OMD8000 Network Planning Principle ISSUE1.1

OMD8000Network Planning Principle

ISSUE1.1

OMD8000Network Planning Principle

ISSUE1.1

Wireless Curriculum

Development Section

OutlineOutline

1. Introduction to GSM Network1.1. GSM System Architecture1.2. GSM Bandwidth1.3. Difference between GSM900/18001.4. GSM Logical Channels

2. Mobile Radio Link2.1. Radio Wave Propagation 2.2. Propagation Models2.3. Antenna Systems2.4. Diversity Techniques2.5. Interference2.6. Interference Reduction2.7. Link Budget Calculation

OutlineOutline

3. Network Planning Procedure

3.1. Cellular Planning Principles

3.2. Network Topologies

3.3. Traffic Estimation

3.4. Coverage Planning

3.5. Frequency Planning

3.6. Site Selection

3.7. Transmission Planning

4. Advanced Network Planning Items 4.1. Network Evolution

4.2. Indoor Coverage Planning

4.3. Tunnel Coverage

4.4. Parameters Planning

Introduction To GSM NetworkIntroduction To GSM Network

1. Introduction to GSM Network 1.1. GSM System Architecture 1.2. GSM Bandwidth 1.3. Difference Between GSM900/1800 1.5. Logical Channels in GSM

we are HERE

GSM System ArchitectureGSM System Architecture

other MSC

other BTS´s

VLR HLREIR

AuCOMC

GSM BandwidthGSM Bandwidth

GSM 900 :

Channel spacing 200kHz

GSM 1800 :

Channel spacing 200kHz

890 915 935 960

duplex distance : 45 MHz

1710 1785 1805 1880

duplex distance : 95 MHz

Operator A Operator B Op. BOp. Anot allocated

System Difference Between GSM900/1800System Difference Between GSM900/1800

GSM 900 and GSM 1800 are twins

GSM 900 GSM 1800 Frequency band 890...960 MHz 1710...1880 MHz

Number of channels 124 372

Channel spacing 200 kHz 200 kHz

Access technique TDMA TDMA

Mobile power 0,8 / 2 / 5 W 0,25 / 1 W

There are no major differences between GSM 900 and GSM 1800

There are no major differences between GSM 900 and GSM 1800

Logical ChannelsLogical Channels

GSM900 and GSM1800 have the some logic channel architecture

Broadcast ControlChannel (BCCH)

Control ChannelsCommon ControlChannel (CCCH)

Traffic Channels (TCH)

FCH SCH BCCH(Sys Info)

TCH/FAGCH RACH SDCCH FACCH

SACCH

TCH/H

TCH/9.6FTCH/ 4.8F, HTCH/ 2.4F, H

PCH

Common Channels (CCH)

Dedicated Channels (DCH)

Logical Channels

Downlink ChannelsDownlink Channels

FCCH

SCH

BCCH

PCH

AGCH

BCCH

CCCH

Common Channels

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channels

Uplink ChannelsUplink Channels

RACH CCCHCommon Channels

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channels

Use of Logical Channels Use of Logical Channels

Search for Frequency Correction Burst

Search for Synchronization sequence

Read System Information

Listen for Paging

Send Access burst

Wait for signaling channel allocation

Call setup

Traffic channel is assigned

Conversation

Call release

FCCH

SCH

BCCH

PCH

RACH

AGCH

SDCCH

FACCH

TCH

FACCH

idle mode

“off” state

dedicated mode

idle mode

Mapping of Logical ChannelsMapping of Logical Channels

Logical channels are mapped to physical channels• Signalling : sequences of 51 frames

• Traffic : sequences of 26 frames

• For combined BCCH CCCH blocks can be either PCH or AGCH

Some blocks may be configured as SDCCH

R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R

F S B B B B C C C C S C C C C C C C CF S C C C C C C C CF S C C C C C C C CF S C C C C C C C CF -

51 TDMA frames ~ 235,4 msecBCCH + CCCH (uplink)

BCCH + CCCH (downlink)

