owa200002 wcdma basic principle issue1.0

HUAWEI TECHNOLOGIES CO., LTD.

All rights reserved

www.huawei.com

Internal

OWA200002 WCDMA RAN Basic

Principle

ISSUE1.0

HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

Chapter 1 Radio Transmission Environment Chapter 1 Radio Transmission Environment

Chapter 2 CDMA FundamentalChapter 2 CDMA Fundamental

Chapter 3 Performance Enhancement MethodsChapter 3 Performance Enhancement Methods

Chapter 4 WCDMA FDD ModeChapter 4 WCDMA FDD Mode


Multi-path Environment

Time

Received

signal

Transmitted

signal


Fading

Distance(m)

Received Power(dBm)

10 20 30

-20

-40

-60

Slow fading

Fast fading


Frequency Selection of Fading

NarrowbandSystem

NarrowbandSystem

Fading

Transmit Signal Received Signalff

P(f) P(f)

Fading

Transmit Signal Received Signalff

P(f) P(f)

BroadbandSystem

BroadbandSystem


Chapter 1 Radio Transmission EnvironmentChapter 1 Radio Transmission Environment






2.1 Multiple Access Technology and Duplex Technology2.1 Multiple Access Technology and Duplex Technology

2.2 CDMA Principle and RAKE Technology2.2 CDMA Principle and RAKE Technology


Multiple Access Technology and Duplex Technology

Multiple access technology

Time division multiple access (TDMA)

Frequency division multiple access (FDMA)

Code division multiple access (CDMA)

Duplex technology

Time division duplex (TDD)

Frequency division duplex (FDD)


Traffic channels: different users are assigned unique code and transmitted over the same frequency band, for example, WCDMA and CDMA2000

Traffic channels: different frequency bands are allocated to different users,for example, AMPS and TACS

Traffic channels: different time slots are allocated to different users, for example, DAMPS and GSM

FrequencyTime

Power

FrequencyTime

Power

FrequencyTime

Power

FDMA

TDMA

CDMA

User

User

User

User User

User

Multiple Access Technology


Characteristics of CDMA System

High Spectral Efficiency

Frequency multiplex coefficient is 1.

soft capacity

Quality

Coverage

Interference

Self-interference system

A UE transmission power is interference for another UE.



2.1 Multiple Access Technology and Duplex Technology2.1 Multiple Access Technology and Duplex Technology

2.2 CDMA Principle and RAKE Technology2.2 CDMA Principle and RAKE Technology


correlation

Correlation is a measure of similarity of between any two arbitrary signals.

EXAMPLE:

-1 1 -1 1 1 1 1 1 -1 1 -1 1 Zero correlation Orthogonal signals

-1 1 -1 1 -1 1 -1 1 1 1 1 1 1 correlation Identical signals

+1 0-1+1 0-1

+1 0-1

+1 0-1


OVSF&Walsh

Creating the orthogonal Creating the orthogonal code sequencescode sequences

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)


Autocorrelation

Autocorrelation is related to the muti-path interference characteristic.

Delay time sequence correlation

0 -1 -1 -1 1 1 -1 1 1

1 -1 -1 1 1 -1 1 -1 -1/7

2 -1 1 1 -1 1 -1 -1 -1/7

3 1 1 -1 1 -1 -1 -1 -1/7

4 1 -1 1 -1 -1 -1 1 -1/7

5 -1 1 -1 -1 -1 1 1 -1/7

6 1 -1 -1 -1 1 1 -1 -1/7Delay time

(chip)

Correlation

1

Example: -1 -1 -1 1 1 -1 1Example: -1 -1 -1 1 1 -1 1


Configuration of Gold Sequence Generator

Gold sequence is used as scrambling Gold sequence is used as scrambling code in WCDMAcode in WCDMA

clong,1,n

clong,2,n

MSB LSB


Spreading

Despreading

Chip

Symbol

Data

Spreading code

Spreading signal=Data×code

Data=Spreading×code

1

-1

1

-1

1

-1

1

-1

1

-1

Spreading code

Spreading and Despreading (DS-CDMA)


