general description of 3g

8/3/2019 General Description of 3G

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Wireless Curriculum Development SectionWireless Curriculum Development SectionWireless Curriculum Development Section

ISSUEISSUE

General Description of 3GGeneral Description of 3G

1.01.0


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Confidential Information of Huawei.No Spreading without Permission. Security Level: Internal

Course ContentsCourse Contents

Chapter 1 Introduction to IMTChapter 1 Introduction to IMT--20002000

Chapter 2 CDMA FundamentalChapter 2 CDMA Fundamental

Chapter 3 Performance Enhancement MethodsChapter 3 Performance Enhancement Methods

Chapter 4 WCDMA FDD ModeChapter 4 WCDMA FDD Mode


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1st Generation1980s (analog)

2nd Generation

1990s (digital)

3rd Generation

current (digital)

3G provides: Complete integrated service solutions High bandwidth Unified air interface

Best spectral efficiency and a step towards PCS

AMPS

Analog to DigitalTACS

NMT

OTHERS

GSM

CDMAIS95

TDMA

IS-136

PDC

UMTSWCDMA

CDMA2000

TD-SCDMA

Development of Mobile CommunicationsDevelopment of Mobile Communications

Voice to Broadband


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

l

1985: FPLMTS, renamed as IMT-2000 in 1996l 1992: 230MHz spectrum was allocated in WRC92

l 1999.3: Key parameters of IMT-2000 RTT were completed

l 1999.11: Technical specifications of IMT-2000 RTT were

completedl 2000: All the network standards of IMT2000 were

completed

l Family concept was adopted in network part

l Standardization organizations such as 3GPP(1998.12),3GPP2 (1999) were established


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Target of IMT-2000Target of IMT-2000

l Global uniform frequency band and standard, global

seamless coverage

l High efficient spectrum utility

l High quality of service, high security

l Easy for evolution from 2G system

l Providing multimedia service

Car speed environment: 144kbps

Walk speed environment: 384kbps

Indoor environment: 2048kbps


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Standards for 3GStandards for 3G

3G system

CDMA2000

3GPP2

FDD mode

WCDMA

3GPP

FDD/TDD mode

TD-SCDMA

CWTS

TDD mode


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Main CDMA 3G ProposalsMain CDMA 3G Proposals

TD-SCDMACWTSChina

W-CDMAETSI(SMG 2)Europe

W-CDMAARIBJapan

TTA2(~W-CDMA)

TTA1(~cdma2000)TTAKorea

W-CDMAT1

cdma2000TIA(TR 45.5)U.S.

Radio Transmission

Technology(RTT)

Regional Standard

Organization(RSO)


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Spectrum Allocation of IMT-2000Spectrum Allocation of IMT-2000

1850 1900 1950 2000 2050 2100 2150 2200 2250

ITU

Europe

USA MSSPCS

A D B BC D CE F A FE MSSReserveBroadcast auxiliary

2165 MHz1990 MHz

1850 1900 1950 2000 2050 2100 2150 2200

2250

1880 MHz 1980 MHz

UMTSGSM 1800 DECT MSS

1885 MHz 2025 MHz

2010 MHz

IMT 2000

MSSUMTS

Japan MSSIMT 2000MSSIMT 2000PHS

1895

1918

BC

1885

A A

2170 MHz

IMT 20002110 MHz 2170 MHz

MSS MSS

CDMATDDWLL

FDDWLL

1980

2025MHz

GSM1800

CDMAFDDWLL

1960

1920

1945

China

cellular(1) cellular(2) cellular(2)

1805 MHz

1865

1865

1870

1885

1890

1895

1910

1930

1945

1965

1970

1975


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3G Spectrum (After WARC2000)3G Spectrum (After WARC2000)

1850 1900 1950 2000 2050 2100 2150 2200 2250

Reserve

UMTSGSM 1800

DECT MSS

MSSIMT 2000PHS MSSIMT 2000

IMT 2000

MSSIMT 2000IMT 2000

IMT 2000

MSSUMTS

MSS

A D B EF A B C

MSS

MSS MSS

[GSM 1800, PCS]

