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1U101 UMTS Network Systems Overview
UMTS Network Systems
Overview
Day 1
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2U101 UMTS Network Systems Overview
Introductory Session
Introductory Session
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3U101 UMTS Network Systems Overview
Introductions
Introductory Session
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Introductory Session
Introduction to AIRCOM
Contents and Session Aims
This session is a get to know
you session It aims to answer the following
questions:
Who are AIRCOM and why arethey here training us?
Should I be here?
Why am I here?
It also aims to cover thelogistics of the course
Whens the
lunch/coffee/cigarette break?
What are we going to learnabout and when?
Target Students
Course Prerequisites
Aims of the Course
Course Schedule and
Organisation
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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 thetechnology behind UMTS
Introductory Session
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Prerequisites
An understanding of the basic concepts of: Telecommunications
Cellular communications
Wireless communications
Introductory Session
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Course ScheduleDay 1 Day 2
9:30-
10:15
Introductory Session1st/2ndGeneration
Cellular SystemsOverview
UTRAN
Drinks Break Drinks Break
10:45-11:30
3rdGeneration Driversand Standards
UTRAN (cont.)
Drinks Break Drinks Break
12:00-12:45
CDMA MobileTechnology Overview
UMTS Core Network
Lunch Lunch
13:45-14:30
UMTS ArchitectureOverview
UMTS Fixed NetworkInterfaces
Drinks Break Drinks Break
15:00-15:45
UTRA Air Interface UMTS Mobiles
Drinks Break Drinks Break
16:15-17:00
UTRA Air Interface(cont.) UMTS Services
17:00-17:30
Day 1 Roundup Course Roundup
Introductory Session
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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
Introductory Session
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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
Introductory Session
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Questions
Any questions?
Introductory Session
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Locator Slide
Introductory Session
1st and 2nd Generat ionCel lu lar Systems 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
1st and 2nd Generation Cellular Systems Overview
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1st and 2nd Generation Cellular Systems Overview
1st and 2nd Generation Cellular
Systems Overview
G C S O
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Contents and Session Aims
1st and 2nd Generation Cellular Systems Overview
This is a background session to
set the scene for UMTS,essentially a cellular historylesson
Firstly we will examine what wemean by cellular
communications We will look at different
generations of cellular andbriefly at major standards
This will allow us to see why 3G
has moved forward in the waythat it has
What is Cellular?
Cellular Generations1st Generation
2nd Generation
2.5G
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What is Cellular? There are three major types of
terrestrial mobile communications
technologies Cellular
Users are provided wide areamobility from multiple basestations with handover permitted
Cordless Communication Users are provided limited
mobility from a dedicated basestation
Paging
Brief numeric, alphanumeric orvoice messages are sent to thesubscriber typically usingsimulcasting
1st and 2nd Generation Cellular Systems Overview
PSTNMSC
Paging
Control
Centre
Cellular
Cordless
Paging
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1st Generation
1976+, though really the
technology of the 1980s Analogue modulation
Frequency Division MultipleAccess
Voice traffic only
No inter-network roamingpossible
Insecure air interface
1st and 2nd Generation Cellular Systems Overview
The 1st Generation of
Cellular 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
1st and 2nd Generation Cellular Systems Overview
1st and 2nd Generation Cellular Systems Overview
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1st Generation Planning
Macrocellular High sites for coverage driven
planning
Antennas above roof height
Frequency planning required
Large cell size Order 30km
Hard handover Only ever connected to a single
cell
1st and 2nd Generation Cellular Systems Overview
Cellular Networks are
commonly represented as
hexagon grids.
The above diagram shows how
different frequencies are used
in different cells in a cellular
network (different frequencies
represented by different
colours).For networks with more cells
than frequencies these must be
planned
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2nd Generation
1990s
Digital modulation
Variety of Multiple Accessstrategies
Voice and low rate circuitswitched data
Same technology roaming
Secure air interface
1st and 2nd Generation Cellular Systems Overview
The 2nd Generation of
Cellular Technology is the
first to use digitalmodulation
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1st and 2nd Generation Cellular Systems Overview
GSM
First networks in 1992
European developed standard,but with worldwide subscriberbase
Different frequency bands GSM450, GSM900, GSM1800,
GSM1900 Largest 2nd Generation
subscriber base
Frequency/Time DivisionMultiple 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 requiring
planning
Hierarchical Cell Structures
Frequency Hopping
Discontinuous Transmission
Power Control
Simple subscriber/trafficanalysis
Capacity limited by number ofTRXs
Hard Handover
1st and 2nd Generation Cellular Systems Overview
GSM networks usemicrocells to provide
additional capacity. As with
1st generation networks
frequency planning is
required
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D-AMPS/PDC
TDMA (D-AMPS) North American TDMA/FDMA
based standard based uponAMPS
Predominantly used in Northand South America
ANSI-41 Core Network Planning Similar to GSM
PDC Japanese TDMA/FDMA based
standard
Predominantly used in Asia
Planning Similar to GSM
1st and 2nd Generation Cellular Systems Overview
TDMA and PDC phones
from 1999/2000
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cdmaOne
First networks in 1996
Derived from Qualcomm IS-95air interface
Largely American subscriberbase with some Asian networks
Code Division Multiple Access This is in many ways the
closest 2nd generation standardto many of the 3rd generationstandards
ANSI-41 core network
Chip rate of 1.2288Mcps
1st and 2nd Generation Cellular Systems Overview
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
and network)
Code Planning
Capacity Interference Limited 1 Connection
2 Connections
3 Connections
1st and 2nd Generation Cellular Systems Overview
Unlike GSM there is no
frequency planning
required for cdmaOne
However soft handover
means that there are
zones where there are
two/three connections
to the network
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Worldwide Mobile Communications inthe 1990s
0
100200
300
400
500
600
700
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
1st and 2nd Generation Cellular Systems Overview
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2.5G
Now...
