UMTS Network Systems Overview Both Days

7/27/2019 UMTS Network Systems Overview Both Days

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U101U101 UMTS Network Systems Overview

UMTS Network SystemsOverview

Day 1


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Introductory Session



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IntroductionsIntroductory Session

Hello

I am Richard Edge, your course presenter


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Introduction to AIRCOM

Contents and Session Aims

This session is a get to know yousession

It aims to answer the followingquestions:

Who are AIRCOM and why arethey here training us?

Should I be here?

Why am I here?

It also aims to cover the logistics ofthe course

Whens the lunch/coffee/cigarettebreak?

What are we going to learn aboutand when?

Target StudentsCourse Prerequisites

Aims of the Course

Course Schedule andOrganisation


5/396U101U101 UMTS Network Systems Overview

Target Students

This course is aimed at: Engineers and technical specialists familiar with telecommunications and

looking for an introduction to UMTS

Technically orientated managers looking to understand the technologybehind UMTS




Prerequisites

An understanding of the basic concepts of: Telecommunications Cellular communications

Wireless communications




Aims of Course

To teach the student about The background to UMTS The basics of CDMA cellular technology

The elements and architecture of a UMTS network

Techniques specific to UMTS

The UMTS air interface


I t d t S i



Course ScheduleDay 1 Day 2

9:30-10:15

Introductory Session1st/2ndGenerationCellular Systems

Overview

UTRAN

Drinks Break Drinks Break

10:45-11:30

3rdGeneration Driversand Standards

UTRAN (cont.)


12:00-12:45

CDMA MobileTechnology Overview

UMTS Core Network

Lunch Lunch

13:45-14:30

UMTS ArchitectureOverview

UMTS Fixed NetworkInterfaces


15:00-15:45

UTRA Air Interface UMTS Mobiles


16:15-17:00

UTRA Air Interface(cont.)

UMTS Services

17:00-17:30 Day 1 Roundup Course Roundup


I t d t S i



How the Sessions are Organised

Locator Slide To remind you where you are when you wake up! Theres also a section title at the top left of the slide...

Contents and Aims

New Material for the Session

Questions (please ask anytime!) Questions to You (to make sure youve been listening and understand)

Questions to Me (if you dont understand or want to know more)

Section Summary





Locator Slide

In t roduc tory Session

1st and 2nd Generation CellularSystems Overview

3rd Generation Drivers andStandards

CDMA Mobile TechnologyOverview

UMTS Architecture Overview

UTRA Air Interface

Day 1 Roundup

Day 2 Introductory Session

UTRAN UMTS Core Network

UMTS Fixed Network Interfaces

UMTS Mobiles

UMTS Services

Course Roundup





Questions

Any questions?


1st and 2nd Generation Cellular Systems Overview


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1U101U101 UMTS Network Systems Overview

Locator Slide


1st and 2nd Generat ion CellularSystems Overview




UTRA Air Interface

Day 1 Roundup


UTRAN UMTS Core Network


UMTS Mobiles

UMTS Services

Course Roundup




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1st and 2nd Generation Cellular SystemsOverview



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Contents and Session Aims1st and 2nd Generation Cellular Systems Overview

This is a background session to setthe scene for UMTS, essentially acellular history lesson

Firstly we will examine what wemean by cellular communications

We will look at differentgenerations of cellular and briefly

at major standards This will allow us to see why 3G

has moved forward in the way thatit has

What is Cellular?

Cellular Generations

1st Generation2nd Generation2.5G



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What is Cellular? There are three major types of

terrestrial mobile communicationstechnologies

Cellular Users are provided wide area

mobility from multiple base stationswith handover permitted

Cordless Communication Users are provided limited mobility

from a dedicated base station

Paging Brief numeric, alphanumeric or voice

messages are sent to the subscribertypically using simulcasting


PSTNMSC

Paging

ControlCentre

Cellular

Cordless

Paging



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Cellular Generations

People talk about mobiletechnology in terms of generations

1st Generation or 1G

2nd Generation or 2G

2.5G

3rd Generation or 3G

But what do these mean?

st a d d Ge e at o Ce u a Syste s O e e

time

Datarate

Progress of data rates withtime and generation



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1st Generation

1976+, though really thetechnology of the 1980s

Analogue modulation

Frequency Division MultipleAccess

Voice traffic only

No inter-network roaming possible Insecure air interface

y

The 1st Generation ofCellular Technology makesuse of analog modulation

techniques such as FM



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1st Generation Standards

AMPS (Analogue Mobile Telephony System) North American Standard in cellular band (800MHz)

TACS (Total Access Communications System) UK originated Standard based on AMPS in 900MHz band

NMT (Nordic Mobile Telephony System) Scandinavian Standard in 450MHz and 900MHz bands

C-450 German Standard in 450MHz band

JTACS (Japanese Total Access Communications System) Japanese Standard in 900MHz band

y



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1st Generation Planning

Macrocellular

High sites for coverage drivenplanning

Antennas above roof height

Frequency planning required

Large cell size

Order 30km Hard handover

Only ever connected to a singlecell

Cellular Networks are commonly

represented as hexagon grids.The above diagram shows howdifferent frequencies are used indifferent cells in a cellular network(different frequencies representedby different colours).For networks with more cells thanfrequencies these must be

planned



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2nd Generation

1990s

Digital modulation Variety of Multiple Access

strategies

Voice and low rate circuit switcheddata

Same technology roaming Secure air interface

The 2nd Generation ofCellular Technology is thefirst to use digital modulation



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GSM

First networks in 1992

European developed standard, but

with worldwide subscriber base Different frequency bands

GSM450, GSM900, GSM1800,GSM1900

Largest 2nd Generation subscriber

base Frequency/Time Division Multiple

Access

Open/Standardised Interfaces

GSM phones from 1999/2000



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GSM Planning Macrocells and microcells

Capacity driven planning

Frequency planning required Optional parameters requiringplanning

Hierarchical Cell Structures

Frequency Hopping

Discontinuous Transmission Power Control

Simple subscriber/traffic analysis Capacity limited by number of

TRXs

Hard Handover

GSM networks use microcells

to provide additional capacity.As with 1st generationnetworks frequency planningis required



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D-AMPS/PDC

TDMA (D-AMPS) North American TDMA/FDMA

based standard based upon AMPS

Predominantly used in North andSouth America

ANSI-41 Core Network

Planning Similar to GSM

PDC Japanese TDMA/FDMA based

standard

Predominantly used in Asia

Planning Similar to GSM

TDMA and PDC phones from1999/2000



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cdmaOne

First networks in 1996

Derived from Qualcomm IS-95 airinterface

Largely American subscriber basewith some Asian networks

Code Division Multiple Access This is in many ways the closest

2nd generation standard to manyof the 3rd generation standards

ANSI-41 core network

Chip rate of 1.2288Mcps

cdmaOne phones from

1999/2000



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cdmaOne Planning

Macrocells and microcells

Single Frequency multiple frequencies for hotspots

Soft Handover (multipleconnections between mobile andnetwork)

