a2 general description of 3g

7/31/2019 A2 General Description of 3G

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Wireless Curriculum Development Section

ISSUE

OWR00001 General Description of 3G

1.0


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

Course Contents

Chapter 1 Introduction to IMT-2000

Chapter 2 CDMA Fundamental

Chapter 3 Performance Enhancement Methods

Chapter 4 WCDMA FDD Mode


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1st Generation

1980s (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

TDMAIS-136

PDC

UMTSWCDMA

CDMA2000

TD-SCDMA

Development of Mobile Communications

Voice to Broadband


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Standardization Course of ITU IMT-2000

1985: FPLMTS, renamed as IMT-2000 in 1996

1992: 230MHz spectrum was allocated in WRC92

1999.3: Key parameters of IMT-2000 RTT were completed

1999.11: Technical specifications of IMT-2000 RTT were

completed

2000: All the network standards of IMT2000 were

completed

Family concept was adopted in network part Standardization organizations such as 3GPP(1998.12),

3GPP2 (1999) were established


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Target of IMT-2000

Global uniform frequency band and standard, globalseamless 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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Standards for 3G

3G system

CDMA2000

3GPP2

FDD mode

WCDMA

3GPPFDD/TDD mode

TD-SCDMA

CWTS

TDD mode


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Main CDMA 3G Proposals

Regional Standard

Organization(RSO)

Radio Transmission

Technology(RTT)

U.S. TIA(TR 45.5) cdma2000

T1 W-CDMA

Korea TTA TTA1(~cdma2000)

TTA2(~W-CDMA)

Japan ARIB W-CDMA

Europe ETSI(SMG 2) W-CDMA

China CWTS TD-SCDMA


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Spectrum 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)

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 E F 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 Services

Time delay

Quality (BER)

background

conversational

streaming

interactive


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Course Contents






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2.1 Radio Transmission Environment

2.2 Multiple Access Technology and

Duplex Technology

2.3 CDMA Principle and RAKE Technology


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Multi-path Environment

Time

Received

signal

Transmitted

signal


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Fading

Transmitted Signal

-40

-35

-30

-25

-20

-15

-10

-5

0

dB

Received Signal


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Fading

Distance(m)

Received Power(dBm)

10 20 30

-20

-40

-60

Slow fading

Fast fading


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Frequency Selection of Fading

NarrowbandSystem

Fading

Transmit Signal Received Signalff

P(f) P(f)

Fading

Transmit Signal Received Signalff

P(f) P(f)

BroadbandSystem


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Multi-path Characteristics of Mobile Channel

Electromagnetic transmission - reflection,scattering,diffraction

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

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 Channel

Static Channel

Indoor Channel

Outdoor-to-indoor pavement Channel

Vehicle mounted Channel

Moving Channel

Birth-death Channel


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Duplex Technology



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Multiple Access Technology and DuplexTechnology

Multiple access technology

Time division multiple access (TDMA)

Frequency division multiple access (FDMA)

Code division multiple access (CDMA)

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

Power

Power

Power

FDMA

TDMA

CDMA

Multiple Access Technology and DuplexTechnology


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Characteristics of CDMA System

High Spectral Efficiency

Frequency multiplex coefficient is 1.

soft capacity

Quality

Coverage

Interference

Self-interference system

A UE transmission power is interference for another UE.


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Processing Procedure of CDMA System

Sourcecoding

Channel

codingSpreading Modulation

Sourcedecoding

Channel

decoding Despreading Demodulation

Radio channel


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Duplex Technology



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correlation

Correlation is a measure of similarity of between any two

arbitrary signals.

EXAMPLE:

-1 1 -1 11 1 1 1

-1 1 -1 1Zero correlation

Orthogonal signals

-1 1 -1 1

-1 1 -1 -11 1 1 11 correlation

Identical signals

+10

-1+10-1

+1

0-1

+10-1


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OVSF&Walsh

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)

Creating the orthogonal code sequences


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Autocorrelation

Autocorrelation is related to the muti-path interference characteristic.

