1-Introduction to UMTS and WCDMA.ppt

8/11/2019 1-Introduction to UMTS and WCDMA.ppt

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Introduction to UMTS & WCDMA

April 2008

Oussama Akhdari

ROSI / INTPS / NAD / RASQ / International Radio support


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2 Groupe France TlcomIntroduction to UMTS & WCDMA / April 2008 /confidential/Oussama Akhdari

3G Generation General Aspects

Introduction to UMTS

UMTS Radio Access Network

QoS Architecture

WCDMA Principles

Agenda


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IMT 2000 Standards

IMT-2000 is a term used by the International Telecommunications Union

(ITU) to refer to many third generation (3G) wireless technology, that

provide higher data speed between mobile phones & base antennas.

ITU activities on IMT-2000 comprise international standardization,

including frequency spectrum & technical specifications for radio & network

components, tariffs and billing, technical assistance & studies on regulatory

and policy aspects.

IMT- DS

WCDMA/UTRA

FDD

Direct Spread

IMT- MC

CDMA2000

Multi-Carrier

IMT- TC

UTRA TDD

TD - SCDMA

Time - Code

IMT- SC

UWC - 136

Single-Carrier

IMT- FT

DECT

Frequency Time

IMT2000 Terrestrial radio interfaces

IMT- OFDM

WiMax

OFDMA

CDMA CDMA -TDMA

Paired Spectrum Paired/Unpaired Spectrum

TDMA TDMA - FDMA

Unpaired Spectrum Paired Spectrum

OFDMA


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IMT 2000 Frequencies

Worldwide frequency plans for IMT-2000 bands already identified

Assigning a non IMT2000 spectrum would result in higher handset prices for 3G

systems complex circuitry to support international roaming across different

frequency bands.

Europe

China

Japan

Korea

North

America

ITU

Alloc.


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3rd Generation Projects

3GPP 3rd Generation Partnership Project www.3gpp.org

Present about 80% of the users within the WorldTechnical specifications for the 3rd Generation Mobile System based onthe evolved GSM core networks and UTRA.

Include a Technical Specification Group (TSG) for the GSM EDGERadio Access Network (GERAN).

Responsible of GSM (2G) and UMTS (3G) including its evolutionHSDPA/HSUPA (3.5G)

Evolution of HSPA / SAE (System Architecture Evolution) / Long TermEvolution (LTE)

3GPP2 3rd Generation Partnership Project 2 www.3gpp2.org

Present about 20% of the Mobile usersWorking on AIE (Air Interface Evolution) / EV-DO Rev. C

IEEE 802.16 & WiMAX Forum

Deployment very shy and limited to fixed WiMax (3.5 GHz)


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3GPP Specification Series www.3gpp.org


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UMTS Terrestrial Radio Access - UTRA

W-CDMA (UTRA FDD)

For the paired band

Uplink and downlink are separated in frequency Chosen as the technology for UMTS publish, wide -area service

TD-CDMA (UTRA TDD)

For the unpaired band

Uplink and downlink are separated in time

Flexible time duration for uplink & downlink for asymmetricaltraffic

Chosen for private, indoor services in the unpaired TDD

FDD Mode TDD Mode

1900 1920 1980

FDD ULTDD

UL/DL

TDD

UL/DLMSS

UL

2010 2025

MSS

DL

2110 2170 2200

FDD DL

FUL

FDL

FUL/DL

FDD Mode TDD Mode

1900 1920 1980

FDD ULTDD

UL/DL

TDD

UL/DLMSS

UL

2010 2025

MSS

DL

2110 2170 2200

FDD DL

1900 1920 1980

FDD ULTDD

UL/DL

TDD

UL/DLMSS

UL

2010 20251900 1920 1980

FDD ULTDD

UL/DL

TDD

UL/DLMSS

UL

2010 2025

MSS

DL

2110 2170 2200

FDD DL

FUL

FDL

FUL/DL


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UTRA FDD - Characteristics

Wide band code division multiple access W-CDMA multiple access

Frequency band Region 1 (Europe)

Uplink1920 - 1980 MHz & Downlink2110 - 2170 MHz

GSM bands: 900 (including E-GSM band) & 1800 bands

ARCEP provided authorization to OFR & SFR to reuse 900

spectrum for UMTS

Mobistar to launch UMTS900 during 2008

New bands attributed to UMTS @ 2.6 GHz (new auctions?)

