01-wcdma wireless principle and key technology_v3.10

© 2007 ZTE Corporation

Operator’s logo

WCDMA Wireless Principle and Key TechnologyWCDMA Wireless Principle and Key Technology

PPT Series for Technology Principle PPT Series for Technology Principle

Name :×××

E-mail :×××WCDMA Product Planning Dept.ZTE Marketing System

Name :×××

E-mail :×××WCDMA Product Planning Dept.ZTE Marketing System

2

Arial, 18pt, bold, italic for the 1st level

Arial, 16pt, bold, italic for the rest

Modification records

Edition Date Writer/Modifier Approver Remark

V3.00 2007-04 Shen junjie

V3.10 2007-08-17 Wang xing / Huang yan Update

AgendaAgenda

WCDMA System Overview

WCDMA Wireless Principle

WCDMA Key Technology




4



Evolution of Cellular Mobile Communication System

First First GenerationGeneration(80s’)(80s’)AnalogAnalog

First First GenerationGeneration(80s’)(80s’)AnalogAnalog

Third Third GenerationGeneration(2000)(2000)Wideband Wideband MultimediaMultimedia

Third Third GenerationGeneration(2000)(2000)Wideband Wideband MultimediaMultimedia

Second Second GenerationGeneration(90s’)(90s’)DigitalDigital

Second Second GenerationGeneration(90s’)(90s’)DigitalDigital

AMPS

TACS

NMT

Others

An

alo

g T

ec

hn

olo

gy

GSM

CDMAIS95

TDMAIS-136

PDC

Market Driven

UMTSWCDMA

CDMA2000

Market Driven

TD-SCDMA

Dig

ita

l T

ec

hn

olo

gy

Vo

ice

Se

rvic

e

Bro

ad

ba

nd

Se

rvic

e

5



Background of 3G

Essential impetus: a wider range and

higher data rate of services, higher sp

ectrum efficiency

Improve the compatibility between dif

ferent networks

The international standard—IMT-2000

comes forth as the requirement

The network supported by IMT-2000 is called 3G.

The network supported by IMT-2000 is called 3G.

6



Target of IMT-2000

Uniform frequency, uniform standard, seamless cover

age

High efficient utilization of spectrum

High quality, high security

Easy evolution to 2G

Provide various new services

7



Wireless Interface Technologies of IMT-2000

16 candidate tech., including 10 land mobile tech., 6 satellite tech.

Land mobile tech includes 8 FDD, 5 TDD

Dominating ground tech:

W-CDMA (Including 5 similar Tech. such as USA W-CDMA and WIMS,

which are merged as WP-CDMA)

CDMA2000 (Including 2 similar Tech.)

UWC-136

TD-SCDMA submitted by China

8



Wireless Interface Standards of IMT-2000

IMT-FTIMT-2000

FDMA/TDMA

IMT-SCIMT-2000TDMA SC

UWC-136 E-DECT

IS-136 DECT

IMT-DSCDMA DS

IMT-MCCDMA MC

IMT-TDCDMA TDD

WCDMA TD-SCDMA

UMTS TDD

CDMA 2000

UMTS FDD

9



3G Technology Evolution

3G

Standard

WCDMAWCDMA

TD-SCDMA CDMA2000

CDMA is the Mainstream Technology of 3GCDMA is the Mainstream Technology of 3GCDMA is the Mainstream Technology of 3GCDMA is the Mainstream Technology of 3G

CN ： based on MAP

CN ： based on ANSI-41

CN ： based on MAP

10



3G Standard and Beyond 3G Evolution

TD-SCDMA TD-SCDMA EnhancedEnhanced

TD-SCDMA TD-SCDMA EnhancedEnhancedTD-SCDMATD-SCDMATD-SCDMATD-SCDMA

2005200520052005

• R4R4 • R5/6R5/6LTELTE

FDD/TDDFDD/TDD

LTELTE

FDD/TDDFDD/TDD• HSDPAHSDPA Phase1Phase1

• HSUPAHSUPA Phase1Phase1• HSDPAHSDPA Phase2Phase2

•HSUPAHSUPA Phase2Phase2• MBMS MBMS

•WCDMAWCDMA •R4R4

2004 2005 2006 2007 2008 After 2009

• R5R5 • R6R6

•CDMACDMA•11XX

• EV-DO 0EV-DO 0 • EV-DO AEV-DO A• BCMCS BCMCS

AIEAIE Phase 2Phase 2

AIEAIEPhase1Phase1N×DON×DO

3GPP 4G3GPP 4G3GPP 4G3GPP 4G

3GPP2 4G3GPP2 4G3GPP2 4G3GPP2 4G

WiMAXWiMAX

802.16d802.16d

WiMAXWiMAX

802.16d802.16d

WiMAXWiMAX

802.16e802.16e

WiMAXWiMAX

802.16e802.16e

11



WCDMA Standard Evolution

Introduce Iu Interface MAX. Speed: 2Mbps Commercial Release 20

01.6+ following CR

R99

R4

R5

R6

2000.3 2001.3 2002.6 Time for function frozen

Control and Bearer

Separation

Introduce IMS Domain

Introduce HSDPA for Radio Interface

Study on Interoperability of

IMS and PLMN/PSTN/ISDN

Circuit Switch Network

MBMS

Study on Frame Structure

12



Characteristics of WCDMA

Bidirectional fast closed-loop power control

Bidirectional coherent demodulation by pilots

Transmitter and receiver diversity

High chip rate(3.84Mcps ） Channel coding tech with high gain

Unnecessary for GPS synchronization among base

stations

Multiple switching technology

Multiple transport rate

Advanced radio resource management algorithm

13



WCDMA Entire IP Network Evolution

R99R99

Billing Billing ServerServer

OMCOMC

SCPSCP

HLRHLR

MMSMMSCC

GMLCGMLC

MSCMSCGMSCGMSC GGSNGGSNSGSNSGSN

PSPSCSCS

R99 CN smoothly evolves from R99 CN smoothly evolves from

GSM/GPRS networkGSM/GPRS network R99 CN smoothly evolves from R99 CN smoothly evolves from