FEB BC

ITU Identifications

Europe

China**

Japan,

Korea (w/o PHS)

Americas***

1700 1750 1800950 1000800 850 900

IMT 2000IMT 2000

2500 2550 2600 2650 2700

IMT 2000

UMTS

GSM

Cellular

PDC

Cellular

MSS

GSM

IMT-

2000

IMT 2000

IMT 2000UPCS

PCS

* *

D

IMT 2000


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QoS Requirements of Different ServicesQoS Requirements of Different Services

Time delay

Quality (BER)

background

conversational

streaming

interactive


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ll 2.1 Radio Transmission Environment2.1 Radio Transmission Environment

l 2.2 Multiple Access Technology and

Duplex Technology

l 2.3 CDMA Principle and RAKE Technology


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Multi-path EnvironmentMulti-path Environment

Time

Received

signal

Transmitted

signal


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FadingFading

l Transmitted Signal

- 4 0

- 3 5

- 3 0

- 2 5

- 2 0

- 1 5

- 1 0

- 5

0

dB

l Received Signal


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FadingFading

Distance(m)

Received Power(dBm)

10 20 30

-20

-40

-60

Slow fading

Fast fading


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Frequency Selection of FadingFrequency Selection of Fading

NarrowbandSystem

FadingFading

Transmit SignalTransmit Signal Received SignalReceived Signalffff

P(f)P(f) P(f)

Fading

Transmit Signal Received Signalff

P(f) P(f)

BroadbandSystem


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Multi-path Characteristics of Mobile ChannelMulti-path Characteristics of Mobile Channel

l Electromagnetic transmission - reflection,scattering,diffraction

l Signal fading can be divided into three parts in radio

environment:

Path loss: with big range of fading

Big scale fading:slow-speed, with middle range of fading, also

with logarithm normal distribution characteristic

Small scale fading: fast-speed, with small range of fading

l Two typical types of small scale fading include:

Rayleigh distribution (not line-of-sight transmission)

Ricean distribution(line-of-sight transmission)


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Category of Typical Radio ChannelCategory of Typical Radio Channel

l Static Channel

l Indoor Channel

l Outdoor-to-indoor pavement Channel

l Vehicle mounted Channel

l Moving Channel

l Birth-death Channel


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l 2.1 Radio Transmission Environment

ll 2.2 Multiple Access Technology and2.2 Multiple Access Technology and

Duplex TechnologyDuplex Technology

l 2.3 CDMA Principle and RAKE Technology


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Multiple Access Technology and Duplex

Technology

Multiple Access Technology and DuplexTechnology

l Multiple access technology

Time division multiple access (TDMA)

Frequency division multiple access (FDMA)

Code division multiple access (CDMA)

l Duplex technology

Time division duplex (TDD)

Frequency division duplex (FDD)


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Traffic channels: differentusers are assigned uniquecode and transmitted overthe same frequency band,for example, WCDMA andCDMA2000

Traffic channels: different frequency bandsare allocated to different users,for example,AMPS and TACS

Traffic channels: different time slotsare allocated to different users, forexample, DAMPS and GSM

Frequ

ency

Time

Power

Frequ

ency

Time

Power

Frequ

ency

Time

Power

FDMA

TDMA

CDMA

User

User

UserUser

U

ser

User

Multiple Access Technology and Duplex

Technology

Multiple Access Technology and DuplexTechnology


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Characteristics of CDMA SystemCharacteristics of CDMA System

lHigh Spectral Efficiency

Frequency multiplex coefficient is 1.

l soft capacity

Quality

Coverage

Interference

l Self-interference system

A UE transmission power is interference for another UE.


