Wcdma Ran Principle

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Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA RAN Principle

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved. Page1

Objectives

Upon completion of this course, you will be able to:

Describe the development of 3G

Outline the advantage of CDMA principle

Characterize code sequence

Outline the fundamentals of RAN

Describe feature of wireless propagation


Contents

1. 3G Overview

2. CDMA Principle

3. WCDMA Network Architecture and protocol structure

4. WCDMA Wireless Fundamental


Different Service, Different Technology

AMPS

TACS

NMT

Others

1G 1980s

Analog

GSM

CDMA IS-95

TDMA IS-136

PDC

2G 1990s Digital

Technologies

drive

3G IMT-2000

UMTS WCDMA

cdma 2000

Demands

drive

TD-SCDMA

3G provides compositive services for both operators and subscribers


3G Evolution

Proposal of 3G

IMT-2000: the general name of third generation mobile

communication system

The third generation mobile communication was first

proposed in 1985，and was renamed as IMT-2000 in the

year of 1996

Commercialization: around the year of 2000

Work band : around 2000MHz

The highest service rate :up to 2000Kbps


3G Spectrum Allocation


Bands WCDMA Used

Main bands

1920 ~ 1980MHz / 2110 ~ 2170MHz

Supplementary bands: different country maybe different

1850 ~ 1910 MHz / 1930 MHz ~ 1990 MHz (USA)

1710 ~ 1785MHz / 1805 ~ 1880MHz (Japan)

890 ~ 915MHz / 935 ~ 960MHz (Australia)

. . .

Frequency channel number＝central frequency×5, for main band:

UL frequency channel number ：9612～9888

DL frequency channel number : 10562～10838


3G Application Service

Time Delay

Error Ratio

background

conversational

streaming

interactive


The Core technology of 3G: CDMA

CDMA

WCDMA

CN: based on MAP and GPRS

RTT: WCDMA

TD-SCDMA CN: based on MAP and GPRS

RTT: TD-SCDMA

cdma2000 CN: based on ANSI 41 and

MIP RTT: cdma2000


Contents

1. 3G Overview

2. CDMA Principle




Multiple Access and Duplex Technology Multiple Access Technology

Frequency division multiple access (FDMA)

Time division multiple access (TDMA)

Code division multiple access (CDMA)


Multiple Access Technology

Power

FDMA

Power

TDMA

Power

CDMA


Multiple Access and Duplex Technology Duplex Technology

Frequency division duplex (FDD)

Time division duplex (TDD)


Duplex Technology

Time

Frequency

Power

TDD

USER 2

USER 1

DL

UL

DL

DL

UL

FDD

Time

Frequency

Power

UL DL

USER 2

USER 1


Contents

1. 3G Overview

2. CDMA Principle




WCDMA Network Architecture

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu-CS Iu-PS

Iur

Iub Iub Iub Iub

CN

UTRAN

UE Uu

CS PS

Iu-CS Iu-PS

CS PS


WCDMA Network Version Evolution

3GPP Rel99 3GPP Rel4

3GPP Rel5

2000 2001 2002

GSM/GPRS CN

WCDMA RTT

IMS

HSDPA 3GPP Rel6

MBMS

HSUPA

2005

CS domain change to NGN

WCDMA RTT


WCDMA Network Version Evolution

Features of R6

MBMS is introduced

HSUPA is introduced to achieve the service rate up to 5.76Mbps

Features of R7

HSPA+ is introduced, which adopts higher order modulation and MIMO

Max DL rate: 28Mbps, Max UL rate:11Mbps

Features of R8

HSPA+ PhaseII is introduced, which adopts 64QAM+MIMO or 64QAM+DC

in downlink (Defined by 3GPP 25.XXX)

LTE is introduced which adopts OFDMA instead of CDMA (Defined by 3GPP

36.XXX)

Max DL rate: 100Mbps, Max UL rate: 50Mbps (with 20MHz bandwidth)


Uu Interface protocol structure

L3

co

ntr

ol

co

ntr

ol

co

ntr

ol

co

ntr

ol

C-plane signaling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC RLC

RLC

Duplication avoidance

UuS boundary

L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

RRC

RLC RLC

RLC RLC

BMC


General Protocol Mode for UTRAN Terrestrial Interface The structure is based on the principle that the layers and

planes are logically independent of each other.

