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Huawei Confidential. All Rights Reserved
WCDMA Principles
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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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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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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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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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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
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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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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
Chapter 3 WCDMA TechnologiesChapter 3 WCDMA Technologies
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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
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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
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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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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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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
-- 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
Chapter 3 WCDMA TechnologiesChapter 3 WCDMA Technologies
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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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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
-- 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
Chapter 3 WCDMA TechnologiesChapter 3 WCDMA Technologies
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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