GSM/GPRS networkGSM/GPRS network R4 CN separate the Control Plane R4 CN separate the Control Plane

from Bearer Plane in CS Domainfrom Bearer Plane in CS DomainR4 CN separate the Control Plane R4 CN separate the Control Plane

from Bearer Plane in CS Domainfrom Bearer Plane in CS DomainR5 CN Introduces IMSR5 CN Introduces IMS ，， RR

AN Adopts IPAN Adopts IPR5 CN Introduces IMSR5 CN Introduces IMS ，， RR

AN Adopts IPAN Adopts IP

RNSRNSBSSBSS

MGWMGWGMGWGMGW GGSNGGSNSGSNSGSN

PSPSCSCS

R4R4 R5R5


OMCOMC

SCPSCP

HLRHLR

MMSMMSCC

GMLCGMLC

CSCSMSCMSC

serverserverGMSCGMSCserverserver


OMCOMC

SCPSCP

HLRHLR

MMSMMSCC

GMLCGMLC

BSSBSSRNSRNS

RNSRNSBSSBSS

MGWMGWGMGWGMGW GGSNGGSNSGSNSGSN

PSPSCSCS

WCDMA Entire IP Network Evolution coincide with the WCDMA Entire IP Network Evolution coincide with the development tendency of the next generation networkdevelopment tendency of the next generation networkWCDMA Entire IP Network Evolution coincide with the WCDMA Entire IP Network Evolution coincide with the development tendency of the next generation networkdevelopment tendency of the next generation network

14



WCDMA CDMA2000

Carrier spacing 5M 1.25/5/10/15/20 MHz

Chip rate 3.84M N*1.2288Mcps N=1,3,6,9,12

Spreading way DS-CDMA DS-CDMA & MC-CDMA

Duplex mode FDD/TDD FDD

Frame size 10ms 20ms （ general data and control channel ）5ms （ basic and designated control channel)

Channel coding Convolutional codes 、 Turbo codes Convolutional codes 、 Turbo codes

Interleave Intra-cutting 、 inter-cutting Intra-cutting

Scrambling Walsh+Gold sequence Walsh+M sequence

Modulation mode QPSK/BPSK QPSK/BPSK

Power control Open-loop and fast closed-loop 1.5KHz ） Open-loop and fast closed-loop （ 800Hz ）

Base station

synchronization

Synchronization/Asynchronous synchronization

Comparison of the Three 3G Technologies (I)

15



WCDMA-TDD TD-SCDMA

Carrier spacing 5M 1.6M

Chip rate 3.84M 1.28M

Spreading way DS-CDMA, SF=1,2,4,8,16 DS-CDMA, SF=1,2,4,8,16

Duplex mode TDD TDD

Modulation mode QPSK/BPSK QPSK

Number of timeslot 15 7

Capacity

（ channel number each timeslot ）8 16

Channel number each carrier 56 48

Capacity

(rate of one timeslot)

220.8kbps 281.6kbps

Rate of one carrier 3.31Mbps 1.971Mbps

Spectrum Utilization 0.662Mbps/MHz 1.232Mbps

Comparison of the Three 3G Technologies (II)

AgendaAgenda



The Basic Principles of Wireless

Communication

WCDMA Wireless Technology





Communication



17



Radio Propagation Characteristics

Multi Access

Spreading Technology

Channel Coding

Interleave Technology

Diversity Technology


Multi Access


Channel Coding



The Basic Principles of Wireless CommunicationThe Basic Principles of

Wireless Communication

18



Characteristic of Radio Propagation

Electromagnetic propagation: direct radiation 、 reflection 、 diffraction and

scattering

Signal attenuation: Path loss ： Loss of electromagnetic waves in large scope of the spread reflect

s the trend of the received signal in the spreading 。 Slow fading ： Loss because of being blocked by the building and hill in the prop

agation path

Fast fading ： Electromagnetic signals rapidly decline in a few dozens wavelengt

h ranges

Description of Fast fading distribution Rayleigh distribution ： non line-of –sight transmission

Rician distribution ： line-of –sight transmission

19



Frequency Frequency off-setoff-set caused by the movement of mobile caused by the movement of mobile ，， thatha

t is Doppler effectt is Doppler effect

Frequency Frequency off-setoff-set caused by the movement of mobile caused by the movement of mobile ，， thatha

t is Doppler effectt is Doppler effect

Sending signal Accepting signal

Interference Interference

0dB

Sending signal

-25dB

Accepting signal

fadingfading

0 + Sending signal Accepting signal

delaydelay

0 2 3 + Sending signal Accepting signal

ditheringdithering

Characteristics of Radio Propagation

20



Multi-Path Effects

receiving signalreceiving signal

timetime

strengthstrength

00

sending signalsending signal

21




Multi Access


Channel Coding




Multi Access


Channel Coding





22



FrequencyTime

Power

FrequencyTime

Power

FrequencyTime

Power

FDMA

TDMA

CDMA

Frequency division multiple access technology Channels in different frequency are allocated to different users, e.g. TACS 、 AMPS 。

Frequency division multiple access technology Channels in different frequency are allocated to different users, e.g. TACS 、 AMPS 。

Time division multiple access technologychannels in different time are allocated to different users, e.g. GSM 、 DAMPS 。

Time division multiple access technologychannels in different time are allocated to different users, e.g. GSM 、 DAMPS 。

Code division multiple access technology

Users distinguished by scramble code, e.g. CDMA

Code division multiple access technology

Users distinguished by scramble code, e.g. CDMA

Multiple Access

23




Multi Access


Channel Coding




Multi Access


Channel Coding





24



Principle of Spreading Frequency

A technology of transmission technology after spreading frequenc

y of signal.

