Training Material_WCDMA Wireless Principle and Key Technology.ppt

8/10/2019 Training Material_WCDMA Wireless Principle and Key Technology.ppt

http://slidepdf.com/reader/full/training-materialwcdma-wireless-principle-and-key-technologyppt 1/123

WCDMA Wireless Princip le and

Key Technology

-UMTS Radio Network Planning & Optimization Dept



秘密▲

WCDMA System Overview

WCDMA Wireless Principle

WCDMA Key Technology

Contents



秘密▲ Evolution of Cellular Mobile

Communication SystemFirst

Generat ion(80s’)

Analog

Third

Generation

(2000)

Wideband

Multimedia

Second

Generat ion(90s’)

Digital

AMPS

TACS

NMT

Others

A n a l o g

T e c h n o l o g y

GSM

CDMAIS95

TDMA

IS-136

PDC

Market

Driven

UMTS

WCDMA

CDMA

2000

Market

Driven

TD-

SCDMA

D i g i t a l T e c h n o l o g y

V o i c e S e r v i c e

B r o a d b a n d S e r v i c e



秘密▲

Background of 3G

Essential impetus: a wider range

and higher data rate of services,

higher spectrum efficiency

Improve the compatibility betweendifferent networks

The international standard—IMT-

2000 comes forth as the

requirement



秘密▲

Target of IMT-2000

Uniform frequency, uniform standard, seamless

coverage

High efficient utilization of spectrum

High quality, high security

Easy evolution to 2G

Provide various new services



秘密▲

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



秘密▲

Wireless Interface Standards of IMT-2000

IMT-FT

IMT-2000

FDMA/TDM

A

IMT-SC

IMT-2000

TDMA SC

UWC-136 E-DECT

IS-136 DECT

IMT-DS

CDMA DS

IMT-MC

CDMA MC

IMT-TD

CDMA TDD

WCDMA TD-SCDMA

UMTS TDD

CDMA 2000

UMTS FDD



秘密▲

3G Technology Evolution

3G

Standard

WCDMA

TD-SCDMA CDMA2000

CDMA is the Mainstream Technology of 3G

CN：based on MAP

CN：based on ANSI-41 CN：based on MAP



秘密▲

3G Standard and Beyond 3G Evolution

TD-SCDMAEnhancedTD-SCDMA

2005

• R4 • R5/6LTE

FDD/TDD• HSDPA

Phase1

• HSUPA

Phase1

• HSDPA

Phase2

•HSUPA

Phase2

• MBMS•WCDMA

•R4

2004 2005 2006 2007 2008 After 2009

• R5 • R6

•CDMA

•1X

• EV-DO 0 • EV-DO A

• BCMCSAIE

Phase 2

AIE

Phase1

N×DO

3GPP 4G

3GPP2 4G

WiMAX

802.16d

WiMAX

802.16e



秘密▲

WCDMA Standard Evolution

Introduce Iu Interface

MAX. Speed: 2Mbps

Commercial Release

2001.6+ 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



秘密▲

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 basestations

Multiple switching technology

Multiple transport rate

Advanced radio resource management algorithm



秘密▲

WCDMA Entire IP Network EvolutionR99

Billing

Server

OMC

SCP

HLR

MMSC

GMLC

MSCGMSC GGSNSGSN

PSCS

R99 CN smoothly evolves from

GSM/GPRS network

R4 CN separate the Control Plane

from Bearer Plane in CS Domain

R5 CN Introduces IMS，

RAN Adopts IP

RNSBSS

MGWGMGW GGSNSGSN

PSCS

R4 R5

BillingServerOMC

SCP

HLR

MMSC

GMLC

CS

MSCserver

GMSCserver

BillingServer

OMC

SCP

HLR

MMSC

GMLC

BSS RNSRNS

BSS

MGWGMGW GGSNSGSN

PSCS

WCDMA Entire IP Network Evolution coincide with the

development tendency of the next generation network



秘密▲

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)



秘密▲

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)