Digital modulation Voice and intermediate rate
circuit/packet switched data
Same technology roaming
Secure air interface Based upon existing dominant
standards such as GSM orcdmaOne
1st and 2nd Generation Cellular Systems Overview
2.5G technologies arebased upon existing 2G
technologies but are
focussed at increasing
the maximum data
rates that the
technologies can
deliver
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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 per timeslot)
Multiple timeslots
Circuit Switched Data rates to57.6kbps (4 slots with 14.4kbps
channel coding per slot) Nokia Cardphone
1st and 2nd Generation Cellular Systems Overview
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GPRS
General Packet Radio Service
Enhancement to the GSMstandard
Utlilises Multiple Channel Coding
Schemes (9.05kbps, 13.4kbps,
15.6kbps, 21.4kbps) Multiple Timeslots
Packet Switching
Packet Switched Data typicallyto rates of 115kbps
Theoretically 171.2kbps for 8timeslots
Ericsson R520
(available 1Q 2001)Sagem MC850
Alcatel One Touch 700
(available October
2000)
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2G and 2.5G Standards Compared
GSM TDMA cdmaOne PDC
MultipleAccess 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 per
Frame
8 6 1 3/6
FrequencyBand
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
y
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Questions
What defines a 1st generation technology and a 2ndgeneration technology?
What is are the main differences between GSM andcdmaOne?
How do 2.5G standards relate to 2G standards?
y
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Session Summary
Weve now set the scene - we can start talking aboutwhere people want to go from here now
The generations of cellular technology may besummarised:
1G is analog voice
2G is digital voice
2.5G is digital intermediate rate data
You also know its the coffee break nowand to comeback at 10:45!
y
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Locator Slide
Introductory Session
1st and 2nd Generation CellularSystems Overview
3rd Generat ion Drivers andStandards
CDMA Mobile TechnologyOverview
UTRA Architecture Overview
UMTS Air Interface
Day 1 Roundup
Day 2 Introductory Session
UTRAN UMTS Core Network
UMTS Fixed Network Interfaces
UMTS Mobiles
UMTS Services Course Roundup
3rd Generation Drivers and Standards
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3rd Generation Drivers and Standards
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Introduction and Session Aims
This session is focussed atlooking at how and why the 3rd
Generation standards haveevolved
Firstly we will look at the goalsand the focus of the ITU in IMT-2000
We will then examine whatdrivers from the regions and thevarious industry bodies whohave an interest in 3rdGeneration
Finally we will round up bylooking at the IMT-2000 cellularstandards
IMT-2000
IMT-2000 spectrum
Drivers from Europe,
America and Asia
Regulatory bodiesStandardisation bodies
Industry associations
3rd Generation CellularStandards
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IMT-2000
IMT-2000 (International Mobile Telecommunications 2000)is a program focussed at providing a single globalstandard for mobile communications
Development started in 1985 as FPLMTS Future Public Land Mobile Telecommunications System
Proposed by the ITU (International TelecommunicationsUnion)
3rd Generation Drivers and Standards
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Who does IMT-2000 serve?
Integrating all the following users
fixed
cellular
cordless
professional mobile radiopaging
satellite
specialised (aeroplane, etc)IMT-2000
terminal and
services
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Aspects of IMT-2000 Networks
Different aspects
of IMT-2000
access networks
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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
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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-2000
Land Mobile UL
IMT-2000
Land Mobile
IMT-2000
Land Mobile DL
IMT-2000
Land 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
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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 C did t T h l3rd Generation Drivers and Standards
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IMT-2000 Candidate TechnologyEvaluation
The ITU issued a request for proposals for the Radio
Transmission Technology (RTT) for IMT-2000 to besubmitted in June 1998
Following this a self evaluation of the RTT submitted wasrequired by September 1998
Candidate technologies were then evaluated according totheir compliance with the goals for IMT-2000
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IMT-2000 Candidate Harmonisation
A number of technologies were submitted many of which
had distinct similarities Of course operators were generally keen on a single
standard to 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
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3G Standardization Environment
Key Players and
their relationships
in the IMT-2000standardisation
environment
IMT 2000
S l t d Ai I t f3rd Generation Drivers and Standards
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Five candidate technologies
were eventually 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 InterfaceStandards
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IMT-2000 Standards
The IMT-2000family of
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 cdmaOnestandard
PCS spectrum overlaps IMT-2000 band
Major Drivers
Spectrum sharing and compatibility with 2G standard
National/International roaming
cdma2000 (cdmaOne operators)
EDGE (TDMA operators)
North America Drivers
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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 operatorper country
Major Drivers
Higher Data Rates
Continued global dominance of European based standard
UMTS
European Drivers
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Japan/Korean Drivers
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
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Cordless Drivers
You cant get 2Mbps out of the cellular standards
Hence a requirement for cordless style standards UMTS TDD Mode
DECT
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Industry Bodies - Radio Regulatory
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/
I d B di T d A i i
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Industry Bodies - Trade Associations
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 CommunicationsConsortium
http://www.uwcc.org/
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P t hi P j t d St d d3rd Generation Drivers and Standards
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Partnership Projects and StandardsOrganisations
Relationships
between thestandards
organisations
3GPP M b O i ti
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3GPP Member Organisations
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 M b O i ti
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3GPP2 Member Organisations
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
Th R d t 3G3rd Generation Drivers and Standards
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The Road to 3G
PossibleEvolution Paths
to 3G
HSCSD
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3rd Generation Cellular