Code Planning

Capacity Interference Limited1 Connection

2 Connections

3 Connections

Unlike GSM there is nofrequency planningrequired for cdmaOneHowever soft handovermeans that there arezones where there aretwo/three connections tothe network

World ide Mobile Comm nications in the1st and 2nd Generation Cellular Systems Overview


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Worldwide Mobile Communications in the1990s

0100

200300400500

600700

1991

1993

1995

1997

1999

2001

Second Generation -D-AMPS

Second Generation -PDC

Second Generation -GSM

Second Generation -cdmaOne

First Generation -Analogue

MillionSubscribers

Year Source:Wideband CDMA for 3rdGeneration Mobile Communications, Artech

House, 1998



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Worldwide Mobile Subscribers

0

500

1000

1500

2000

1995 2000 2005 2010

European UnionCountries

North America

Asia Pacific

Rest of World

MillionSubscribers

Year Source:Third Generation MobileCommunications, Artech House, 2000

2 G1st and 2nd Generation Cellular Systems Overview


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2.5G

Now...

Digital modulation Voice and intermediate ratecircuit/packet switched data

Same technology roaming

Secure air interface

Based upon existing dominantstandards such as GSM orcdmaOne

2.5G technologies arebased upon existing 2Gtechnologies but arefocussed at increasingthe maximum data ratesthat the technologies candeliver

HSCSD1st and 2nd Generation Cellular Systems Overview


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HSCSD

High Speed Circuit Switched Data

Enhancement to the GSM standard Utilises: Multiple channel coding schemes

(4.8kbps, 9.6kbps, 14.4kbps pertimeslot)

Multiple timeslots

Circuit Switched Data rates to57.6kbps (4 slots with 14.4kbpschannel coding per slot)

Nokia Cardphone

GPRS1st and 2nd Generation Cellular Systems Overview


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GPRS

General Packet Radio Service

Enhancement to the GSM standard Utlilises Multiple Channel Coding Schemes

(9.05kbps, 13.4kbps, 15.6kbps,21.4kbps)

Multiple Timeslots

Packet Switching

Packet Switched Data typically torates of 115kbps

Theoretically 171.2kbps for 8timeslots

Ericsson R520(available 1Q 2001)

Sagem MC850 Alcatel One Touch 700(available October 2000

IS 95B1st and 2nd Generation Cellular Systems Overview


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IS-95B

Enhancement to cdmaOnestandard

Utilises High rate coding scheme

Combined code channels

packet switching

Packet Switched Data to rates of114kbps Qualcomm PDQ

Smartphone

2G d 2 5G St d d C d1st and 2nd Generation Cellular Systems Overview


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2G and 2.5G Standards Compared

GSM TDMA cdmaOne PDC

Multiple

Access

TDMA TDMA CDMA TDMA

Modulation GMSK /4-DQPSK QPSK /4-DQPSK

CarrierSpacing

200kHz 30kHz 1.25MHz 25kHz

Frame Length 4.615ms 40ms 20ms 20ms

Slots perFrame

8 6 1 3/6

Frequency

Band

450/ 900/ 1800/

1900

800/ 1900 800/ 1900 850/ 1500

Max DataRate

HSCSD:115kbps

GPRS: 115

172kbps

IS-136+:43.2kbps

IS-95A:14.4kbpsIS-95B:

115.2kbps

28.8kbps

FrequencyHopping

Yes No N/A No

Handover Hard Hard Soft Hard

Questions1st and 2nd Generation Cellular Systems Overview


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Questions

What defines a 1st generation technology and a 2nd generationtechnology?

What is are the main differences between GSM and cdmaOne?

How do 2.5G standards relate to 2G standards?

Session Summary1st and 2nd Generation Cellular Systems Overview


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Session Summary

Weve now set the scene - we can start talking about wherepeople want to go from here now

The generations of cellular technology may be summarised: 1G is analog voice

2G is digital voice

2.5G is digital intermediate rate data

You also know its the coffee break nowand to come back at10:45!

Locator Slide3rd Generation Drivers and Standards


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Locator Slide



3rd Generat ion Drivers andStandards


UTRA Architecture Overview

UMTS Air Interface

Day 1 Roundup


UTRAN

UMTS Core Network


UMTS Mobiles

UMTS Services

Course Roundup

3rd Generation Drivers and Standards


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Introduction and Session Aims


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Introduction and Session Aims

This session is focussed at lookingat how and why the 3rd Generationstandards have evolved

Firstly we will look at the goals andthe focus of the ITU in IMT-2000

We will then examine what driversfrom the regions and the variousindustry bodies who have an

interest in 3rd Generation Finally we will round up by looking

at the IMT-2000 cellular standards

IMT-2000IMT-2000 spectrum

Drivers from Europe,America and AsiaRegulatory bodies

Standardisation bodiesIndustry associations

3rd Generation CellularStandards

IMT-20003rd Generation Drivers and Standards


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IMT-2000

IMT-2000 (International Mobile Telecommunications 2000) is aprogram focussed at providing a single global standard formobile communications

Development started in 1985 as FPLMTS Future Public Land Mobile Telecommunications System

Proposed by the ITU (International Telecommunications Union)

Who does IMT-2000 serve?3rd Generation Drivers and Standards


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Who does IMT-2000 serve?

Integrating all the following users

fixedcellular

cordless

professional mobile radio

paging

satellite

specialised (aeroplane, etc)IMT-2000 terminaand services

Aspects of IMT-2000 Networks3rd Generation Drivers and Standards


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Aspects of IMT-2000 Networks

Different aspects oIMT-2000 acces

networks

What are the IMT-2000 goals?3rd Generation Drivers and Standards


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What are the IMT 2000 goals?

Data Rates

Local area - 2 Mbps In office, stationary

Limited mobility - 384 kbps

Urban pedestrian

Full mobility - 144 kbps

Rural in car

High spectrum efficiency compared to existing systems

High flexibility to introduce new services

IMT-2000 Spectrum3rd Generation Drivers and Standards


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IMT 2000 Spectrum

1800 20501900 1950 20001850 2100 2150 2200

ITU

(WARC-92)

Europe

Japan

Korea

USA

1885 1980 2010 2025 2110 2170 2200

1920 1980 2010 2025 2110 2170 2200

1920 1980 2110 2170

2110 21701920 1980

1850 1910 1930 1990 2110 2200

MSS MSS

IMT-2000

Land Mobile

IMT-2000

Land Mobile UL

IMT-2000Land Mobile UL

IMT-2000

Land Mobile

IMT-2000

Land Mobile DL

IMT-2000Land Mobile DL

UMTS

Paired UL

UMTS

Paired DL

UMTS

SAT

UMTS

SAT

UMTS

Unpaired

UMTS

Unpaired

IMT-2000

Land Mobile

PCS

UL

PCS

DLReserved

1900

DECTGSM 1800

1880

IMT-2000 Future Spectrum3rd Generation Drivers and Standards


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IMT 2000 Future Spectrum

ITU

(WRC-2000)