秘密▲


WCDMA Wireless Principle


Contents



秘密▲

Radio Propagation Characteristics

Multi Access

Spreading Technology

Channel Coding

Interleave Technology

Diversity Technology

The Basic Principles ofWireless Communication



秘密▲

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 reflects the trend of the received signal in the

spreading。 Slow fading：Loss because of being blocked by the building

and hill in the propagation path

Fast fading：Electromagnetic signals rapidly decline in a fewdozens wavelength ranges

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

Rician distribution：line-of –sight transmission



秘密▲

Frequency off -set caused by the mo vement of mo bi le that

is Dopp ler effect

Sending signal Accepting signal

Interference

0dB

Sending signal

-25dB

Accepting signal

fading

0 +


delay

0 2 3 +


dithering

Characteristics of Radio Propagation



秘密▲

Multi-Path Effects

receiving signal

time

strength

0

sending signal



秘密▲


Multi Access


Channel Coding



The Basic Principles of

Wireless Communication



秘密▲

Power

Power

Power

FDMA

TDMA

CDMA

Frequency division multiple

access technology Channels in different frequency are

allocated to different users, e.g. TACS

AMPS

Time division multiple accesstechnology channels in different time are allocated to

different users, e.g. GSM

DAMPS

Code division multiple accesstechnology

Users distinguished by scramble code, e.g.

CDMA

Multiple Access



秘密▲


Multi Access


Channel Coding







秘密▲ Principle of Spreading Frequency

A technology of transmission technology after spreading

frequency of signal.

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

Fast

Spreading

Sequence

Slow

Information

Sent

TX

Slow

Information

Recovered

RX

Fast

Spreading

Sequence

Wideband

Signal





秘密▲ Spreading Mode

Direct sequence spread（DS－SS）

Base band data is spreaded by multiplication of pseudo-noise sequence and base-

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 detection

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



秘密▲ 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



秘密▲


Multi Access


Channel Coding







秘密▲

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<10-6 Can satisfy the

data communication





P i i l f I l T h l



秘密▲ Principle of Interleave Technology

Advantage

Interleave is to change the sequence of data to random theunexpected 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.



秘密▲


Multi Access


Channel Coding







秘密▲

Concept of Diversity Technology

Double meanings：scattered transmission, concentrative

process.

Achieved by using and finding the independent multi-access

signals 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

秘密



秘密▲

Diversity Categories

Space diversity

Also called antenna diversity, if the distance between the antennaeis 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 theenvironment 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

秘密▲



秘密▲


WCDMA Wireless Principle A

The Basic Principles of Wireless

Communication

WCDMA Wireless Technology


Contents

秘密▲



秘密▲

Spreading Technology of WCDMA

Channel Coding of WCDMA

Interleave Technology of WCDMA

Diversity Technology of WCDMA


秘密▲



秘密▲

Symbol rate×

SF = 3.84Mcps

WCDMA，

SF of uplink channeliezd code：

4~256

SF of downlink channelized code:4~512

OVSF: Orthogonal Variable Spreading Factor

OVSF Code Scramble Code

Data bit

Chip

after

Spreading

Spreading of WCDMA

秘密▲

S di S bli d d l ti f WCDMA



秘密▲

∑

∑

Real part

and

Imaginary part

separate

Pulse

shaping

Pulse

shaping

serial

parallel

transfer

serialparallel

transfer

……

……

DL physical channel 1Cch,SF,m

j

I+jQ

Sdl,n

G1

Cch,SF,m

j

I+jQ

Sdl,n

G2

DL physical channel 2Gp

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：

秘密▲



秘密▲

Real part

and

Imaginary part

separate

Pulse

shaping

Pulse

shaping

cos(wt)

-sin(wt)

Sdpch,n

S

Re(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

ccCc βcDPCCH

Q

Spreading, Scrambling and modulation of WCDMA

Uplink physical channel spreading and modulation：

秘密▲



秘密▲

Despreading of WCDMA

Method of despreading

Input signal

Local PN code

When T=Ts, judge

Output after despreading

integral

0

Ts

(*)dt

秘密▲



秘密▲

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

ketch map of Spreading and Despreading of WCDMA

秘密▲



秘密▲

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-jamming

秘密▲



秘密▲








秘密▲Characteristics of Convolutional code



秘密▲ 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.