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 FDD3rd Generation Drivers and Standards
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UMTS FDD
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 C d t GSM3rd Generation Drivers and Standards
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UMTS Compared to GSMUMTS GSM
Carrier Spacing 5MHz 200kHz
Frequency ReuseFactor
1 1-18
Power ControlFrequency
1500Hz 2Hz or lower
Quality Control Radio ResourceManagement
algorithms
Frequency Planningand Network
OptimisationFrequency Diversity 5MHz bandwidth gives
multipath diversity withrake reciever
Frequency Hopping
Packet Data Load Based PacketScheduling
Time Slot basedScheduling with GPRS
Transmit Diversity Supported to improvedownlink capacity Not supported bystandard but may beapplied
UMTS Compared to IS953rd Generation Drivers and Standards
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UMTS Compared to IS95UMTS IS-95
Carrier Spacing 5MHz 1.25MHz
Chip Rate 3.84Mcps 1.2288McpsPower ControlFrequency
1500Hz Uplink 800Hz,Downlink slow
Base StationSynchronisation
No Yes via GPS
Frequency Inter
FrequencyHandovers
Yes, slotted mode
measurements
Possible but
measurements notspecified
Packet Data Load Based PacketScheduling
Packets as short CScalls
Radio ResourceManagement
Efficient algorithms toprovide QoS
Not required forspeech only
Transmit Diversity Supported to improvedownlink capacity
Not supported bystandard
UMTS TDD3rd Generation Drivers and Standards
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UMTS TDD
Universal Mobile Telecommunications System Frequency
Division Duplexing Mode Built onto enhanced GSM core network
Utilises: QPSK modulation
Multiple channel coding and bearer rates
CDMA
TDD
Asynchronous operation
Data up to rates of 2Mbps (typically less)
cdma20003rd Generation Drivers and Standards
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cdma2000
Built onto ANSI-41 core network
Utilises: QPSK modulation
Multiple channel coding and bearer rates
CDMA
FDD
Multiple carriers on the downlink to allow compatibility withcdmaOne
Synchronous operation
Data up to rates of 2Mbps (typically less)
EDGE3rd Generation Drivers and Standards
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EDGE
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 Compared3rd Generation Drivers and Standards
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3rd Generation Standards ComparedUMTS FDD UMTS TDD cdma2000 EDGE
Multiple
Access
CDMA CDMA CDMA TDMA
Modulation QPSK QPSK QPSK 8-PSK
CarrierSpacing
5MHz (200kHzraster)
5MHz (200kHzraster)
3.75MHzUL/1.25MHz DL
200kHz/1.6MHz
Frame Length 10ms 10ms 20ms 4.615ms
Slots per
Frame
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 Data
Rate
2Mbps 2Mbps 2Mbps 521/4750kbps
Synchronous No No Yes Yes
Handover Soft Hard Soft Hard
4th Generation3rd Generation Drivers and Standards
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4th Generation...
Probably 2005-2007
Broadband data rates in excessof 1Mbps
Probably 10MHz+ carriers
...
Questions3rd Generation Drivers and Standards
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Questions
What is IMT-2000 and why is it related to UMTS?
Why do the American operators want cdma2000 andEDGE?
What is the major difference between UMTS andcdma2000?
Session Summary3rd Generation Drivers and Standards
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Session Summary
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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Locator Slide
Introductory Session
1st and 2nd Generation CellularSystems Overview
3rd Generation Drivers andStandards
CDMA Mobi le Technolo gyOverview
UMTS Architecture Overview
UMTS Air Interface
Day 1 Roundup
Day 2 Introductory Session
UTRAN UMTS Core Network
UMTS Fixed Network Interfaces
UMTS Mobiles
UMTS Services Course Roundup
CDMA Mobile Technology Overview
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CDMA Mobile Technology Overview
Contents and Session AimsCDMA Mobile Technology Overview
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Contents and Session Aims
This session aims to coversome basic CDMA terminologyand technology before dealingwith UMTS in more detail
Key generic areas of CDMAinclude
How CDMA works and relatesto other multiple accessschemes
How the codes are generatedand what their properties are
Soft Handover - what and how?
The pilot channel
Multiple Access
Strategies ExplainedCDMA for Cellular
Codes in CDMA
Soft Handover
The Pilot Channel
Multiple Access ExplainedCDMA Mobile Technology Overview
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Multiple Access Explained
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 ableto pick out their speech from everybody elses speech.
Everybody is using the same medium to talk - the air inthe room
Clich ExplanationCDMA Mobile Technology Overview
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Clich Explanation
This is Multiple Access Many conversations/channels share the same medium
There are a number of different Multiple Access (MA)strategies you can try:
Time Division Multiple Access(TDMA)
Frequency Division Multiple Access(FDMA)
Code Division Multiple Access(CDMA)
TDMA at the Cocktail PartyCDMA Mobile Technology Overview
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TDMA at the Cocktail Party
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 andbegin again - 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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TDMA
frequency
time
User 1 User 1
Timeslot Period Frame Period
Idealised TDMA
(with no guard
periods)
Available
Frequency
Band
FDMA at the cocktail partyCDMA Mobile Technology Overview
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FDMA at the cocktail party
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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FDMA
frequency
time
User 1
Frame Period (we may still need
frames/timeslots for signaling)
Channel
Bandwidth
Idealised FDMA
(with no guard
bands)
FDMA/TDMACDMA Mobile Technology Overview
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FDMA/TDMA
Of course we could also be clever and use a combination
of TDMA and FDMAlike in GSM This is commonly referred to as simply TDMA
FDMA/TDMACDMA Mobile Technology Overview
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FDMA/TDMA
frequency
time
Channel
Bandwidth
Timeslot Period Frame Period
User 1 User 1Idealised
FDMA/TDMA
(with no guardbands or guard
periods)
FH at the Cocktail PartyCDMA Mobile Technology Overview
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FH at the Cocktail Party
If we combine TDMA and FDMA and change the frequency oftransmission every 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 Hopping Spread Spectrum
f
requency
timeUser 1 User 1
Channel
Bandwidth
Timeslot Period Frame Period
Idealised FH (with
no guard bandsor guard periods)
Frequency Hopping Power SpectrumCDMA Mobile Technology Overview
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Frequency Hopping Power Spectrum
Time Averaged
Power Spectrum
Frequency
Frequency
Frequency
Frequency
Power
Power
Power
Power
Instantaneous Power
Spectra for a channel indifferent frames
CDMA at the Cocktail PartyCDMA Mobile Technology Overview
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CDMA at the Cocktail Party
We can actually be more sophisticated than this.