Europe

Japan

Korea

USA

2200 3000600 1000 1400 1800 2400

806 960 1710

1880

2500 2690

890 960 1710

GSM 1800GSM 900

New IMT-2000 New IMT-2000 New IMT-2000

Cellular PCS

IMT-2000 Candidate Technology Evaluation3rd Generation Drivers and Standards


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IMT-2000 Candidate Technology Evaluation

The ITU issued a request for proposals for the RadioTransmission Technology (RTT) for IMT-2000 to be submitted

in June 1998 Following this a self evaluation of the RTT submitted was

required by September 1998

Candidate technologies were then evaluated according to their

compliance with the goals for IMT-2000

IMT-2000 Candidate Harmonisation3rd Generation Drivers and Standards


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000 Ca d date a o sat o

A number of technologies were submitted many of which haddistinct similarities

Of course operators were generally keen on a single standardto allow global roaming and economies of scale

Operators Harmonisation Group (OHG)

This led to two partnership projects being set up: 3rd Generation Partnership Project (3GPP)

Dealing with UMTS FDD/TDD and related candidate technologies a

3rd Generation Partnership Project 2 (3GPP2)

Dealing with cdma2000 and related candidate technologies

3G Standardization Environment3rd Generation Drivers and Standards


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Key Players andtheir relationshipsin the IMT-2000standardisation

environment

IMT-2000 Selected Air Interface Standards



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Five candidate technologies wereeventually selected:

IMT-DS (Direct Spread)UMTS FDD

IMT-MC (Multi Carrier)

cdma2000

IMT-TC (Time Code)

UMTS TDD IMT-SC (Single Carrier)

EDGE/UWC-136

IMT-FT (Frequency Time)

DECT

IMT 2000 Selected Air Interface Standards

IMT-2000 Selected Core Network Standards



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Three candidate technologies willbe used:

GSM MAP Evolved

ANSI-41 Evolved

IP Based

Driven forward by 3GIP

IMT 2000 Selected Core Network Standards

IMT-2000 Standards3rd Generation Drivers and Standards


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The IMT-200family of standards

North America Drivers3rd Generation Drivers and Standards


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North America and US influenced countries Dominated by 2G TDMA/cdmaOne

USA has slower growth because recipient party pays Mess of digital systems at 800 and 1900 MHz

US manufacturers have pushed forward growing cdmaOne standard

PCS spectrum overlaps IMT-2000 band

Major Drivers

Spectrum sharing and compatibility with 2G standard

National/International roaming

cdma2000 (cdmaOne operators)

EDGE (TDMA operators)

European Drivers3rd Generation Drivers and Standards


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Europe and European Influenced Countries GSM provided 2nd generation roaming across Europe

Plenty of Capacity at 1800MHz

IMT2000 band compatible with current spectrum usage leads to nospectrum sharing issues

EU enforced standardisation means UMTS for at least 1 operator percountry

Major Drivers

Higher Data Rates

Continued global dominance of European based standard

UMTS

Japan/Korean Drivers3rd Generation Drivers and Standards


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Japan and Korea PHS and PDC left Japanese manufacturers isolated

IMT2000 band compatible with current spectrum usage leads to nospectrum sharing issues

Political US relationships...

Major Drivers

Capacity for Voice Global market for cellular infrastructure

UMTS

Cordless Drivers3rd Generation Drivers and Standards


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You cant get 2Mbps out of the cellular standards

Hence a requirement for cordless style standards UMTS TDD Mode

DECT

Industry Bodies - Radio Regulatory3rd Generation Drivers and Standards


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ITU (International) http://www.itu.int/

ERO (EU) European Radio Office

http://www.ero.dk/

RA (UK) Radiocommunications Agency

http://www.radio.gov.uk/

FCC (USA) Federal Communications

Commission

http://www.fcc.gov/

Industry Bodies - Trade Associations3rd Generation Drivers and Standards


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UMTS Forum http://www.umts-forum.org/

GSM Association http://www.gsmworld.com/index1.html

CDMA Development Group http://www.cdg.org/

GSM Suppliers Association http://www.gsacom.com/home.html

Universal Wireless Communications Consortium http://www.uwcc.org/

Industry Bodies - Standards Groups3rd Generation Drivers and Standards


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3GPP UMTS FDD and TDD

Standards Development

http://www.3gpp.org/

3GPP2 cdma2000

Standards Development

http://www.3gpp2.org/

3GIP IP Core Network

http://www.3gip.org/

Partnership Projects and StandardsOrganisations



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Organisations

Relationshipsbetween thestandardsorganisations

3GPP Member Organisations3rd Generation Drivers and Standards


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ETSI (EU) http://www.etsi.org/

ARIB (Japan) http://www.arib.or.jp/arib/english/

T1 (USA) http://www.t1.org/

TTC (Japan) http://www.ttc.or.jp/e/

TTA (Korea) http://www.tta.or.kr/

CWTS (China) http://www.cwts.org/cwts/index_eng.html

3GPP2 Member Organisations3rd Generation Drivers and Standards


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TIA (USA) http://www.tiaonline.org/

TTA (Korea) http://www.tta.or.kr/

TTC (Japan) http://www.ttc.or.jp/e/

ARIB (Japan)

http://www.arib.or.jp/arib/english/

CWTS (China) http://www.cwts.org/cwts/index_eng.html

The Road to 3G3rd Generation Drivers and Standards


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Possible EvolutioPaths to 3G

HSCSD

3rd Generation Cellular3rd Generation Drivers and Standards


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2002+

Digital modulation

Voice and high rate data

Multi technology roaming

Secure air interface

Standards

UMTS FDD (CDMA based) UMTS TDD (CDMA based)

cdma2000 (CDMA based)

EDGE (TDMA based)

UMTS FDD

U i l M bil T l i i S F



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Universal Mobile Telecommunications System FrequencyDivision Duplexing Mode

Built onto enhanced GSM core network Utilises:

QPSK modulation

Multiple channel coding and bearer rates

Variable spreading factors and multi-code transmission CDMA

FDD

Asynchronous operation

Data up to rates of 2Mbps (typically less)

UMTS Compared to GSMUMTS GSM



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UMTS GSMCarrier Spacing 5MHz 200kHz

Frequency Reuse

Factor

1 1-18

Power Control

Frequency

1500Hz 2Hz or lower

Quality Control Radio ResourceManagement

algorithms

Frequency Planning

and Network

Optimisation

Frequency Diversity 5MHz bandwidth gives

multipath diversity withrake reciever

Frequency Hopping

Packet Data Load Based PacketScheduling

Time Slot based

Scheduling with GPRS

Transmit Diversity Supported to improvedownlink capacity

Not supported by

standard but may be

applied

UMTS Compared to IS95UMTS IS-95



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UMTS IS-95Carrier Spacing 5MHz 1.25MHz

