1.Umts Fundamentals

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MobileComm Technologies India Pvt. Ltd.

Dallas . Atlanta . Washington . LA . Sao Paulo . New Delhi . Toronto. Muscat.Sydney

INTRODUCTION TO TELECOMMUNICATION


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Copyright 2010 MobileCommTechnologies India Pvt. Ltd.

All rights reservedMobileCommis committed to providing our customers with quality instructor ledTelecommunications Training.This documentation is protected by copyright. No part of the contents of thisdocumentation may be reproduced in any form, or by any means, without the prior written consent ofMobileCommTechnologies .Document Number: RK/CT/3/2010

This manual prepared by: MobileCommTechnologies

MobileComm Technologies(India)Pvt. Ltd.424, First Floor, Udyog Vihar Phase -4,Gurgaon-122002Headquarter:MobileComm Professionals Inc.1255 West 15th Street, Suite 440Plano, TX, 75075Tel: (972) 633-5100Fax: (972) 633-5106

www.mcpsinc.com
http://www.mcpsinc.com/http://www.mcpsinc.com/


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6/5/2012 SALAF HAYAT

MODULE CONTENTS

Standardisation and frequency bands

Multiple access schemes

Main properties of UMTS air interface

HSDPA and HSUPA


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4

ITU (Global guidelines and recommendations)

IMT-2000: Global standard for third generation (3G) wireless

communications

3GPP is a co-operation between standardisation bodiesETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA(South Korea)

GSM

EDGE UMTS

WCDMA - FDD

WCDMA - TDD

TD-SCDMA

3GPP2 is a co-operation between standardisation bodiesARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea)

CDMA2000

CDMA2000 1x

CDMA2000 1xEV-DO


Standardisation of 3G cellular networks


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UMTS FDD Frequency band evolution


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THE PROBLEM

LIMITED RESOURCES (FREQUENCY) MANY USERS

So many users, limitedresource ?

SolutionMultiple Access

The Problem



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Channel 1Channel 2Channel 3

Frequency

Time

FDMAfrequency divisionmultiple access

Chan-nel 1

Chan-nel 2

Chan-nel 3

Frequency

Time

TDMAtime divisionmultiple access

Frequency

Time

Code

CDMAcode divisionmultiple access

WCDMA3.84 MHz

Multiple Access Technologies



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What is the multiple access

Technique in UMTS?

WCDMA

Lets understand WCDMA



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5 - Code Multiplexing

Powerspectrum

User 1

User 2

User 3

User 4User 5

Spreading

Code 1

Code 2

Code 3

Code 4

Code 5

Composite signal

5 MHz

Codes discriminate users

Term Wideband and Code Explained



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Spreading codes (channelization codes) used to differentiate mobiles and services different lengths (spreading factor) according to service in UMTS Orthogonal Variable Spreading Factor (OVSF) in UMTS Low Cross Correlation, High Auto Correlation

Scrambling codes used to differentiate un-synchronized codes (from other UEs or Node-Bs) 1 scrambling code per sector on downlink PN code family in UMTS

CODES IN WCDMA



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Scrambling code

Channelization code 1



User 1 signal

User 2 signal

User 3 signal

BTS

1 - Downlink Transmission on a Cell Level

Codes Multiplexing



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BTS

Channelization code

2 - Uplink Transmission on a Cell Level

Scrambling code 2

User 2 signal

Scrambling code 3

User 3 signal

Channelization code

Channelization code

Scrambling code 1

User 1 signal

Codes Multiplexing



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C0(0)=[1]

C2(1)=[1-1]

C2(0)=[11]

C4(0)=[1111]

C4(1)=[11-1-1]

C4(2)=[1-11-1]

C4(3)=[1-1-11]

C8(0)=[11111111]

C8(1)=[1111-1-1-1-1]

C8(2)=[11-1-111-1-

1]

C8(3)=[11-1-1-1-111]

C8(0)=[1-11-11-11-1]

C8(5)=[1-11-1-11-11]

C8(6)=[1-1-111-1-11]

C8(7)=[1-1-11-111-1]

C16(0)=[............]C16(1)=[............]

C16(15)=[.....

......]

C16(14)=[...........]

C16(13=[...........]

C16(12)=[...........]

C16(11)=[...........]

C16(10)=[.......

....]

C16(9)=[............]

C16(8)=[............]

C16(7)=[............]

C16(6)=[............]

C16(5)=[............]

C16(4)=[............]

C16(3)=[............]

C16(2)=[............]

SF=

1

SF=

2

SF=

4

SF=

8

SF=1

6

SF=25

6

SF=51

2

...

Channelisation Code Tree



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15/4215Frequency (Hz)

Voice user (R=12,2 kbit/s)

Packet data user (R=384 kbit/s)

Po

werdensity(W/Hz)

R

Frequency (Hz)

Gp=W/R=24.98dB

Powerdensity(W/H

z)

R

Gp=W/R=10dB

Spreading sequenceshave a different length Processing gaindepends on the userdata rate

Processing Gain Examples



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The more processing gain the system has, themore the power of uncorrelated interfering signalsis suppressedin the despreadingprocess

Thus, processing gain can be seen as animprovement factor in the SIR (Signal toInterference Ratio) of the signal after despreading

Example: Voice AMR 12.2 Kbps Gp=10*log(3840000/12200)= 25 dB

After despreadingthe signal power has to betypically few dB above the interference and noise:Eb/No = 5dB; therefore the required widebandsignal-to-interference ratiois 5dBGp= -20 dB.