Carrier Bandwidth

2x5 MHz (theoretical occupied bandwidth = Chip rate 3,84 Mcps)

Services

Both circuit and packet data & asymmetric bitrates

AMR Multi Rate Wide Band AMR

Multi service possible

User Rate Up to 384 Kbits/s

FDD foreseen for Macro & Microcellular coverage for all Orange MCos.


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3G vs. 2G Network services

A 3G networks has a very flexible air interface that can meet thedemands of both packet services and circuit switched voice or data.


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Frequency resources within 3G MCo

The standard resources allocation is 3 carriers per MCo

The resources allocation is country dependent (Local

Telecommunication authority strategy)

Uplink (MHz) Downlink (MHz) Total (MHz) Third carrier Available MHz Total (MHz)

Mobistar 1964.9 - 1979.7 2154.9-2169.7 215 MHz Yes (1 carrier is used) 1910-1915 15 MHz

Orange Spain 1935 - 1950 2125-2140 215 MHz Yes 1900-1905 15 MHz

Orange France 1964.9 - 1979.7 2154.9-2169.7 215 MHz Yes (2 carriers are used) 1910.1-1915.1 15 MHz

Orange Poland 1920.5 - 1935.3 2110.5 - 2125.3 215 MHz Yes 1915.1-1920.1 15 MHz

Orange Romania 1950.1 - 1964.9 2140.1 - 2154.9 215 MHz Yes (2 carriers are used) 1904.9 - 1909.9 15 MHz

Orange Slovekia 1920 - 1940 2110 - 2130 220 MHz Yes (2 carriers are used) 1900-1905 15 MHz

Orange Switzerland 1950 - 1965 2140 - 2155 215 MHz Yes 1905-1910 15 MHz

Orange UK 1969.7 - 1979.7 2159.7 - 2169.7 210 MHzNo (OUK granted only 2

carries, both used)1904.9 - 1909.9 15 MHz

Mobinil (Granted) 1930 - 1935 2120 - 2125 25 MHz

Mobinil end 2010 1930 - 1940 2120 - 2130 210 MHz

Orange Reunion 1940.2 - 1945.2 2130.2 - 2135.2 2

5 MHz 1 carrier is availableOrange Carabe 1940.2 - 1945.2 2130.2 - 2135.2 25 MHz 1 carrier is available

Not GrantedNot Granted

MCoUMTS FDD UMTS TDD

Not Granted1 carrier is available


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FT Group Supplier

FT Group 3G Referenced Suppliers for Access

Alcatel-Lucent

Huawei

Nokia Seimens Networks NSN

Orange Senegal 3G trial hold with Huawei

Mobistar Huawei( ALU Swapped)

Orange Spain E/// & NSN

Orange France ALU& NSN

Orange Poland NSN& Huawei

Orange Romania Huawei

Orange Slovekia ALU

Orange Switzerland NSN

Orange UK NSN

Mobinil ( Egypt ) NSN & Huawei

Orange Reunion Huawei

Orange Carabe ALU

Orange Moldova Huawei

Cell Plus (Mauritius) Huawei

MCo Mco Suppliers


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3G Generation General Aspects

Introduction to UMTS


QoS Architecture

WCDMA Principles

Agenda


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WCDMA Access structure


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UMTS radio access network

Node B

Radio base station like the BTS inGSM

RF Processing (Modulation,Coding, Interleaving, Spreading, de-spreading)