Chip Rate 3.84Mcps 1.2288Mcps

Power ControlFrequency

1500Hz Uplink 800Hz,Downlink slow

Base Station

Synchronisation

No Yes via GPS

Frequency Inter

Frequency

Handovers

Yes, slotted mode

measurements

Possible but

measurements not

specified

Packet Data Load Based PacketScheduling

Packets as short CS

calls

Radio Resource

Management

Efficient algorithms to

provide QoS

Not required for

speech only

Transmit Diversity Supported to improvedownlink capacity

Not supported by

standard

UMTS TDD3rd Generation Drivers and Standards


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Universal Mobile Telecommunications System FrequencyDivision Duplexing Mode

Built onto enhanced GSM core network

Utilises: QPSK modulation


CDMA

TDD

Asynchronous operation


cdma20003rd Generation Drivers and Standards


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Built onto ANSI-41 core network

Utilises: QPSK modulation


CDMA

FDD

Multiple carriers on the downlink to allow compatibility with cdmaOne

Synchronous operation


EDGE3rd Generation Drivers and Standards


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Enhanced Data for GSM Evolution Sometimes called E-GPRS (Enhanced GPRS)

Enhancement to the GSM and TDMA standards

Utlilises: 8PSK Modulation

Possible 1.6MHz carrier under IS-136

8 Channel Coding Schemes

Multiple Timeslots

TDMA

Data up to rates of 384kbps (typically less)

3rd Generation Standards ComparedUMTS FDD UMTS TDD cdma2000 EDGE



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MultipleAccess

CDMA CDMA CDMA TDMA

Modulation QPSK QPSK QPSK 8-PSKCarrierSpacing

5MHz (200kHzraster)

5MHz (200kHzraster)

3.75MHzUL/1.25MHz DL

200kHz/1.6MHz

Frame Length 10ms 10ms 20ms 4.615ms

Slots perFrame

15 15 16 8/16/64

MultipleRates

Multi-code,Variable

Spreading Factor

Multi-code, multi-slot

SupplementalChannels, Multiplespreading Factors

Multiple channelcode, multi-slot

Chip Rate 3.84Mcps 3.84Mcps 3.6868Mcps

Max DataRate

2Mbps 2Mbps 2Mbps 521/4750kbps

Synchronous No No Yes Yes

Handover Soft Hard Soft Hard

4th Generation...3rd Generation Drivers and Standards


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Probably 2005-2007

Broadband data rates in excess of

1Mbps Probably 10MHz+ carriers

...

Questions3rd Generation Drivers and Standards


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What is IMT-2000 and why is it related to UMTS?

Why do the American operators want cdma2000 and EDGE?

What is the major difference between UMTS and cdma2000?

Session Summary3rd Generation Drivers and Standards


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In this session we have discussed: The key goals of IMT-2000

The drivers for 3rd generation from the regions

The key industry bodies and their relationships

The four cellular air interfaces for IMT-2000 are:

UMTS FDD

UMTS TDD cdma2000

EDGE

Locator SlideCDMA Mobile Technology Overview


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1st and 2nd Generation Cellular

Systems Overview 3rd Generation Drivers and

Standards

CDMA Mobi le TechnologyOverview

UMTS Architecture Overview UMTS Air Interface

Day 1 Roundup


UTRAN

UMTS Core Network UMTS Fixed Network Interfaces

UMTS Mobiles

UMTS Services

Course Roundup

CDMA Mobile Technology Overview


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Contents and Session AimsCDMA Mobile Technology Overview

Thi i i t


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This session aims to cover somebasic CDMA terminology andtechnology before dealing withUMTS in more detail

Key generic areas of CDMAinclude

How CDMA works and relates toother multiple access schemes

How the codes are generated andwhat their properties are

Soft Handover - what and how?

The pilot channel

Multiple AccessStrategies Explained

CDMA for Cellular

Codes in CDMA

Soft Handover

The Pilot Channel

Multiple Access Explained

I i i kt il t



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Imagine you are in a cocktail party

Now imagine you are trying to talk to somebody (rather than fighting your way to the punch bowl again...)

If you are trying to listen to somebody you need to be able topick out their speech from everybody elses speech.

Everybody is using the same medium to talk - the air in theroom

Clich Explanation

Thi i M lti l A



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This is Multiple Access Many conversations/channels share the same medium

There are a number of different Multiple Access (MA) strategiesyou can try:

Time Division Multiple Access(TDMA)

Frequency Division Multiple Access(FDMA)

Code Division Multiple Access(CDMA)

TDMA at the Cocktail Party

We divide time into a number of timeslots



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We divide time into a number of timeslots

Everybody takes turns to speak within a timeslot

Once everybody has spoken we go back to the start of the list and beginagain - this is a frame

This ensures that two conversations/channels dont get confused.

Conversation/Channel separation is provided in time.

Bit of problem if people speak late or early We may need guard periodsbetween timeslots when nobody speaks

People need to know when to speak We need signaling to tell people their timeslot

TDMACDMA Mobile Technology Overview


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frequency

time

User 1 User 1

Timeslot Period Frame Period

Idealised TDMA(with no guardperiods)

AvailableFrequencyBand

FDMA at the cocktail party

We divide the available frequency band into a number of frequency



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We divide the available frequency band into a number of frequencychannels of the same channel bandwidth

People speak continuouslyat different frequencies/pitches, and useearpieces to filter out frequencies theyre not interested in.

Again this ensures that two conversations dont get confused.

Conversation/Channel separation provided in frequency.

Bit of a problem as the filters arent perfect We may need guard bandsbetween timeslots when nobody speaks

People need to know the frequency of the conversation We need signaling to tell people their frequency channel

FDMACDMA Mobile Technology Overview


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fre

quency

time

User 1

Frame Period (we may still needframes/timeslots for signaling)

ChannelBandwidth

Idealised FDMA(with no guardbands)

FDMA/TDMA

Of course we could also be clever and use a combination of



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Of course we could also be clever and use a combination ofTDMA and FDMAlike in GSM

This is commonly referred to as simply TDMA

FDMA/TDMACDMA Mobile Technology Overview

Ti l t P i d F P i d


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fre

quency

time

ChannelBandwidth


User 1 User 1 IdealisedFDMA/TDMA (withno guard bands orguard periods)

FH at the Cocktail Party

If we combine TDMA and FDMA and change the frequency of transmission



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If we combine TDMA and FDMA and change the frequency of transmissionevery frame we have Frequency Hopping

Frequency hopping improves the received quality of theconversation/channel

We can tolerate the occasional collision of words:

The next word is almost certain to get through

We can always repeat the odd word

This generally wont have too great an impact on the meaning of the conversation.