Theoretical Basis: Shannon theory C=Wlog2(1+S/N)

FastSpreadingSequence

SlowInformation

Sent

TX

SlowInformationRecovered

RX

FastSpreadingSequence

WidebandSignal

25



f

S （ f ）

f0

Before spreading

signal

S （ f ）

ff0

After spreading

signal

S （ f ）

ff0

After despreading

signal

White noise

f

S （ f ）

f0

Before despreading

signal

White noise

signal interference White noise

Sketch Map of Spreading

26



Spreading Mode

Direct sequence spread （ DS － SS ） Base band data is spreaded by multiplication of pseudo-noise sequence and bas

e-band pulse, the pseudo-noise sequence generated by the pseudo-noise generator

BER subject to Multiple Access Interference and near-far effect Power control can overcome the near-far effect, but it is limited by power detecti

on accuracy WCDMA uses DS-SS

Frequency hopping spread （ FH-SS ） Data is transmitted in the random channel by the carrier frequency hopping Before FH again, data is transmitted using traditional narrowband modulation No near-far effect

27



Characteristics of Spreading Communication

High anti-multi-path- interference capability

Anti-sudden-pulse

High security

Lower transmitting power

Easy to implement large-capacity Multiple Access Communication

Occupy band wide

Complex realization

28




Multi Access


Channel Coding




Multi Access


Channel Coding





29



Purpose of Channel Coding

purpose: By adding redundant information in the original data stream, receivers

can detect and correct the error signal, and improve data transmission

rates.

No correct coding: BER<10-1 ~ 10-2Can not satisfy

the communication

Convolutional coding ： BER<10-3Can satisfy the

speech communication

Turbo coding ： BER<10-6Can satisfy the

data communication

30



Principle of Channel Coding

Channel coding

Error-correcting ability obtains by adding redundancy in the original da

ta

Convolutional coding and Turbo coding （ 1/2 ， 1/3 ） are widely appl

ied.

Increase redundancy and transmission time

Suitable to correct few non-continuous errors

31




Multi Access


Channel Coding




Multi Access


Channel Coding





32



Principle of Interleave Technology

advantage Interleave is to change the sequence of data to random the unexpected

errors

Advance the correcting validity

disadvantage ： Increase the processing delay

Especially, Several independent random errors may intertwined for the

unexpected error .

x1 x6 x11 x16 x21

x2 x7 … x22

x3 x8 … x23

x4 x9 … x24

x5 x10 … x25

Data input

A = (x1 x2 x3 x4 x5 … x25)

Data output

A’= (x1 x6 x11 x16… x25)

e.g.

33




Multi Access


Channel Coding




Multi Access


Channel Coding





34



Concept of Diversity Technology

Double meanings ： scattered transmission, concentrative process.

Achieved by using and finding the independent multi-access signal

s in the wireless communication environment .

If the signals in one path decay seriously, but in other independent

path are still strong.

advantage ： Easy to achieve relatively stable signal

Achieve the diversity gain

Improve SNR

35



Diversity Categories

Space diversity Also called antenna diversity, if the distance between the antennae is greater

than half of the wavelength, the signals from different antenna are not related.

Time diversity The signal repeats over Channel Coherent time interval, so that the environment

is independent.

Frequency diversity The signal repeats in the different frequencies.

Polarization Diversity Signal reflects in the different direction, since the reflection coefficients of

different polarization directions are not the same, the signals in different

polarization direction is not related

AgendaAgenda


WCDMA Wireless Principle A


Communication






Communication



37



Spreading Technology of WCDMA

Channel Coding of WCDMA

Interleave Technology of WCDMA

Diversity Technology of WCDMA





WCDMA Wireless Technology WCDMA Wireless Technology

38



Symbol rate × SF = 3.84McpsSymbol rate × SF = 3.84Mcps

WCDMAWCDMA ，， SF of uplink channeliezd codeSF of uplink channeliezd code ：： 4~2564~256

SF of downlink channelized code:4~512SF of downlink channelized code:4~512

OVSF: Orthogonal Variable Spreading Factor OVSF: Orthogonal Variable Spreading Factor

Symbol rate × SF = 3.84McpsSymbol rate × SF = 3.84Mcps

WCDMAWCDMA ，， SF of uplink channeliezd codeSF of uplink channeliezd code ：： 4~2564~256

SF of downlink channelized code:4~512SF of downlink channelized code:4~512

OVSF: Orthogonal Variable Spreading Factor OVSF: Orthogonal Variable Spreading Factor

OVSF Code Scramble Code

Data bitChip after Spreadin

g

Spreading of WCDMA

39



∑∑

Real part

and

Imaginary part

separate

Pulse

shaping

Pulse shaping

serial

parallel

transfer

serial parallel transfer …

…

……

DL physical channel 1Cch,SF,m

j

I+jQSdl,n

G1

Cch,SF,m

j

I+jQSdl,n

G2

DL physical channel 2

Gp

Gp

P-SCH

S-SCH

cos(wt)

-sin(wt)

T

T

Re(T)

Im(T)

