WCDMA Concepts & Overview

8/10/2019 WCDMA Concepts & Overview

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GSM & UMTS Evolution

1990/91 1994 97 98 1999/2000 01 year

Phase 1Tele & Bearer

Services

FR speech

SMS

Data 9.6 kbps

Phase 2

SupplementaryServices

HR speech

96 97 98 99

99

Phase 2+

HSCSD, GPRS & EDGE

PS Domain

New Services

IN-applicationsEFR & AMR

.

Annual ReleaseR4 R5 R6 R7

99 02 04 06

WCDMA

UTRAN

VHE

.

ATM CNTD-SCDMA

IMS

HSDPA

HSUPAWLAN

Integration

new servicese.g. PoC, MBMS

W-AMR

MIMO

WLANIntegration

GSM

UMTS

2011

?

2G

2.5G3G

3.5G


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UMTS Network (Rel. 99)

PSTN

ISDN

PDNe.g.InternIntranet

IW: Interworking

TC: Transcoding

Gb

Iu(PS)

Gi

Iu(CS)

A

Gn

GSM BSS

Iur

UE=ME+USIM

Uu

Um

External

network

GMSCMSC

VLR

AuCHLREIRCSE

GGSNSGSN

IW &TCBSC

& PCU

TRAU

RNC

RNC

UTRAN

BTS

BTS

Abis

Node B

Iub

Node

BIub

Node B

TS 23.002

Gr

GfGe

F

C / D

Gc

CAP

IP

BillingSyste

E

CGF

Ga


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Some Radio Concepts


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WCDMA RECEPTION ISSUES


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Multipath Propagation

Rapid changes in signal strength over a smallarea or time interval.

Time dispersion caused by multipath propagation

delays

Inter Symbol Interference (ISI)

Fast Fading (Rayleigh Fading)


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Shadow fading

(Slow Fading, Log-Normal Fading, Turn theCorner-effect) is used to describe the loss of

energy that has been caused by an obstacle.


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Path Loss

is used to describe the loss of energy due todistance. As the radio wave propagate through

the space its power falls off proportional to at

least the inverse of the square of the range (1/r2 )


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Solutions to above problems

Strong coding (Turbo or Convolutional) andinterleaving used to recover any bit errors at the

receive.

A Rake Receiver is used to combine the energy

of the most significant multipath components and

reduce the fading.

Fast power control is used to compensate for

the fast (Rayleigh) fading.


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CODES IN WCDMA


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Types of Codes

Channelization Codes (CC)

Scrambling Codes (SC)


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CHANNELIZATION CODES

The main purpose of the channelization codes isto separate the data channels in the uplink and

the downlink coming from the same transmitter.


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SCRAMBLING CODES

The main purpose of the scrambling codes is toseparate the each transmitter (cell in DL) in the

uplink and the downlink.


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Since the bandwidth of the scrambling code ischosen to be much larger than the bandwidth of

the information-bearing signal, the encoding

process enlarges the spectrum of the signal. The

resulting signal is also called a spread spectrumsignal


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WCDMA Power Control


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Three types deployed in WCDMA

Open loop power control

Inner loop power control

Outer loop power control


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Uplink Open Loop Power Control


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Downlink Open Loop Power Control


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Uplink Inner loop Power Control


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Downlink Inner Loop Power Control


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Uplink Outer loop Power Control


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Downlink Outer loop Power Control


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WCDMA Hand Over


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Soft Handover diversity gain in the

uplink


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Soft Handover diversity gain in the

downlink


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Hand Over Algorithm


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THANKS FOR YOUR TIME

WCDMA Concepts & Overview

Documents