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Electrical Downtilt

Overview

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Agenda

Electrical Downtilt

Variable Electrical Downtilt

Remote ControlledVariable Electrical Downtilt(Teletilt)

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Used to

Control coverage

Reduce Interference

2 methods:-

Mechanical

Electrical

Downtilt

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Electrical / MechanicalDowntilt

No downtilt

Mechanicaldowntilt

Electricaldowntilt

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Electrical DowntiltCoverage

No downtilt Electrical downtilt

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Mechanical DowntiltCoverage

No downtilt Mechanical downtilt

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C/I - Electrical Downtilt

Minimal Co channelinterference

Assuming 7/21 reuse

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C/I - Mechanical Downtilt

High Co channelinterference

Assuming 7/21 reuse

4/12 reuse evenworse

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Co Channel Interference

MechanicalElectrical

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Comparing Downtilt Methods

10 Electricaldowntilt

10 Mechanicaldowntilt

6 Electrical+ 4 Mechanical

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Co-channel Interference vs Downtilt

Interferencereceived from amobile in a co-channel cell

Electrical downtiltprovides muchbetter interferencesuppression

Typically can be

worse as there isnormally more than1 co-channel basestation

Mechanical0Changein

interferencereceivedfromco-channelbasestation

[dB]2 4 6 10

-40

-30

-20

-10

0

Down tilt angle [deg]

8

Electrical

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C/I vs Downtilt Angle for Electrical &Mechanical Tilt

Electrical downtilt:Signal reduced,interference reducedmore, therefore the C/Iis increased

Mechanical downtilt:Eventually signal isreduced but not asmuch as interference,therefore C/I reduced

Independent of

antenna heights(20,40& 60m)

In real world - someflattening of curves

2 4 6 10 120

0

20

40

60

20

40

60Electrical downtilt

Mechanical downtilt

Downtilt angle

8-10

10

Changein

C/Iratio

[dB]

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EDT and CDMA

Despite common frequencies thereare still key benefits for CDMA

from EDT

Soft hand-off zones become criticalfor capacity and dropped calls

Pilot signals for paging & controletc. create pollution whichbecomes a major factor forcapacity and quality.

Cell sites beforeoptimisation

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CDMA and Mechanical Downtilt

Soft hand-off zones large.

Limited capacity

Increases areas wherepilot pollution could be aproblem.

Cell sites afteroptimisation by

mechanical downtilt

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CDMA and Electrical Downtilt

The soft hand-off zonesare optimised,

maximises capacity.

Pilot pollution minimised

optimises call quality

maximises capacity.Cell sites after

optimisation byelectrical downtilt

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Back Lobes and Downtilt

Backlobes are also tilted with electrical downtilt

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Benefits of Electrical Tilt

Improved Signal to Interference (C/I) ratioLess dropped calls

Improved reputation

Improved revenue

Interference

No Interference

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Variable Electrical Downtilt

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Deltec Varitilt andTeletilt antennasfeature variableelectrical downtilt

Variable Electrical DowntiltHow it works

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Variable Electrical Downtilt -Easy toadjust

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Control Systems: HandheldController

Handheld Controller

Sets downtilt of single antenna

Adjusts and reads antenna tilt

Menu-driven operation

Commands are sent via aconnection panel in the cellsite shelter (one connector perantenna)

Battery powered (rechargeable)

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Variable Electrical Downtilt -No need to swap or move

7 2

5 OR

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Variable Electrical Downtilt -Simplify Planning

What antenna do I use?

2, 5, 7or 9

???

2 - 10

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Variable Electrical Downtilt -Optimise for the Real world

Ideal Real

Variations between modelling tool and reality Changes to the environment

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Effects of Backtilt

0 Total(6 EDT - 6 MDT )

6 Total(6 EDT + 0 MDT )

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Variable Electrical Downtilt -Simplify stock holding

2-10

4

?

6

8

2

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Easy to adjust antennas

No need to change or move antennas

Simplifies planning (Choosing antennas)

Can optimise antennas for real world

Improved network performance

Better revenue

Simplify stock holding

Variable Electrical DowntiltBenefits

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Remote Controlled VariableElectrical Downtilt

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Adjustments in minutes

From your desk

No site downtime

No extra manpower / equipment

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Teletilt Variable Electrical Downtilt

Independent ofweather

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Optimise your network withTeletilt

Easy to fine tune

Correct handovers

Reduce interference

Fill in holes

Balance traffic

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Check your settings with Teletilt

What is the tilt?

62

???7

5

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Drive Testing with Teletilt

Adjust as you test

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Current 4-5 Months 7-8 Months 12 Months

Splitter

Controller6 Actuator

Controller3 Actuator

Controller6 Actuator

or 3 Actuator(Can also bemounted up

mast)

IN OUT IN OUT

New stepper motoractuator integrated

into antennawith EDT

range sensor

Red handheld controllerno longer required

for new installations

BTS BTS

BTS BTS

BTS

Multi-droppedcontrollers

(3 to 6 Actuator)to support up to

18 single bandantennas

System supportsantennas withinternal orexternal actuators

Splitter

DCPOWER

DCPOWER

DCPOWER

DCPOWER

DCPOWER

RS485 RS485

RS485 RS485

Management SystemRoadmap

Remotecontrolcapability

800/900/1800/1900 and MultibandAntennas with integratedbrush motor actuators

UMWD Wide Band Antenna(with field retro-fittablestepper motor actuator)

Antennas

Red Hand Held Controller(brush motor compatible) New local controller(stepper motor compatible)Control Systems One control system to controlall actuators (stepper motor andbrush motor)

Full remote control overwide area network

800/900, Multiband and UMWDWide Band Antennas (all with integratedstepper motor actuators)

IssueA 4 Oct 2001

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Teletilt Benefits Fast adjustment

Adjustment independent of

Time

Weather

Site access difficulties

No interruption of service

No special requirement for

Equipment

Manpower

The downtilt is known

Ability to fine tune coverage

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Teletilt Benefits Financial &Customer

$$$

Savings in Labour

Savings in equipment hirecosts

Savings in downtime

(loss in revenue)

Increase revenue throughimproved performance

Improved customer service:

Optimise networkperformance

Avoid outages

Respond quickly tochanging traffic patterns