3. WCDMA Radio Planning Fundamentals

2 © Nokia Siemens Networks WCDMA Planning Fundamentals/Jan2008Customer Confidential

WCDMA Radio Planning FundamentalsDeepak YadavJan’2008

3 © Nokia Siemens Networks NetAct Simulation Procedure/Jan2008Customer Confidential

Contents

Scope of 3G Network PlanningWCDMA Planning Process OverviewInput ParametersLink Budget OverviewSite Selection CriteriaCo Sitting and Interference Issues Nominal Planning FundamentalsNetAct Simulations Process Overview


Simplified Network Planning Flowchart

Create nominal plan

Define search areas

Site selection

Detailed site design

Site acquisition

CW Measurement

Identify site options

Site construction

Initial network dimensioning


Scope of 3G network planning

Packet Switched Core


Network planning process & relation to business planning

marketing

business plan

traffic assumptions

Networkdimensioning

Code & freq. & interference plan

transmission plan

final NW topology/

architecture

parameter planning

coverage plan

Networkoptimization


New issues in WCDMA planning process wrt GSM

CoveragePlanning andSite Selection

ParameterPlanning

PropagationmeasurementsCoverageprediction

SiteacquisitionCoverageoptimisation

External InterferenceAnalysis

NetworkConfigurationandDimensioning

DEFINITION PLEMENTATION

Traffic distributionService distributionAllowed blocking/queuingSystem features

IdentificationAdaptation

Area / Cellspecific

Handoverstrategies

Maximumnetworkloading

Other RRM

NetworkOptimisation

O & M

Surveymeasurements

Statistical performance analysis

Quality Efficiency Availability

Capacity Requirements

Requirementsand strategyfor coverage,quality andcapacity,

per service

Multiple services

Coverage and capacitycoupling

Multiple services


Radio networks Dimensioning Overview

COVERAGECOVERAGE CAPACITYCAPACITY

COMPROMISE BETWEEN COVERAGE AND CAPACITYCOMPROMISE BETWEEN COVERAGE AND CAPACITY


UTRAN Radio Dimensioning

Customer Requirements

LINK BUDGETLINK BUDGET

Rel’99, CPICH, HSDPA, HSUPA

RF Planning Parameters• interf marg

• HO gain• environment

• etc.

RF Planning Parameters• interf marg

• HO gain• environment

• etc.

System Parameters

• Eb/No• TX power

• etc.

System Parameters

• Eb/No• TX power

• etc.

Infrastr. Parameters• # of sectors• antennas

• req cov area• etc.

Infrastr. Parameters• # of sectors• antennas

• req cov area• etc.

DIM TOOLDIM TOOL

Air Interface Dimensioning

(Capacity: Rel’99 + HSPA )

Traffic Demand

• per bearer• # of subs

• GoS• etc.

Traffic Demand

• per bearer• # of subs

• GoS• etc.

System Parameters

• spectral efficiency

• etc.

System Parameters

• spectral efficiency

• etc.

Number of NodeBs

NodeB Type

NodeB configuration:

- Amount

- BB dim

- NDR annex

- etc.

And NodeB Upgrade:

- #CHC / #FSM

- #Carrier

- Sectorisation

- …

Per area and Per area and

per Phaseper Phase

DIM TOOLDIM TOOL

NodeB Dimensioning CHC, DRIC, FSM)

- Ou

tpu

t to

war

d A

cces

s p

lan

nin

g


Coverage VS Capacity Dimensioning:Cell Breathing

• This diagram shows cells are unloadunload

This diagram shows when some cells are loadedloaded

Cell-A

Cell-C

Cell-B

Results => Results => Coverage Holes!Coverage Holes!

Cell-A

Cell-C

Cell-B

Cell breathing


Coverage VS Capacity Dimensioning:Fixed Uplink Load - To avoid Coverage holes

"actual" Loading, (ie from the traffic inputs defined in dimensioning)

This diagram shows a Fixed Uplink Load design

Results => No or Results => No or Min Coverage Min Coverage Holes!Holes!