If we know the characteristics of the persons voice we can tune in towhat they are saying and ignore what other people are saying
This is like CDMA where the conversation/channel separation isprovided by the characteristics of the channel
i.e. the code
The only problem is that we do pick up some of the noise from theother channels 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
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CDMA Power SpectrumCDMA Mobile Technology Overview
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CDMA Power Spectrum
Power Spectrum for the
equivalent unspreadchannel
FrequencyFrequency
PowerPower
Power Spectrum post
spreading
Note: The power
spectrum has been
spread similar to that in a
Frequency Hopping
system
More CDMA permutationsCDMA Mobile Technology Overview
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p
Of course we can start getting a bit clever again...
CDMA/FDMACDMA Mobile Technology Overview
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frequency
time
code
Idealised
CDMA/FDMA(with no guard
bands)
CDMA/FDMA can be used to
provide multiple carriers OR
to provide Frequency DivisionDuplexing - separate carriers
for the uplink and downlink
CDMA/TDMA/FDMA...CDMA Mobile Technology Overview
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frequency
time
code
Idealised
CDMA/TDMA/FDMA(with no guard bands
or guard periods)
Combining CDMA and TDMA can be
used to provide Time DivisionDuplexing
CDMA SpreadingCDMA Mobile Technology Overview
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p g
Channel
Tx Bit Stream Rx Bit Stream
Air Interface
Chip Stream
Code Chip Stream Code Chip Stream
Essentially Spreading involves changing the symbol rate on the air interface
Identica
l codes
Spreading Despreading
P P
P
f
f
P
f
f
P
f
Spreading and DespreadingCDMA Mobile Technology Overview
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p g p g
Tx Bit Stream
Rx Bit Stream
Code Chip Stream
Code Chip Stream
Air Interface
Chip Stream
1
-1X
X
Spreading
Despreading
SpreadingCDMA Mobile Technology Overview
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p g
If the Bit Rate is Rb, the Chip Rate is Rc, the energy per
bit Eb and the energy per chip Ecthen
We say the Processing GainGpis equal to:
Commonly the processing gain is refereed to as theSpreading Factor
b
c
cb
R
REE .
b
cp
R
RG
CDMA Mobile Technology Overview
Spreading in noise
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Channel
Spreading Code Spreading Code
Wideband Noise/Interference
Signal Signal
Tx Signal Rx Signal (= Tx Signal + Noise)
p g
The gain due to despreading of the signal over widebandnoise is the Processing Gain
P
f
P
f f
P
P
f
P
f
Types of CodesCDMA Mobile Technology Overview
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yp
There are essentially two typesof codes used in CDMA
networks: Channelisation Codes
Are used to separate channelsfrom a single cell or terminal
Scrambling Codes
Are used to separate cells andterminals from each other rather
than purely channels
Channelisation/scramblingcodes may be either:
short (the length of the code is
equal to the bit period)
long (longer than the bit period)
S1
S2
S3
C1 C2 C3
C1 C2 C3
C1 C2 C3
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Channelisation Code GenerationCDMA Mobile Technology Overview
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Channelisation codes can be generated from a Hadamard
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
xx
xx
Note: These two codes
correlate if they are time
shifted
Scrambling Code GenerationCDMA Mobile Technology Overview
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Scrambling codes are not orthogonal since they are not
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 (for CDMA one)
Scrambling Code GenerationCDMA Mobile Technology Overview
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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 value
for offset
Output sequence: 1,0,1,0,1,1,0,0,1,0,0,0,...
Orthogonality of CodesCDMA Mobile Technology Overview
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If orthogonal mean interference power over a bit is zero
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 andDespreading
CDMA Mobile Technology Overview
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Despreading
Channelc1 c1
c2 c2
P
f
P
f
P
f
P
f
P
f
P
f
f
P
f
P
Since the channels are orthogonal the resultinginterference is entirely removed by the despreadingprocess
CDMA in CellularCDMA Mobile Technology Overview
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Cellular systems have multipath channels with a delayspread
Channels from the same transmitter are no longer perfectlyorthogonal
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 macrocellstypically)
The orthogonality factor gives the percentage of interference that is
rejected
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Visualising the Processing GainCDMA Mobile Technology Overview
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W/Hz W/Hz W/Hz
W/Hz W/Hz dBW/HzEb
Io
Ec
Io
Eb
Io
Eb/Io
Eb
No
Eb/NoEb
No
W/Hz dBW/Hz
Signal
Intra-cell Noise
Inter-cell Noise
Before
Spreading
After
Spreading With Noise
After
Despreading
/Correlation
Post
Filtering
Orthog = 0
Post
FilteringOrthog > 0
f f f
f f f
f f
A Channelised TransmitterCDMA Mobile Technology Overview
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Channel 1Bit Stream
Channel 2
Bit Stream
Channel 3
Bit Stream
Pulse Shaping
and Modulation
c1
c2
c3
s1Typically in a multi-channel transmitter,
channels are first spread and channelised
using the channelisation codes, then
combined and finally scrambled together.