In other words, the signal power can be 20 dBunderunderthe interference and the WCDMAreceiver can still detect the signal

Processing gain


C Li i


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SF =128

Speech 8 kbps Data 64 kbps Data 384 kbps

BTS

SF =

32SF =4

The coverage limits are determined bythe Uplink link Budget

Coverage Limits



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FREQUENCY PLANNING IN UMTS


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GSM900/1800: 3G (WCDMA):

W CDMA P i i l


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Fast Power Control

Soft Handover

W-CDMA Principles


F B i


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COVERAGE

CAPACITY QUALITY

POWER

Few Basics.


U d t di P C t l


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LOWER PowerPer User HIGHER Numberof Users

HIGHER PowerPer User LOWER Numberof Users

Understanding Power Control


I t f


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No orImproper Power Control leads to High interference that impacts Coverage,Capacity and Quality

Power Ctrl

ON

OFF

Interference


Power Control


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TX Power is adjusted regularly so that each connection is received with the required

Eb/No of its service Uplink: Avoid Near-Far-Problem

Downlink: Power share allocation

Policy: No one gets a higher quality (Eb/No) than he needs. Everyone gets exactlythe required quality or is not served at all

no unnecessary increase of interference for other mobiles no waste of common power resource in the downlink

Power Control


Interference Limit


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When the number of users in the cellincreases, the interference levelincreases (noise rise), the required

received power at the base station toreach a given Eb/No (quality)increases

For high interference level, therequired received power becomesinfinite: power control is unstable pole capacity

Coverage and capacity are linked inCDMA systems

For high interference level, therequired received power becomesinfinite: power control is unstable pole capacity

Coverage and capacity are linked in

CDMA systems

0

2

4

6

8

1012

14

16

18

20

0 10 20 30 40 50 60 70

Number of simultaneous users per sector

Interferencelevelrelativ

etoNoiselevel

(dB)

Interference Limit


Downlink Power Limit : Cell breathing


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Considering the limitation of maximal transmit power, the increase of

required received power due to high traffic will lead to decrease the cellrange

The cell coverage decreases when the traffic increases : so-calledcellbreathingphenomenon

Coverage and capacity are linked in CDMA systems

Downlink Power Limit : Cell breathing



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Taking advantage of Multipath: Rake Receiver


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TX

D(t)

Delay0

Delay1

C(t-0)

+C(t-1)

Delay (1)

RX

C(t-n

)

Delay (0)

Delay (n)RX

RX

C(t)

0

1

n

Take advantage of

multipath diversity

BTS

UE

Spreading &

Scrambling

Taking advantage of Multipath: Rake Receiver



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POWER CONTROL

Power control (PC) in WCDMA


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Fast, accurate power control is of utmost importance particularly in UL;

UEs transmit continuously on same frequency Always interferencebetween users

Poor PC leads to increased interference reduced capacity

Every UE accessing network increases interference

PC target to minimise the interference Minimize transmit power of each

link while still maintaining the link quality (BER)

Mitigates 'near far effect in UL by providing minimum required power for eachconnection

Power control has to be fast enough to follow changes in propagationconditions (fading)

Step up/down 1500 times/second

Power control (PC) in WCDMA

Power Control types


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Power control functionality can be divided to three main types

Open loop power control

Initial power calculation based on DL pilot level/pathloss measurement by UE

Outer (closed) loop power control

Connection quality measurement (BER, BLER) and comparison to QoS target

RF quality target (SIR target) setting for fast closed loop PC based on connection

quality

Fast closed loop power control

Radio link RF quality (SIR) measurement and comparison to RF quality target (SIRtarget)

Power control command transmission based on RF quality evaluation

Change of transmit power according to received power control command

Power Control types


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HANDOVERS

Different Types of Handover


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Soft Handover Softer Handover Hard Handover

SRNC DRNC

Node B

UE

Core Network

SRNC

Node B

UE

Core NetworkSRNC

UE

Core Network

GSM / GPRBSS

SRNC

UE

Core Network

GSM / GPRBSS

Inter RNC Intra Node B

Different Types of Handover


Soft Handover


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In UL selection of the best signal on a framebasis at RNC level - selection diversity

In DL Maximum Ratio combining due to RAKE

receiver at UE

In UL Maximum. Ratio Combining at Node B

In DL Maximum Ratio combining due to RAKEreceiver at UE

Soft HO

Softer HO

RNC

RNC

Soft Handover



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SERVICES IN UMTS

UMTS QoS class


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UMTS QoS class

NRT Data Call

BackgroundClass

PS Data Call

Interactive Class

PS Data Call

Streaming Class

PS Data Call

Conversational Class

CS Data Call

CS Data Call CS Voice Call

CS Call

RT Data Call

PS Call

Call

HSDPA


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2002.6 R5 released

2003.6 HSDPA (High Speed Downlink Packet Access) was added into R5

HSDPA is smoothly evolved from WCDMA R99 without any big effect to the existing

R99 network

1 new transport channel: HS-DSCH

3 new physical channels HS-PDSCH, HS-SCCH and HS-DPCCH

MAC-hs sub-layer, HARQ (Fast Hybrid Automatic Repeat reQuest), Fast Scheduling

and AMC (Adaptive Modulation and Coding)

HSDPA --Max. downlink data rate: 14.4Mbps


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AMC


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Node B

CQI (Report periodically)

Modulation (QPSK, 16QAM) self-adaptiveGood channel state: 16QAMBad channel state: QPSK

Coding rate (1/3, 3/4, etc.) self-adaptiveGood channel state: 3/4

Bad channel state: 1/3

Efficiently utilize the channel condition

Good channel state: higher speedBad channel state: lower speed

Codes adjustingGood channel state: more codesBad channel state: fewer codes


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HSUPA


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1.Umts Fundamentals