Spreading, Scrambling and modulation of WCDMA

Downlink physical channel spreading and modulation ：

40



Real part and

Imaginary part separate

Pulse shaping

Pulse shaping

cos(wt)

-sin(wt)

Sdpch,n

SRe(S)

Im(S)

∑

Cd,1 βd

I

cc

Q

j

I+jQ

∑

∑

DPDCH1

Cd,3 βdDPDCH3

Cd,5 βdDPDCH5

Cd,2 βdDPDCH2

Cd,4 βdDPDCH4

Cd,6 βdDPDCH6

cc

Cc βcDPCCH

Q

Spreading, Scrambling and modulation of WCDMA

Uplink physical channel spreading and modulation ：

41



Despreading of WCDMA

Method of despreading

Input signal

Local PN code

When T=Ts, judge

Output after despreading

integral

0

Ts

(*)dt

42



Symbol

Spreading

Despreading

1-1

1-1

1

-1

1-1

1-1

Data = 010010

Spreading code

Spread signal= Data × code

Spreading code =1 -1 -1 1 -1 1 1 -1 ( SF = 8 )

Data = Spread signal × code

Chip

Sketch map of Spreading and Despreading of WCDMA

43



Spreading Gain

Spreading definition and processing gain

Processing gain: PG=Wc/R

Wc: chip rate

R: signal rate

PG=10lg(Wc/R), dB units

Despreading by receiver will be able to resume the original signal

More spreading of multiples, higher the processing gain, stronger anti-jammin

g

44












45



Convolutional Code

Mainly used in the voice channel and control signal channel

Coding rate is 1/2 和 1/3 。

Output 0 G0 = 557 (octal)

Input D D D D D D D D



Rate 1/3 convolutional coder

46



Characteristics of Convolutional code

Easy decode

Short delay

Generally use the Viterbi Algorithm

Channel bit error rate is 10 － 3 magnitude

Suitable to realtime service

e.g. speech and video service.

47



Turbo Code

Used in Data service channel

Code Rate is 1/3

Can be implemented in the transmission for large block and long delay

services

Turbo coding structure is based on two or more weak error control code Turbo coding structure is based on two or more weak error control code

combinations. The information bits are interleaved in the two Encoder, and combinations. The information bits are interleaved in the two Encoder, and

generate two information flow. At last, this information can be multiplexed generate two information flow. At last, this information can be multiplexed

and puncturedand punctured

Decoding needs cycle iterative calculationDecoding needs cycle iterative calculation

InterleaverEncoder 1

Encoder 2

Mu

ltip

lex

inputoutput

48



Characteristics of Turbo Codes

Complex decoding

Use the LOG-MAP arithmetic

Channel bit error rate is 10 － 6 magnitude

Very suitable to non-realtime package service which is BER sensit

ive & delay insensitive , e.g. WWW, FTP, E_mail , multimedia trans

mission .

49












50




Intra-frame interleave

Bits transform in the internal frame

Inter-frame interleave

Data transform among the frames

Intra-Turbo codes interleave

Complex nesting of intra-frame and inter-frame interleave

51












52




Open-loop transmit diversity Use space-time coding , fire from two antenna, comprehensively utilize

the time and space diversity

Closed-loop transmit diversity Feedback from the receiver controls the parameters of the transmitting

antenna, it is the time diversity with feedback technology.

Interleave A implied time diversity

RAKE receive technology A implied time diversity. The multi-access signal used by RAKE is

considered the signal sent by transmitter several times.

AgendaAgenda




WCDMA Capacity Feature

Radio Resource Management








54



Capacity of WCDMA

UL capacity interference limited

DL capacity power limited

55



Power Rise

Power rising occurs because of the Multiple Access Interference (MAI) resulting from the non-orthogonal code channels.

WCDMA network Meeting Room

Code channel transmit talk with dialects Channel power voice tone Promised channel quality listen clearly Channel power rise voice tone rise Power climb voice climb Collapse over the range can not listen for each other Interference outside the cell Noise outside the room

56



Power Rise

Quantity of Subscriber

Quantity of Subscriber-- The Total Bandwidth Received by Node BT

he T

otal

Ban

dwid

th P

ower

Rec

eive

d by

Nod

e B

(dB

m)

57




WCDMA capacity feature

WCDMA capacity is Soft Capacity

The Concept of Soft Capacity

Inter-convertibility between system capacity and communication qualit

y

Different service has different capacity

Different proportion of services has different capacity for mixed servic

es

58



Trade off between System capacity and service qualityTrade off between System capacity and service qualityTrade off between System capacity and service qualityTrade off between System capacity and service quality

Different service combination and proportion has different capacity

Different service has

different capacity

Soft Capacity

59



Quality

Quality

Cov

erag

e

Cov

erag

e

CapacityCapacity

All the WCDMA technologies adopted is try to achieve All the WCDMA technologies adopted is try to achieve

the most optimal balance of the three factorsthe most optimal balance of the three factors

All the WCDMA technologies adopted is try to achieve All the WCDMA technologies adopted is try to achieve

the most optimal balance of the three factorsthe most optimal balance of the three factors

Crucial Factors for WCDMA Capacity

60



Factors Impact on WCDMA capacity Category

Power Control Reducing interference, saving power and Increasing capacity

Radio Resource Manage

ment （ RRM ）

Handover Control Impacting the capacity through applying different proportion and algorithm of soft

handover

Admission Control Admitting a connection base on the load and the admission threshold of planned

capacity

Load ControlMonitoring system load and adjusting the ongoing services to avoid overload

OVSF Code The Allocation of codes impacts the maximum number of simultaneous connections.