RNC Radio Network Controller

Controls radio resources of severalNode Bs

Manage the Radio AccessBearers for user data transport

Control user mobility

Supports the Iu interface to the corenetwork

RNSRadio Network Subsystem

Like BSS in GSM


Iu

Iur

UTRAN

Iub

RNS

RNSNodeB

NodeB

RNC

NodeB

NodeB

RNC


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RNC Roles: Serving, Drift, Controlling

RNC SRNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

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.UE

UTRANSRNSRNS

SRNCEach connected mode UE is

controlled by a Serving RNC

(SRNC)

The SRNC terminates Iu

towards the CN

DRNC SRNC

Core Network


Iu Iu

Iur

Iub IubIub Iub

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.UE

UTRANSRNSDRNS

MacroDiversity

Combining/

splitting

function

DRNCInter RNC soft handover requires

a second RNC to be involved

Such an RNC lending resources

to an SRNC for a specific UE acts

as a Drif t RNC(DRNC).

CRNCEach RNC acts as

Contr oll in g RNC (CRNC) for

the directly connected Node

Bs and their cells

The CRNC controls the radio

resources of its cells

CRNC CRNC

Core Network


Iu Iu

Iur

Iub IubIub Iub

UTRANRNSRNS


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UTRAN interfaces

Iur interface

logical interface between RNCs

Iur is a point-to-point interface betweentwo RNCs

allows more independent radio resourcemanagement compared to GSM

RNC mobility (soft handover)

Data from the serving RNC is transferredto the drifting RNC through the Iurinterface.

Iub interfaceInterface between RNC and Node B

Allows the RNC & BTS to negotiate aboutradio resources

Transports uplink & downlink transport

frames & O&M dataManage Data & signaling Traffic

2 E1 required @ least when HSPA isintroduced

High Traffic Areas may need a higher IuBcapacity


Iu

Iur

UTRAN

Iub

RNS

RNSNodeB

NodeB

RNC

NodeB

NodeB

RNC


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Core network - packet switched

HLR - Home Location Register

permanent database ofsubscriber data

Iu - PS

for packet switched services

SGSN - Serving GPRS SupportNode

switch for packetswitched (PS)services

GGSN - Gateway GPRS Support

Node

switch from mobile network toexternal networks for packetswitched services

Core NetworkCNIu-PS

GGSNSGSN

MSC/VLR GMSC

HLR


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Iu interface main Function

Establishing, maintaining, and releasing radio access bearers

Performing intra-system & inter-system handovers as well as SRNCrelocations

Transferring NAS signaling messages between UE & CN (direct transfer)

Location services - transfers requests from CN to RAN, and location

information from RAN to CN.

Simultaneous access to CS & PS core network domains for single UE

Paging the user, provides the CN with the capability to page user

equipment

Controlling the security by sending the security keys to RAN and by

Setting the operation mode for security functionsReporting data volume

Controlling the tracing of the user equipment activity


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21Groupe France TlcomIntroduction to UMTS & WCDMA / April 2008 /confidential/Oussama Akhdari

3G Generation General Aspects Introduction to UMTS


QoS Architecture

WCDMA Principles

Agenda


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UMTS QoS Architecture

UMTS QoS is provided by the UMTS bearer service, which consists of

two parts:

Radio access bearer (RAB) service

Provides the confidential transport of user data between the UE andCN with a QoS that is adequate for the negotiated UMTS bearer

Consists of a radio bearer (RB) service & a Iu bearer service

The RB service is realized in the radio link control (RLC) layer between

the SRNC & the UE, using UTRA FDD/TDD, while the Iu bearer service

provides transport between the UTRAN & CN

CN bearer serviceconnects the UMTS CN with CN gateway to theexternal network


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CN = Core network

TE = Terminal Equipment

MT = Mobile Termination


TE MT UTRAN CN Iu

EDGE

NODE

CN

Gateway

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service

(RAB)

CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService (RB)

UTRA FDD/TDD

Service

(Radio PhysicalBearer Service)

Physical

Bearer Service

TETE MT UTRAN CN Iu

EDGE

NODE

CN

Gateway

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service

(RAB)

CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService (RB)

UTRA FDD/TDD

Service

(Radio PhysicalBearer Service)

Physical

Bearer Service

TE


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24 Groupe France Tlcom

Introduction to UMTS & WCDMA / April 2008 /confidential/Oussama Akhdari


The RABis the service that the access stratum provides through its service

access points (SAP) to the non-access stratum (NAS) for transfer of user

data between the user equipment (UE) and the core network (CN)

The RABprovides transport of user data with the quality of service (QoS)

adequate to the UMTS bearer service negotiated on the non-access stratum.

This service is based on the characteristics of the radio interface and ismaintained for a moving user equipment

A bearer service includes all aspects to enable the provision of a contracted

QoS. These aspects are the control signaling, user plane transport, and QoS

management functionality

The UMTS operator offers the UMTS bearer service, which provides the

UMTS QoS.


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QoS Classes

There are four different QoS classes (or traffic classes) for UMTS

bearer service and radio access bearer service: conversational

streaming

interactive

background

The main distinguishing factor between these classes is how delay

sensitive the traffic is.

Conversational class is meant for traffic that is very delay sensitive,

while background class is the most delay insensitive traffic class. RNC manages the QoS requirements.

Data Integrity

sensitive

+

Delay

sensitive

-

+ -

Data Integrity

sensitive

+

Data Integrity

sensitive

+

Delay

sensitive

-

+

Delay

sensitive

-

+

Data Integrity

sensitive

+

Data Integrity

sensitive

+

Delay

sensitive

-

+

Delay

sensitive

-

+ --

Data Integrity

sensitive

+

Data Integrity

sensitive

+

Delay

sensitive

-

+

Delay

sensitive

-

+


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QoS Classes

Traffic classes provide the means for the network to differentiate between

end-to-end user applications according to their required trafficcharacteristics.

The purpose is to offer good quality connections for both real time & non-

real time traffic between MS and the background data networks.

The radio interface is the main capacity limiting factor & must be planned

& controlled to achieve the required system performance

Error correction and delay is managed and prioritized to ensure good

quality connections.


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Application Groups

Traffic class Conversational Class Streaming class Interactive class Background class

Fundamental

characteristics

Conversational RT. Preserve time

relation (variation)

between information

entities of the stream

. Conversational

pattern (stringent &

low delay)

. Streaming RT. Preserve time

relation (variation)

between information

entities of the stream

. Interactive besteffort

. Request response

pattern

. Preserve payload

content

. Background besteffort

. Destination is not

expecting the data

within a certain time

. Preserve payload

content

Example of the

applicationVoice Streaming video Web browsing

Background

download of emails

Service classes and priorities are one of the main differences between 2G

and 3G. Priorities are obtained from CN.

WCDMA RAN uses the QoS parameters obtained from CN to optimize

the use of radio resources. In GSM BSS, packet-switched traffic is always

lower priority traffic, using only whatever resources are available.


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3G Generation General Aspects Introduction to UMTS


QoS Architecture

WCDMA Principles

Agenda


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WCDMA Transmitter

The WCDMA transmitter looks similar to the TDMA transmitter, with

the synchronization, control/signaling and multiple user data channels.

In a WCDMA transmitter, neither time nor frequency is used to separatedifferent users, but codes in an operation known as spreading.


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W-CDMA No Frequency reuse

W-CDMA = Wideband Code Division Multiple Access

Users are separated with code sequences: spreading / despreadingtechnique

All users are transmitting simultaneously on the same frequency

In FDD mode, different frequencies are used on uplink and downlink

Frequency Planning No Frequency Planning

All cells are assigned

the same frequency

All cells within a

given cluster are

assigned different setof frequencies


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Spread spectrum technique

The user bits are coded with a unique sequence (code).