Desired signal

Other user’s signal

Desired spreadingsignal

Spreading code

Data after despreading

Other spreading signal

Other signal after integration

1

-1

1

-1

1

-1

8

-8

1

-1

8

-8

Data after integration

Other signal after despreading

Spreading and Despreading (DS-CDMA)


Sourcecoding

Channel coding

Spreading Modulation

Source decoding

Channel decoding Despreading Demodulation

Radio channelRadio channelRadio channelRadio channel

Processing Procedure of CDMA System


Spectrum Analysis of Spreading & Despreading

Spreading code

Spreading code

Signal Combination

Narrowband signal

f

P(f)

Broadband signal

P(f)

f

Noise

P(f)

f

Noise+Broadband signal

P(f)

f

Recovered signal

P(f)

f


Principle of RAKE Receiver

Receive set

Correlator 1

Correlator 2

Correlator 3

Searcher correlator

Calculate the time delay and signal strength

CombinerThe

combined signal

tt

s(t) s(t)

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


Structure of RAKE Receiver

∑ Q

∑ I

Combiner

I

MatchedFilter

PhaseRotator

Channelestimator

DelayEqualizer

I

Q

Path 1

Path 2

Path 3

Input signal

Correlator

Codegenerators Q


Advantages of CDMA

RAKE receiver is adopted

The time diversity effect generated by channel coherence time is efficiently used.

frequency diversity

Wideband frequency spectrum

Higher interference tolerance and security performance

Low signal transmission power

Great flexibility in carrying multiple services with largely different bit rate and QoS requirement.

Different spreading factors for different services with different data rates

High spectral efficiency

All users can share the same frequency spectrum simultaneously.

Supporting soft handover and softer handover.


HSDPA Key Techniques - OverviewHSDPA Key Techniques - Overview

AMC Fast SchedulingHARQ （ Hybrid ARQ ）

16QAMSF16, 2ms and CDM/TDM 3 New Physical Channels


AMC (Adaptive Modulation & Coding) based on Channel Quality Feedback

Adjust data rate to compensate channel conditions

− Good channel condition – Higher rate

− Bad channel condition – Lower rate

Adjust the coding rate to compensate channel conditions

− Good channel condition –3/4

− Bad channel condition –1/3

Adjust the modulation scheme to compensate channel conditions

− Good channel condition –16QAM

− Bad channel condition – QPSK

Channel Quality Feedback (CQI)

UE measures the channel quality (SNR) reports (every 2ms or more cycle) to Node-B

Node-B choose modulation and block size, data rate primarily based on CQI

AMC (Adaptive Modulation & Coding) based on Channel Quality Feedback

Adjust data rate to compensate channel conditions

− Good channel condition – Higher rate

− Bad channel condition – Lower rate

Adjust the coding rate to compensate channel conditions

− Good channel condition –3/4

− Bad channel condition –1/3

Adjust the modulation scheme to compensate channel conditions

− Good channel condition –16QAM

− Bad channel condition – QPSK

Channel Quality Feedback (CQI)

UE measures the channel quality (SNR) reports (every 2ms or more cycle) to Node-B

Node-B choose modulation and block size, data rate primarily based on CQI

HSDPA Key Techniques - AMCHSDPA Key Techniques - AMC

High data rate

Low data rate


HSDPA Key Techniques - HARQHSDPA Key Techniques - HARQ

Conventional ARQ–Received Transmitted blocks are decoded–Checked for CRC errors on decoded blocks–If errors

•discard the error bolcks•Request the trasmitter for retransmission

Conventional ARQ–Received Transmitted blocks are decoded–Checked for CRC errors on decoded blocks–If errors

•discard the error bolcks•Request the trasmitter for retransmission

Hybrid ARQ–Received Transmitted blocks are decoded–Checked for CRC errors on decoded blocks–If errors

•Store the erroneous block without discarding•Request the trasmitter for retransmission•Combine the received re-trasmission with previously received trasnmisison