The Mobile Radio LinkThe Mobile Radio Link

we are HERE 2.1. Radio Wave Propagation

2.2. Propagation Models

2.3. Antenna Systems

2.4. Diversity Techniques

2.5. Interference

2.6. Interference Reduction

2.7. Link Budget Calculation

Theory of Wave Propagation Theory of Wave Propagation

Theory of wave propagation is an exact science

Mobile TelecommunicationsMobile Telecommunications

Multi-path propagation

radio path is a miserable propagation medium

Limited transmit energy

transmitting power of mobiles determines service range

battery life-time

Limited spectrum

sets upper limit for data rates (Shannon´s theorem)

additional effort needed for channel coding

frequencies need to be re-used ==> self- interference

Many mobile users

Radio Propagation EnvironmentRadio Propagation Environment

Multi-path propagation

Shadowing

Terrain structures

Reflections

Interferences

ReflectionsReflections

Strong echoes can cause excessive propagation delayif within equalizer window and

can cause self-interference if out of equalizer window

direct signalstrong reflected signal

equalizer window 16 s

amplitude

delay time

long echoes, out of equalizer window:==> interference contributions

Fading(1)Fading(1)

Slow fading (Lognormal Fading)

shadowing due to large obstacles on propagation direction

Fast fading (Rayleigh fading)serious interference of several signals

“fading dips”, “radio holes”

+10

0

-10

-20

-300 1 2 3 4 5 m

level (dB)

920 MHzv = 20 km/h

Fading(2)Fading(2)

time

power

2 sec 4 sec 6 sec

+20 dB

mean value

- 20 dB

lognormal fading

Rayleighfading

Signal VariationsSignal Variations

Rayleighfading

Lognormalfading

Large scalevariation

Cause Superposition ofmultiplepropagationpaths withdifferent phase

Shadowing orreflexion by cars,trees, buildings

Prop. path profile, terrain& clutter structure, Earthcurvature

Correlation < 10 ... 100m > 100m

Prediction unpredictable mostlypredictable(buildings!!)

predictable (maps, terraindatabase)

Planningmethod

apply statisticalthresholds forRayleigh fadingsignals

considerlognormaldistributionaround localmean (use = 3... 10dB)

use maps or digitalterrain & clutterdatabases to predict (50..200m pixel resolution)

PropagationPropagation

Free- space propagation signal strength decreases as the with distance increases

specular reflection

diffuse reflection

Reflection

Specular R.amplitude: A --> *A ( < 1)

phase : --> - polarization: material dependant phase shif

t

Diffuse R.amplitude: A --> *A ( << 1)

phase : --> random phase

polarization : random

D

PropagationPropagation

Absorption heavy amplitude attenuation material dependant phase shifts the wave’s depolarization

Diffraction wedge- model

knife edge

multiple knife edges

A A - 5..30 dB


we are HERE

2.1. Radio Wave Propagation




2.5. Interference



Propagation ModelPropagation Model

Historical CCIR- Model for radio/ TV-stationsnot very accurate nor serious

Okumura- Hataempirical model

measured and estimated additional attenuations

estimations for larger distances (range: 5 .. 20km)

Not suitable for small distances ( < 1km)

Hata’s ModelHata’s Model

Adapted for 900 MHz, Europe, different land usage classes

L A B f h a h

h d Lb m

b morpho

log . log ( )

( . . log ) log

1382

44 9 655with

f frequency in MHz

h BS antenna height [m]

a(h) function of MS antenna height

d distance between BS and MS [km]

and

A= 69.55, B = 26.16 (for 150 .. 1000 MHz)

A= 46.3 , B = 33.9 (for 1000 ..2000MHz)

additional attenuation dueto land usage classes

Land Usage TypesLand Usage Types

Urban small cells, 40..50 dB/dec attenuation

Forest heavy absorption; 30..40 dB/dec;

differs with season (foliage losses)

Open, farmlands easy, smooth propagation conditions

Water signal propagates very easily ==> dangerous !

Mountain faces strong reflections, long echoes

Glaciers very strong reflections; extreme delays

strong interferences over long distance

Hilltops can be used as barriers between cells

do NOT use as antenna sites locations

Walfish- Ikegami ModelWalfish- Ikegami Model

Model for urban microcellular propagationAssumes regular city layout (“Manhattan grid”)Total path loss consists of three parts:

line-of-sight loss LLOS

roof-to-street loss LRTS

mobile environment losses LMS

hw

b

d

The Mobil Radio LinkThe Mobil Radio Link

we are HERE





2.5. Interference



Antenna CharacteristicsAntenna Characteristics

Lobesmain lobes

side / back lobes

front-to-back ratio

Half-power beam-width (3 dB- beam width)