秘密▲



秘密▲

Turbo Code Used in Data service channel

Code Rate is 1/3

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

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

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

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

multiplexed and punctured Decoding needs cycle iterative calculation

Interleaver

Encoder 1

Encoder 2

M u l t i p l e xinput output

秘密▲



秘密▲

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 sensitive & delay

insensitive , e.g. WWW, FTP, E_mail ,

multimedia transmission.

秘密▲



秘密▲






秘密▲



秘密▲


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

秘密▲



秘密






秘密▲



秘密


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 feedbacktechnology.

Interleave

A implied time diversity

RAKE receive technology

A implied time diversity. The multi-access signal used byRAKE is considered the signal sent by transmitter several

times.

秘密▲



秘密




WCDMA Capacity Feature

Radio Resource Management


Contents

秘密▲



Capacity of WCDMA

秘密▲



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



秘密▲

WCDMA C it F t




WCDMA capacity feature

WCDMA capacity is Soft Capacity

Concept of soft capacity

Inter-convertibility between system capacity and

communication quality

Different service has different capacity

Different proportion of services has different capacity

for mixed services

秘密▲

S ft C it



Trade off between System capacity and service quality

Different service

combination and

proportion has

different capacity

Soft Capacity

秘密▲

C i l F f WCDMA C i



Capacity

All the WCDMA technologies adopted is try to achieve

the most optimal balance of the three factors

Crucial Factors for WCDMA Capacity

秘密▲

F t Aff ti WCDMA C it



Factors Impact on WCDMA capacity Category

Power Control Reducing interference, saving power and Increasing capacity

Radio Resource

Management

RRM

Handover ControlImpacting 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 Control Monitoring 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.

MUDReducing 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



秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control

Code Allocation Spreading


秘密▲

Power Control



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

principle is that any potential surplus transmitted power forservice must be controlled.

秘密▲

Near Far Effect



Each term inal is an

inter ference sou rce to the

oth ers. The Near-far effect

wi l l impact the capacity

t remendous ly

Power

f

Power contro l wi l l reduce

the cros s inter ference

s igni f icant ly and improve

the total capacity

Near-Far Effect

Power

f

秘密▲ Multi-Access Interference



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

Mu l t i - A c c e s s In t e r f e r en c e S k e t c h Map

Output

Time Synchronizat ion

秘密▲

Purpose of Power Control



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

秘密▲

Category of Power Control



Category of Power Control

Open Loop

Measure the channel interference condition and adjust the initialtransmitted 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.

秘密▲

Open Loop Power Control



Open Loop Power Control

General principals of open loop power control

Open loop power control is applied to estimate the initial

transmitted code 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 requirements of

establishing service, current downlink total Transmitted

Power and interference from neighbor cell etc..



秘密▲ Close Loop – Inner Loop Power Control



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..

秘密▲

Close Loop Outer Loop Power Control



NodeB UE

TPC instruction

Inner loop

Set SIRtar

Get data flow

with stable BLER

Measure BLER

of 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

秘密▲

Close Loop Open Loop Power Control



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.

秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



秘密▲

Purpose of Handover Control



When UE is mov ing from the coverage area of one si te to

another si te, or th e qual i ty of s erv ice is decl ined by external

inter ference dur ing a cal l, the cal l mus t be handed o ver to an idle

channel for sustain ing the serv ice. Handover is a key techn ology

for m obi le network ing

Purpose of Handover Control

秘密▲

Handover Types



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)

秘密▲

Handover Demonstration



Handover Demonstration

Hard

Handover

Soft

Handover

秘密▲

Soft Handover/Softer Handover



A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

秘密▲ 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.

