1 WCDMA Principle.

8/4/2019 1 WCDMA Principle.

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Huawei Confidential. All Rights Reserved

WCDMA Principles


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2 Internal Use

Chapter 1 IntroductionChapter 1 Introduction

Chapter 2 WCDMA Network StructureCDMA Network Structure

Chapter 3 WCDMA TechnologiesChapter 3 WCDMA Technologies

Chapter 4 WCDMA RNC AreaChapter 4 WCDMA RNC Area


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3 Internal Use

Mobile Network EvolutionMobile Network Evolution

1G

Analogue

2G

Digital

2.5GPacket Data

2.75G

Enhanced Data

NMT

NMT

TACS

TACS

AMPS

AMPS

GSM

GSM

CDMA

CDMA

TDMA

TDMA

PDC

PDC

GPRS

GPRS

EDGE

EDGE

CDMA 1X

CDMA 1X

WCDMA

WCDMA

TD-SCDMA

TD-SCDMA

cdma20001X EV-DO

cdma20001X EV-DO

2M, 14M

2M

2.4M

384K

144K

1982-1996+ 1992-2002+ 2001+ 2004+ 2002-2004+

115K


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4 Internal Use

Standardization Course of ITU IMT-2000Standardization Course of ITU IMT-2000

1985: ITU-T form FPLMTS.Later renamed as IMT-2000 in

1996

1992: 230MHz spectrum was

allocated in WARC92

Standardization organizations

such as 3GPP(1998.12),

3GPP2(1999) were

established

2000: All the network

standards of IMT2000 were

completed

Family concept was

adopted in network part

ITU-MC

CDMA2000

ITU-DS

WCDMA

ITU-TC

UMTS

TDD

ITU-SC

UWC-136

ITU-FT

DECT

IMT2000

3GPP 3GPP2 CWTS ETSI


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5 Internal Use

Main CDMA 3G ProposalsMain CDMA 3G Proposals

Regional Standard

Organization(RSO)

Radio Transmission

Technology(RTT)

U.S. TIA(TR 45.5) cdma2000

T1 WCDMA

Korea TTA TTA1(~WCDMA)

TTA2(~cdma2000)

Japan ARIB WCDMA

Europe ETSI(SMG 2) WCDMA

China CWTS TD-SCDMA


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6 Internal Use

Target of IMT2000Target of IMT2000

Global uniform frequency band and standard, global seamless

coverage

High efficient spectrum utility

High quality of service, high security

Easy for evolution from 2G system Providing multimedia service

Car speed environment: 144kbps

Walk speed environment: 384kbps

Indoor environment: 2048kbps


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QoS Requirements of Different ServicesQoS Requirements of Different Services

Sensitivityof delay

Sensitivityof error

background

conversational

streaming

interactive


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WCDMA FDDWCDMA FDD

WCDMA FDDMultiple access method DS-CDMA

Duplex Method Frequency Division

Frequency Band Uplink : 1920-1980MHz, Downlink : 2110-2170MHz

Base Station Synchronization Asynchronous/Synchronous operation

Chip Rate 3.84Mcps

Frame Length 10ms

Service multiplexing Multiple Services with different QoS aremultiplexed on a single connection

Multi-user detection, smart antennas Supported by standard, optional in implementation

Power Control Fast Power Control, 1.5KHz

Handover Softer, Soft & Hard Handover

Transmit Diversity Open & Closed Loop

Voice Coding AMR Voice Coding, rate 4.75kb 12.2kbps


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WCDMA Voice EvolutionWCDMA Voice EvolutionWCDMA Voice EvolutionWCDMA Voice Evolution

Adopt AMR voice coding, and support voice quality of 4.75Kbps

~ 12.2Kbps

Adopt soft handover and transmit diversity to improve system

capacity

Provide high fidelity voice mode

Fast power control


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Data Service Evolution of WCDMAData Service Evolution of WCDMAData Service Evolution of WCDMAData Service Evolution of WCDMA

Support maximum 2Mbps data service

Support packet switch

Adopt ATM platform currently

Provide QoS

Common Packet Channel(CPCH) and Downlink Share

Channel(DSCH) can support Internet packet services better

Provide high-quality support for uplink-downlink symmetric data

service, such as voice, video phone, conference TV


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WCDMA Network StructureWCDMA Network Structure

GSM /GPRS BSS

BTS

BSC

PCU

SS7

SCP

SMS

SCE

PSTN/other PLMN

Internet,

Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CGBG

GGSN

PS backbone

Other PLMN

CS domain

PSdomain

NodeB

RNC

UTRAN

Iu-CS

Iu-PS

A

Gb


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WCDMA InterfacesWCDMA Interfaces