RAKE Receiver The advanced receiving and baseband processing technology is introduced to

overcome the fast fading

Key TechnologySmart Antenna Reducing interference, saving power and expanding coverage through tracking the

user with beam forming antenna array.

MUD Reducing the Multi-Access Interference (MAI).

Service Class and

CombinationThe class and combination of services impact the capacity directly Service Attribute

Wireless EnvironmentWireless environment such as interferences, UE position and mobility etc. can influent

the cell capacity

Wireless Propagation

Environment

Factors Affecting WCDMA Capacity

AgendaAgenda













62



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control

Code Allocation Spreading

Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Radio Resource ManagementRadio Resource Management

63



Power Control

CDMA is not a new technology

Power control is a key technology of CDMA system

Power control is the key path for launching the large scale CDMA

commercial network

CDMA is a typical self-interference system, thus the chief CDMA is a typical self-interference system, thus the chief

principle is that any potential surplus transmitted power for principle is that any potential surplus transmitted power for

service must be controlled.service must be controlled.

CDMA is a typical self-interference system, thus the chief CDMA is a typical self-interference system, thus the chief

principle is that any potential surplus transmitted power for principle is that any potential surplus transmitted power for

service must be controlled.service must be controlled.

64



Each terminal is an Each terminal is an

interference source to the interference source to the

others. The Near-far effect others. The Near-far effect

will impact the capacity will impact the capacity

tremendouslytremendously

Each terminal is an Each terminal is an

interference source to the interference source to the

others. The Near-far effect others. The Near-far effect

will impact the capacity will impact the capacity

tremendouslytremendously

Power

f

Power control will reduce Power control will reduce

the cross interference the cross interference

significantly and improve significantly and improve

the total capacitythe total capacity

Power control will reduce Power control will reduce

the cross interference the cross interference

significantly and improve significantly and improve

the total capacitythe total capacity

Near-Far Effect

Power

f

65



Multi-Access Interference

WCDMA is a self-interference system Cause: Spectrum sharing; lacking of idealized self-correlated and

cross-correlated spread codes.

Phenomenon: Power Rising

Frequency

Time

Codes

Multi-Access Interference Sketch Map

Output

TimeSynchronization

66



Purpose of Power Control

• Overcome near-far effect and compensate signal fading

• Reduce multi-access interference and guarantee cell capacity

• Extend battery life

Downlink Power Control

Cell transmitted power

Report power control bit (TPC)

UE transmitted signal

Power control command (TPC)

Uplink Power Control

67



Category of Power Control

Open Loop

Measure the channel interference condition and adjust the initial transmitted power

Open Loop

Measure the channel interference condition and adjust the initial transmitted power

Close Loop － Inner Loop

Measure the SIR (Signaling to Interference Ratio), compare with the target SIR value, and then send power control instruction to UE.

The frequency of CDMA close loop power control is 1500Hz.If measured SIR>target SIR, decrease the UE transmitted power.If measured SIR <target SIR, increase the UE transmitted power.

Close Loop － Inner Loop

Measure the SIR (Signaling to Interference Ratio), compare with the target SIR value, and then send power control instruction to UE.

The frequency of CDMA close loop power control is 1500Hz.If measured SIR>target SIR, decrease the UE transmitted power.If measured SIR <target SIR, increase the UE transmitted power.

Close Loop － Outer Loop

Measure the BLER (Block Error Rate), and adjust the target SIR.

Close Loop － Outer Loop

Measure the BLER (Block Error Rate), and adjust the target SIR.

68



Open Loop Power Control

General principals of open loop power control

Open loop power control is applied to estimate the initial transmitted c

ode power (TCP) for a new radio link.

The downlink Open Loop Power Control is using P-CPICH signal which

is measured by UE to estimate the initial TCP and the following factors

will also be considered, such as service QoS and data rate, Eb/No requi

rements of establishing service, current downlink total Transmitted Po

wer and interference from neighbor cell etc..

69



Try to get the equal receiving Try to get the equal receiving

Eb (Energy per bit) of each UEb (Energy per bit) of each U

E at Node BE at Node B

Try to get the equal receiving Try to get the equal receiving

Eb (Energy per bit) of each UEb (Energy per bit) of each U

E at Node BE at Node B

NodeB UE

TPC instruction

Measure receiving SIR and

compare to target SIR

Inner loop

Set SIRtar

1500Hz1500Hz1500Hz1500Hz

Each radio link has Each radio link has

its own control its own control

circlecircle

Each radio link has Each radio link has

its own control its own control

circlecircle

Close Loop – Inner Loop Power Control

70



Close Loop – Inner Loop Power Control

General principals of inner loop power control

The receiver compares the SIR value of received signal with target SIR, and then

sends back TPC instruction. According to the instruction, the sender will decide

to increase/decrease the transmitted power, The adjusted rang=TPC_cmd×TPC_

STEP_SIZE

Inner loop power control is required for the following channels ： DPCH, PDSCH, PCPCH

Inner loop power control is not required for the following channels ： P-CPICH(S-CPICH), P-CCPCH(S-CCPCH), PRACH etc..

71



NodeB UE

TPC instruction

Inner loop

Set SIRtar

Get data flow Get data flow

with stable BLERwith stable BLER

Get data flow Get data flow

with stable BLERwith stable BLER

Measure BLER Measure BLER

of TRCHof TRCH

Measure BLER Measure BLER

of TRCHof TRCH

Outer Loop

RNC

Measure receiving BLER and compare to

target BLER

Set BLERtar

10-100Hz

Close Loop – Outer Loop Power Control

Measure receiving SIR and

compare to target SIR

72



Close Loop – Open Loop Power Control

General principals of open loop power control

The algorithm is implemented as following: Employ the inner loop power control to keep SIR close

to target SIR; Measure the quality of service, e.g. through CRCI report, and tune the target SIR with

pre-defined step; Therefore keep the call in good quality event in changing wireless propagation

environment.