Antenna down-tilting

Polarization

Antenna bandwidth

Antenna impedance

Mechanical size

Coupling Between AntennasCoupling Between Antennas

Horizontal separationneeds approx. 5distance for sufficient decoupling

antenna patterns superimposed if distance too close

Vertical separation distance of 1provides good decoupling values good for RX /TX decoupling

Minimum coupling loss

main lobe

5 .. 10

Installation ExamplesInstallation Examples

Recommended decouplingTX - TX: ~20dB

TX - RX: ~40dB

Horizontal decoupling distance depends on Antenna gain Horizontal rad. pattern

Omnidirectional antennasRX + TX with vertical separation

RX, RX div. , TX with vertical separation (“fork”)

Vertical decoupling is much more effective

0,2m

omnidirectional.: 5 .. 20mdirectional : 1 ... 3m

Installation ExamplesInstallation Examples

Directional antennasbeamed sites

Antenna (down-) tiltingimprove spot coverage

reduce interference

5..8 deg

FeederFeeder

Feeder Parameter

Type Diameter 900MHz 1800MHz

(mm) dB/100m dB/100m

3/8” 10 14 10

5/8” 17 9 6

7/8” 25 6 4

1 5/8” 47 3 2

Keeping the Feeder as short as it can

Distributed AntennasDistributed Antennas

Leaky feeders cables with very high loss per length unit

==> “distributed antenna”

often used for tunnel coverage

this kind of feeder is very expensive

Fiber-optic distribution feeder distribute RF signal via (very thin) fiber-optic cables

radiate from discrete antenna points at remote locations

50 Ohm

Propagation loss: 4 ... 40 dB/100m

coupling loss: ~ 60 dB (at 1m dist.)

RepeatersRepeaters

The repeaters are used to relay signal into shadowed areas :

behind hills

into valleys

into buildings

Needs a host cellChannel selective repeater or wide-band repeater

decoupling ~40 dB needed


we are HERE





2.5. Interference



DiversityDiversity

Time diversity

Frequency diversity

Space diversity

Polarization diversity

Multi-path diversity

coding, interleaving

frequency hopping

multiple antennas

Dual-polarized antennas

equalizer

t

f

Benefit From DiversityBenefit From Diversity

Diversity gain depends on environmentIs there coverage improvement by diversity ?

antenna diversity

5dB more signal strength

more path loss acceptable in link budget

higher coverage range

R

R(div) ~ 1,3 R A 1.7 A 70% more coverage per cell needs less cells in total

The above case can be satisfied only under Ideal condition. That is environment is infinitely large and flat

InterferenceInterference

we are HERE





2.5. Interference



InterferenceInterference

Signal quality =sum of all expected signals carrier (C )sum of all unexpected signal interference (

I )=

• GSM specification : C / I >= 9 dB

expected signal atmosphericnoise

other signals

Effects of InterferenceEffects of Interference

Affects signal quality

Causes bit errorsrepairable errors : channel coding, error correction

irreducible errors : phase distortions, random FM

Interference situation isnon- reciprocal uplink If. =/= downlink If.

unsymmetrical different situation at MS and BS

Concept C/I

Signal Quality in GSMSignal Quality in GSM

RX Quality (RXQUAL parameter)RXQUAL classes 0 ... 7

bit error rate before all decoding/ corrections

RXQUAL Mean BER BER rangeclass (%) from... to0 0,14 < 0,2%1 0,28 0,2 ... 0,4 %2 0,57 0,4 ... 0,8 %3 1,13 0,8 ... 1,6 %4 2,26 1,6 ... 3,2 %5 4,53 3,2 ... 6,4 %6 9,05 6,4 ... 12,8 %7 18,1 > 12,8 %

usable signal

unusablesignal

good

acceptable

Interference sourcesInterference sources

Multi-path components (long echoes) Frequencies reusingExternal interferences

• Network performance shall be interference-limited rather than coverage- limited

Push interference limits as far as possible

Methods for reducing InterferenceMethods for reducing Interference

Frequency planning

Suitable site locations

Antenna (down-)tilting

good location

bad location

Methods for reducing InterferenceMethods for reducing Interference

Frequency hoppinga diversity technique, interference reduction as a side-effect

frequency diversity ==> less fading loss

de-coding gain

interference averaging

Quality based power control evaluate signal level AND quality

DTXsilent transmitter in speech pauses

Adaptive antennasfollow the user

concentrate signal energy to certain directions

Adaptive channel allocationalways assign best available frequency during call-setup