This is sometimes called frequency hopping spread spectrum This is because the total bandwidth used for an individual conversation is greater

than that strictly required for the individual conversation

i.e. the spectrum has been spread

Frequency Hopping Spread SpectrumCDMA Mobile Technology Overview



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frequency

timeUser 1 User 1

ChannelBandwidth


Idealised FH (withno guard bands orguard periods)

Frequency Hopping Power SpectrumCDMA Mobile Technology Overview

Power


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Time AveragedPower Spectrum

Frequency

Frequency

Frequency

Frequency

PowerPower

Power

Instantaneous PowerSpectra for a channel in

different frames

CDMA at the Cocktail Party We can actually be more sophisticated than this.

f f



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If we know the characteristics of the persons voice we can tune in to whatthey are saying and ignore what other people are saying

This is like CDMA where the conversation/channel separation is provided bythe characteristics of the channel

i.e. the code

The only problem is that we do pick up some of the noise from the otherchannels

This limits the number of conversations/channels that can use the same medium

We also need to know the code in use We need signaling to tell people their code

This is sometimes called Direct Sequence Spread Spectrum

CDMA - Direct Sequence Spread Spectrum



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frequency

time

code

Frame Period (we may still needframes/timeslots for signaling)

CDMA Power SpectrumCDMA Mobile Technology Overview


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Power Spectrum for theequivalent unspreadchannel

FrequencyFrequency

PowerPower

Power Spectrum postspreading

Note: The power spectrumhas been spread similar tothat in a FrequencyHopping system

More CDMA permutations

Of course we can start getting a bit clever again...



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g g g

CDMA/FDMACDMA Mobile Technology Overview


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fre

quency

time

code

IdealisedCDMA/FDMA (withno guard bands)

CDMA/FDMA can be used toprovide multiple carriers OR toprovide Frequency DivisionDuplexing - separate carriers forthe uplink and downlink

CDMA/TDMA/FDMA...CDMA Mobile Technology Overview


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fre

quency

time

code

IdealisedCDMA/TDMA/FDMA(with no guard bands orguard periods)

Combining CDMA and TDMA can be usedto provide Time Division Duplexing

CDMA SpreadingCDMA Mobile Technology Overview

Essentially Spreading involves changing the symbol rate on the air interface

Spreading Despreading


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Channel

Tx Bit Stream Rx Bit Stream

Air InterfaceChip Stream

Code Chip Stream Code Chip Stream

Identicalcodes

Spreading Despreading

P P

P

f

f

P

f

f

P

f

Spreading and Despreading

1



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Tx Bit Stream

Rx Bit Stream

Code Chip Stream

Code Chip Stream

Air InterfaceChip Stream

1

-1

X

X

Spreading

Despreading

Spreading

If the Bit Rate is Rb, the Chip Rate is Rc, the energy per bit Ebd th hi E th



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and the energy per chip Ecthen

We say the Processing GainGpis equal to:

Commonly the processing gain is refereed to as the SpreadingFactor

b

ccbR

REE .

b

cp

R

RG

Tx Signal Rx Signal (= Tx Signal + Noise)


Spreading in noise

P

f fP


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Channel

Spreading Code Spreading Code

Wideband Noise/Interference

Signal Signal

The gain due to despreading of the signal over wideband noiseis the Processing Gain

P

f

f f

P

f

P

f

Types of Codes

There are essentially two types ofcodes used in CDMA networks:


S2


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Channelisation Codes

Are used to separate channelsfrom a single cell or terminal

Scrambling Codes

Are used to separate cells andterminals from each other ratherthan purely channels

Channelisation/scrambling codesmay be either: short (the length of the code is

equal to the bit period)

long (longer than the bit period)

S1

S3

C1 C2 C3

C1 C2 C3

C1 C2 C3

Channelisation Codes

Channelisation codes are orthogonal and hence providechannel separation



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channel separation

Number of codes available is dependant on length of code Channelisation codes require an equal number of 1s and -1s

to be orthogonal

This is because we use integration to demodulate the signal

Typically channelisation codes are used to spread the signal

Channelisation Code Generation

Channelisation codes can be generated from a Hadamardmatrix



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matrix

A Hadamard matrix is:

Where x is a Hadamard matrix of the previous level

For example 4 chip codes are:

1,1,1,1 1,-1,1,-1

1,1,-1,-1

1,-1,-1,1

xxxx

Note: These two codescorrelate if they are time

shifted

Scrambling Code Generation

Scrambling codes are not orthogonal since they are notsynchronised to each other at the receiver



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synchronised to each other at the receiver

Hence it is sufficient to use Pseudo Random sequences Maximal length sequences used which repeat after 2R-1bits

R relates to the number of taps in the generator

Scrambles signals but can also be used to de-scramble

Sequences with different offsets do not correlate Generate a single code

Plan the offsets on the downlink

Scrambling Code Generation



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1 2 3 R-1 R

1 2 3 4 5 OUTPUT1 0 1 0 1 -

1 1 0 1 0 1

0 1 1 0 1 0

0 0 1 1 0 1

1 0 0 1 1 0

0 1 0 0 1 1

0 0 1 0 0 1

0 0 0 1 0 0

Start valuefor offset

Output sequence: 1,0,1,0,1,1,0,0,1,0,0,0,...

Orthogonality of Codes

If orthogonal mean interference power over a bit is zero



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Sum = 0

=> Orthogonal

Sum = 1

=> Correlated

Sum = -0.75

=> Non-orthogonal

Bit Period Chip Period

X

1

-1

0.25

-0.25

0.25

-0.25

Code

Signal Chip Stream

Bit Value

Multi Channel Spreading and Despreading


P

f fP


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Channelc1 c1

c2 c2

P

f

P

f

P

f

P

f

P

f

fP

Since the channels are orthogonal the resulting interference isentirely removed by the despreading process

CDMA in Cellular Cellular systems have multipath channels with a delay spread

Channels from the same transmitter are no longer perfectly orthogonal

Ch li ti d l f tl h i d



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Channelisation codes are no longer perfectly synchronised

Downlink Channels on the same cell interfere with each other Worst case scenario can be treated as white noise

Otherwise use orthogonality factor (0.6 in urban macrocells typically)

The orthogonality factor gives the percentage of interference that is rejected

CDMA in Cellular


P P


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c2 c2

Channelc1 c1

P

f fP

P

f

f

P

P

f

P

f

P

f

P

f

Multipath reduces the orthogonality of the downlink codesresulting in interference between channels from the sametransmitter

Visualising the Processing GainW/Hz W/Hz W/Hz

Ec

IoBefore

SpreadingAfter

Spreading With Noise



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W/Hz W/Hz dBW/HzEb

Io

Io

Eb

Io

Eb/Io

Eb

No

Eb/NoEb

No

W/Hz dBW/Hz

Signal

Intra-cell Noise

Inter-cell Noise

Spreading Spreading With Noise

After

Despreading/

Correlation

Post

Filtering

Orthog = 0

Post

Filtering

Orthog > 0

f f f

f ff

f f

A Channelised Transmitter

Channel 1 Pulse Shaping and



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Bit Stream

Channel 2Bit Stream

Channel 3Bit Stream

gModulation

c1

c2

c3

s1Typically in a multi-channel transmitter,channels are first spread and channelisedusing the channelisation codes, thencombined and finally scrambled together.