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CDMA Noise CalculationCDMA Mobile Technology Overview
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We can say (approximately - assuming perfect powercontrol) that the Eb/Nois equal to:
Where:
Eb/No= Energy per bit/Noise Power Spectral Density M = Number of Users or Codes Used
h= Loading factor in the cell
Gp= Processing Gain
v = Voice activity factor
= Orthogonality Factor
i = the other to own cell interference ratio
h
v
1
i1
1G
M
1
N
Ep
0
b
CDMA Capacity CalculationsCDMA Mobile Technology Overview
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y
The Eb/Norequired to achieve a desired BER can becalculated/simulated for a given receiver
We can say that the number of users we can support isapproximately equal to:
h
v
1
i1
1G
NE
1M p
required0
b
CDMA Capacity CalculationsCDMA Mobile Technology Overview
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However imperfect power control will create a 30-40%
reduction in the capacity on the uplink (downlink channelswill 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 ChannelsCDMA Mobile Technology Overview
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Pilot channels are effectively channels used in the cell
selection process 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 andtiming information
Soft HandoverCDMA Mobile Technology Overview
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Soft Handover is where more then one cell is incommunication with a terminal
The cells in communication with the terminal are known asan active set
The best serving cell is known as the primary cell- andmaintains the primary channel
Other channels are known as handover channels The gain associated with soft handover is known as the
macrodiversity gain
This occurs due to the uncorrelated nature of fast fading between
cells and the variation in slow fading between cells Note that slow fading is not entirely uncorrelated for different cells
Hard Handover (e.g.GSM)CDMA Mobile Technology Overview
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HandoverHysteresis
Margin
RX_Lev
Direction of Travel
Cell A Cell BA hard handover
between cells A and
B in GSM
In a hard handover
the mobile is only
ever
instantaneously
connected to a
single cell
Distance
Soft Handover (e.g. in cdmaOne)CDMA Mobile Technology Overview
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Active set = 1 = 2 = 1Pilot Ec/Io
T_ADD
T_DROP
Cell A Cell A and Cell B Cell B
Direction of Travel
Add Time Delay Drop Time Delay
A soft handover
between cells A and
B in cdmaOne
In a soft handover
the mobile is may
be instantaneously
connected to more
than one cell
Distance
Why Soft Handover is Good in CDMACDMA Mobile Technology Overview
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Why Soft Handover is Good inCDMA
Near- Far Effect
Hard Handover can lead torelatively deep penetration intoneighbour cells
Soft Handover allows PowerControl from all Active Set cells
Probability of dropped callreduced due to link redundancyin handover region
Macrodiversity gain
Why Soft Handover is Bad inCDMA
Transmission overhead inbackhaul
Addition of downlink noise intothe system
Engineering of handover zones
becomes highly critical
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Cell BreathingCDMA Mobile Technology Overview
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An increase in traffic results is an increase in interference
Mobiles at the extremities of cells may be pushed out ofthe 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 -Power Control
CDMA Mobile Technology Overview
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Power Control If somebody is shouting louder than they need it increases
the overall noise This is inefficient as it reduces the number of people who
can have conversations
We need to speak as quietly as possible to maximise the
number of simultaneous This is called Power Controlin mobile networks
In CDMA networks it is very important that this powercontrol is efficient
We use fast power control with a much quicker feedback loop thanin TDMA networks
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QuestionsCDMA Mobile Technology Overview
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What is a pilot channel?
How does soft handover differ from hard handover? How do scrambling codes differ from channelisation
codes?
Why is multipath fading bad from a CDMA point of view?
Session SummaryCDMA Mobile Technology Overview
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In this session we have discussed:
CDMA and how it relates to and differs from other multiple accesstechnologies
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
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UMTS Architecture Overview
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UMTS Architecture Overview
Contents and Session AimsUMTS Architecture Overview
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This session aims to give theuser a first pass overview of the
architecture behind UMTS To explain the major
architectural blocks
To give a first introduction to themajor network elements and
interfaces To talk about how UMTS will
interface with existingtechnologies
UMTS High Level
ArchitectureThe Core Network
UTRAN
The User Equipment
Interfaces
Access ModesUMTS and GSM
Public Land Mobile Network (PLMN) A Public Land Mobile Network is
UMTS Architecture Overview
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A Public Land Mobile Network isdefined in the specifications asconsisting of:
One or more switches with acommon numbering plan androuting plan
Switches act as the interfacesto external networks
A PLMN can be regarded as anindependenttelecommunications entity
The PLMN can be separatedinto
Core NetworkAccess Network
Core Network
Access Network
PLMN
UMTS Architecture Overview
UMTS High Level Architecture
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User Equipment
UMTS
TerrestrialRadio Access
Network
Core Network
UU IUUE UTRAN CN
To this definition, the 3GPP standards add an additionalarchitectural block, the User Equipment
Major Network Elements in UMTS
UMTS Architecture Overview
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UU IU
UE UTRAN CN
CU
IUb
IUr
USIM
ME
Node B
Node B
Node B
Node B
RNC
RNC
MSC/VLR
SGSN GGSN
GMSC
HLR
PLMN,PSTN,
ISDN
Internet,
X25
Packet
Network
Mobile
Equipment
UMTS SIM
Radio
Network
Controller
Radio
Network
Controller
Serving
GSNGateway
GSN
Gateway
MSC
Mobile