The bits of the code are called chips and the chip rate is higher than the

user bit rate

Time

Domain

Bandwidth = 3.84 Mhz for UMTS

Code Ci(t)

Resulting spread signal

Di (t) = Si (t) x Ci(t)

Bit1 Bit2

Source signal Si (t)

before spreading

Frequency

Domain

Narrowband signal

Bit Rate =Rb

Chip Rate =Rc = 3.84 Mcps in UMTS

Chip Rate =RcSpreading Factor

SF =Rc/Rb


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Channelization coding


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Spreading Example

Spreading with a spreading factor of 4 is shown in the Figure below.


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Spreading / Despreading

In the receiving path, despreading

is achieved by auto-correlation with

the same code

Due to low cross-correlation

properties with other codes, the

received signal energy is increasedcompared to noise and other signal

interference

The gain due to despreading is

called processing gain

Example for PS 128 Kbps:

dBkbps

kcps

RateBitUser

RateChipPG 77.1430

128

3840


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Spreading / Despreading

The figure shows the properties of the Channelization (Orthogonal) codes.


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Spreading example

De-spreading applied to

another user with a different

spreading code

Increase the data rate by 8

corresponds to a widening of

the occupied spectrum of the

spread user data signal


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Channelization codes

Orthogonal Variable Spreading Factor (OVSF) are used for channelization

for spreading

The codes are mutually orthogonal, if they are synchronized in the time

domain

Codes are taken from the OVSF code tree

The code tree corresponds to different discrete Spreading Factor

(SF) levels, SF=1, 2, 4, 8(n2)

SF: 4 - 512 is allowed in the WCDMA DL

SF: 4 - 256 is allowed in the WCDMA UL

Following codes are not allowed to be used:

Codes between a used code and the code tree root

Codes following a used code


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Spreading codes: OVSF code tree

SF = 1 SF = 2 SF = 4 SF = 8

Up

t

oSF

=

256

SF = 1 SF = 2 SF = 4 SF = 8

Up

t

oSF

=

256


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Uplink and Downlink Channelization Code Usage

Downlink: Channelization Codes used to distinguish data channels

coming from each cell

Uplink: Channelization Codes used to distinguish data channels

coming from each User Equipment, UE


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Spreading and scrambling codes

Spreading codes (channelization codes)

used to differentiate mobiles and services

different lengths (spreading factor) according to service in UMTSOrthogonal Variable Spreading Factor (OVSF) in UMTS

Scrambling codes

To distinguish between User Equipments in uplink

To distinguish between cells in downlink

DLUL

Node B

Spreading

OVSF(Service/ user identifier)

Scrambling

PN

(Cell identifier)

DescramblingDespreading

UE

Descrambling Despreading

Spreading

OVSF

(Service identifier)

Scrambling

PN

(User identifier)

What do YOU hear


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The CDMA Cocktail Party A) If you only speak Japanese?

B) If you only speak English?

C) If you only speak Italian?

D) If you only speak Japanese, but the

Japanese-speaking person is all the way

across the room?

E) If you only speak Japanese, but the

Spanish-speaking person is talking very

loudly?


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Scrambling Coding


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SC: Scrambling Code

Downlink Scrambling Code

SC#2

SC#0

SC#1

SC#116

SC#114

SC#115

RNC

SC#2

SC#0

SC#1

SC#2

SC#0

SC#1

SC#2

SC#0

SC#1

SC#116

SC#114

SC#115

SC#116

SC#114

SC#115

SC#116

SC#114

SC#115

RNC

Downlink scrambling code

The number of codes used in the downlink is restricted to 8192 in

Total to speed up the process for the UE to find the correctscrambling code.

512 of these are primary codes (the rest are secondary codes, 15 codesper primary).

The primary codes are divided into 64 code groups each group

containing 8 different codes.One code per cell (sector/carrier) : Configurable by operator

Only the primary scrambling code is used for all Common Channels


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Filtering

Filtering allows the transmitted bandwidth to be significantly reduced

without losing the content of the digital dataimproves the spectralefficiency

Raised-Cosine Data Filter

occupied bandwidth = symbol rate x (1+ )


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Near-Far-Problem

Illustration Example:Up to around 80 dB attenuation between UE1

and UE2

If UE1 and UE2 transmitted with the same power, UE1 would jam

UE2 : so-called near-far effect

Solution :power control

Need for an efficient power control able to fight against slow AND

fast fading!

