WCDMA Principles.pdf

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WCDMA Principle


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

3G Overview

CDMA Principle

WCDMA Network Architecture and protocol structure

WCDMA Wireless Fundamental

Physical Layer Overview

Physical Channels

Physical Layer Procedure


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

3G Overview

CDMA Principle




Physical Channels



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

3G Overview

CDMA Principle




Physical Channels



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

WCDMA LTE (Long term evolution) is introduced

OFDMA is adopted instead of CDMA

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


Contents

3G Overview

CDMA Principle




Physical Channels



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 Coding


Source Decoding


Transmission

Reception


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

11101........................0000100

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

11101........................0000010 0 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 Coding


Source Decoding


Transmission

Reception


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 bitrate 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 Coding


Source Decoding


Transmission

Reception


Service Signal

Radio Channel

Service Signal

Receiver


Modulation Overview

1 0 0 1

time

Basic steady radio wave:

carrier = A.cos(2πFt+φ)

Amplitude Shift Keying:

A.cos(2πFt+φ)

Frequency Shift Keying:

A.cos(2πFt+φ)

Phase Shift Keying: A.cos(2πFt+φ)

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

φ=0 φ=π φ=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(ωot)

±Acos(ωot + π/2)

φ 1 1 π/4 1 -1 7π/4 -1 1 3π/4 -1 -1 5π/4

)cos(2: φω +oAQPSK


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 Spreading Modulation

Source Decoding

Channel Decoding Despreading Demodulation

Transmission

Reception


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

dBm

-20 -15 -10 -5

5 10 15 20

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


Contents

3G Overview

CDMA Principle




Physical Channels



UTRAN Network Structure

RNS

RNC

RNS

RNC

Core Network

NodeB NodeB NodeB NodeB

Iu-CS Iu-PS

Iur

Iub Iub Iub Iub

CN

UTRAN

UE Uu

CS PS Iu-CS Iu-PS

CS PS


Contents

3G Overview

CDMA Principle




Physical Channels



WCDMA Radio Interface Channel Definition

Logical Channel = information container

Defined by <What type of information> is transferred

Transport Channel = characteristics of transmission

Described by <How> and with <What characteristics> data is transmitted over the radio interface

Physical Channel = specification of the information global content

providing the real transmission resource, maybe a frequency , a specific set of codes and phase


Logical Channel

Control channel

Traffic channel Dedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)


Transport Channel

Dedicated Channel (UL,DL) (DCH)

Broadcast channel (DL) (BCH)

Forward access channel (DL) (FACH)

Paging channel (DL) (PCH)

Random access channel (UL) (RACH)

High-speed downlink shared channel(UL,DL) (HS-DSCH)

Common transport channel

Dedicated transport channel


Physical Channel

A physical channel is defined by a specific carrier frequency, code (scrambling code, spreading code) and relative phase.

In UMTS system, the different code (scrambling code or spreading code) can distinguish the channels.

Most channels consist of radio frames and time slots, and each radio frame consists of 15 time slots.

Two types of physical channel: UL and DL

Physical Channel

Frequency, Code, Phase


Downlink Physical Channel

Downlink Dedicated Physical Channel (DL DPCH)

Downlink Common Physical Channel

Primary Common Control Physical Channel (P-CCPCH)

Secondary Common Control Physical Channel (S-CCPCH)

Synchronization Channel (SCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Common Pilot Channel (CPICH)

High-Speed Physical Downlink Shared Channel (HS-PDSCH)

High-Speed Shared Control Channel (HS-SCCH)


Uplink Physical Channel

Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel (Uplink DPDCH)

Uplink Dedicated Physical Control Channel (Uplink DPCCH)

High-Speed Dedicated Physical Channel (HS-DPCCH)

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)


Function of Physical Channel

NodeB

UE

P-CCPCH-Primary Common Control Physical Channel

P-CPICH--Primary Common Pilot Channel SCH--Synchronisation Channel

Cell Search Channels

DPDCH--Dedicated Physical Data Channel

DPCCH--Dedicated Physical Control Channel

Dedicated Channels

Paging Channels PICH--Paging Indicator Channel

SCCPCH--Secondary Common Control Physical Channel

PRACH--Physical Random Access Channel

AICH--Acquisition Indicator Channel Random Access Channels

HS-DPCCH--High Speed Dedicated Physical Control Channel

HS-SCCH--High Speed Share Control Channel

HS-PDSCH--High Speed Physical Downlink Share Channel

High Speed Downlink Share Channels

Thank You

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Documents

WCDMA Principles.pdf