Cell-A

Cell-C

Cell-B

Cell-A

Cell-D

Cell-H

Cell-E

Cell-F

Cell-C

Cell-B

Cell-G

• No (or minimum)

coverage holes problems

• More cells required

• Traffic mobility taken

into account. (Note:

dimensioning assumes

uniform traffic

distribution)

eg. Actual UL load = 8%

eg. Fixed UL load = 30%


Input parameters – overview

CAPACITY RELATED Spectrum Available User Profile and Traffic Growth

Forecast Traffic Density Map

CAPACITY RELATED Spectrum Available User Profile and Traffic Growth

Forecast Traffic Density Map

COVERAGE RELATED Coverage Regions Area Type Information

COVERAGE RELATED Coverage Regions Area Type Information

QUALITY RELATED MS Class Indoor Coverage Location Probability Blocking Probability

QUALITY RELATED MS Class Indoor Coverage Location Probability Blocking Probability

Gives an Estimation of the Equipment Necessary to Meet the Network Requirements

Network Dimensioning Activities

Radio Link Budget Calculation

Cell Size Calculation Capacity Calculation Transmission Network

Estimate

Gives an Estimation of the Equipment Necessary to Meet the Network Requirements

Network Dimensioning Activities

Radio Link Budget Calculation

Cell Size Calculation Capacity Calculation Transmission Network

Estimate

Input Categories


Summary of Dimensioning Inputs

Dense Urban Urban Suburban Rural

Voice # of subs & mErl per sub

# of subs & mErl per sub



CS data # of subs & mErl per sub




PS data # of subs & kbps per sub

# of subs & kbps per sub



Coverage area km2 km2 km2 km2

Location probability % % % %

Standard deviation dB dB dB dB

Fade margin dB dB dB dB

Penetration loss dB dB dB dB

Area correction factor dB dB dB dB

MS / Node B antenna height m m m m


Link Budget Overview

Noise figure

Cable losses

Soft handover gain,

antenna gain

Building Penetration loss

Body loss

Margins

PATH LOSS (L)

Max AllowedPath Loss (L)

= Tx Signal + All Gains – Other Losses – Rx Sensitivity


Bit rate bit/s 64000 aTotal TX power available dBm 21 bTX antenna gain dBi 2 cBody loss dB 0 dTX EIRP per traffic channel dBm 23 e=b+c-dRX antenna gain dBi 18 fRX cable and connector losses dB 3 gReceiver noise figure dB 3 hThermal noise density dBm/Hz -174 jCell loading % 70 kNoise rise due to interference dB 5.23 l=10*log10(1/(1-(k/100)))Total effect of noise dBm/Hz -171 m=h+jInformation rate dBHz 48.06 n=db(a)Effective required Eb/No dB 2.54 oRX sensitivity dBm -115.40 p=l+m+n+o+correction factorSoft Handoff Gain dB 4.5 qFast fading Margin dB 2.5 rLog normal fade margin dB 11.6 sIn-building penetration loss (urban) dB 20 tMaximum path loss urban dB 123.80 pl=e+f+q-g-p-r-s-t

Path loss = Tx signal + all gains - losses - ( SNR + Noise)


Site Selection Criteria


Site Selection Criteria

Proper site location determines usefulness of its cells

Sites are expensive

Sites are long-term investments

Site acquisition is a slow process

Hundreds/thousands of sites needed per network

Base station sites are valuableBase station sites are valuablelong-term assets for the operatorlong-term assets for the operator


How do I asses a site option?

Each site needs to be assessed on several grounds.RadioTransmissionAccessPowerPlanning

Ideally every site option reported by the surveyor would pass in each of the areas listed above.


Bad GSM Sites

In GSM, there were two types of bad sites.Donkeys - Low sites which provide very little coverage.

Donkeys carry so little traffic that they often never pay for themselves.

Boomers - High sites which propagate much further than is needed. A boomer will cause localised interference and prevent capacity being added to

some other sites in the area.

Small “Donkey” site Large “Boomer” site


Bad UMTS Sites

Good radio engineering practice doesn’t change much for UMTS. It just becomes more important.