Application

Protocol

Data

Stream(s)

ALCAP(s)

Transport

Network

Layer

Physical Layer

Signaling

Bearer(s)

Control Plane User Plane

Transport Network

User Plane

Transport Network

Control Plane

Radio

Network

Layer

Signaling

Bearer(s)

Data

Bearer(s)

Transport Network

User Plane


Iu-CS Interface

ALCAP

Control Plane

Transport Network

Control Plane

User plane Radio

Network

Layer

Transport Network

User Plane

Transport

Network

Layer

A B

RANAP

AAL2 PATH

ATM

Physical Layer

SAAL NNI

SCCP

MTP3-B

Iu UP

SAAL NNI

MTP3-B

Transport Network

User Plane


Iu-PS Interface

Control Plane User plane Radio

Network

Layer

Transport Network

User Plane Transport

Network

Layer

Transport Network

User Plane

C

RANAP

ATM

SAAL NNI

SCCP

MTP3-B

Iu UP

AAL Type 5

IP

UDP

GTP-U

Physical Layer


Iub Interface

ALCAP

Control Plane

Transport Network

Control Plane

User plane Radio

Network

Layer

Transport Network

User Plane

Transport

Network

Layer

Transport Network

User Plane

NBAP

AAL2 PATH

ATM

Physical Layer

SAAL UNI

Iub FP

SAAL UNI

NCP CCP


Iur Interface

ALCAP

Control Plane

Transport Network

Control Plane

User plane Radio

Network

Layer

Transport

Network

Layer

A B

RNSAP

AAL2 PATH

ATM

Physical Layer

SAAL NNI

SCCP

MTP3-B

Iur Data

Stream

SAAL NNI

MTP3-B

Transport Network

User Plane Transport Network

User Plane


Contents

1. 3G Overview

2. CDMA Principle




Processing Procedure of WCDMA System

Source

Coding Channel Coding & Interleaving

Spreading Modulation

Source

Decoding Channel Decoding

& Deinterleaving Despreading Demodulation

Transmission

Reception

chip modulated

signal bit symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver


WCDMA Source Coding

AMR (Adaptive Multi-Rate)

Speech

A integrated speech codec with 8

source rates

The AMR bit rates can be controlled

by the RAN depending on the

system load and quality of the

speech connections

Video Phone Service

H.324 is used for VP Service in CS

domain

Includes: video codec, speech codec,

data protocols, multiplexing and etc.

CODEC Bit Rate (kbps)

AMR_12.20 12.2 (GSM EFR)

AMR_10.20 10.2

AMR_7.95 7.95

AMR_7.40 7.4 (TDMA EFR)

AMR_6.70 6.7 (PDC EFR)

AMR_5.90 5.9

AMR_5.15 5.15

AMR_4.75 4.75



Transmitter

Source



Source



Transmission

Reception

chip modulated

signal bit symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver


WCDMA Block Coding - CRC

Block coding is used to detect if there are any

uncorrected errors left after error correction.

The cyclic redundancy check (CRC) is a common method

of block coding.

Adding the CRC bits is done before the channel encoding

and they are checked after the channel decoding.


WCDMA Channel Coding

Effect

Enhance the correlation among symbols so as to recover the signal when

interference occurs

Provides better error correction at receiver, but brings increment of the

delay

Types

No Coding

Convolutional Coding (1/2, 1/3)

Turbo Coding (1/3)

Code Block

of N Bits

No Coding

1/2 Convolutional

Coding

1/3 Convolutional

Coding

1/3 Turbo Coding

Uncoded N bits

Coded 2N+16 bits

Coded 3N+24 bits

Coded 3N+12 bits


WCDMA Interleaving

Effect

Interleaving is used to reduce the probability of consecutive bits

error

Longer interleaving periods have better data protection with more

delay

1110

1.........

............

...000

0100

0 0 1 0 0 0 0 . . . 1 0 1 1 1

1110

1.........

............

...000

01000 0 … 0 1 0 … 1 0 0 … 1 0 … 1 1

Inter-column permutation

Output bits

Input bits

Interleaving periods:

20, 40, or 80 ms



Source



Source



Transmission

Reception

chip modulated

signal bit symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver


Correlation

Correlation measures similarity between any two arbitrary

signals.