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Processing Procedure of CDMA SystemProcessing Procedure of CDMA System

Sourcecoding

Channel

codingSpreading Modulation

Source

decoding

Channel

decodingDespreading Demodulation

Radio channel


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l 2.1 Radio Transmission Environment

l 2.2 Multiple Access Technology and

Duplex Technology

ll 2.3 CDMA Principle and RAKE Technology2.3 CDMA Principle and RAKE Technology


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correlationcorrelation

l

Correlation is a measure of similarity of between any twoarbitrary signals.

l EXAMPLE:

-1 1 -1 11 1 1 1

-1 1 -1 1

Zero correlation

Orthogonal signals

-1 1 -1 1

-1 1 -1 -1

1 1 1 11 correlationIdentical signals

+10

-1

+10-1

+10

-1

+10

-1


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OVSF&WalshOVSF&Walsh

SF = 1 SF = 2 SF = 4

C ch,1,0 = (1)

C ch,2,0 = (1,1)

C ch,2,1 = (1,-1)

C ch,4,0 =(1,1,1,1)

C ch,4,1 = (1,1,-1,-1)

C ch,4,2 = (1,-1,1,-1)

C ch,4,3 = (1,-1,-1,1)

l Creating the orthogonal code sequences


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AutocorrelationAutocorrelation

l Autocorrelation is related to the muti-path interference characteristic.

Delay time (chip)

Correlation

Delay time sequence correlation

0 -1 -1 -1 1 1 -1 1 11 -1 -1 1 1 -1 1 -1 -1/7

2 -1 1 1 -1 1 -1 -1 -1/73 1 1 -1 1 -1 -1 -1 -1/7

4 1 -1 1 -1 -1 -1 1 -1/7

5 -1 1 -1 -1 -1 1 1 -1/76 1 -1 -1 -1 1 1 -1 -1/7

1

Example: -1 -1 -1 1 1 -1 1


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Configuration of Gold Sequence GeneratorConfiguration of Gold Sequence Generator

clong,1,n

clong,2,n

MSB LSB

l Gold sequence is used as scrambling code in WCDMA


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Spreading and Despreading (DS-CDMA)Spreading and Despreading (DS-CDMA)

Spreading

Despreading

Chip

Symbol

Data

Spreading code

Spreading signal=Datacode

Data

=Spreadingcode

1

-1

1

-1

1-1

1

-1

1

-1

Spreading code


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Desired signal

Other users signal

Desired spreading signal

Spreading code

Data after despreading

Other spreading signal

Other signal after integration

1

-1

1

-1

1

-1

8

-8

1-1

8

-8

Data after integration

Other signal after despreading

Spreading and Despreading (DS-CDMA)Spreading and Despreading (DS-CDMA)


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Spreading code

Spreading code

SignalCombination

Spectrum Analysis of Spreading & DespreadingSpectrum Analysis of Spreading & Despreading

Narrowband signal

f

P(f)

Broadband signal

P(f)

f

Noise

P(f)

f

Noise+Broadband signal

P(f)

f

Recovered signal

P(f)

f


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Principle 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 andsignal strength

Combiner The combinedsignal

tt

s(t) s(t)


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Structure of RAKE ReceiverStructure of RAKE Receiver

Q

I

Combiner

I

Matched

Filter

PhaseRotator

Channelestimator

Delay

Equalizer

I

Q

Path 1

Path 2

Path 3

Input signal

Correlator

Code

generators Q


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Advantages of CDMAAdvantages of CDMA

l RAKE receiver is adopted

The time diversity effect generated by channel coherence time is

efficiently used.

l frequency diversity

Wideband frequency spectrum

l Higher interference tolerance and security performance

Low signal transmission power

l Great flexibility in carrying multiple services with largely different

bit rate and QoS requirement.

Different spreading factors for different services with different data

rates

l High spectral efficiency

All users can share the same frequency spectrum simultaneously.

l Supporting soft handover and softer handover.


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Introduction to Diversity TechniqueIntroduction to Diversity Technique

l Reduce the effects of fading

fast fading caused by multipath

Slow fading caused by shadowing

l Improve the reliability of communication

l Increase the coverage and capacity

l Macroscopic diversity

Soft handover and softer handover

Reduce large-scale fading

l Microscopic diversity

l Diversity technique is used to obtain uncorrelated

signals for combining


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Microscopic DiversityMicroscopic Diversity

l Time diversity

Channel coding, Block interleaving, error-correction

l Frequency diversity

The user signal is distributed on the whole bandwidth

frequency spectrum

l

Space diversity Receive diversity

Transmit diversity

l Polarization diversity

Vertical polarization

Horizontal polarization


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Basic Combining MethodsBasic Combining Methods

l Maximal-Ratio Combiner The mutipath signals are weighted proportional to their

signal SNR and then summed.

l Equal-Gain Combiner

Equal-gain combining is similar to maximal-ratio

combining, but there is no attempt to weight the signalbefore addition.

l Selection Combiner

Choose the signal with the highest instantaneous quality,

so the output quality is equal to that of the best incoming

signal.