In UMTS A “Donkey” will never pay for itself.A “Boomer” will reduce the range and capacity of surrounding sites.

Two major factors determine whether a site is considered good, a “Donkey” or a “Boomer”, They are:

Site location.Antenna height.

Other parameters can be used in an attempt to control booming sites but it is far better to avoid building them in the first place.


Importance of Controlling 'Little i'

WCDMA is an interference-limited network. I.e. capacity of the network is directly linked to how interference is maintained/controlled.From the Radio Network Planning point of view, the "little i" - other-to-own cell interference- is the only thing that can really be influenced by the Planner during the site selection and planning stage. WCDMA RF planning is all about having good dominance in the desired coverage area.Unlike in GSM, that there is no frequency plan to "play" with in order to minimise the effects of bad sites.

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1( kk

k

kbK

kDL vi

RWNoE

1)/()/(

1

kkk

kbK

kDL vi

RWNoE

1)/()/(

1

Uplink Load EquationUplink Load EquationUplink Load EquationUplink Load Equation Downlink Load EquationDownlink Load EquationDownlink Load EquationDownlink Load Equation


Importance of Controlling 'Little i'

Planners have to select the sites diligently so that the other-to-own cell interference ratio is MINIMIZED by planning clear dominance areas during site selection / planning phase.

0 500 1000 1500140

145

150

155

160

165

170

DL throughput in kbps

Max

imum

pro

paga

tion

loss

(dB

)

128 kbps

i = 0.2i = 0.2i = 0.4i = 0.4i = 0.6i = 0.6i = 0.8i = 0.8

BTS TX power 43 dBm

MS TX power 21 dBm

Ec/Io -16.5 dB

BTS Eb/No 1.5

MS Eb/No 5.5

Other to own cellinterference ratio i

0.2, 0.4, 0.6,

0.8

Orthogonality 0.6

Channel profile ITU VehicularA, 3 km/h

MS speed 3 km/h

MS/BTS NF 8 dB / 4 dB

Antenna gain 16 dBiRESULT: Doubling of the "little i" will cause throughput to decrease to 70% of the original value


i = Coverage Overlap

Some overlap is required to allow soft handover to occurNeed to control amount of interference since the network capacity is directly related to it. Soft handover helps to reduce interference. (Soft HO Gain)Too much overlap:

– Increases interference to other cells --> reduce capacity

– Increases Soft Handover overhead --> reduce capacity


Bad Site Location

wanted cellboundary

uncontrolled, stronginterferences

interleaved coverage areas:weak own signal, strong foreign signal

Avoid hill-top locations for BS sites (same for GSM) uncontrolled interference interleaved coverage no sharp dominance areas awkward Soft/Hard HO behaviours BUT: good location for microwave links ! (TNP jurisdiction)


wanted cellboundary

Good Site Location

Prefer sites off the hill-tops use hills/high rise buildings to separate cells contiguous coverage area well defined dominance areas needs only low antenna heights if sites are slightly elevated above valley bottom


Characteristics of a good site

It has good clearance, no obstacles around, and it overlooks the surrounding rooftops. This site will give good macro coverage.

Bad site; blocked by neighbour building


Characteristics of a good site

BAD: In a urban/dense urban area, too high a site is a bad site since it will introduce too much interference to other sites in the network(remember the little i)

while for a rural area it's a good site.

Uplink Load EquationUplink Load EquationUplink Load EquationUplink Load Equation

Downlink Load Downlink Load EquationEquation

Downlink Load Downlink Load EquationEquation

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

kkk

kbK

kDL vi

RWNoE

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Examples of Bad Sites

Typical mess! =>GSM1800 antennas with space div. between CDMA (IS-95) antennas and pointing directly at the high building

GSM1800 and GSM900 antennas are too close=> Not enough isolation => Intermodulation and spurious emission.

These situations can easily be avoided!!

Time consuming and costly to fix.


Arghhh… note how far you can see -roughly 10km = TOO FAR. There is a riveras well, so interference is enormous. Sitedistance is about 700meters in thisphase!! Site was good in phase 1when distance between sites was 4km!