UE 1

UE 2

Before despreading After despreading


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Power control

In UMTS FDD, all users are sharing the same frequency band

W-CDMA requires power control to minimize the level of interference

(interference-limited system)

Power controlis applied on both uplink and downlink

Power control minimizes the transmission power to match the quality

target for each radio access bearer service

No one should get more power than necessary to reach the required

QoSAvoids near-far problem on uplink

Minimizes waste of common power resource on downlink


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Interference limited

When the number of users in the cell increases, the interference level

increases (noise rise), the required received power at the base station to

reach a given Eb/Nt(quality) increases

For high interference level, the required received power becomes

infinite: power control is unstable pole capacity

0

2

4

6

8

10

12

14

16

18

20

0 10 20 30 40 50 60 70

Number of simultaneous users per sector

Interference

levelrelative

to

Noise

level

(dB)


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Cell breathing

Considering the limitation of maximal transmit power, the increase

of required received power due to high traffic will lead to decrease

the cell range

The cell coverage decreases when the traffic increases : so-called

cell breathing phenomenon

Coverage and capacity are linked in CDMA systems

L d t l


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Deployed intersite distance

Load control

In order to avoid power control instability and coverage holes due to high

traffic level the level of interference received by a base station should be

controlled by means of admission and load control algorithms


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Other W-CDMA particularities

No frequency reuse pattern

Scrambling code planning required

512 scrambling codes in W-CDMA

Soft-handover capability

RAKE receiver

SC#116

SC#114

SC#115

SC#2

SC#0

SC#1


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Mobile connected to more than onebase station during handover procedure

Called softer handover for sector

cells of the same site

Soft Handover for Dedicated

Channels (circuit and packet data)

Hard Handover

HS-DSCH

Inter-frequency handovers

Inter-RAT Handovers

Soft Handover i

Macrodiversity

Received

Pilot

Signal

Node-B 2

3 dB

Node-B 1

Same carrier

RNC


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Soft Handover ii

AdvantagesAvoids link failure during handover, make before break handover

Reduces the interference level by decreasing the required UEtransmit power

Increases downlink quality thanks to macro-diversity at the UE

receiver level

Drawbacks

Increases the required number of traffic channels

Can create too much downlink interference : trade-off on the

percentage area of soft-handover


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RAKE receiver

Reflections, diffractions, attenuations caused by obstacles will lead to

multipath

RAKE receiveris a spread-spectrum receiver that is able to track and

demodulate resolvable multipath components : takes benefit of multipath

diversity

In W-CDMA, with 3.84 Mcps, a RAKE receiver will be able to

discriminate multipath having delays higher than one chip duration (0.26

s)

Th RAKE R i


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The RAKE Receiver

CDMA Mobile Station RAKE Receiver Architecture

Each finger tracks a single multipath reflection

Also be used to track other base stations signal during softhandover

One finger used as a Searcher to identify other base stations

Finger #1

Finger #2

Finger #N

Searcher Finger

Combiner

Sum ofindividualmultipathcomponents

Power measurementof NeighboringBase Stations

Th RAKE R i


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0 50 100 150 200 250 300 350 400-2

0

2

4

6

8

10

12

14

16

18

0 50 100 150 200 250 300 350 400-2

0

2

4

6

8

10

12

14

16

18

0 50 100 150 200 250 300 350 400-2

0

2

4

6

8

10

12

14

16

18

The RAKE Receiver

1/2-chip delay

To Viterbi

Decoder

Composite Received Signal

PN, Walsh Codes

1/2-chip delay

1/2-chip delay

Ai

Ai

Ai

Correlator

Correlator

Correlator

Equal Combining, ML Combining,or Select Strongest

time

0 50 100 150 200 250 300 350 400-2

0

2

4

6

8

10

12

14

16

18

1

23

1

23

1

23

1

23

1

2

3 + Interference

+ Interference

+ Interference


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RAKE receiver ii

It combines the delayed replicas of the transmitted signal to improve

reception quality : time-diversity technique

Identify the delay positions on which significant energy arrives andallocate correlation receivers (RAKE fingers) to those peaks