Input parameters include target BLER, CRC indicator and SIR Error, output parameter is SIR Target.

Open loop power control algorithm is implemented in two ways: FER period report triggered; FER

event report triggered.

The uplink open loop power control algorithm is executed in the RNC while the downlink one is

executed in the UE.

73



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



74



When UE is moving from the coverage area of one site to another

site, or the quality of service is declined by external interference

during a call, the call must be handed over to an idle channel for

sustaining the service. Handover is a key technology for mobile

networking

Purpose of Handover Control

75



Handover Types

Soft Handover Intra-Node B soft handover (Softer Handover) Inter-Node B soft handover Inter-RNC soft handover (involving Iur interface)

Hard Handover Inter-frequency hard handover Intra-frequency hard handover (forced hard handover) Inter-RAT hard handover (between different Radio Access Technology,

e.g. WCDMA and GSM) Inter-mode handover (e.g. between FDD and TDD)

76



Handover Demonstration

Hard

Handover

Soft

Handover

77



A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

Soft Handover/Softer Handover

78



WCDMA General Handover Procedures

Measurement Control

UTRAN demands the UE to start measurement through issuing a measurement

control message.

Handover decision

UTRAN makes the decision based on the measurement reports from UE. The

implementation of handover decision is various for different vendors. It impacts

on the system performance critically.

Handover execution

UTRAN and UE execute different handover procedure according to the handover

command .

79



(A) RNC sends measurement control message to UE (Measurement Control)

(B) UE starts measurement task with the parameters included in the message, and reports measurement results（ Measurement Report ）

(C) RNC stores the measurement results according to frequencies and cells

(D) RNC Estimates the quality of each carrier (including intra-frequency and inter-frequency)

(E) Quality

Decision

(G) Allocate resource in target cell of the virtual active set, prepare to execute handover

(F) maintain the active set and monitored set

(H) Allocate resource in target cell, prepare to execute handover

Current carrier has good quality

Other system has good quality

Other carrier has good quality

（ I ） If handover is required, RNC sends handover command with target cell to UE

Handover Flows

80



General Procedure of Handover Control (I)

Measuring

The measurement objects are decided by RNC. Usually, either

Ec/N0 or RSCP (Received Signal Code Power) of P-CPICH channel

is used for handover decision.

ZTE RNC adopts Ec/N0 measurement, because Ec/N0 embodies

both the received signal strength and the interference. The relation

of Ec/N0 and RSCP is shown as follows:

Ec/N0 ＝ RSCP/RSSI

In the above equation ， RSSI （ Received Signal Strength Indi

cator ） is measured within the bandwidth of associated channels

81



General Procedure of Handover Control (II)

Filtering

The measurement results should be filtered before being reported. Measurement filtering can be regarded as a low pass filtering procedure.

The following equation is applied for filtering

Fn=(1-a)Fn-1 ＋ a*Mn

Variants definition ：Fn ： filtered measurement result ；Fn-1 ： last filtered measurement result ；Mn ： latest Ec/I0 or RSCP measurement result received from physical lay

er;a = 1/2(k/2), k means the “Filter coefficient”, which is included in the Measur

ement Control message. It is decided by the UTRAN.

F0 is initialized by the first measurement result M1.

82



Reporting

Period report triggered handover

Event report triggered handover

Base on the filtered measurement result

Base on the event

Soft Handover

Hard Handover

Period

Event

Measurement result filtered in

UE

Event decided in RNC

Handover decided in RNCMeasurement result filtered in UE Event decided in UE

Handover decided in RNC

General Procedure of Handover Control (III)

83



General Procedure of Handover Control (IV)

Handover algorithm

All the handover algorithms including soft handover, hard handover an

d so on are implemented on the event decision made from measureme

nt report.

Events defined in 3GPP specifications

Intra-frequency events ： 1A~1F

Inter-frequency events ： 2A~2F

Inter-RAT events ： 3A~3D

84



Concepts Related to Handover

Active Set: A set of cells that have established radio links with a certain

mobile station. User information is sent from all these cells.

Monitored Set: A set of cells that are not in the active set but are monitored

according to the list of adjacent cells assigned by the UTRAN.

Detected Set: A set of cells that are neither in the active set nor in the

monitor set

85



An Example of Handover Procedure

Pilot Ec/Io of cell 1

time

PilotEc/Io

Connect to cell1 Event 1A Event 1C Event 1B （ add cell2 ）（ replace cell1 with cell 3 ）（ remove cell3 ）



⊿t ⊿t ⊿t

86



RNS Relocation

Core NetworkCore Network

Service RNS

Target RNS

Service RNS

Target RNS

Iu Iu

Iur

RNSRadio Network Sub-system

RNS relocation can : Reduce the Iur traffic significantly

Enhance the system adaptability

87



Hard Handover

Hard handover measurement is much more complex for UE than

soft handover measurement.

Inter-frequency hard handover requires UE to measure the signal

of other frequency.

WCDMA employs compressed mode technology to support inter-

frequency measurement.

88



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



89



Purpose of Compressed Mode

In order to support inter-frequency and inter-RAT handover, UE is required to perform inter-frequency and Inter-RAT measurement periodically.

The UE with one transceiver does not have the opportunity to perform inter-frequency measurement during the service period (especially the voice call) , because the transceiver is busy in transmitting and receiving the signals all the time.