Well shit happens … who could have knownthat they were going to build this high building one year after installation ?! Planners shouldhave anticipated this during initial site surveys!

Examples of Bad SitesLittle i, Little i, Little i !!!


Examples of Bad Sites

The TX/RX and Rx div antennas are not pointingin the same direction! Installation problem.

Is this installation OK? The satellite dish is in near field of the GSM900 antennas -> some effects for sure. Definite interference to satellitesystem. But could not be tested because the satellite system was not in use! Avoid installing antennas in close proximity to other objects since its radiation pattern will be altered.


Examples of GOOD Sites

Enough space between the two Tx/Rx and Rx Div., AND pointing in the same direction! Site survey point of view: Provides clear dominance to the desired coverage area.


Summary of Site Selection Guidelines

The objective is to select a site location which covers the desired area but keeps emissions to a minimum.The site should be located as close to the traffic source as possible.

– The closer the site is to the traffic, the less output power will be required by the user equipment and node B. This will minimise the noise affecting other users on both the serving cell as well as other nearby cells.

The antenna height selected will depend largely on the type of environment in which the site is to be located. Eg Dense Urban, Urban, Suburban, Rural.The key factor to be considered is how well can the emissions be controlled.


Summary of Site Selection Guidelines You can "feel" the site only if you are there! If one or more of these characteristics are not fulfilled by the

examined site, the Field Planner should REJECT the site and choose another site

Be flexible, even creative! Try to think of all the possible implementation solutions that the site could support: different pole heights, split poles for different sectors, etc.

Always check neighbouring sites, to be sure your chosen candidate is "fitting" well into the surrounding, e.g. for coverage, SHO zones,etc.


Using Existing Cellular Sites

Most UMTS networks will be built around an existing GSM network.Many GSM networks were built around existing analogue sites.In the early days of analogue cellular sites were often located to give maximum coverage. No thought was given to capacity issues.Despite causing problems in high capacity networks, many of these high sites are still in operation today.Most cellular networks contain these nightmare sites.When rolling out UMTS around an existing network it is vital to avoid these sites.


UMTS Configurations

Most vendors support the same basic configurations.

• Omni

• 3 sector

• 6 sector

Each vendor supports their own variations on these configurations.

• Some solutions eliminate the need for RF plumbing.

• Some require similar amounts of equipment to a GSM BTS.

• Some increase the number of antennas on a site.

The configuration can be affected by the wide variety of UMTS antennas.


Co-locating a Node B at a GSM site

Isolation requirements between UMTS and GSM systems can be derived from UMTS and GSM specifications. In many cases equipment performance will exceed the requirements in the

specifications. Each vendor should be able to provide information which can be used to

improve the isolation requirements.The isolation requirements will affect

– Choice of antenna configuration

– Filtering at both the GSM and UMTS sites.Isolation is the attenuation from the output port of a transmitter to the input port of the receiver.


Interference Issues

Wideband Noise - unwanted emissions from modulation process and non-linearity of transmitterSpurious Emissions - Harmonic, Parasitic, Inter-modulation productsBlocking - Transmitter carriers from another systemInter-modulation Products - Spurious emission, specifications consider this in particular

– Active: non-linearities of active components - can be filtered out by BTS

– Passive: non-linearities of passive components - cannot be filtered out by BTS

Other EMC problems - feeders, antennas, transceivers and receivers


Interference IssuesNonlinear system transfer function can be expressed as a series expansion

In the case of one input frequency, vin = cos 1t, output will consist of harmonics, m1

– Fundamental (m = 1) frequency is the desired one.– If m > 1, there are higher order harmonics in output => harmonic distortion.– Can be generated both inside an offender or a victim system.

In the case of two input frequencies, vin = cos 1t + cos 2t , output will consist of harmonics m1 + n2, where n and m are positive or negative integers.

– Intermodulation is the process of generating an output signal containing frequency components not present in the input signal. Called intermodulation distortion (IMD).