Frequency HoppingFrequency Hopping

Diversity techniquefrequency diversity can reduce fast fading effects

useful for static or slow-moving mobiles

Cyclic base-band hoppingBS hops cyclic between its allocated frequencies (min. =3 TRX)

RF hoppingeither cyclic or random hopping

needs wideband combiner

can use any frequency included in the Hopping list (not on 1st TRX)

Frequency diversity for static mobilesfeature: interference averaging

Power ControlPower Control

Save battery life-time

Minimize interference

GSM : 15 steps and 2 dB for each

Use power control in both uplink & downlinklevel or quality-driven

time

signallevel target level

e.g. -85 dm

Power control not allowedon BCCH carrier

DTXDTX

DTX: discontinuous transmissionswitch transmitter off in speech pauses and silence periods

both sides transmit only silence updates (SID frames)

comfort noise generated by transcoder

VAD: voice activity detectiontranscoder function

Transcoder is informed on use of DTX/ VAD (in call setup)

Battery saving and Interface Reducing

Battery saving and Interface Reducing


we are HERE





2.5. Interference



Link BudgetLink Budget

Why we need a link budget?

Which will decide the coverage range ?

The coverage range is limited by the weaker one (up or down link)

Two-way communication neededlink usually limited by mobile power

Desired result: downlink = uplink

Link budget must be balanced

Network PlanningNetwork Planning

we are HERE 3.1. Cellular Planning Principles





3.6. Site Selection


Network Planning PrincipleNetwork Planning Principle

marketing

business plan

traffic assumptions

initial NWdimensioning

freq. & inter-ference plan

transmission plan

final NW topology

parameter planning

coverage plan

Scope of Network PlanningScope of Network Planning

Network planning teamdata acquisition

site survey

field measurement evaluation

CW design and analysis

transmission planning

• Network design• number and configuration of BS

• antenna systems specifications

• BSS topology

• dimensioning of transmission lines

• frequency plan

• network evolution strategy

• Network performance• grade of service (blocking)

• outage calculations

• interference probabilities

• quality observation

• Operator’s requirements• subscriber forecasts

• coverage requirements

• quality of service

• recommended sites

• External information sources• terrain & morphological data

• population data

• bandwidth available

• frequency co-ordination constraints

Input DataInput Data

Mapsmain cities

important roads

location of mountain ranges

inhabited area

shore lines

Local knowledgecity skylines

typical architecture

structure of city

Demographic DataDemographic Data

Statistical yearbooklargest towns, cities

population distribution

where are expected customers?

Local knowledgepopulation migration routes

traffic volumes

subscriber concentration points

300 000 pop.

400 000 pop.

250 000 pop.

Network ConfigurationNetwork Configuration

Estimate number of BS neededVERY rough initial assumption :

total operator’s bandwidth

planned freq. re-use rate

number of BS needed for traffic reasons

Evaluate achievable cell sizes=f (topography, requirements, signal levels,

environment, ...)

number of BS needed for coverage reasons

Normally: BS coverage >> BS traffic ==> problem with finance people

= average number of TRX allowed per cell

Finances Marketing

Planning


we are HERE






3.6. Site Selection


Cell HierarchiesCell Hierarchies

Umbrella Cell/Macro cell

Micro cell

Pico cell

Satellite Cell

Macro Cell NetworkMacro Cell Network

Cost-effective solutionSuitable for covering large areas

large cell ranges

high antenna positions

Cell ranges 2 ..20km (depends on geography!)

Used with low traffic volumestypically rural areas

road coverage

Commonly use omnidirectional antennasuse beamed antenna for road coverage

2..20 km

Optimization for coverage

Micro Cell NetworkMicro Cell Network

Capacity oriented networkadditional capacity by multiple cell coverage

Suitable for areas with high traffic

Mostly used with beamed cellsmost cost-efficient solution

best usage of available cell sites

Typical applicationsmedium towns

suburbs

Typical coverage range: 0,5 .. 2km

Optimization for capacity

0,5 .. 2km

Cell coverage rangeCell coverage range

Achievable cell coverage range depend on

frequency band (450, 900, 1800 MHz)