Identical and Orthogonal signals:

Correlation = 0

Orthogonal signals

-1 1 -1 1

-1 1 -1 1

1 1 1 1

+1

-1

+1

-1

+1

-1

+1

-1

Correlation = 1

Identical signals

-1 1 -1 1

1 1 1 1

-1 1 -1 1

C1

C2 +1

+1

C1

C2


Orthogonal Code Usage - Coding

UE1: ＋1 －1

UE2: －1 ＋1

C1 : －1 ＋1 －1 ＋1 －1 ＋1 －1 ＋1

C2 : ＋1 ＋1 ＋1 ＋1 ＋1 ＋1 ＋1 ＋1

UE1×c1：－1 ＋1 －1 ＋1 ＋1 －1 ＋1 －1

UE2×c2：－1 －1 －1 －1 ＋1 ＋1 ＋1 ＋1

UE1×c1＋ UE2×c2：－2 0 －2 0 ＋2 0 ＋2 0


Orthogonal Code Usage - Decoding

UE1×C1＋ UE2×C2: －2 0 －2 0 ＋2 0 ＋2 0

UE1 Dispreading by c1: －1 ＋1 －1 ＋1 －1 ＋1 －1 ＋1

Dispreading result: ＋2 0 ＋2 0 －2 0 －2 0

Integral judgment: ＋4 (means＋1) －4 (means－1)

UE2 Dispreading by c2: ＋1 ＋1 ＋1 ＋1 ＋1 ＋1 ＋1 ＋1

Dispreading result: －2 0 －2 0 ＋2 0 ＋2 0

Integral judgment: －4 (means－1) ＋4 (means＋1)


Spectrum Analysis of Spreading & Dispreading

Spreading code

Spreading code

Signal

Combination

Narrowband signal

f

P(f)

Broadband signal

P(f)

f

Noise & Other Signal

P(f)

f

Noise+Broadband signal

P(f)

f

Recovered signal

P(f)

f


Spectrum Analysis of Spreading & Dispreading

Max allowed interference

Eb/No

Requirement

Power

Max interference caused by

UE and others

Processing Gain

Ebit

Interference from

other UE Echip

Eb / No = Ec / No ×PG


Process Gain

Process Gain

Process gain differs for each service.

If the service bit rate is greater, the process gain is smaller,

UE needs more power for this service, then the coverage of

this service will be smaller, vice versa.

)rate bit

rate chiplog(10Gain ocessPr


Spreading Technology

Spreading consists of 2 steps:

Channelization operation, which transforms data symbols into

chips

Scrambling operation is applied to the spreading signal

scrambling channelization

Data

symbol

Chips after

spreading


WCDMA Channelization Code

OVSF Code (Orthogonal Variable Spreading Factor) is used as

channelization code

SF = 8 SF = 1 SF = 2 SF = 4

C ch,1,0 = (1)

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

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

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

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

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

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

C ch,8,0 = (1,1,1,1,1,1,1,1)

C ch,8,1 = (1,1,1,1,-1,-1,-1,-1)

C ch,8,2 = (1,1,-1,-1,1,1,-1,-1)

C ch,8,3 = (1,1,-1,-1,-1,-1,1,1)

C ch,8,4 = (1,-1,1,-1,1,-1,1,-1)

C ch,8,5 = (1,-1,1,-1,-1,1,-1,1)

C ch,8,6 = (1,-1,-1,1,1,-1,-1,1)

C ch,8,7 = (1,-1,-1,1,-1,1,1,-1)

……


WCDMA Channelization Code

SF = chip rate / symbol rate

High data rates → low SF code

Low data rates → high SF code

Radio bearer SF Radio bearer SF

Speech 12.2 UL 64 Speech 12.2 DL 128

Data 64 kbps UL 16 Data 64 kbps DL 32





Purpose of Channelization Code

Channelization code is used to distinguish different

physical channels of one transmitter

For downlink, channelization code ( OVSF code ) is used to

separate different physical channels of one cell

For uplink, channelization code ( OVSF code ) is used to

separate different physical channels of one UE


Purpose of Scrambling Code

Scrambling code is used to distinguish different

transmitters

For downlink, scrambling code is used to separate different

cells in one carrier

For uplink, scrambling code is used to separate different

UEs in one carrier


Scrambling Code

Scrambling code: GOLD sequence.

There are 224 long uplink scrambling codes which are used for

scrambling of the uplink signals. Uplink scrambling codes are

assigned by RNC.

For downlink, 512 primary scrambling codes are used.


