed towards the donor cell (LOS) so

that there is

stronger received downlink power from

BTS.

minimum downlink amplification needed.

minimum spurious or interfering signals;i.e. higher C/I.

stronger uplink signals to the BTS.

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DonorAntenna

Popular belief that Yagis are best fitted as a donor antenna.

Yagis have low gains and high horizontal sidelobe

levels.

Radiation pattern of a typical 12 dBi Yagi antenna

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DonorAntenna

30 - 40 corner reflector or log-periodic antennas are better suited

with higher gain (~18dBi) and F/B ratio (> 40dB).

Radiation pattern of a 30 degree, 18 dBicorner reflector antenna

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DonorAntenna

Grid Parabolic Antennas are best suited for repeater applications.

Very high gain : 18 ~ 25 dBi Narrow beamwidth : < 10 deg

Radiation pattern of a typical 23 dBi

grid parabolic antenna

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ServiceAntenna

Planar antenna with broad radiation pattern, depending

on requirements

lower gain antenna gives broader vertical

beamwidth. use radiating cable for better vertical

fill.

Antenna is directed to the center of the coverage area.

For tunnels, use Yagi antennas.

For indoor, use special indoor antennas.

Use minimum 7/8" coaxial cable to minimize loss

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OutdoorRepeaterApplications

Most Repeaters Systems are interfaced with the common Outdoor

and Indoor applications. We integrate Channel Selective Repeaters

and Band Selective Repeaters to give coverage in rural and urban

areas.

Repeater coverage for a main road Island Coverage when microwave linkis not possible / available

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TypicalCoverageImprovements

Blk

135

Blk

135

Before After

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RepeaterSetupConsiderations

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AntennaIsolation

A repeater can act as an oscillator if the signal feedback is greater

than the gain.

Isolation between donor & service antenna should be atleast

10 - 15 dB more than system gain.

Fair distance from donor antenna for proper isolation is

estimated

to be 10-15m vertical spacing.

To measure, inject a known power into one antenna

(or use tracking

generator function),

& measure the

level received bythe other on aspectrum analyzer.

Donor

isolation

Spectrum ServiceAnalyzer

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FactorsAffectingIsolation

Antenna Pattern

Antenna null should be pointing towards the other

antenna.

Donor and Service antennas should have high F/B

ratio.

Vertical Separation

Narrow vertical aperture in the vertical antenna pattern.

Environmental Separation

Reflection and attenuation properties of materials near the

antenna

can influence isolation drastically.

Concrete towers improves isolation as signals are attenuated

and

reflected.


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EffectiveDonorPathLoss(EDoPL)

ERP Donor RepeaterService

PLBTS-RR

PLRR-MS(max)Lcoax Lcoax

PLRR-MS(min)EDoPL

BTS MSmin MSmax

This comprises all losses and gains between the BTS output and

the donor port of the repeater.

EDoPL is assumed to be equal for uplink and downlink.

EDoPL can be found by

checking with the Switch the BTS power setting, PBTS; connecting a spectrum analyzer to the end of the donot

cable

and reading the received level, Pin-rr;

EDoPL = PBTS - Pin-rr

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EffectiveDonorPathLoss(EDoPL)

The uplink noise level arriving from the repeater to the BTSNu = Nth-rr + Grr + NFrr - EDoPLwhere

Nth-rr = thermal noise of a GSM channel (-121 dBm @ 20C)Grr = uplink gain setting of repeaterNFrr = repeater noise figure (typ 5 to 9 dB)

To minimize noise interference at the BTS, let Nu be 3 dB less than

thermal noise of BTS, Nth-bts;i.e. Nu = -(121+3) = -124 dBm.

Assuming NFrr = 7 dB,the maximum repeater gain setting is determined by

Nu = Nth-rr + Grr + NFrr - EDoPL-124 = -121 + Grr + 7 - EDoPL

Grr = EDoPL - 10

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RepeaterSaturation

Downlink

Repeater input power (Pin) is too strong

Pin (dBm) => Pout (dBm) - Minimum Gain(dB) May need external attenuator

Repeater Gain set too High

Maximum Gain (dB) 9dB or

delay spread is less than 15.5 s.

Placing the repeater between the donor BTS and theservice

area satisfies this requirement.


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Interference&Handover

Band selective repeaters must be used with caution onsites close to the cell border

Signal strength of donor and adjacent cells are close. May result in some calls being originated at an adjacent

cell

but outside its cell borders.

Donor antenna performance is important.

Problem do not occur for channel selective repeaters

Only the chosen GSM channels are repeated.

Superior to band selective for outdoor large area coverage.

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ImportantRepeaterSpecifications

Broadband, Band Selective, Channel Selective, Hybrid.

Number of channels.

Output power per carrier.