– Most harmful are 3rd order (|m| + |n| = 3) products.– Can be generated both inside an offender or a victim system.

x y = a0 + a1x + a2x2 + a3x3 + ...System


Interference from Other System

GSM spurious emissions and intermodulation results of GSM 1800 interfere WCDMA receiver sensitivity

WCDMA spurious emissions interfere GSM receiver sensitivity

GSM transmitter blocks WCDMA receiver

WCDMA transmitter blocks GSM receiver

GSM GSM 1800 1800

ULUL

GSM GSM 1800 1800

DLDL

1710-1785 MHz

1805-1880 MHz

UMTS UMTS UL UL

UMTS UMTS DLDL

1920-1980 MHz

2110-2170 MHz

40 MHz


M Distortion from GSM1800 DL to WCDMA UL

• GSM1800 IM3 (3rd order intermodulation) products hits into the WCDMA FDD UL RX band if:

• 1862.6 f2 1879.8 MHz

• 1805.2 f1 1839.6 MHz

WCDMADL

WCDMAUL

GSM1800DL

GSM1800UL

1710 - 1785 MHz1805 - 1880 MHz 1920 - 1980 MHz2110 - 2170 MHz40 MHz

f1 f2

fIM3

fIM3 = 2f2 - f1

X dBc

• For active elements IMproducts levels are higherthan IM products producedby passive components• Typical IM3 suppressionvalues for power amplifiers are -30 … -50 dBc depending on frequencyspacing and offset• Typical values for passiveelements are -100 … -160 dBc


Harmonic distortion

Harmonic distortion can be a problem in the case of co-siting of GSM900 and WCDMA.GSM900 DL frequencies are 935 - 960 MHz and second harmonics may fall into the WCDMA TDD band and into the lower end of the FDD band.

GSM900935 - 960 MHz

WCDMATDD

WCDMA FDD1920 - 1980

...

2nd harmonics

fGSM = 950 - 960 MHz

1900 -1920 MHz

2nd harmonics can be filtered out at the output of GSM900

BTS.

f


Isolation Requirements

GSM 900 GSM 1800 UMTSReceiving band

(UL)890 – 915 MHz 1710 – 1785 MHz 1920 – 1980 MHz

Transmitting band(DL)

935 – 960 MHz 1805 – 1880 MHz 2110 – 2170 MHz

GSM 1800 TxGSM 1800 Tx

1805 MHz1805 MHz 1880 MHz1880 MHz

UMTS RxUMTS Rx

1920 MHz1920 MHz 1980 MHz1980 MHz

GSM 1800 RxGSM 1800 Rx

1710 MHz1710 MHz 1785 MHz1785 MHz

UMTS RxUMTS Rx

2110 MHz2110 MHz 2170 MHz2170 MHz

For example - To prevent UMTS BTS blocking: with transmit power = 43 dBm For example - To prevent UMTS BTS blocking: with transmit power = 43 dBm

Max level of interfering signal for blocking = -15 dBm in UMTSMax level of interfering signal for blocking = -15 dBm in UMTS

Isolation required = 58 dBmIsolation required = 58 dBm


Achieving Isolation Requirements

Isolation can be provided in a variety of different ways.

By antenna selection and positioning.By filtering out the interfering signal.By using diplexers and triplexers with

shared feeder and multiband antennas.

UMTSUMTS

GSMGSM

FilterFilter

UMTSUMTS

GSMGSM

DiplexerDiplexer

UMTSUMTS

GSMGSM


Co-siting - Antenna Installations

Difficult to calculate isolation between two antennas and measurements are required.Best configurations - antennas pointing in different directions or where there is vertical separation between antennasThe following configurations will should all give 30dB isolation.

dddd

dd

90º90º 120º120º

dd

dd180º180º

dd

d = 0.3 - 0.5 md = 0.3 - 0.5 m d = 1 - 3 md = 1 - 3 m d = 0.5 - 2 md = 0.5 - 2 m


Site sharing with third party systems

Some UMTS sites might be co-located with other non GSM operators.

PMR Broadcast Navigation

Some of these systems use older equipment which might be more vulnerable to EMC issues.Need to define minimum antenna separations between systemsBetter to avoid sites used for safety critical applications.