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WCDMA Rx/Tx DiversityWCDMA Rx/Tx Diversity

l Forward link capacity is the bottle neck of CDMA cellular

system capacity. WCDMA standard has deeply researched

the application of transmission diversity. New transmit

diversity scheme has been put forward. It will improve

forward link capacity.

l Open loop transmission diversity

transmit diversity based on space-time block coding (STTD)

Time switched transmit diversity on SCH (TSSD)

l Closed loop transmission diversity, FBI domain

l Site selection diversity(macro diversity) cell selection, FBIdomain

Transmitter Antenna DiversityTransmitter Antenna Diversity


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Transmitter Antenna Diversity

Based on Time-space Block Coding

Transmitter Antenna Diversity

Based on Time-space Block Coding

b2b0b1 b3

b0b1 b2 b3

-b2 b3 b0 -b1

Antenna 1

Antenna 2

Channel bits

STTD encoded channel bits

for antenna 1 and antenna 2.


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Time Switched Transmit Diversity on SCHTime Switched Transmit Diversity on SCH

Antenna 1

Antenna 2

acsi,0

acp

acsi,1

acp

acsi,14

acp

Slot #0 Slot #1 Slot #1

acsi,2

acp

Slot #2


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Closed Loop Transmit DiversityClosed Loop Transmit Diversity

Spread/scramble

w 1

w 2

DPCHDPCCH

DPDCH

Rx

Rx

CPICH1

Tx

CPICH2

An

An

Tx

W eight Generation

w1 w2

Determine FBI messagefrom Uplink DPCCH


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Receiving Effects for Different Multi-path DiversityReceiving Effects for Different Multi-path Diversity

5 1 0 1 5

S NRd B)0 . 0 0 0 1

0 . 0 0 1

0 . 0 1

0 . 1

1

B

E

R

1 - p a t h r a y l

2 - p a t h r a y l

5 - p a t h r a y l

No a t t e n u a t i o n


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S t A tS t A t


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Smart AntennaSmart Antenna

Omni antenna Directional antenna Smart antenna

C C t tC C t t


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Characteristics of WCDMA FDDCharacteristics of WCDMA FDD


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Characteristics of WCDMA FDDCharacteristics of WCDMA FDD

l Satisfy the minimum performance requirement of IMT2000

l Compatible with GSM-MAP core network

l Comparatively steady version R99 has been released

l Support open loop and closed loop transmit diversity mode

l Support Common Packet Channel(CPCH) and Downlink Share

Channel, adapt to Internet data access mode

l Support macro diversity, selection diversity of NodeB location

l Support different fast power control algorithms and open loop,

out loop power control

l Fully support UE locating services

WCDMA Voice EvolutionWCDMA Voice Evolution


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WCDMA Voice EvolutionWCDMA Voice Evolution

l Adopt AMR voice coding, and support voice quality of

4.75Kbps ~ 12.2Kbps

l Adopt soft handover and transmit diversity to improve

system capacity

l Provide high fidelity voice mode

l Fast power control

Data Service Evolution of WCDMAData Service Evolution of WCDMA


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Data Service Evolution of WCDMAData Service Evolution of WCDMA

l Support maximum 2Mbps data service

l Support packet switch

l Adopt ATM platform currently

l Provide QoS

l Common Packet Channel(CPCH) and Downlink Share

Channel(DSCH) can support Internet packet services better

l Provide mobile IP service(dynamic allocation of IP addresses)

l TFCI domain provides dynamic data rate

l Provide high-quality support for uplink-downlink symmetric

data service, such as voice, video phone, conference TV


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