Within each correlation receiver, track the changing phase andamplitude values and correct them (thanks to pilot symbol estimation)

Combine the demodulated and phase-adjusted symbols across all

active fingers and present them to the decoder for further processing(maximal ratio combining)

S di S t Ad t


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Spreading Spectrum Advantages

The wideband transmission has the advantage of being less sensitive to

frequency selective interference and fading.

The power density of the spectrum is decreased several timesand the

transfer of information is still possible even below background noise.

CDMA is very spectrum efficientdue to the possibility of reusing each

carrier in each cell.

High Capacity in comparison with GSM

Soft handoveris required in WCDMA.

S di S t D b k


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Spreading Spectrum Drawbacks

The power levels of all UEs transmissions received at the BS must be

equal if the bit rates are equal and therefore fast power control is

necessary

As UEs in soft handover mode require resources of more than one cell,the system capacity may be reduced.

questions


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an exchange!

based on discussions!

share our experiences

anyquestions?lets discuss!


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L i l h l i


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Logical channels i

PCCH - Paging control Channel (DL)DL Paging information

BCCH - Broadcast Control Channel (DL)

DL System control information

e.g. Cell identity, UL interference level

CCCH - Common control Channel (UL/DL)

For transmitting control information between the network and UEs

The CCCH is commonly used by UEs having no RRC connection andafter cell reselection

e.g. initial access (RRC connection request, cell update)

Logical channels ii


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Logical channels ii

CTCH - Common Traffic Channel (DL)

channel to transfer dedicated user information to all or a group ofUEs

e.g. SMS Cell broadcast

DCCH - Dedicated Control Channel (UL/DL)

transmits dedicated control information between UE and UTRAN

e.g. measurement reports, radio bearer setup

DTCH - Dedicated Traffic Channel (UL/DL)

The DTCH carries user datae.g. speech, Fax, video, web, ...

DL Transport Channels i


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DL Transport Channels i

BCH - Broadcast Channel

For broadcasting of system information over entire cellno power control, fix bit rate

PCH - Paging Channel

association with Page Indicator Channel PICH, to support efficient

sleep mode procedures

must be broadcast over entire cell

FACH - Forward Access Channel

Common DL channel used for transmission of

control information

small amount of packet data

open loop power control

D T Ch l ii


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DL Transport Channels ii

DCH - Dedicated Channel

DCH is the only Dedicated Transport Channel

Channel dedicated to one UE

Supports

Fast Power Control, variable bit rate, SHO, transmit diversity,beam forming

DSCH - Downlink Shared Channel

Similar to the FACH

Carries dedicated user data and/or control information

Always associated with a downlink DCH (with SF of 256)

DSCH supports

sharing between different users

no SFH, but Fast PC due to associated DCH

UL T t Ch l


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UL Transport Channels

RACH - Random Access Channel

carries control information or small amounts of packet data e.g. for initial access or non-real-time dedicated control or traffic

data

transmitted over entire cell supported by open loop power control

CPCH - Common Packet Channel

Similar to DSCH in DL, used for transmission of bursty data traffic

possibility to

transmit over part of the cell (beam forming)

change rate fast

fast power control

initial risk of collision, but collision detection (CD/CA-ICH)

is shared by the UEs in a cell -> common resource

DCH - Dedicated Channel (same as for UL)

Ph i l Ch l


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Physical Channels

Channels without connection to transport channels are called Stand-

alone channels

All Stand-alone channels exist in DL only

Stand alone channels are

CPICH Common Pilot Channel

SCH Synchronization Channel (Primary & Secondary)