A Interface

A-bis

Um

MSCMSC

BSCBSC

BTSBTS

UE

SGSNSGSN

Gb

GSM

Iub

Uu

MSCMSC

RNCRNC

NodeBNodeB

UE

SGSNSGSN

Iu-PSIu-CS

Iub

Uu

RNCRNC

NodeBNodeB

UE

Iur

WCDMA

UTRANBSS



Section 1Section 1

-- Correlation FunctionCorrelation Function

- OVSF and PN code- OVSF and PN code- Information Spreading & Recovery- Information Spreading & Recovery

- Rake Receiver- Rake Receiver

Section 2Section 2

- WCDMA Transmission Block Diagram- WCDMA Transmission Block Diagram

Section 3Section 3

- Power Control- Power Control- Handover- Handover

- Diversity- Diversity




Correlation FunctionCorrelation FunctionCorrelation FunctionCorrelation Function

Correlation is a measure of similarity between any two arbitrary

signals.

EXAMPLE:

-1 1 -1 11 1 1 1-1 1 -1 1

Zero correlationOrthogonal signals

-1 1 -1 1

-1 1 -1 1

1 1 1 11 correlation

Identical signals

+1

0

-1+1

0

-1

+1

0-1

+1

0

-1



Orthogonal FunctionOrthogonal Function

Orthogonal functions have zero correlation. Two binary sequences are

orthogonal if their XOR output contains equal number of 1s and 0s

0000

0101

0101

EXAMPLE:

1010

0101

1111



OVSF & Walsh CodeOVSF & Walsh Code

SF = 1 SF = 2 SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)


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SF and Service RateSF and Service Rate

Symbol Rate*SF=Chip Rate

In WCDMA system, if chip rate=3.84MHz, SF=4, then symbolrate=960Kbps;

Symbol Rate=(Service Rate + Checking Code)*Channel Coding Rate*

Repeat or Puncture Rate

In WCDMA system, if service rate=384Kbps, channel coding=1/3 Turbo

coding, then symbol rate=960Kbps;


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Scrambling CodeScrambling Code

Scrambling codes

GOLD sequence.

Uplink scrambling codes

Uplink scrambling codes are used to distinguish different UEs

Downlink scrambling codes

For downlink physical channels, a total of 218 -1 = 262,143 scrambling

codes can be generated.

Only scrambling codes k = 0, 1, , 8191 are used.

8192 codes are divided into 512 groups, each of which contains 16

scrambling codes.

The first scrambling code of each group is called primary scramblingcode (PSC), and the other 15 ones are secondary scrambling codes

(SSC).


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21 Internal Use

OVSF and PN Code UsageOVSF and PN Code Usage

OVSF Code PN Code

Usage Uplink : Separate physicaldata (DPDCH) & controlchannels (DPCCH) from thesame terminal

Downlink : Separatedownlink connections todifferent UEs within the cell

Uplink : Separation of UEs

Downlink : Separation ofcells

Length Uplink : 4 256 chips

Downlink : 4 512 chips

Uplink/Downlink :

10ms = 38400 chips

Number of codes Number of codes under onescrambling factor = spreadingfactor

Uplink : Several Million

Downlink : 512

Code Family Orthogonal VariableSpreading Factor (OVSF)

Gold code

Bandwidth Spreading increasetransmission bandwidth

No change in transmissionbandwidth


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Information spreading over orthogonal codesInformation spreading over orthogonal codes

1 0 0 1 1

0110 0110 0110 0110 0110

1001 0110 0110 1001 1001

User Input

Orthogonal

Sequence

Tx Data

+1

-1

+1

-1


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Information recoveryInformation recovery

1 0 0 1 1+1

-1

Rx Data 1001 0110 0110 1001 10010110 0110 0110 0110 01101111 0000 0000 1111 1111

Correct Function

? ? ? ? ?

Rx Data 1001 0110 0110 1001 1001

0101 0101 0101 0101 01011100 0011 0011 1100 1100

Incorrect Function


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Spreading and De-spreadingSpreading and De-spreading

information pulse interference White noise

The improvement of time-domain information rate means that the bandwidth of spectrum-domain

information is spread.

S(f) is the energy density.

f

S f

The spectrum before spreading

information

f0

The spectrum before despreading

information

Interference/noise

S f

f0 f f0

The spectrum after despreading

information

Interference/noise

S f

f

The spectrum after spreading

information

f0

S f

f


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25 Internal Use

Principle of RAKE ReceiverPrinciple of RAKE ReceiverPrinciple of RAKE ReceiverPrinciple of RAKE Receiver

RAKE receiver help to overcome on the multi-path fading and enhance

the receive performance of the system

Receive set

Correlator 1

Correlator 2

Correlator 3

Searcher correlatorCalculate the

time delay and

signal strength

Combiner The combined

signal

tt

s(t) s(t)


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Section 1Section 1




Section 2Section 2


Section 3Section 3





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Block Diagram of WCDMA SystemBlock Diagram of WCDMA System

Source

coding

Channel

codingSpreading Modulation

Sourcedecoding

Channel

decodingDespreading Demodulation

Radio channel


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Common Technical TermsCommon Technical Terms

Bit, Symbol, Chip:

A bit is the input data which contain information

A symbol is the output of the convolution, encoder, and the

block interleaving

A chip is the output of spreading

Processing Gain:

Processing gain is the ratio of chip rate to the bit rate. Closely related to spreading factor, SF.