surroundings, environment

link budget figures

antenna types

antenna positioning

minimum required signal levels

Hexagons and CellsHexagons and Cells

Three hexagons Three cells


we are HERE






3.6. Site Selection


Traffic EstimationTraffic Estimation

Estimate number of subscribers over timelong-term predictions

numbers available from marketing people

Expected traffic load per subscriberdifferent subscriber segments

expected behavior of user segments

Particular habits of subscribers e.g. mainly heavy indoor usage

phoning while in traffic jams

Busy hour conditionstime of day

traffic patterns

Traffic PlanningTraffic Planning

Estimation of traffic expected• number of subscribers in area

• traffic load per subscriber

• geographical area to cover

==> traffic per sq.km

==> traffic per cell

==> number of TRX needed per BS

• allow extra capacity for roamers and busy hour traffic

Bottleneck of the system shall not be caused by transmission

Traffic PatternsTraffic Patterns

Traffic is not evenly spread across the day (or week)

Estimated traffic must be able to cope with peak loads

Busy hour traffic is typically twice that of the average hour

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 hr

%

peak time

off-peak


we are HERE






3.6. Site Selection


Coverage PlanningCoverage Planning

external inputs:(traffic, subs. forecast,coverage requirements...)

Initial network dimensioning TRXs, cells, sites bandwidth needed NW topology

nominal cell plansuggestions for site locations cell parameters coverage achieved

coverage prediction signal strength multi-path propagation

coverage, ok?

site inspection

site accepted ?

real cell planfield measurements

planningcriteria fulfilled?

N

N

N

create celldata forBSC

go tofrequency planning

Coverage RequirementsCoverage Requirements

Roll-out phases & time schedules

Coverage level requirementsagree on min. levels for outdoor

coverage

Loss requirements

Indoor coverage areas

Mobile classes to plan for

Operator’s cell deployment strategies

omni-cells in rural areas?

3-sector cells in urban areas?

phase 1CW launch

rolloutphase 2

rolloutphase 3

Coverage PlanningCoverage Planning

Lossdue to coverage gaps Pno_cov

due to interferences PIf

Total probable coverage area for a cell:(1- Pno_cov) * (1- PIf)

Full coverage of an area can never be guaranteed ! common values: 90 .. 95% probability

(time and location probabilities)

Network planningNetwork planning

we are HERE



3.3. Dimensioning



3.6. Site Selection


Frequency PlanningFrequency Planning

Why we reuse the frequency?

8 MHz = 40 channels * 8 timeslots = 320 users ==> max. 320 simultaneous calls!!!

Limited bandwidth

==> re-use frequencies as often as possible

Interferences are unavoidable

==> minimize total interferences in network

Allocate frequency combination that creates least overall interference

conditions in the network

Use calculated propagation predictions for frequency allocations

Frequency Planning(1)Frequency Planning(1)

Target: find solution with minimum interferences in total network

Traditional methodhexagonal cell patterns

regular grid

cluster sizes

frequency re-use distance D = R *sqrt(3*cluster-size)

R

D

Do not use this ancient concept!

Frequency Planning(2)Frequency Planning(2)

Frequency planning always consider the worst case

actual situation is less severe

power control, actual traffic and distribution of MS improve situation

Average frequency re-use rate as a criteria for good allocation scheme:

practicallimits

safe, butuneconomical

physicallimit

0 10 20

Frequency Re-UseFrequency Re-Use

Re-use frequencies as often as possible

increases network capacity

but maybe cause some interferences

Do not usehexagon cell patterns

systematic frequency allocation

Butinterference matrix calculation

calibrated propagation models

minimize total interference in network

R

D

f2

f3

f4f5

f6

f7

f3

f4f5

f6

f2

f3

f4f5

f6f2

f3

f4f5

f6

f7

f2

f3

f4f5

f7

f2

f3

f4f5f2

f3

f4f5

f6

f7

Multiple Re-use RatesMultiple Re-use Rates

Frequency re-use ratemeasure for effectiveness of frequency plan

trade-off : effectiveness interferences

Interactions (iteration loops) with coverage planning

Multiple re-use rates increase effectiveness of freq. plan

compromise between safe, interference free planning and effective resource usage

1 3 6 9 12 15 18 21

safe planning(BCCH layer)normal planning

(TCH macro layer)

tight re-use planning (tight layer)

same frequencyin every cell(spread spectrum)

Multiple Re-use RatesMultiple Re-use Rates

Capacity increase with multiple re-use rates:e.g. network with 300 cells

bandwidth : 8 MHz (40 radio channels)

Single re-use: =12==> NW capacity = 40/12 * 300 = 1000 TRX

Multiple re-use:BCCH layer: re-use =14, (14 freq.)

normal TCH: re-use =10, (20 freq.)

tight TCH layer: re-use = 6, (6 freq.)