Maximum gain and adjustable range.

Noise figure.

Automatic gain control.

Spurious emission : 36 dBm in G9 band (ETS 300342).: 30 dBm in G18 band

Mean Time Between Failure (MTBF).

Other features remote connection via PSTN or GSMmodem. Interface to OMC.

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RepeaterSiteSelection

Good LOS (Line Of Sight) with donor cell and intendedcoverage

area.

Good donor signal level received at site.

Example: A repeater with maximum 95dB gain and 37dBmoutput

power requires a minimum input signal of -58dBm toproduce max

output power.

Sufficient antenna mounting space for good isolation.

Good air ventilation with shelter (preferred).

Easy access to repeater.

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ProcedureinRepeaterCellSetup

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StepsInSettingUpRepeaterCell

Pre-Installation Drive Test

Repeater Design

Repeater Installation

Repeater Commissioning

Post-Installation Drive Test

Optimization

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Pre-InstallationDriveTest

Determine drive test route for existing coverage area.

Identify weak spots. Repeater Coverage Design

Before

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RepeaterInstallation

Optimize Donor Antenna

Spectrum Analyzer Service

Donor

Isolation Measurement

isolation

Configure Repeater

Test Calls

Optimize Coverage

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Optimize Donor Antenna

Direct Donor antenna towards donor cell. Scan for optimum donor carrier strength using spectrum

analyzer.

Adjust antenna until maximum donor signal strength is

achieved.

Measurement of Coupling Loss (Isolation)

Measure the signal received by the other antenna on aspectrum

analyzer.

Isolation (coupling loss) is the difference between the 2power

levels.

Inject a signal of known power level into one antenna.

Configure Repeater

Set to carrier frequency/bandwidth.

Adjust Attenuation to achieve optimum DL & UL output

power. Set appropriate threshold for alarms.


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Test Calls

Calls set up and voice quality.

Test for any abnormal drop calls.

Handovers between neighbour cells.

Optimize Service Antenna Orientate antenna to achieve desired network coverage.

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Post-InstallationDriveTest

Perform drive test on pre-determined route.

Verify coverage enhancement at weak spots. Optimize repeater coverage

Repeater Cell

Blk135

After

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ImpactonDonorCell

Enhanced network coverage at affected areas.

Increase in cell traffic.

Possible congestion due to increase in traffic. Higher handover in donor cell due to increase in traffic.

Higher drop calls due to more handover and traffic congestion.

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RepeaterBlockDiagrams

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ChannelSelectiveRepeater

ALC

C-ATT

PA1

M-ATT

LNA1

40dB

Downlink

-30dBTest

Donor Ant

DT

C-ATT

PA3 20dB

PA4 C-ATT

20dB

OMT UL Freq SelectComputer with Data card Module

Alarm

Modem IndicatorWireless Modem

OMC

Channel Filter 20dB

f1 f1

ALC

C-ATT PA2

20dBChannel

f2 Filter f2 DLF req Select Module Mobile

ALC MT Ant

-30dB Test

Channel Mobile

f1 Filter f1 M-ATT

ALC 40dB LNA2

Uplink

Channel

f2 Filter f2

Main Control Unit Power Li-ionSupply BATT

External Power

OMT

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BandwidthAdjustableRepeater

ALC

M-ATT C-ATT

LNA1 PA1

Band Band

Test Downlink f1 Filter f1 f2 Filter f2Donor DL Freq Select Module Mobile

Ant Ant

DTALC Test MT

C-ATT M-ATT

PA2 LNA2

Band BandUplink Mobile

f2 Filter f2 f1 Filter f1UL Freq Select Module

OMT Alarm Power Li-ionComputer with Indicator Main Control Unit Supply BATT

Data card Modem

Wireless Modem

External Power

OMC OMT

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BandSelectiveRepeater

ALC

M-ATT C-ATTCDMA Freq

CDMA Freq LNA1 PA1 FC1, FC2FC1, FC2 30dB Band 15dB

-30dB Downlink f1 Filter f1fC1, fC2 Test fC1, fC2

Donor DL Freq Select MobileAnt Module Ant

ALC -20dB Test

C-ATT M-ATT Mobile

PA3 LNA2

15dB Channel 30dB

f2 Filter f2 Uplink

UL Freq Selectand PA Module

OMT Computer withData card Alarm Power Li-ion

Modem Indicator Main Control Unit Supply BATT

Wireless Modem

External Power

OMC OMT

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HybridRepeater

ALC

C-ATTPA1


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-30dBTest


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M-ATT

LNA1

40dB

Downlink


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20dB

C-ATT

20dB


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f1


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Band BandFilter f1+fo f2 Filter f2+fo