Forward direction/ Downlink : Information path from base station to

mobile station

Reverse direction/ Uplink : Information path from mobile station to

base station


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29 Internal Use

WCDMA SystemWCDMA System

Source Coding

Voice : Adaptive multirate technique with rate 4.75kbps 12.2kbps

Channel Coding

CRC Attachment. Check for error during transmission. Voice : CRC check returns error, discard information

Data : CRC check returns error; ask for retransmission

Convolutional or Turbo Coding

Convolution coding for voice and low speed signaling

Turbo Coding for large data transmission. Better performance than convolutional coding

Interleaving

Distribute error over data transmitted

Rate Matching

Match symbol rate to that accepted by spreading

Rate matching technique : Repeat or puncturing


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WCDMA SystemWCDMA System

Spreading

Spreading (OVSF code) SF 4 512, depends on data rate

Scrambling (Gold Code)

Modulation

QPSK


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Section 1Section 1




Section 2Section 2


Section 3Section 3




P C t lP C t l


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Power ControlPower Control

Open Loop Power Control

Set initial power for transmission of PRACH

Closed Loop Power Control

Inner Loop Power Control Uplink : Controls power of NodeB.Downlink : Ensures all power received at NodeB are just enough to

maintain satisfactory connection

Fast Power Control : 1.5khz

Outer Loop Power Control

Set SIRthreshold based on BER/BLER

O L P C t lO L P C t l


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Open Loop Power ControlOpen Loop Power Control

Controlled by UE.

Determine UE initial transmission power for random access procedure.

Not in use when inner loop power control running.

UE obtain information from network on:

CPICH power

Uplink interference level

Constant value (Default = 2dB)

UE Initial Power = CPICH power CPICH_RSCP + UL interference +UE Initial Power = CPICH power CPICH_RSCP + UL interference +

ConstantConstant

System information :

CPICH power, UL interference & constant

PRACH Tx power


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Inner Closed Loop Power ControlInner Closed Loop Power Control

Power Control Bit Located in UE & NodeB

Controls power of dedicated physical channels

Power controls occurs at 1500Hz, thus known as

fast power control

NodeB and UE continuously measure and compare

SIRmeasured with SIRthreshold value, and inform each

other to increase /reduce its power accordingly.

UE1 UE2 UE3 UE4

With Optimum Power Control

UE1

UE2

UE3

UE4

Without Power Control

Received

Received

(SIR)measured

NodeB

UE2

UE3

UE1

UE4

SIR threshold

O t Cl d L P C t l


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Outer Closed Loop Power ControlOuter Closed Loop Power Control

Adjust SIR for every user

Needed to keep track of changes in radio environment Aims to provide required quality

IfSIRthreshold reaches its maximum, system has to perform

- inter-frequency/inter-system handover- RRC connection release

BER/BLER Value

Change in (SIR)threshold

RNCSIR threshold

H d


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HandoverHandover

Softer handoverSofter handover-

Handover between intra-frequency cells under the control of the same BTS- Radio link connection to new target cell is created before existing connection

being deleted.

Soft handoverSoft handover- Handover between intra-frequency cells under the control of the different BTSs

Hard handoverHard handover- Condition of hard handover:

Intra-frequency handover, cells controlled by different RNCs and no Iur interfacebetween them

Inter-frequency handover

Inter-system handover

Interruption in voice or data communication occurs but this interruption

does not effect the user communication

S ft/S ft H dS ft/S ft H d


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Soft/Softer HandoverSoft/Softer Handover

Selection combination in the RNC during soft handoff

Maximum ratio combination in the NodeB during softer handoffs

Combine all the

power from each

sector

Power received from

a single sector


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Transmission Diversity : STTDTransmission Diversity : STTD

Space Time transmit Diversity (STTD)

Transmission

diversity

processing

Restoring data stream

Path1

Path2

Antenna 2

Antenna 1

B0 B1 B2 B3

B2 B3 B0 B1

B0 B1 B2 B3

B0 B1 B2 B3


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Transmission Diversity : TSTDTransmission Diversity : TSTD

Time Switch transmit Diversity (TSTD)

Used in synchronization physical channel ( SCH)

Transmission

diversity

processing

Data stream 1

Data stream 2

Data stream Restoring data stream

Path1

Path2

Antenna 2

Antenna 1


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1 WCDMA Principle.

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