Rake Receiver

Correlator Phase Rotator Delay EqualizerI


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Code Generators

(S & C)

ChannelEstimator

Matched Filter

Q Q

A typical rake receiver with threefingers

CDMA Noise Calculation We can say (approximately - assuming perfect power control)

that the Eb/Nois equal to:



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Where: Eb/No= Energy per bit/Noise Power Spectral Density

M = Number of Users or Codes Used

h= Loading

Gp= Processing Gain

l= Sectorisation Gain

v = Voice activity factor

O = Orthogonality Factor

OvG

MNE pb

111

11

11

0

lh

CDMA Capacity Calculations

The Eb/Norequired to achieve a desired BER can becalculated/simulated for a given receiver



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We can say that the number of users we can support isapproximately equal to:

OvG

N

EM p

required

b1

11

1

11

0

lh

CDMA Capacity Calculations

However imperfect power control will create a 30-40%reduction in the capacity on the uplink (downlink channels will



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always be ideally weighted)

Soft handover also impacts the capacity on the downlink -approximately 20-40% of channels will be required forhandover

Control and pilot channels require transmitted power - again

impacting the downlink

Pilot Channels

Pilot channels are effectively channels used in the cell selectionprocess



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Pilots contain no baseband information - no bits The pilot is spread by the all 1s channelisation code

Effectively the pilot is the scrambling code

The required pilot channel SNR is referred to in Ec/Io

Pilots allow channel estimation In cdmaOne the pilot also gives the mobile phase and timing

information

Soft Handover Soft Handover is where more then one cell is in communication

with a terminal

The cells in communication with the terminal are known as an



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The cells in communication with the terminal are known as an

active set The best serving cell is known as the primary cell- and

maintains the primary channel

Other channels are known as handover channels

The gain associated with soft handover is known as themacrodiversity gain

This occurs due to the uncorrelated nature of fast fading between cellsand the variation in slow fading between cells

Note that slow fading is not entirely uncorrelated for different cells

Hard Handover (e.g.GSM)

RX L

Direction of Travel



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HandoverHysteresis

Margin

RX_Lev

Cell A Cell BA hard handoverbetween cells A and Bin GSM

In a hard handoverthe mobile is onlyever instantaneouslyconnected to a singlecell

Distance

Soft Handover (e.g. in cdmaOne)

Active set = 1 = 2 = 1Pilot Ec/Io



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Pilot Ec/Io

T_ADDT_DROP

Cell A Cell A and Cell B Cell B

Direction of Travel

Add Time Delay Drop Time Delay

A soft handoverbetween cells A and Bin cdmaOne

In a soft handover themobile is may beinstantaneouslyconnected to morethan one cell

Distance

Why Soft Handover is Good in CDMA

Why Soft Handover is Good inCDMA

Near Far Effect


Why Soft Handover is Bad inCDMA

Transmission overhead in backhaul


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Near- Far Effect

Hard Handover can lead torelatively deep penetration intoneighbour cells

Soft Handover allows PowerControl from all Active Set cells

Probability of dropped call reduced

due to link redundancy in handoverregion

Macrodiversity gain

Transmission overhead in backhaul

Addition of downlink noise into thesystem

Engineering of handover zonesbecomes highly critical

More CDMA at the Cocktail Party - CellBreathing

The more noise the louder you have to speak to hear the same amount ofthe conversation

You get to a point where you cant shout louder and cant have a



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You get to a point where you can t shout louder and can t have aconversation where you are standing

The further away you are the louder you have to speak

If it is noisy only people standing close together can have a conversation

As it gets noisy the area that can be covered by a conversation decreases

If it is quiet then the area covered by a conversation can be larger This is called Cell Breathingand occurs in mobile CDMA networks

Cell Breathing An increase in traffic results in an increase in interference

Mobiles at the extremities of cells may be pushed out of thecells effective coverage area due to decreased E /N



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cells effective coverage area due to decreased Eb/No

This effect may occur over the course of 24 hours due tochanges in traffic demand over peak hours

6am Noon 9pm

More CDMA at the Cocktail Party - PowerControl

If somebody is shouting louder than they need it increases theoverall noise



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This is inefficient as it reduces the number of people who canhave conversations

We need to speak as quietly as possible to maximise thenumber of simultaneous

This is called Power Controlin mobile networks

In CDMA networks it is very important that this power control isefficient

We use fast power control with a much quicker feedback loop than inTDMA networks

Power Control

The Near-Far Effect

If equal transmit powersR i d Si l St th f Path Loss = 150dB

MSb



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Received Signal Strength fromMSa higher than required

MSb Eb/Nosignificantly reduced

Near mobiles dominate on theuplink

Cell area and capacity reduced

Solution Fast power control

Large Dynamic Range for mobiles

Path Loss = 150dB

Path Loss = 100dB

MSa

Questions

What is a pilot channel?

How does soft handover differ from hard handover?



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How do scrambling codes differ from channelisation codes? Why is multipath fading bad from a CDMA point of view?

Session Summary

In this session we have discussed: CDMA and how it relates to and differs from other multiple access

technologies



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technologies

What channelisation and scrambling codes are and what they do

What we mean by a pilot channel

How soft handover works

What we mean by cell breathing and the near far effect

Locator Slide




UTRAN

UMTS Core Network



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Systems Overview



UMTS A rch itecture Overview

UMTS Air Interface

Day 1 Roundup

UMTS Core Network


UMTS Mobiles

UMTS Services

Course Roundup



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This session aims to give the usera first pass overview of thearchitecture behind UMTS

UMTS High LevelArchitecture


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To explain the major architecturalblocks

To give a first introduction to themajor network elements andinterfaces

To talk about how UMTS will

interface with existing technologies

The Core NetworkUTRANThe User Equipment

Interfaces

Access ModesUMTS and GSM

Public Land Mobile Network (PLMN) A Public Land Mobile Network is

defined in the specifications asconsisting of:

One or more switches with a



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common numbering plan androuting plan

Switches act as the interfaces toexternal networks

A PLMN can be regarded as anindependent telecommunications

entity The PLMN can be separated into

Core Network

Access Network

Core Network

Access Network

PLMN


UMTS High Level Architecture

To this definition, the 3GPP standards add an additionalarchitectural block, the User Equipment


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User EquipmentUMTS

Terrestrial Radio

Access Network

Core Network

UU IUUE UTRAN CN

Major Network Elements in UMTS

USIM

Node B

Node BRNC MSC/VLR GMSC

PLMN,PSTN,

UMTS SIM

Radio NetworkController

GatewayMSC

MobileSwitching

Centre

Iu-cs



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UU IU

UE UTRAN CN

CUIUb

IUr

US

ME

ode

Node B

Node BRNC SGSN GGSN

HLR

ISDN

Internet,

X25PacketNetwork

MobileEquipment


Serving GSNGateway

GSN

Home LocationRegister

Iu-ps

IUb

Functions of the CN

Switching

Service Provision



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Transmission of user traffic between UTRAN(s) and/or fixednetwork

Mobility Management

Operations, Administration and Maintenance

Major Elements of the Core Network

Home Location Register (HLR) The database storing the master copy of a users profile