DL Band Freq Select Module

ALC

PA2

Channel

f3 Filter f3+fo DL Channel Freq

OMTComputer with

Donor Ant

DT

PA3

ALC

Band Band

f2+fo Filter f2 f1+fo Filter

UL Band Freq Select Module

ALC

PA4

Channel

UL Channel Freq f3+f o F il ter

f1

Select Module

C-ATT

20dB

C-ATT

20dB

M-ATT

LNA2

40dB

Downlink

-30dBTest

MT

Mobile Ant

Mobile

Data card Select Module f3

Wireless Alarm IndicatorMainControl Unit

P owe r S uppl y L i- io nBAT T

Modem Modem

External Alarm Sensors

OMC

External Power

OMT

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IndoorBandSelectiveRepeater

ALC

M-ATT

LNA1 PA1

30dB Band

-30dB Downlink f1 Filter f1+fo

DonorTest

DL Freq Select and PA Module Mobile

Ant Ant

DT ALC MT

M-ATT

PA2 LNA2

Band 30dB Mobile

f1+fo Filter f1 Uplink

UL Freq Select and PA Module

OMT Computer with Power Li-ionData card Alarm Indicator Main Control Unit Supply BATT

Wireless Modem

Modem

External Alarm Sensors

OMC External Power 220VAC

OMT

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IndoorWidebandBooster

ALC

M-ATT

LNA1 PA1

Downlink

Donor Mobile

Ant Ant

DT MTALC

M-ATT

PA2 LNA2

Uplink Mobile

Alarm Main Control Power Li-ion

Modem Indicator Unit Supply BATT

Computer with OMTData card

Wireless Modem

Power 220VAC External

OMT

OMC

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FrequencyShift Repeater

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LimitationsofaConventionalRepeater

High uplink noise, especially for band-selective and wideband

repeaters

Repeater coverage is uplink limited, based on thermal noiselevel

reaching the BTS

Requires careful uplink gain setting

Difficulty in deploying high power repeaters

Minimum isolation requirements or risk of

oscillation

Requires careful choice of donor and service

antenna

Requires large tower for effective implementation

Dependent on best donor traffic conditions

Mainly suited for use in indoor coverage

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FSR vsRepeater

A conventional repeater can act as an oscillator if

the signal feedback is greater than the gain.

Isolation between donor and service antennashould be at least 10 - 15 dB more than systemgain.

Fair distance from donor antenna for properisolation; e.g. 15-20 m vertical separation and atleast 120 degree horizontal separation fornormal repeater setup for high gain operation

The FSR works on the principle that the outputsignal frequency of a channel selective repeater is

shifted from the input frequency

lower antenna isolation requirement (e.g. 70dBfor inband FSR regardless the system gain)

Fair distance from donor antenna for properisolation; e.g. 1-2 m vertical separation; lessstringent horizontal separation requirement

Isolation

Vertical

Separation

Repeater

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FrequencyShiftRepeater(FSR)

The FSR is a point-to-multipoint, frequency-shifting repeater system

that overcomes antenna isolation problem in conventional repeatersystem.

Supports 2 or 4 channel frequencies.

Available in 2W, 10W or 20W.

Comprises of Master Unit (Direct or Wireless Coupling) and Remote

Unit.

Available in GSM-DCS, GSM-GSM, DCS-DCS, GSM-CDMA,

GSM-1.5GHz.

Wireless remote and local monitor function (OMT).

Optional powerful remote repeater network administration (OMC).

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SystemApplications

Point-to-Point using Direct Coupling Main Unit.

1800MHz

RU

MU

900MHz

900MHz

GSM BTS

900MHz

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SystemApplications

Point-to-Point using Wireless Coupling Main Unit.

Internal or ExtAntenna Internal or Ext

Antenna

Wireless CouplingMain Unit Remote

UnitGSM Mobile

GSM BTS

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SystemApplications

Point-to-Multipoint using Direct Coupling Main Unit.

RUF1

F2MU

F2 F1

F1 F2

GSM BTS F1RU RU

F1

F1 F1

F1

F1 F1

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SystemApplications

Point-to-Multipoint using Wireless Coupling Main Unit.

WC MU RU

F1 F1

F2

F1

F2F2

F1

GSM BTS RU RU

F1

F1 F1

F1

F1 F1

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Optical Repeater

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SystemBlockDiagram

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MainUnitBlockDiagram

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RemoteUnitBlockDiagram

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OpticalRepeaterApplications

Fiber optic coupled Repeaters are often used for In- Buildings and

also for some outdoor systems.

Airports and underground exhibition halls are some of the common

areas where fiber optic repeaters are used.

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Summary

1. Introduction to Repeaters

2. Repeater Setup Considerations3. Procedure in Repeater Cell Setup

4. Repeater Block Diagrams

5. Frequency Shift Repeater

6. Optical Repeater

Documents

Repeater Doc