Switching
Centre
Home
Location
Register
Iu-ps
Iu-cs
IUb
Functions of the CNUMTS Architecture Overview
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Switching
Service Provision Transmission of user traffic between UTRAN(s) and/or
fixed network
Mobility Management
Operations, Administration and Maintenance
Major Elements of the Core NetworkUMTS Architecture Overview
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Home Location Register (HLR)
The database storing the master copy of a users profile 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 ArchitectureOther MSC
UMTS Architecture Overview
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IUCN
MSC/VLR
SGSN GGSN
GMSC
HLR
Serving
GSNGateway
GSN
GatewayMSC
Mobile
SwitchingCentre
Home
Location
Register
Other SGSN
Other MSC
UTRAN
UTRAN
External
CircuitSwitched
Networks
External
Packet
Switched
Networks
Iu-cs
Iu-ps
Gs
Gn
Gn
Gr Gc
DD
Gi
FF
Functions of UTRANUMTS Architecture Overview
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Provision of Radio Coverage
System access control Security and privacy
Handover
Radio resource management and control
Elements of UTRANUMTS Architecture Overview
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Radio Network Controller
Owns and controls radio resources in its domain Service Access point for all services that UTRAN provides the CN
Node BActs as the radio basestation
Converts the data flow between the Iuband Uuinterfaces
General UTRAN ArchitectureUMTS Architecture Overview
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UU IU
UTRAN
IUb
IUr
Node B
Node B
Node B
Node B
RNC
RNC
Radio
Network
Controller
Radio
Network
Controller
Iu-ps
Iu-cs
IUb
CN (MSC)
CN (SGSN)
UE
Functions of the UEUMTS Architecture Overview
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Display and user interface
To hold the authentication algorithms and keys User end termination of the air interface
Application platform
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General UE ArchitectureUMTS Architecture Overview
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UU
UE
CU
USIM
ME
Mobile
Equipment
UMTS SIM
UTRANTerminal
Equipment
Major Interfaces in UMTSUMTS Architecture Overview
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There are four major newinterfaces defined in UMTS
IuThe interface betweenUTRAN and the CN
Iur
The Interface between
different RNCs Iub
The interface between theNode B and the RNC
Uu
The air interface
RNC
Node-
B
RNC
UE
CN
Uu
Iu
Iub
Iur
Iu - the Core Network to UTRAN InterfaceUMTS Architecture Overview
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There are two parts to the Iuinterface
Iu-psconnecting UTRAN to thePS Domain of the CN
Iu-csconnecting UTRAN to theCS Domain of the CN
No radio resource signalling
travels over this interface The Iuinterface divides the
UMTS network into the radiospecific UTRAN and the CNresponsible for switchingrouting and service provision
RNC
Node-
B
RNC
UE
CN
Uu
Iu
Iub
Iur
Iur- the Inter-RNC InterfaceUMTS Architecture Overview
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The Iurinterface allows softhandovers between Node-Bs
attached to different RNCs It is an open interface to allow
the use of RNCs from differentmanufacturers
Its functions may besummarised: Support of basic inter-RNC
mobility
Support of Dedicated andCommon Channel Traffic
Support of Global ResourceManagement
RNC
Node-
B
RNC
UE
CN
Uu
Iu
Iub
Iur
Iub- the RNC to Node-B InterfaceUMTS Architecture Overview
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The Iubis an open interface toallow the support of different
manufacturers supplying RNCsand Node-Bs
Its major functions are: Carries dedicated and common
channel traffic between the
RNC and the Node-B Supports the control of the
Node-B by the RNC
RNC
Node-
B
RNC
UE
CN
Uu
Iu
Iub
Iur
Uu- the Air InterfaceUMTS Architecture Overview
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Clearly the Uumust bestandardised to allow multiple
UE vendors to be supported bya network
The major functions of the Uuare to:
Carry dedicated and common
channel traffic across the airinterface
Provide signaling and controltraffic to the mobile from theRNC and the Node-B
RNC
Node-
B
RNC
UE
CN
Uu
Iu
Iub
Iur
UMTS Interface ImplementationUMTS Architecture Overview
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ATM/IP Network
RNCNode
B
NodeB
Node
B
MSC
RNC
SGSN
NodeB
IubIu_csIu_ps
Iur
Access Modes for UMTSUMTS Architecture Overview
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In this course we will concentrate on the UMTS FDD airinterface
However we should bear in mind that a number of otheraccess modes are possible
Within UTRAN
Outside of UTRAN
Access Modes within UTRAN
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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
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
radio relay
Additional Access Networks
Th UMTS CN i b i
UMTS Architecture Overview
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The UMTS CN is beingdesigned with the possibility
of interfacing to additionalAccess Networks other thanUTRAN
GRAN - GSM/GPRS RadioAccess Network
ERAN - EDGE RadioAccess Network
BRAN - Broadband RadioAccess Network(HIPERLAN2)
DECT - Digital Enhanced
Cordless Telephony
UMTS-CN
DECT
BRAN GRAN
ERAN
UTRAN
UMTS and GSMInternet PSTN
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RBS
RNC
Node-B
Iub
RBS RBS RBS
RNC
Node-B Node-B
UTRAN
CoreNetwork
SGSN MSC
GGSN
Iu-csIu-psIu-cs
Iu-ps
IubIub
BSC
BTS
Iur
A-bis
A
Gb
GMSC
BSS/
Architecture of a UMTS bearer service
CN C
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TE TEUE UTRANCN
edge node
CNgateway
End-to-End Service
TE/UE Local
Bearer Service UMTS Bearer Service
Radio Access Bearer Service
External Bearer
Service
CN Bearer
Service
Radio Bearer
Service
IuBearer
ServiceBackbone Network
Service
UTRA FDD/TDD
ServicePhysical Bearer
Service
UMTS Protocol Stratums
I d t id
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In order to provideseparation between radio
access functionality andservice quality provision,protocols in UMTS aredivided into two stratums
Access Stratum
Encompasses layers 1and 2 of the OSI 7 layer
model, and the lower part oflayer 3
Non-access Stratum
Encompasses layers 4 to7 of the OSI 7 layer model,and the upper part of layer 3
N
onAccessStratum
AccessStratum
L1 L1 L1L1
L2L2L2L2
L5L5
L4L4
L6 L6
L7 L7
L3 lower L3 lower L3 lower L3 lower
L3 upper L3 upper
Uu IuUE UTRAN CN
Questions
Wh t l t d UTRAN i t f?