Compressed mode can provide idle slot based transmission time window, which can be used for inter-frequency measurement, for the UEs in connected state, e.g. CELL_DCH.

90



Compressed Mode

Compressed Mode Transmission Diagram

Transmit gaps（Maximum 7 slots = 4.7ms） 1 frame（10ms）

10ms

91



Generation of Compressed Mode Frame

Puncturing Lower the symbol rate of physical channel when processing the rate m

atching procedure

SF halving Employ half SF, e.g. employ SF64 to replace SF128

High layer scheduling Decrease the bit rate from up layer

92



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



93



Admission Control

The admission control is employed to admit the access of

incoming call. Its general principal is based on the availability and

utilization of the system resources.

If the system has enough resources such as load margin, code,

and channel element etc. the admission control will accept the call

and allocate resources to it.

94



Purpose of Admission Control

The admission control should implement admission or rejection fo

r the new users, new RAB and new RL (for example handover) acc

ording to the current resource situation. The admission control will

sustain the system stability firstly and try the best to satisfy the ne

w calling service QoS request, such as service rate, quality (SIR or

BER), and delay etc., basing on the radio measurement.

95



Admission Control in Uplink

Itotal_old+ΔI >Ithreshold

The current RTWP (Received Total Wide Power) value of cell, which is reported by Node B

AccessThreshold

Interference capacityService priorityReserved capacity for handover

Iown-cell

0~N

Iother-cell

The forecasted interference including the delta interference brought by the incoming service is calculated by the admission algorithm, and its result depends on the QoS and transmission propagation environment

96



Admission Control in Uplink

Different ultimate user numbers

Different interference threshold under different ultimate user nu

mber conditions

Different ultimate throughputs


Quantity of Subscriber-- The Total Bandwidth Received by Node B

Th

e T

ota

l Ba

nd

wid

th P

ow

er

Re

ceiv

ed

by

No

de

B (

dB

m)

Ultimate Situation for different service rateThroughput

Throughput -- The Total Bandwidth Received by Node B

The

Tot

al B

andw

idth

Pow

er R

ecei

ved

by N

ode

B (

dBm

)

97



Admission Control in Downlink

Ptotal_old+△P>=Pthreshold Access Threshold

The forecasted TCP value including delta power required for the incoming service is calculated by the admission algorithm, and its result depends on the QoS and transmission propagation environment.

The current TCP value of cell, which is reported by Node B

（ Transmitted Carrier Power*Pmax ）

Max TCP of cellService priorityReserved capacity for handover

98




Th

e T

otal

Tra

nsm

issi

on P

ower

(dB

m)

Red ： low speed serviceBlue ： high speed service

The above figure illustrates the relation between ultimate user The above figure illustrates the relation between ultimate user

number corresponds to different service rate and distance number corresponds to different service rate and distance

under equidistant distribution conditionunder equidistant distribution condition

The above figure illustrates the relation between ultimate user The above figure illustrates the relation between ultimate user

number corresponds to different service rate and distance number corresponds to different service rate and distance

under equidistant distribution conditionunder equidistant distribution condition

Admission Control in Downlink

99



Admission Control Analysis

The service can be either one-direction or bi-direction type. For bi-

direction service, it is admitted only after both uplink and downlink

are admitted.

Admission control is the only access entry for the incoming

services, its strategy will directly effect the cell capacity and

stability, e.g. call loss rate, call drop rate.

100



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



101



Load controlThe purpose of load control is to keep the

system load under a pre-planned threshold

through decreasing the load in several ways,

therefore to improve the system stability.

The speed and positi

on changing of UE m

ay worsen the wirele

ss environment.

Increasing of transmitted power will increase the system load

Purpose of Load Control

102



负荷控制

Start

DecisionLight load Over load

Normal load

1. Handover in and access are forbidden

2. TCP increasing is forbidden

3. RAB service rate degrade4. Handover out5. Release call

Load Control Flows

1. Handover in and access are allowed2. Transmitted code power (TCP) increasing is allowed3. RAB service rate upgrade is allowed

1. Handover in and access are allowed2. TCP increasing is allowed

103



Load Control in Uplink

Triggers RTWP (Received Total Wind-band Power) value from measurement report excee

ds the uplink overload threshold;

Admission control triggers when rejecting the high priority service’s access due

to insufficient load capacity in uplink.

Methods for decreasing load Decrease the target Eb/N0 of service in uplink;

Decrease the rate of none real time data service;

Handover to GSM system;

Decrease the rate of real time service, e.g. voice call;

Release calls.

Methods for increasing load Increase the service rate.

104



Load Control in Downlink

Triggers TCP (Transmitted Carrier Power) value from measurement report exceeds the do

wnlink overload threshold; Admission control triggers when denying the high priority service’s access due t

o insufficient load capacity in downlink.

Methods for decreasing load Decrease the downlink target Eb/N0 of service in downlink; Decrease the rate of none real time data service; Handover out to coverage-shared light loaded carrier; Handover out to GSM system; Decrease the rage of real time service, e.g. voice call; Release calls.

Methods for increasing load Increase the service rate.

105



Cell breathing is one of the means for load control

The purpose of cell breathing is to share the load of hot-The purpose of cell breathing is to share the load of hot-

spot cell with the light loaded neighbor cells, therefore to spot cell with the light loaded neighbor cells, therefore to

improve the utilization of system capacity.improve the utilization of system capacity.

The purpose of cell breathing is to share the load of hot-The purpose of cell breathing is to share the load of hot-

spot cell with the light loaded neighbor cells, therefore to spot cell with the light loaded neighbor cells, therefore to

improve the utilization of system capacity.improve the utilization of system capacity.