Hybrid ARQ–Received Transmitted blocks are decoded–Checked for CRC errors on decoded blocks–If errors

•Store the erroneous block without discarding•Request the trasmitter for retransmission•Combine the received re-trasmission with previously received trasnmisison

HARQ with Soft Combining

NodeBNodeB

UEUE Packet1?Packet1? NN

Packet 1Packet 1 Packet 1Packet 1

Packet 1Packet 1

Packet1?Packet1?+

AA

Packet2Packet2

Transmitter

Receiver


HSDPA Key Techniques - Fast scheduling

Scheduler may be based on

CDM, TDM

Channel condition

Amount of data waiting in the queue (delay)

Fairness (satisfied users)

Cell throughput, etc

Scheduler may be based on

CDM, TDM

Channel condition

Amount of data waiting in the queue (delay)

Fairness (satisfied users)

Cell throughput, etc

Scheduling determines which user

shall be transmitted.

Scheduling determines which user

shall be transmitted.


HSDPA Key Techniques – CDM and TDM

Channelization codes allocatedfor HS-DSCH transmission

8 codes (example)SF=16

SF=8

SF=4

SF=2

SF=1

User #1 User #2 User #3 User #4

TTI

Shared channelization

codes

10 ms20 ms40 ms80 ms

Earlier releases

2 msRel 5 (HS-DSCH)

“sub-frames” (2560 chips)


HSDPA Key Techniques – 16QAM

HSDPA Modulation

QPKS

16QAM


Introduction to 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

Macroscopic diversity

Soft handover and softer handover

Reduce large-scale fading

Microscopic diversity


Microscopic Diversity

Time diversity

Channel coding, Block interleaving, error-correction

Frequency diversity

The user signal is distributed on the whole bandwidth frequency spectrum

Space diversity

Receive diversity

Transmit diversity

Polarization diversity

Vertical polarization

Horizontal polarization


Basic Combining Methods

Maximal-Ratio Combiner

The multi-path signals are weighted

proportional to their signal SNR and then

summed.

Equal-Gain Combiner

Equal-gain combining is similar to maximal-

ratio combining, but there is no attempt to

weight the signal before addition.

Selection Combiner

Choose the signal with the highest

instantaneous quality, so the output quality is

equal to that of the best incoming signal.


Smart Antenna Reduce interference

Increase coverage and capacity

Wanted signal

interference


Smart Antenna

Omni antenna Directional antenna Smart antenna


Characteristics of WCDMA FDD

Channel bandwidth: 5MHz

Chip rate: 3.84Mcps

Frame length: 10ms

Voice coding: AMR (Adaptive Multi-Rate)

Uplink and downlink modulation: QPSK/QPSK

Coherence demodulation aided with pilot

Fast closed loop power control: 1500Hz

Handover: soft/hard handover

Support synchronous and asynchronous NodeB

operation


Characteristics of WCDMA FDD

Satisfy the minimum performance requirement of IMT2000

Compatible with GSM-MAP core network

Comparatively steady version R99 has been released

Support open loop and closed loop transmit diversity mode

Support Common Packet Channel(CPCH) and Downlink

Share Channel, adapt to Internet data access mode

Support macro diversity, selection diversity of NodeB

location

Support different fast power control algorithms and open

loop, out loop power control

Fully support UE locating services


WCDMA Voice Evolution

Adopt AMR voice coding, and support voice

quality of 4.75Kbps ~ 12.2Kbps

Adopt soft handover and transmit diversity to

improve system capacity

Provide high fidelity voice mode

Fast power control


Data Service Evolution of WCDMA

Support maximum 2Mbps data service

Support packet switch

Adopt ATM platform currently

Provide QoS

Common Packet Channel(CPCH) and Downlink Share Channel(DSCH) can support Internet packet services better

Provide mobile IP service(dynamic allocation of IP addresses)

TFCI domain provides dynamic data rate

Provide high-quality support for uplink-downlink symmetric data service, such as voice, video phone, conference TV

www.huawei.com

Thank You

owa200002 wcdma basic principle issue1.0

Documents