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Visitor Location Registor (VLR) The database holding a copy of a visiting users profile

Mobile Switching Centre (MSC) Switch for Circuit Switched Services

Gateway MSC Serving GPRS Support Node

Router for Packet Switched Services

Gateway GSN

General Core Network Architecture

MSC/VLR GMSC

GatewayMSC

MobileSwitching

Centre

Other MSC

UTRAN

External Circuit

SwitchedIu-cs


FF


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IU

CN

MSC/VLR

SGSN GGSN

GMSC

HLR

Serving GSNGateway

GSN

Home LocationRegister

Other SGSN

UTRAN

Networks

External Packet

Switched

Networks

Iu-ps

Gs

GnGn

Gr Gc

DD

Gi

Functions of UTRAN

Provision of Radio Coverage

System access control



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Security and privacy Handover

Radio resource management and control

Elements of UTRAN

Radio Network Controller Owns and controls radio resources in its domain



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Service Access point for all services that UTRAN provides the CN Node B

Acts as the radio basestation

Converts the data flow bewteen the Iuband Uuinterfaces

General UTRAN Architecture

Node B

Node BRNC


Iu-cs


CN (MSC)


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UU IU

UTRAN

IUb

IUr

Node B

Node BRNC


Iu-ps

IUb

CN (SGSN)

UE

Functions of the UE

Display and user interface

To hold the authentication algorithms and keys



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User end termination of the air interface Application platform

Elements of the UE

Mobile Equipment The radio terminal used for radio communication over the Uuinterface



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UMTS Subscriber Identity Module The smartcard that holds the subscriber identity, authentication and

encryption keys etc

Additionally one can define a Terminal Equipment item that sitswith the UE

This carries the application specific user interface

The interface for the TE may be provided by Bluetooth for example

General UE Architecture

USIM

UMTS SIM



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UU

UE

CU

ME

MobileEquipment

UTRANTerminal

Equipment

Major Interfaces in UMTS

There are four major newinterfaces defined in UMTS

Iu


CN

I


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The interface between UTRANand the CN

Iur

The Interface between differentRNCs

Iub

The interface between the Node Band the RNC

Uu

The air interface

RNC

Node-

B

RNC

UE

Uu

u

Iub

Iur

Iu - the Core Network to UTRAN Interface There are two parts to the Iu

interface

Iu-psconnecting UTRAN to the PS

D i f th CN


CN

I


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Domain of the CN Iu-csconnecting UTRAN to the CS

Domain of the CN

No radio resource signalling travelsover this interface

The Iuinterface divides the UMTS

network into the radio specificUTRAN and the CN responsible forswitching routing and serviceprovision

RNC

Node-

B

RNC

UE

Uu

u

Iub

Iur

Iur- the Inter-RNC Interface The Iurinterface allows soft

handovers between Node-Bsattached to different RNCs

It i i t f t ll th


CN

I


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It is an open interface to allow theuse of RNCs from differentmanufacturers

Its functions may be summarised: Support of basic inter-RNC mobility

Support of Dedicated and CommonChannel Traffic

Support of Global ResourceManagement

RNC

Node-

B

RNC

UE

Uu

u

Iub

Iur

Iub- the RNC to Node-B Interface The Iubis an open interface to allow

the support of differentmanufacturers supplying RNCsand Node-Bs


CN

I


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Its major functions are: Carries dedicated and common

channel traffic between the RNCand the Node-B

Supports the control of the Node-B

by the RNC

RNC

Node-

B

RNC

UE

Uu

u

Iub

Iur

Uu- the Air Interface Clearly the Uumust be

standardised to allow multiple UEvendors to be supported by anetwork


CN

Iu

I


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The major functions of the Uuareto:

Carry dedicated and commonchannel traffic across the airinterface

Provide signaling and control trafficto the mobile from the RNC and theNode-B

RNC

Node-

B

RNC

UE

Uu

Iub

Iur

UMTS Interface Implementation

NodeB

SGSN



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ATM/IP Network

RNCNodeB

NodeB

MSC

RNC

NodeB

IubIu_csIu_psIur

Access Modes for UMTS

In this course we will concentrate on the UMTS FDD airinterface

However we should bear in mind that a number of other accessmodes are possible



143/396


modes are possible

Within UTRAN

Outside of UTRAN

Access Modes within UTRAN

There are four access modes that will be contained withinrelease 2000 of the 3GPP standards

Direct Sequence FDD Mode 1

Based on UMTS FDD air interface



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Based on UMTS FDD air interface

Multi Carrier FDD Mode 2

Based on cdma2000

TDD Mode

Based on UMTS TDD air interface

ODMA

Supplement to UMTS TDD mode based on using a second UE as a radiorelay

Additional Access Networks The UMTS CN is being

designed with the possibility ofinterfacing to additional AccessNetworks other than UTRAN

GRAN GSM/GPRS Radio

UMTS-CN



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GRAN - GSM/GPRS RadioAccess Network

ERAN - EDGE Radio AccessNetwork

BRAN - Broadband RadioAccess Network (HIPERLAN2)

DECT - Digital EnhancedCordless Telephony

DECT

BRAN GRAN

ERAN

UTRAN

UMTS and GSM

Core

NetworkSGSN MSC

Internet PSTN

GGSN GMSC



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RBS

RNC

Node-B

Iub

RBS RBS RBS

RNC

Node-B Node-B

UTRAN

SGSN MSC

Iu-csIu-psIu-cs

Iu-ps

IubIub

BSC

BTS

Iur

A-bis

A

GbBSS/

Architecture of a UMTS bearer serviceTE TEUE UTRAN

CNedge node

CNgateway

End-to-End Service

TE/UE Local External Bearer



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TE/UE LocalBearer Service UMTS Bearer Service

Radio Access Bearer Service

External BearerService

CN BearerService

Radio Bearer

Service

IuBearer ServiceBackbone Network

Service

UTRA FDD/TDDService

Physical BearerService

UMTS Protocol Stratums In order to provide separation

between radio accessfunctionality and service qualityprovision, protocols in UMTS

are divided into two stratums

NonAc

ces L6 L6

L7 L7


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are divided into two stratumsAccess Stratum

Encompasses layers 1 and 2of the OSI 7 layer model, andthe lower part of layer 3

Non-access Stratum

Encompasses layers 4 to 7of the OSI 7 layer model, andthe upper part of layer 3

ssStratum

AccessStratum

L1 L1 L1L1

L2L2L2

L2

L5L5

L4L4

L6 L6

L3 lower L3 lower L3 lower L3 lower

L3 upper L3 upper

Uu IuUE UTRAN CN

Questions What elements does UTRAN consist of?

What is the primary role of UTRAN?

What additional access modes does UMTS support over UMTSFDD?



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What additional access modes does UMTS support over UMTSFDD?