Delay time (chip)

Correlation

Delay time sequence correlation0 -1 -1 -1 1 1 -1 1 1

1 -1 -1 1 1 -1 1 -1 -1/72 -1 1 1 -1 1 -1 -1 -1/73 1 1 -1 1 -1 -1 -1 -1/74 1 -1 1 -1 -1 -1 1 -1/75 -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 Generator

clong,1,n

clong,2,n

MSB LSB

Gold sequence is used as scrambling code in WCDMA


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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)


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Spreading code

Spreading code

Signal

Combination

Spectrum 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 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 Receiver

Q

I

Combiner

I

MatchedFilter

PhaseRotator

Channelestimator

DelayEqualizer

I

Q

Path 1

Path 2

Path 3

Input signal

Correlator

Code

generators

Q


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Advantages of CDMA

RAKE receiver is adopted

The time diversity effect generated by channel coherence time isefficiently used.

frequency diversity

Wideband frequency spectrum

Higher interference tolerance and security performance Low signal transmission power

Great flexibility in carrying multiple services with largely different

bit rate and QoS requirement.

Different spreading factors for different services with different data

rates

High spectral efficiency

All users can share the same frequency spectrum simultaneously.

Supporting soft handover and softer handover.


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Course Contents






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Introduction to Diversity Technique

Reduce the effects of fading

fast fading caused by multipath

Slow fading caused by shadowing Improve the reliability of communication

Increase the coverage and capacity

Macroscopic diversity

Soft handover and softer handover Reduce large-scale fading

Microscopic diversity

Diversity technique is used to obtain uncorrelated

signals for combining


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Microscopic Diversity

Time diversity

Channel coding, Block interleaving, error-correction

Frequency diversity

The user signal is distributed on the whole bandwidth

frequency spectrum

Space diversity

Receive diversity

Transmit diversity

Polarization diversity

Vertical polarization

Horizontal polarization


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Basic Combining Methods

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

signal SNR and then summed.

Equal-Gain Combiner

Equal-gain combining is similar to maximal-ratiocombining, but there is no attempt to weight the signal

before addition.

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 Diversity

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.

Open loop transmission diversity

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

Time switched transmit diversity on SCH (TSSD)

Closed loop transmission diversity, FBI domain

Site selection diversity(macro diversity) cell selection, FBI

domain

T itt A t Di it


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Transmitter Antenna Diversity

Based on Time-space Block Coding

b2b0 b1 b3

b0 b1 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 SCH

Antenna 1

Antenna 2

acsi,0

acp

acsi,1

acp

acs

,1

acp

Slot #0 Slot #1 Slot #1

acs

,

acp

Slot #2


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Closed Loop Transmit Diversity

Spread/scramble

w1

w2

DPCHDPCCH

DPDCH

Rx

Rx

CPICH1

Tx

CPICH2

An

An

Tx

Weight Generation

w1 w2

Determine FBI message

from Uplink DPCCH


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Receiving Effects for Different Multi-path Diversity


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Smart Antenna

Wanted signal

interference

Reduce interference Increase coverage and capacity


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Smart Antenna

Omni antenna Directional antenna Smart antenna


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Course Contents






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Characteristics of WCDMA FDD

Channel bandwidth: 5MHz

Chip rate: 3.84Mcps

Frame length: 10ms

Voice coding: AMR (Adaptive Multi-Rate)

Uplink and downlink modulation: QPSK/QPSK

Coherence demodulation aided with pilot

Fast closed loop power control: 1500Hz

Handover: soft/hard handover

Support synchronous and asynchronous NodeB

operation


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Characteristics of WCDMA FDD

Satisfy the minimum performance requirement of IMT2000

Compatible with GSM-MAP core network

Comparatively steady version R99 has been released

Support open loop and closed loop transmit diversity mode

Support Common Packet Channel(CPCH) and Downlink Share

Channel, adapt to Internet data access mode

Support macro diversity, selection diversity of NodeB location

Support different fast power control algorithms and open loop,out loop power control

Fully support UE locating services


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WCDMA 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 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 mobile IP service(dynamic allocation of IP addresses)

TFCI domain provides dynamic data rate Provide high-quality support for uplink-downlink symmetric

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


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a2 general description of 3g

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