==> NW cap. = (1 +2 +1)* 300 = 1200 TRX

cap NBW

re usei

i

.

Frequency Co-ordinationFrequency Co-ordination

Regulations for international boundaries25 dBV/m at borderline

10 dBV/m at 15km distance from border

Set of preferential and reserved frequencies must be mutually agreed between operators

A

B

C

15km

internationalborderline


we are HERE



3.3. Dimensioning



3.6. Site Selection


Site locationsSite locations

Cells performance has a close relationship with site location

Sites are expensive

Sites are long-term investments

Site acquisition is a slow process

Hundreds of sites needed per network

Base station site is a valuablelong-term asset for the operator

Bad Site LocationBad Site Location

Avoid hill-top locations for BS sitesuncontrolled interferences

interleaved coverage

awkward HO behaviors

but: good location for microwave links!

wanted cellboundary

uncontrolled, stronginterferences

interleaved coverage areas:weak own signal, strong foreign signal

Good Site LocationGood Site Location

•Prefer sites off the hill-tops• use hills to separate cells

• contiguous coverage area

• needs only low antenna heights if sites are slightly elevated above valley bottom

wanted cellboundary

Site Selection CriteriaSite Selection Criteria

Radio criteria

good view in main beam direction

no surrounding high obstacles

good visibility of terrain

room for antenna mounting

LOS to next microwave site

short cabling distances

Non-radio criteria

space for equipment

availability of leased lines or microwave link

power supply

access restrictions

house owner

rental costs

Site Acquisition ProcessSite Acquisition Process

radio planner

fixed networkplanner

measurementteams

architect

network operator

site huntersite owner

Site InformationSite Information

Questionnaire sheetcollect all necessary information about site detailssite coordinates, height above sea level, exact address

house owner

type of building

building materials (photo)

possible antenna heights

360deg photo (clearance view)

neighbourhood, surrounding environment

drawing sketch of rooftop

antenna mounting conditions

access possibilities (truck, road, roof)

BS location, approx. feeder lengths

Network planningNetwork planning

we are HERE



3.3. Dimensioning



3.6. Site Selection


Transmission PlanningTransmission Planning

Cost for transmission lines account for a great portion of NW operational costs per year==> design for minimum overall costs !

Fixed part design

MSC

BSC Hub

BTS

BSS

BTS

BTS

BTS

Radio part design

BTS

BSS

BTS

BTS

BTS

Transmission ConceptTransmission Concept

Transmission media

Transmission techniques

Transmission methods

Fiber

Coaxial cable

Copper cable

Microwave radioTerrestrial/satellite

PDH SDH

PCMISDN ATM

Tra

nsm

issi

on

eq

uip

men

tHDSL

CATV

Microwave LinksMicrowave Links

High capacity transmission linksOperating frequencies: 7 .. 38 GHz band

• Contra needs extra frequencies weather dependant link quality

(rainfall) not always available at ideal

sites (LOS path) long distance hops are

problematic

• Pro low operating costs easy to install flexible quick & reliable solution

Terminalstation A

Terminalstation B

Repeaterstation

Fresnel ZoneFresnel Zone

Line-of-sight path needed between both nodes of a microwave link

Keep 1st Fresnel zone clear of obstacles

N-th Fresnel zone: Ellipse around direct path, where path difference to direct line is n * /2.

d

b

1st Fresnel zone2nd 3rd

Radius for n-th zone = b * sqrt(n)bd km

f MHzm274

[ ]

[ ][ ]

Basic Transmission TopologiesBasic Transmission Topologies

Transmission topologies are often dictated by availability of lines.