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What elements does UTRAN consist of?
What is the primary role of UTRAN? What additional access modes does UMTS support over
UMTS FDD?
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Locator Slide
Introductory Session Day 2 Introductory Session
UMTS Air Interface
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Introductory Session
1st and 2nd Generation CellularSystems Overview
3rd Generation Drivers andStandards
CDMA Mobile TechnologyOverview
UMTS Architecture Overview
UMTS Air Interface
Day 1 Roundup
Day 2 Introductory Session
UTRAN
UMTS Core Network
UMTS Fixed Network Interfaces
UMTS Mobiles
UMTS Services
Course Roundup
UMTS Air Interface
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UMTS Air Interface
Contents and Session Aims
UMTS Air Interface
This session aims to explain the
O i f th Ai
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This session aims to explain theprotocols and operation of the
air interface To give an overview of the
UMTS specific operation of theair interface
To look at the protocol structure
To investigate the Frame andTimeslot structure of the majorair interface channels
Overview of the Air
Interface
Logical, Transport and
Physical Channels on
the Air Interface
The Dedicated
Channels
Role of the Air Interface
To provide a number of bearer or physical channels to
UMTS Air Interface
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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
error performance 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
UMTS Air Interface
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Parameter Value
Multiple Access Scheme Direct Sequence CDMADuplexing Method FDD
Chip Rate 3.84 Mcps
Carrier Spacing 5 MHz
Carrier Spacing Raster 200 kHz
Frame Length 10 ms
Slots per Frame 15
Inter-cell Synchronisation NoneSpreading factor Variable (4-512)
User Data Rate 8->384 kbps
Multiple Access Scheme
UMTS FDD mode makes use of a CDMA style multiple
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UMTS FDD mode makes use of a CDMA style multipleaccess scheme
In the case of UMTS this is commonly referred to asWideband CDMA
However there are elements of FDMA and TDMA inUMTS
Common channels for paging and packet access share codesbetween UEs (TDMA)
Multiple carriers are used per operator (FDMA)
Duplexing Method
UMTS FDD mode makes use
UMTS Air Interface
190MHz
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UMTS FDD mode makes useof Frequency Division
Duplexing The Uplink and Downlink
Channels are carried onseparate carriers
In the case of UMTS in
Europe: The Uplink band is between
1.92 and 1.98GHz
The Downlink band isbetween 2.11 and 2.17GHz
The Uplink/DownlinkSeparation is 190MHz
190MHz
UMTS Uplink UMTS Downlink
Chip Rate
The chiprate used in UMTS FDD mode is 3 84Mcps
UMTS Air Interface
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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
Provided a similar bandwidth to cdma2000 to allow shared use of filtersetc in UEs
Note:Initially UMTS was specified as having a chip rate of4.096Mcps. You may find some old texts and papers referring to this chip rate
Carrier Spacing and Carrier SpacingRaster
Th i l i i f
UMTS Air Interface
5MHz
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15U101 UMTS Network Systems Overview
The nominal carrier spacing forUMTS is 5Hz
This was chosen to comply withthe American market, wherespectrum has been awarded in5MHz 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
license conditions, or to theoperators discretion
200kHz
Adjacent Channel Interference
Adjacent channel interference may have a significant
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16U101 UMTS Network Systems Overview
Adjacent channel interference may have a significantimpact on UMTS capacity
Required attenuation (by standards) adjacent carrier 33dB
2nd adjacent carrier 43dB
Since only have 2 or 3 carriers typically at least oneadjacent carrier will be transmitted by a third party
This can partially be negated by a flexible carrier spacingbased upon a 200kHz raster
Adjacent Operator Interference
UMTS Air Interface
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Distant Serving
Macrocell
Close
Interferring
Microcell
Interference
Signal50dB path loss
150dB path loss
UK Spectrum Allocations Example
D D DE E EC C CA A A A B B B
UMTS Air Interface
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U101 UMTS Network Systems Overview
Hutchison
One2One
Vodafone
BT Cellnet
Orange
14.6MHz 14.8MHz10MHz 10MHz 10MHz0.3MHz0.3MHz
20MHz
Radio Frame Structure
Radio Frame Period = Tf = 10ms
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U101 UMTS Network Systems Overview
Tslot = 666.7ms = 2560 chips
Radio Frame Period = Tf = 10ms
Frames are used for channel format control 15 slots, #0#14
Slots are used 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
UMTS Air Interface
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U101 UMTS Network Systems Overview
72 Radio Frames make a Superframe
Superframe Period Tsf= 720msSuperframes are used for
#0 #1 #2 #i #71
Tsf = 720ms
Inter Cell Synchronisation
Cells in a UMTS network are not synchronised in time with
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U101 UMTS Network Systems Overview
Cells in a UMTS network are not synchronised in time witheach other.