Session Summary In this session we have discussed the major elements of the

UMTS network architecture

In following sessions we will discuss each element in moredetail



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detail

Locator Slide Introductory Session


3rd Generation Drivers andSt d d


UTRAN

UMTS Core Network


UMTS Air Interface


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UMTS Air Interface Day 1 Roundup


UMTS Mobiles

UMTS Services

Course Roundup

UMTS Air Interface


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UMTS Air Interface


UMTS Air Interface

This session aims to explain theprotocols and operation of the airinterface

To give an overview of the UMTSspecific operation of the air

Overview of the AirInterface

Logical Transport and


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p pinterface

To look at the protocol structure

To investigate the Frame andTimeslot structure of the major airinterface channels

Logical, Transport andPhysical Channels on the

Air Interface

The Dedicated Channels

Role of the Air Interface To provide a number of bearer or physical channels to support

data transfer over the radio path.

To provide control channels to manage the cell

To provide a number of traffic channels at an acceptable errorf d t i t

UMTS Air Interface


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To provide a number of traffic channels at an acceptable errorperformance and at various rates

To provide signalling channels for call set up, etc.

In providing all of this to also:

Ensure an efficient use of the available spectrum Minimise interference to other cells and services

Minimise the use of power, particularly from the mobile

Provide synchronisation

UMTS FDD Air Interface Overview

Parameter ValueMultiple Access Scheme Direct Sequence CDMA

Duplexing Method FDD

Chip Rate 3.84 McpsCarrier Spacing 5 MHz

UMTS Air Interface


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Carrier Spacing 5 MHz

Carrier Spacing Raster 200 kHz

Frame Length 10 ms

Slots per Frame 15

Inter-cell Synchronisation None

Spreading factor Variable (4-512)

User Data Rate 8->384 kbps

Multiple Access Scheme UMTS FDD mode makes use of a CDMA style multiple access

scheme

In the case of UMTS this is commonly referred to as WidebandCDMA

UMTS Air Interface


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However there are elements of FDMA and TDMA in UMTS Common channels for paging and packet access share codes between

UEs (TDMA)

Multiple carriers are used per operator (FDMA)

Duplexing Method UMTS FDD mode makes use of

Frequency Division Duplexing

The Uplink and DownlinkChannels are carried on

separate carriers

UMTS Air Interface

190MHz


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In the case of UMTS in Europe: The Uplink band is between 1.92

and 1.98GHz

The Downlink band is between

2.11 and 2.17GHz The Uplink/Downlink Separation

is 190MHz

UMTS Uplink UMTS Downlink

Chip Rate The chiprate used in UMTS FDD mode is 3.84Mcps

This leads to a carrier bandwidth of approximately 5MHz

This chip rate was chosen because it: Could be generated simply from existing GSM clock rates

UMTS Air Interface


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Provided a similar bandwidth to cdma2000 to allow shared use of filters etc inUEs

Note:Initially UMTS was specified as having a chip rate of 4.096Mcps. You may find some old texts and papers referring to this chip rate

Carrier Spacing and Carrier Spacing Raster The nominal carrier spacing for

UMTS is 5Hz

This was chosen to comply with

the American market, wherespectrum has been awarded in

UMTS Air Interface

5MHz


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p5MHz blocks

It is possible to move the centrefrequency of the carrier on a200kHz raster

We can have carrier spacingsbetween 4.4MHz and 5.6MHz

This may be set within the licenseconditions, or to the operatorsdiscretion

200kHz

Adjacent Channel Interference Adjacent channel interference may have a significant impact on

UMTS capacity

Required attenuation (by standards) adjacent carrier 33dB

UMTS Air Interface


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2nd adjacent carrier 43dB

Since only have 2 or 3 carriers typically at least one adjacentcarrier will be transmitted by a third party

This can partially be negated by a flexible carrier spacing basedupon a 200kHz raster

Adjacent Operator Interference

UMTS Air Interface


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Distant ServingMacrocell

Close InterferringMicrocell

Interference

Signal50dB path loss

150dB path loss

UK Spectrum Allocations ExampleD D DE E EC C CA A A A B B B

Hutchison Vodafone Orange

UMTS Air Interface


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One2One BT Cellnet

g

14.6MHz 14.8MHz10MHz 10MHz 10MHz0.3MHz0.3MHz

20MHz

Radio Frame Structure Radio Frame Period = Tf = 10ms

Frames are used for channel format control

15 slots, #0#14 Slots are use for power control

UMTS Air Interface


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Tslot

= 666.7ms = 2560 chips

Slots are use for power control

38400 chips

Tslot= 2560 chips = 666.7ms

#0 #1 #2 #i #14

Tf = 10ms = 38400 chips

Superframe Structure 72 Radio Frames make a Superframe

Superframes are used for

Superframe Period Tsf= 720ms

UMTS Air Interface


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#0 #1 #2 #i #71

Tsf = 720ms

Inter Cell Synchronisation Cells in a UMTS network are not synchronised in time with

each other.

This removes the need for tight synchronisation between thebase stations

UMTS Air Interface


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There is no need for GPS receivers at sites This makes implementation of picocells and their integration with the

network more simple as satellite LoS is not required

3rd Party Transmission requirement are less stringent

Spreading Factor and User Data Rates UMTS has been designed to provide flexibility to allow the user

to use multiple services, some of which we cannot foresee atthe moment

Rather than having a fixed bit rate and spreading factor, eachof the channels on the user interface has a range of bit rates

UMTS Air Interface


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of the channels on the user interface has a range of bit ratesthat can be used

This makes the channels more complicated than for GSMbutcertainly more flexible

Air Interface Access StratumL3

Radio ResourceControl RRC

Radio LinkControl RLC

Control Plane

SignallingUser Plane

Information

UMTS Air Interface


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L2

L1

Medium AccessControl MAC

Physcial Layer

Logical Channels

TransportChannels

Physical

Channels

Radio Resource Control Layer The RRC layer forms the lower

part of the OSI layer 3

It is responsible for:

Bearer Control Monitoring

L3 Radio ResourceControl RRC


Control Plane


Information

UMTS Air Interface


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Physical

Channels

Power Control

Measurement Reporting

Paging

Broadcast Control

L2

L1


Physical Layer

Logical Channels

Transport

Channels

Radio Resource Control Layer FunctionalEntities

The RRC layer resides at the RNC serving a cell or UE

The RRC Layer can be split into 3 functional entities Dedicated Control Functional Entity (DCFE)

One per UE in connection

f f

UMTS Air Interface


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All functions and signalling specific to a single UE

Paging and Notification control Functional Entity (PNFE)

One per cell

Paging of idle mode UEs

Broadcast Control Functional Entities (BCFE)

One per cell

Broadcasting of system information

Radio Link Control Layer The RLC layer forms the upper

part of the OSI layer 2


Logical Link ControlAcknowledged and

k l d d d t t f



Control Plane


Information

UMTS Air Interface


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Physical

Channels

unacknowledged data transfer L2

L1


Physical Layer

Logical Channels

Transport

Channels

The Medium Access Control Layer The MAC Layer forms the lower

part of layer 2


Random Access Physical Link Control



Control Plane


Information

UMTS Air Interface


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P

Documents

UMTS Network Systems Overview Both Days