Costs vs. fail safety (redundancy)

POINT-TO-POINT

MULTIDROP CHAINLOOP

STAR (CONCENTRATION POINTS)

Network topologyNetwork topology

Prefer centralized or decentralized NW architecture

2 small BSC plus cheap transmission

1 large BSC plusexpensive transmission

MSC

BTS

BSC

BTS

BTS

BTS

BSC/ MSC

BTS

BTS

BTS

BTS

Cross-ConnectsCross-Connects

Transmission equipment to branch data streams between different link sets

Non-blocking stageeach input stream is routed to an output stream

Tasksswitching between link sets

switching between timeslots of a PCM trunk

dropping & inserting timeslots

Advanced Network Planning ItemsAdvanced Network Planning Items

we are HERE 4.1. Network evolution

4.2. Indoor coverage

4.3. Tunnel coverage

4.4. Parameters

4.5. Network Optimizing

Cell Size EvolutionCell Size Evolution

LARGE CELLS5-50 kmEarly 80's

SMALL CELLS1-5 kmMid-end 80's

MICROCELLS100 m - 1 kmMid 90

PICOCELLS10-100m

MACRO CELLS

's 's

LAYERED NETWORK

Smaller Cells Bring Higher Capacities but ...Smaller Cells Bring Higher Capacities but ...

Logistics of planning and implementation

=> bottleneck to small cell deployment

Small cells must be integrated into network & managed by

advanced BSS

Layered NetworkLayered Network

Micro cell

Macro cell

Micro cell

Micro cell

Network Capacity evolutionNetwork Capacity evolution

Measure for network spectral efficiency:Erl/ (MHz * sq.km)

A function ofbandwidth

frequency efficiency of technology

frequency re-use

cell sizes

trunking gains

Frq. hoppingFrq. hopping

DTXDTX

DirectedRetry

DirectedRetry

PowerControl

PowerControl

Half-ratecode

Half-ratecode

Loaddistribution

Loaddistribution

Trafficreason HO

Trafficreason HO

multiple cellcoverage

multiple cellcoverage


4.1. Network evolution



4.4. Parameters

We are HERE

Why IndoorsWhy Indoors

• Cellular competition moves indoors• Subscribers expect continuous coverage and quality• Outdoor cells do not provide sufficient coverage indoors

INDOOR SOLUTION

Good Quality!

BenefitsBenefits

Low Transmitting Powers (BTS/MS)

Dedicated Indoor Solution

Good Quality

Safety

MS Battery Life

Office Equipment

Less Interference

Continuous Coverage

Subscriber value

Continuous Service

Building LossesBuilding Losses

Signal levels in buildings are estimated by applying a building penetration loss margin

Big differences between rooms with window and deep indoor(10 ..15 dB)

Pref = 0 dB

Pindoor = -3 ...-15 dB

Pindoor = -7 ...-18 dB

-15 ...-25 dB no coverage

rear side :-18 ...-30 dB

signal level increases with floor number :~1,5 dB/floor (for 1st ..10th floor)

Building Penetration LossBuilding Penetration Loss

Signal losses for building penetration vary greatly with building materials used, e.g.:

mean value sigmareinforced concrete wall, windows 17 dB 9concrete wall, no windows 30 dB 9concrete wall within building 10 dB 7brick wall 9 dB 6armed glass 8 dB 6wood or plaster wall 6 dB 6window glass 2 dB 6

No major differences for 900 or 1800 MHz

Total building loss =add median values

superimpose standard deviations

add (lognormal) margin for higher probabilities

In-Building Path LossIn-Building Path Loss

Simple path loss model for in-building environment

outdoor losses: Okumura‘s formula

Lout = 42,6 + 20 log( f ) + 26 .. 35 log( d )

wall losses:

Lwall = f(material; angle)

indoor losses: linear model for picocells

Lin = L0 + d

building type losses application example

old house 0,7 dB/m (urban residential)

commercial type 0,5 dB/m (modern offices)

open room, atrium 0,2 dB/m (museum, train station)

Lout

Lwall

Lin

Indoor Coverage SolutionsIndoor Coverage Solutions

Small BTSmini BTS

PrimeSite

Repeatersactive, passive

optical

Antennasdistributed antennas

radiating cable

Signal distributionpower splitters

optical fiber

Indoor PlanningIndoor Planning

Example

• 1.2 MHz allocation

• 50 mErl/subscriber , 2% blocking

• two-floor Re-Use, separate frequencies within a floor

• a) three floors

• 27 Erl => 540 subs

• b) ten floors

• 90 Erl => 1800 subs

Example1.2 MHz allocation, one 6-TRX cell50 mErl/subscriber, 2% blockingno Re-Use of frequenciesa) three floors

36 Erlangs => 720 subscribersb) ten floors

36 Erlangs => 720 subscribers

Single cell approach Multicell approach

t

f5

f6

f5

f1

f2

f1

f3

f4

f3f1..f6

f1..f6

f1..f6

Radiating cableRadiating cable

Coaxial cable with perforated leads

==> energy leak

Radiating losses 10 ..40 dB per 100mcoupling loss typ. 55 dB (at 1m ref. dist.)