This removes the need for tight synchronisation betweenthe base stations
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
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U101 UMTS Network Systems Overview
UMTS has been designed to provide flexibility to allow theuser to use multiple services, some of which we cannot
foresee at the moment
Rather than having a fixed bit rate and spreading factor,each of the channels on the user interface has a range ofbit rates that can be used
This makes the channels more complicated than forGSMbut certainly more flexible
Air Interface Access Stratum
L3Radio
ResourceControl Plane
Si lliUser Plane
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U101 UMTS Network Systems Overview
L3
L2
L1
Resource
Control RRC
Radio Link
Control RLC
Medium Access
Control MAC
Physcial Layer
Signalling Information
Logical
Channels
Transport
Channels
Physical
Channels
Radio Resource Control Layer
The RRC layer forms the lower
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U101 UMTS Network Systems Overview
Physical
Channels
ypart of the OSI layer 3
It is responsible for: Bearer Control
Monitoring
Power Control
Measurement Reporting Paging
Broadcast Control
L3
L2
L1
RadioResource
Control RRC
Radio Link
Control RLC
Medium
Access Control
MAC
Physical Layer
Control PlaneSignalling
User PlaneInformation
Logical
Channels
Transport
Channels
Radio Resource Control LayerFunctional Entities
The RRC layer resides at the RNC serving a cell or UE
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U101 UMTS Network Systems Overview
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
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
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U101 UMTS Network Systems Overview
Physical
Channels
y pppart of the OSI layer 2
It is responsible for: Logical Link Control
Acknowledged andunacknowledged data transfer
L3
L2
L1
Radio
Resource
Control RRC
Radio Link
Control RLC
Medium
Access Control
MAC
Physical Layer
Control PlaneSignalling
User PlaneInformation
Logical
Channels
Transport
Channels
The Medium Access Control Layer
The MAC Layer forms the lower
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U101 UMTS Network Systems Overview
Physical
Channels
ypart of layer 2
It is responsible for: Random Access
Physical Link Control
Ciphering
Multiplexing and ChannelMapping to the Physical Layer
L3
L2
L1
Radio
Resource
Control RRC
Radio Link
Control RLC
Medium
Access Control
MAC
Physical Layer
Control PlaneSignalling User PlaneInformation
Logical
Channels
Transport
Channels
Medium Access Control LayerFunctional Entities
MAC-b
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U101 UMTS Network Systems Overview
Handles the broadcast channel (BCH) and is located in the Node-B in the UTRAN
MAC-c/sh Handles the common and shared channels and is located in the
RNC in the UTRAN
MAC-d Handles the dedicated channels and is located in the RNC
The Physical Layer
The Physical Layer forms layer
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2 of the OSI protocol stack
It is responsible for: Carrying traffic and signalling
across the air interface
L3
L2
L1
Radio
Resource
Control RRC
Radio Link
Control RLC
Medium
Access Control
MAC
Physical Layer
Control PlaneSignalling User PlaneInformation
Logical
Channels
Transport
Channels
Physical
Channels
Protocol Termination in the AccessStratum
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User Equipment Node-B Radio Network Controller
RRC RRC
RLCRLC
MAC MAC
Physical Physical
Note:Some Layer 2 functionality regarding the
broadcast functionality resides in the Node-B
UMTS Channel Types and Functions
There are three types of channel across the air interface
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ypand access stratum that we are interested in:
Logical Channels
Between the RLC and MAC layers
Transport Channels
Between the MAC and Physical layers
Physical Channels
Between Physical Layers at the Node-B and UE
Major Logical Channels in UMTS
Control Channels
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BCCH Broadcast Control Channel
PCCH Paging Control Channel
CCCH Common Control Channel
DCCH Dedicated Control Channel
Traffic Channels DTCH Dedicated Traffic Channel
CTCH Common Traffic Channel
Logical Control Channels
The Broadcast Control Channel(BCCH) is a downlink
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( )channel for broadcasting system control information
The Paging Control Channel(PCH) is a downlink channelthat transfers paging information
The Dedicated Control Channel(DCCH) is a point-to-pointbi-directional channel transmitting control information
between a specific UE and the UTRAN
The Common Control Channel(CCCH) is a bi-directionalchannel transmitting control information between Ues andthe UTRAN
Logical Traffic Channels
The Dedicated Traffic Channel(DCH) is a point-to-point
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( ) p pchannel dedicated to a single UE for the transfer of user
information
The Common Traffic Channel(CTCH) is a point-to-pointunidirectional channel for transfer of user information to agroup of UEs
Common Control Channels
Major Transport Channels for UMTS
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BCH Broadcast Channel
FACH Forward Access Channel
PCH Paging Channel
RACH Random Access Channel
CPCH Common Packet Channel
Dedicated Channels DCH Dedicated Channel
DSCH Downlink Shared Channel
Common Transport Channels
The Broadcast Channel(BCH) is a cell-wide channel that is used tob d t t d ll ifi i f ti Th BCH i l
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U101 UMTS Network Systems Overview
broadcast system and cell-specific information. The BCH is always
transmitted over the entire cell with a low fixed bit rate. The Paging Channel(PCH) is a cell-wide channel that is used to carry
control information to a UE when the system does not know thelocation cell of the UE
The Forward Access Channel(FACH) is a downlink channel that is
used to carry control information to a UE when the system knows thelocation cell of the UE. May also carry short user packets.
The Random Access Channel(RACH) is an uplink control channelfrom the UE. May also carry short user packets
The Common Packet Channel(CPCH) is a contention based uplink
channel used for transmission of bursty data traffic.
Dedicated Transport Channels
The Downlink Shared Channel (DSCH) is a downlink
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channel shared by several UEs carrying dedicated control
or traffic data.
The Dedicated Channel (DCH) is a channel dedicated toone UE used in uplink or downlink.
Common Control Channels P-CCPCH Primary Common Control Physical Channels (DL)
Major Ph