Cell Breathing

106



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control


Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



107



WCDMA system adopts primary scrambling code to distinguish the cells

and channel code to distinguish physical channels in downlink, and adopts

scrambling code to distinguish users in uplink. The OVSF (Orthogonal

Variable Spreading Factor) code tree is a sparse resource and only one tree

can be used in each cell. In order to make full use of the capacity, and

support as many connections as possible, it is important to plan and

control the usage of channel code resource.

Although the uplink scrambling codes are sufficient, the RNC should plan

to use the codes for avoiding allocating same code to different users in

inter-RNC handover scenario.

Purpose of Code Resource Planning

108



Code Resource Planning

Code types in WCDMA system Uplink Scrambling Code

Uplink Channel Code

Downlink Scrambling Code

Downlink Channel Code

The uplink scrambling code and downlink scrambling code can be planned easily,

and uplink channel code does not need planning, therefore, only the downlink channel

code is planned with certain algorithm in RNC.

Each cell has one primary scrambling code, which correlates with a channel code

tree. The downlink channel code tree is a typical binary tree with each layer

corresponds to a certain SF ranging from SF4 to SF512.

109



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)

Generation of Channel Code

110



OVSF Code Tree

111



SF=8

SF=32

SF=16

Channel Code Characters

Code allocation restriction ： The code to be allocated must fulfill the condition that its ancestor nod

es including from father node to root node and offspring nodes in the

sub tree are not allocated;

Code allocation side effect ： The allocated node will block its ancestor nodes and offspring nodes, t

hus the blocked nodes will not be available for allocation until being un

blocked .

112



Strategy of Channel Code Allocation

Full utilization

The fewer the blocked codes, the higher the code tree utilization rate.

Low Complexity

Short code first.

Allocate codes for common channels and physical shared channels prior

to dedicated channels.

Guarantee the code allocation for common physical channels.

Apply certain optimized strategy to allocate codes for downlink dedicated

physical channels.

113



An Example of Code Allocation

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

SF = 4

SF = 8

SF = 16

SF = 32

SF = 4

SF = 8

SF = 16

SF = 32

Red circles represent the codes that have been allocated ；Green circles represent the codes that are blocked by the allocated offspring codes ；Blue circles represent the codes that are blocked by the allocated ancestor codes;

Black circles represent the codes that are to be allocated;

Choose one code from

three candidates

AgendaAgenda













115



RAKE Receiver

Multi-User Detection (MUD)

RAKE Receiver


WCDMA Key TechnologyWCDMA Key Technology

116



d1 d2

d3

RAKE Receiver can effectively overcome the multi-path RAKE Receiver can effectively overcome the multi-path

interference, consequently improve the receiving performance.interference, consequently improve the receiving performance.

RAKE Receiver can effectively overcome the multi-path RAKE Receiver can effectively overcome the multi-path

interference, consequently improve the receiving performance.interference, consequently improve the receiving performance.

RAKE Receiver

The multi-path signals contain some useful energy , therefore the

CDMA receiver can combine these energy of multi-path signals to

improve the received signal to noise ratio.

RAKE receiver adopts several correlation detectors to receive the

multi-path signals, and then combines the received signal energy.

117



RAKE Receiver

Single path receiving circuit



Multi-path search engine

Calculate signal strength and

delay

Combiner Combined Signal

tt

s(t) s(t)

Receiver

118



RAKE Receiver


RAKE Receiver


WCDMA Key TechnologyWCDMA Key Technology

119



Multi-User Detection

WCDMA telecommunication system can provide communication environment for simultaneous multi-user access. The research result indicates that multi-access interference and channel noise have different statistical characters.

Multi-access interference has the estimable and reproducible features.

The purpose of MUD is to reduce the multi-access interference till 0 through collecting the useful information of all users and adopting certain signal processing method.

120



Multi-User Detection Technology

The CDMA receiver is based on the principal of RAKE receiving, and the interference

from other users is treated as noise.

The capacity of RAKE receiving based CDMA system is interference limited.

The true optimal receiver adopts join-detection technology to detect all the received s

ignals, and removes the interference from other users.

Multi-User Detection (MUD), also named as Join-detection or Interference-elimination ，can reduce the multi-access interference, thereby improve the capacity.

MUD can eliminate the near-far effect.

The near optimal MUD receiver and interference eliminated receiver are actually appli

ed instead of the true optimal MUD receiver because of the implementation complexit

y.

121



True Optimal Multi-User Detection

The true optimal detection consists of K matched filters and one Vi

terbi algorithm implementation.

The complexity has an exponents relation to the user number.

Matched Filter 1

SynchronizeZ1 （ i

）

Matched Filter 2Z2 （ i

）

Matched Filter kZk

（ i ）

Viterbi Algorithm

Implementation

b1 （ i）

b2 （ i）

bk

（ i ）

r(t)

Synchronize

Synchronize

122



Linear De-correlation Detection

De-correlation detection transforms the multi-access interference,

which is generated in multi-user environment, into an equivalent tr

ansmission response matrix ， i.e. the channel codes correlation m

atrix R 。 The complexity has an exponents relation to the user number.

Matched Filter 1

Matched Filter 2

Matched Filter k

Linear Transform

ation R － 1

b1

b2

bk

r(t)

Bit Decision

Bit Decision

Bit Decision

123



Summary

WCDMA Wireless Technology Spreading Channel Coding (Convolutional Coding, Turbo coding) Interleaving Diversity

WCDMA Radio Resource Management （ RRM) Power Control Handover Control Admission Control Load Control Code Allocation

WCDMA Key Technology RAKE Receiver MUD

01-wcdma wireless principle and key technology_v3.10

Documents