Produce constant fieldstrengths along cable runs

Operate in wide frequency rangeradiating losses become higher with frequency

Very large bending radii disturbs field distribution

Formerly often used for tunnel coverage

VERY EXPENSIVE

Indoor Coverage ExamplesIndoor Coverage Examples

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

1:1:1

1:1

4th floor

3rd floor

2nd floor

1st floor

ground floor

With repeaterrelay outdoor signal into target building

needs donor cell; adds coverage, no capacity

With indoor BTS and distributed antennasheavy losses by power splitting and cabling

Outdoor AntennaGain: 18 dBi

Indoor AntennaGain: 9dBi

Target Indoor Coverage Building

7/8'' Cable Loss: 4dB / 50mCable length : 25m

-50 dBm

4th Floor

3rd Floor

1st Floor

Ground Floor

2nd Floor

RepeaterRepeater

Passive repeaterneeds strong external signal

useful only with very short cables

seldomly used

Active repeater amplifies and re-transmits all re

ceived signals

Wideband or narrowband repeater

•Application examplesplaces with coverage need and little traffic

remote valleys

tunnels

underground coverage (e.g. garages)

needsdecoupling > amplification

The Light-bulb PrinciplesThe Light-bulb Principles

several smaller sites provide more indoor coverage area than a single large site

... is better than ...

Newspaper PrinciplesNewspaper Principles

Indoor coverage may be expected in locations where there is no enough daylight to comfortably read a newspaper without artificial illumination

• Where NOT? e.g.hotel lobby

elevator

hallways

• Where? e.g.rooms with window

near a window

atrium-style places

• The newspaper-principle

Wave Propagation in TunnelsWave Propagation in Tunnels

Tunnels are very friendly environment for radio wave propagation

Tunnels are very friendly environment for radio wave propagation

Ideal antenna position: center of cross-section

Distance to walls: min. 2

Tunnel cross-section shape unimportant, if > 10

Time dispersion decreases with distance ==>constant

Mount antenna ~50..100m before tunnel entrance

Good signal coupling between successive tunnels

Tunnel Cross-SectionTunnel Cross-Section

Filling factor determines propagation conditionsTypical ranges for filling factors

road tunnels: 10%

Metro: 60..90%

filling factor =----------


we are HERE

4.1. Network evolution



4.4. Parameters

BSS ParametersBSS Parameters

Relevant BSS parameter for NW planningfrequency allocation plan

logical radio interface configuration

transmit power

definition of neighboring cells

definition of location areas

handover parameters

power control parameters

cell selection parameters

radio link time-out settings

topology of BSC- BTS network

Handover TypesHandover Types

Intra-cell same cell, different carrier or timeslot

Inter-cell different cells (normal case)Inter-BSC different BSC Inter-MSC different MSC areasInter-PLMN (technically feasible, not supported)

Intra-cell

Inte-rcell

inter-BSC

Handover CriteriaHandover Criteria

1. Interference, UL and DL2. Bad C/I ratio3. Uplink Quality 4. Downlink Quality 5. Uplink Level 6. Downlink Level 7. Distance8. Rapid Field Drop

9. MS Speed10. Better Cell, i.e. periodic

check (Power Budget)11. Good C/I ratio12. PC: Lower quality/level

thresholds (DL/UL)13. PC: Upper quality/level

thresholds (DL/UL)

Location Area DesignLocation Area Design

Location updating affects all mobiles in network

Location update in idle mode

Location update after call completion

Location updateresults in signaling and processing load within the network (international location updates!)

Avoid ping-pong location updatesLocation area 1

Location area 2

major road

Paging vs. Location update TrafficPaging vs. Location update Traffic

PagingLocation update

# of cells in Loc. area

signalingtraffic

optimum numberof cells in Loc. area

function of user density,cell size, call arrival rate ...function of

user mobility

minimize signaling traffic

optimum varies with network evolution

Documents

OMD8000 Network Planning Principle ISSUE1.1