秘密▲ Handover Flows



(A) RNC sends

measurement control

message to UE (MeasurementControl)

(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

Currentcarrier has

good quality

Othersystem

has good

qualityOther carrier has

good quality

（I）If handover is required, RNC sends

handover command with target cell to UE

秘密▲

General Procedure of Handover Control (I)



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

Indicator ）is measured within the bandwidth of associated channels

秘密▲

General Procedure of Handover Control (II)



General Procedure of Handover Control (II)

FilteringThe 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

layer;

a = 1/2(k/2), k means the ―Filter coefficient‖, which is included in the

Measurement Control message. It is decided by the UTRAN.

F0 is initialized by the first measurement result M1.

秘密▲

General Procedure of Handover Control (III)



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 RNC

Measurement result filtered in UE

Event decided in UE

Handover decided in RNC

General Procedure of Handover Control (III)

秘密▲

General Procedure of Handover Control (IV)



General Procedure of Handover Control (IV)

Handover algorithm All the handover algorithms including soft handover,

hard handover and so on are implemented on the

event decision made from measurement report.

Events defined in 3GPP specifications

Intra-frequency events：1A~1F

Inter-frequency events：2A~2F

Inter-RAT events：3A~3D

秘密▲

Concepts Related to Handover



p

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

秘密▲

An Example of Handover Procedure



An Example of Handover Procedure

Pilot Ec/Io of cell 1

time

Pilot

Ec/Io

Connect to cell1 Event 1A Event 1C Event 1B

（add cell2）（replace cell1 with cell 3）（remove cell3）



⊿t ⊿t ⊿t

秘密▲

RNS Relocation



RNS Relocation

Core NetworkCore Network

Service

RNSTarget

RNS

Service

RNSTarget

RNS

Iu Iu

Iur

RNS

Radio Network Sub-system

RNS relocation can : Reduce the Iur traff ic signif icant ly

Enhance the sys tem adaptabi l i ty

秘密▲

Hard Handover



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.

秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control





秘密▲

Compressed Mode



Compressed Mode

Compressed Mode Transm ission Diagram

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

10ms

秘密▲

Generation of Compressed Mode Frame



p

Puncturing Lower the symbol rate of physical channel when

processing the rate matching procedure

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

High layer scheduling Decrease the bit rate from up layer

秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



秘密▲

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.

秘密▲ Purpose of Admission Control



The admission control should implement admission or rejection

for the new users, new RAB and new RL (for example handover)according to the current resource situation. The admission

control will sustain the system stability firstly and try the best to

satisfy the new calling service QoS request, such as service rate,

quality (SIR or BER), and delay etc., basing on the radio

measurement.

秘密▲ Admission Control in Uplink



I total_old +ΔI >I threshold

The current RTWP (Received

Total Wide Power) value of cell,

which is reported by Node B

Access

Threshold

Interference capacityService priority

Reserved capacity for

handover

I own-

cell

0

~ N

I other- cell

The forecasted interference including the deltainterference brought by the incoming service is

calculated by the admission algorithm, and its

result depends on the QoS and transmission

propagation environment

秘密▲

Admission Control in Uplink



Admission Control in Uplink

Different ultimate user numbers Different interference threshold under different ultimate

user number conditions

Different ultimate throughputs

Quantity of Subscriber

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

T h e T o t a l B a n d

w i d t h P o w e r R e c e i v e d b y N o d e B ( d B m )

Ultimate Situation for different service rate

Throughput

Throughput -- The Total Bandwidth Received by Node B

T h e T o t a l B a n d w

i d t h P o w e r R e c e i v e d b y N o d e B ( d B m )

秘密▲ Admission Control in Downlink



P total_old + △P>=P threshold

Access

Threshold

The forecasted TCP value including deltapower 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 cell

Service priority

Reserved capacity for

handover

秘密▲

Admission Control in Downlink



Quantity of Subscriber

T h e T o t a l T r a n s m i s s i o n P o w e r ( d B m )

Red：

low speed serviceBlue：high speed service

The above figure illustrates the relation between ultimate user

number corresponds to different service rate and distance

under equidistant distribution condition

秘密▲ Admission Control Analysis



The service can be either one-direction or bi-direction

type. For bi-direction service, it is admitted only afterboth uplink and downlink are admitted.