AICH Acquisition Indication Channel

PICH Paging Indicator Channel

CSICH CPCH Status Indicator ChannelCD/CAICH Collision Detection / Channel Assignment

Indicator Channel


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DL Physical Channels - CPICH

CPICH - Common Pilot ChannelPrimary CPICH (PCPICH)

SF=256, predefined bit/symbol sequence, fixed channelization code

Scrambled with the primary scrambling code Only one PCPICH per cell

Used for level measurements & channel estimation

The PCPICH is the phase reference for all DL physical channels

Transmitted over the entire cell

Secondary CPICH (SCPICH)

SF=256, arbitrary channelization code

Zero, one or several SCPICH per cell Not necessarily transmitted over entire cell


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DL Physical Channels - Other Stand-Alone


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DL Physical Channels - Other Stand-Alone

AICH - Acquisition Indication Channel

SF256, Frame length 20ms 5120 chips/slot Used to confirm reception of (P)RACH

PICH - Paging Indicator Channel

SF=256, carries the paging indicators

associated with an SCCPCH to which a PCH transport channel is

mapped Once a PI message has been detected on the PICH, the UE decodes

the next PCH frame transmitted on the SCCPCH whether there is apaging message intended for it.

CSICH - CPCH Status Indication Channel

CD/CA-ICH - CPCH Collision Detection/Channel Assignment IndicatorChannel

All CPCH related physical channels support the operation of the ULCPCH transport channel


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UL DPCH

UL Physical Channels

UL Channels associated with a transport channel PRACH - Physical Random Access Channel

Carries RACH

open loop power control / collision risk

PCPCH - Physical Common Packet Channel

Carries CPCH

Fast power control on the message part / open loop for pre-ample

DPCCH - Dedicated Physical Control Channel

Pilot field, TFCI field, FBI field, TPC field

DPDCH - Dedicated Physical Data Channel

Carries real user data + Layer 3 signaling on DCCH


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Valid for all Dedicated Physical Channels

Existing in uplink or downlink

Possibility to use beam forming

Possibility to change rate fast on a frame basis (10 ms)

Fast power control (Closed Loop Power Control)

DL Physical Channel Example


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One radio frame, Tf= 10 ms

TPC

NTPCbits

Slot #0 Slot #1 Slot #i Slot #14

Tslot= 2560 chips, 10*2kbits (k=0..7)

Data2

Ndata2bits

DPDCH

TFCI

NTFCIbits

Pilot

Npilotbits

Data1

Ndata1bits

DPDCH DPCCH DPCCH

DL Physical Channel Example

Example of physical channel structure: DL - DPDCH

Signaling information (DPCCH) is time multiplexed with DPDCH

UL Physical Channel Example


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Pilot

Npilotbits

TPC

NTPCbits

Data

Ndatabits

Slot #0 Slot #1 Slot #i Slot #14

Tslot= 2560 chips, 10 bits

1 radio frame: Tf= 10 ms

DPDCH

DPCCHFBI

NFBIbitsTFCI

NTFCIbits

Tslot= 2560 chips, Ndata= 10*2kbits (k=0..6)

UL Physical Channel Example

Example of physical channel structure: UL - DPDCH/DPCCH

DPCCH and DPDCH are in UL NOT time multiplexed, they are I/Q

multiplexed.

Use of DPCCH


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Use of DPCCH

On the DPCCH channel the following information is transmitted

Pilot field

Bit sequence known in the receiver and and used for radio channelestimation

Optimal adaptation of RAKE receiver

TFCI field

Transport Format Combination Indicator

FBI field (UL DPCCH only)

Feed Back Information given by the UE to the Node B

for optimizing

closed loop transmit diversity mode (phase &

amplitude)

site selection diversity transmission (SSDT)TPC field

Transmit Power Control

This field is used to transmit the power control commands to theNode B (UL) or the the UE (DL).

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1-Introduction to UMTS and WCDMA.ppt

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