Primary Scrambling Code Group

Primary

scrambling

codes for

downlink

physical

channels

Group 0

…

Primary scrambling code 0

……

Primary scrambling code

8*63

……

Primary scrambling code

8*63 +7 512 primary

scrambling

codes

……

……

Group 1

Group 63



64 primary

scrambling code

groups

Each group consists of 8

primary scrambling codes


Code Multiplexing

Downlink Transmission on a Cell Level

Scrambling code

Channelization code 1



User 1 signal

User 2 signal

User 3 signal

NodeB


Code Multiplexing

Uplink Transmission on a Cell Level

NodeB

Scrambling code 3

User 3 signal

Channelization code

Scrambling code 2

User 2 signal

Channelization code

Scrambling code 1

User 1 signal

Channelization code



Source



Source



Transmission

Reception

chip modulated

signal bit symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver


Modulation Overview

1 0 0 1

time

Basic steady radio

wave:

carrier = A.cos(2pFt+f)

Amplitude Shift

Keying:

A.cos(2pFt+f)

Frequency Shift

Keying:

A.cos(2pFt+f)

Phase Shift Keying:

A.cos(2pFt+f)

Data to be transmitted:

Digital Input


Modulation Overview

Digital Modulation - BPSK

1

t

1 1 0

1

t -1

NRZ coding

fo

BPSK

Modulated

BPSK signal

Carrier

Information signal

f=0 f=p f=0

1 10 2 3 4 9 8 7 5 6

1 10 2 3 4 9 8 7 5 6

Digital Input

High Frequency

Carrier

BPSK Waveform


Modulation Overview

Digital Modulation - QPSK

-1 -1

1 10 2 3 4 9 8 7 5 6

1 10 2 3 4 9 8 7 5 6

NRZ Input

I di-Bit Stream

Q di-Bit Stream

I

Component

Q

Component

QPSK Waveform

1

1

-1

1

-1

1

1

-1

-1

-1

1 1 -1 1 -1 1 1 -1


Modulation Overview

NRZ coding

90o

NRZ coding

QPSK

Q(t)

I(t)

fo

±A

±A ±Acos(ot)

±Acos(ot + p/2)

f

1 1 p/4

1 -1 7p/4

-1 1 3p/4

-1 -1 5p/4

)cos(2: f tAQPSK o


Demodulation

QPSK Constellation Diagram

1 10 2 3 4 9 8 7 5 6

QPSK Waveform

1,1

-1,-1

-1,1

1,-1

1 -1 1 -1 1 -1 -1 1 -1 1

-1,1

NRZ Output


WCDMA Modulation

Different modulation methods corresponding to different

transmitting abilities in air interface

HSDPA: QPSK or 16QAM R99/R4: QPSK



Source

Coding Channel Coding


Source

Decoding

Channel

Decoding Despreading Demodulation

Transmission

Reception

chip modulated

signal bit symbol

Service

Signal

Radio

Channel

Service

Signal

Transmitter

Receiver


Wireless Propagation

Received

Signal

Transmitted

Signal

Transmission Loss:

Path Loss + Multi-path Fading

Time

Amplitude


Propagation of Radio Signal Signal at Transmitter

Signal at Receiver

-40

-35

-30

-25

-20

-15

-10

-5

dB

0

0

dB

m

-20

-15

-10

-5

5

10

15

2

0

Fading


Fading Categories

Fading Categories

Slow Fading

Fast Fading


Diversity Technique

Diversity technique is used to obtain uncorrelated signals

for combining

Reduce the effects of fading

Fast fading caused by multi-path

Slow fading caused by shadowing

Improve the reliability of communication

Increase the coverage and capacity


Diversity

Time diversity

Channel coding, Block interleaving

Frequency diversity

The user signal is distributed on the whole bandwidth

frequency spectrum

Space diversity

Polarization diversity


Principle of RAKE Receiver

Receive set

Correlator 1

Correlator 2

Correlator 3

Searcher correlator Calculate the

time delay and

signal strength

Combiner The combined

signal

t t

s(t) s(t)

RAKE receiver help to overcome on the multi-path fading and enhance the receive

performance of the system


Summary

In this course, we have discussed basic concepts of WCDMA:

Spreading / Despreading principle

UTRAN Voice Coding

UTRAN Channel Coding

UTRAN Spreading Code

UTRAN Scrambling Code

UTRAN Modulation

UTRAN Transmission/Receiving

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Documents

Wcdma Ran Principle