Admission control is the only access entry for the

incoming services, its strategy will directly effect thecell capacity and stability, e.g. call loss rate, call drop

rate.

秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



秘密▲

Purpose of Load Control



Load controlThe purpose of load control is to keep thesystem load under a pre-planned threshold

through decreasing the load in several ways,

therefore to improve the system stability.

The speed and

position changing of

UE may worsen the

wireless environment.

Increasing of

transmitted power

will increase the

system load

秘密▲ 荷Load Control Flows



Start

Decision Light load Over load

Normal load

1. Handover in and access

are forbidden

2. TCP increasing isforbidden

3. RAB service rate degrade

4. Handover out

5. Release call

1. Handover in and

access are allowed

2. Transmitted code

power (TCP) increasing

is allowed

3. RAB service rate

upgrade is allowed

1. Handover in

and access are

allowed2. TCP

increasing is

allowed

秘密▲ Load Control in Uplink



Triggers

RTWP (Received Total Wind-band Power) value frommeasurement report exceeds 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.

秘密▲ Load Control in Downlink



Triggers

TCP (Transmitted Carrier Power) value from measurement reportexceeds the downlink overload threshold;

Admission control triggers when denying the high priority service’s

access due to 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.

秘密▲ Cell Breathing



Cell breathing isone of the means

for load control

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

spot cell with the light loaded neighbor cells, therefore to

improve the utilization of system capacity.

秘密▲



Power Control

Handover Control

Compressed Mode

Admission Control

Load Control



秘密▲ Purpose of Code Resource Planning



WCDMA system adopts primary scrambling code to distinguish

the cells and channel code to distinguish physical channels indownlink, 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 controlthe 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.

秘密▲ 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.

秘密▲ Generation of Channel 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)

秘密▲ OVSF Code Tree



秘密▲

Channel Code Characters



SF=8

SF=32

SF=16

Code allocation restriction:

The code to be allocated must fulfill the condition that its ancestor nodesincluding 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, thus

the blocked nodes will not be available for allocation until being unblocked.

秘密▲ 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.

秘密▲ 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

秘密▲

Contents









秘密▲



RAKE Receiver

Multi-User Detection (MUD)


秘密▲ RAKE Receiver



d

d

2

d

3

RAKE Receiver can effectively overcome the multi-path

interference, consequently improve the receiving performance.

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.

秘密▲ RAKE Receiver



Single path

receiving circuit

Single path

receiving circuit

Single path

receiving circuit

Multi-path search

engine

Calculate signal

strength and

delay

Combiner Combined

Signal

tt

s(t) s(t)

Receiver

秘密▲



RAKE Receiver

Multi-User Detection (MUD)


秘密▲ Multi-User Detection



WCDMA telecommunication system can provide communicationenvironment 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.

秘密▲ 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 interferencelimited.

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

the received signals, 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 applied instead of the true optimal MUD receiver because

of the implementation complexity.

秘密▲ True Optimal Multi-User Detection



The true optimal detection consists of K matched filters and one

Viterbi algorithm implementation. The complexity has an exponents relation to the user number.

Matched Filter 1

Synchronize

Z1（

i）

Matched Filter 2Z2（i）

Matched Filter kZk （i）

Viterbi

Algorithm

Implementation

b1（

i）

b2（i）

bk （i）

r(t)

Synchronize

Synchronize

秘密▲ Linear De-correlation Detection



De-correlation detection transforms the multi-access

interference, which is generated in multi-user environment, intoan equivalent transmission response matrix，i.e. the channel

codes correlation matrix 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

秘密▲ Summary




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



Date post:	02-Jun-2018
Category:	Documents
Upload:	jeffrey-price
View:	222 times
Download:	0 times

Training Material_WCDMA Wireless Principle and Key Technology.ppt

Documents