UMTS antennas

Other systems

Minimum separation


Antenna installation issues: Clearance angle

h (meters)

d (meters)Clearance angle

Rules of thumb:

• h d/2, d < 10 m

• h d/3, 10 < d < 20 m

• h d/4, d > 30 m

Antenna

d (meters)

Top view

Side view


Antenna installation

d has to be >3.2 m

Safety margin of 15 between the reflecting surface and the 3 dB lobe


Antenna installation: Other RF-systems

Not Acceptable

D O C U M E N T T Y P E 1 ( 1 )

T y p e U n itO r D e p a r tm e n tH e r eT y p e Y o u r N a m e H e r e T y p e D a te H e r e

A c c e p ta b le

B e c a re fu l w i thb a c k - lo b e !


Nominal Planning for UMTS


What is a nominal plan?

A nominal plan is initially a hypothetical wireless network.The nominal plan is the starting point for the cell rollout process and will evolve into the final network design.As physical sites are identified and acquired, the nominal plan is amended.

Nominal Plan

Final Network Design

Rollout process


Initial Network Dimensioning

Spreadsheet based analysis.Used in the license application.Identifies the approximate number of sites required.Identifies the approximate site radii required for:

Urban/Suburban/Rural areasVoice/Data services

Used as a major input to the nominal plan.

Urban Suburban RuralVoice 1.8 km 3.1 km 4.4 km64 kb/s 1.6 km 2.7 km 3.5 km384 kb/s 1.1 km 2.4 km 3.2 km

Typical cell radii estimates

Maximum range to support all services

Service not supported in this environment

Service supported


Create Nominal Plan

Position a hexagonal grid of sites over the desired coverage area.The radius of each hexagon can be determined from the previous slide.The capacity of the network can then be analyzed to detect:

Hot spots that require cell splits.Under used cells that could be

removed from the plan.

Example nominal plan for Jersey


Define Search Areas

The sites in a nominal plan are only imaginary.To become a real network, physical sites are required.A suitable physical site must be found for each nominal site.A suitable physical site must amongst other things:

Give adequate radio coverage.Have connectivity into the transmission network.Be aesthetically and politically acceptable to the local community.Have power nearby, good access and a co-operative owner.

A survey of each nominal site is normally carried out to identify possible site options which meet the above criteria.


Define Search Areas

Guidelines have to be given to the surveyor so the options give appropriate radio coverage.The guideline is given in the form of a search area. Could be:

– Radius from the nominal site.

– One or more polygons following height contours.

Or


Identify Site Options

Surveyor visits each search area and identifies potential site options.The first sites to be considered should be

– Existing radio sites.

– Sites offered from major site owners (MSO) E.g. Utilities & Railways.

All options should meet certain criteria to ensure that they are– Technically acceptable.

– Build able

A good idea to consult with the planning/zoning authority during the survey.Good training of surveyors will save time later in the build process.


Identify Site Options

The surveyor will prepare a report listing the options.Report will include:

– Accurate grid reference.

– Accurate height of structures or available antenna windows.

– Photographs of the site.

– 360º panoramic photos from site or if obstructed from nearby location/structure.

A

D

C B


Site Selection

Normally a desk study.Evaluate radio coverage and transmission.

Quickly eliminate unsuitable options.

Rank the remaining sites in order of preference.

Nominate a preferred option and possibly a backup option.

A3rd

D1st

C2ndB - Unsuitable


Detailed Site Design

Prior to commencement of construction work, a detailed site design is required.Includes

Antenna and feeder requirements.Antenna azimuths and tilts.Equipment capacity requirements

Can’t be completed in isolation. Must take into account other sites.

60º

60º

180º180º

300º

300º

Ant 1

Ant 2

Ant 5

Ant 4

Ant 6

Ant 3


Evaluate Nominal Network Coverage

Run a coverage array for the nominal network.Check that the coverage is in line with your expectations.Adjust site locations and add additional sites if improvements to coverage is necessary.Check for excessively high sites.


Thank You

3. WCDMA Radio Planning Fundamentals

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