Iterview Questions Umts

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UMTS: High Speed Packet Access (HSPA) Technology

Syed Saifullah Hussain Shah

Oriental Institute of Technology

Kharian

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Outline

• Introduction• Basics of CDMA• UMTS: WDMA Release 99• UMTS: HSDPA Release 5• UMTS: HSUPA Release 6

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Introduction

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• The International Telecommunications Union (ITU)defined the key requirements for International Mobile Telecommunications 2000 (IMT-2000) services.

• These requirements were that the system should supportdata rates of:

• 2 Mbps in fixed or in-building environments• 384 kbps in pedestrian or urban environments•144 kbps in wide area mobile environments

• IMT-2000 is more commonly known as… 3G.

IMT-2000 (3G)

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Europe

2000 2001 2002 2003

Japan

America

PDC

GSM

AMPS/D-AMPS

IS-95A IS-95B

D-AMPS

GPRS EDGE

W-CDMA

HSCSD

CDMA2000

2G System

3G System

Easy upgradeUpgrade requiring new modulationUpgrade requiring entire new radio system

Migration Path

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Timeline: For UMTS and CDMA2000

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Number of 3G subscribers: 550 Million

Source: www.3gtoday.com: (Retired), Above slide: July 31, 2007

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• Universal Mobile Telecommunication System/Wide-band CDMA is a 3G, Direct Sequence CDMA-based Radio Access Network (RAN), with chip rate of 3.84 Mcps.

• Designed to be deployed under GSM/GPRS network.

• “WCDMA” refers to the FDD Physical Layer and the protocols that support it.

• “UTRAN” refers to the WCDMA Radio Access network.

• “UMTS” refers to the entire network.

What is UMTS/WCDMA?

Reference: WCDMA(UMTS) Overview, QUALCOMM UMTS University.

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UMTS Releases

• Release 99: WCDMA

• Release 4: TD-SCDMA

• Release 5: HSDPA

• Release 6: HSUPA

• Combined HSDPA and HSUPA is called HSPA.

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The UMTS Network


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The carrier frequency is designated by the UTRA Absolute Radio Frequency Channel Number (UARFCN), where

Fcenter = UARFCN * 200 KHz

UMTS/WCDMA Bandwidth

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UMTS Terminology

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UMTS Network Topology


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Basics of CDMA

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CB D

FG E

A

CB D

FG E

A

CB D

FG E

A AA A

AA A

A

AA A

AA A

A

AA A

AA A

A

FrequencyReuse Factor = 7 for

AMPS

FrequencyReuse Factor = 7 for

AMPSCC

BB DD

EEAA

FFGG

AA

CDMA UniversalFrequency ReuseCDMA UniversalFrequency Reuse

Frequency Reuse Factor = 4 for TDMA systems

Universal Frequency Reuse

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Universal Frequency Reuse

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Codes in UMTS/WCDMA

• OVSF Codes: Orthogonal Codes• Gold Codes: Spreading Codes

• DL PSC: 512, SSC: 7680• UL Scrambling Codes: 16.8 million

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Orthogonal functions have zero correlation.

Two binary sequences are orthogonal if the

process of “XORing” them results in an equal

number of 1s and -1s:

Example: -1 -1 1 1

-1 1 -1 1

1 -1 -1 1

Orthogonal Sequences

Orthogonal codes in WCDMA are termed orthogonal variable spreading factor (OVSF) codes.

Orthogonal Codes

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User Separation using Orthogonal Codes


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Recovering the user data


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OVSF Codes


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OVSF Code Usage

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OVSF Tree


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• Gold codes (produced using M-sequences)

• M-sequences (maximum length pseudorandombinary sequences) or PN codes

Gold Codes


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Generation of Gold Codes (25-1)

• Using two preferred M-sequence generators of degree r,with a fixed non-zero seed in the first generator.

• The Downlink Gold code sequences are of length 218-1.They begin at phase 0, go up to phase 38399, and arerepeated.

• The Uplink Gold code sequences are of length 225-1.


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Cross-Correlation of Gold Codes

Example: N=18, t(n)=1+210=1025ACF=218=262,144, Normalized=1.Normalized Cross corr.=0.0039

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UMTS: WCDMA Release 5

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Generic Physical Layer Procedures


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Spreading and Scrambling (DL)


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Spreading and Scrambling (UL)


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Scrambling Codes

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UMTS Channels


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Soft Handover


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High Speed Packet Access (HSDPA): Release 5

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Evolution of 3G

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Evolution of 3G: Data Rates

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Packet Data in Release 99

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Reference: WCDMA (UMTS) HSDPA Protocols and Physical Layer, QUALCOMM UMTS University.

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How does HSDPA address the limitations of Release 99?

• Adaptive modulation and coding

– Fast feedback of channel condition

– QPSK and 16-QAM

– Coding from R=1/3 to R=1

• Multi-Code operation

– Multiple codes allocated per user

– Fixed spreading factor

• Node B scheduling

– Physical Layer HARQ

HSDPA Basic Concepts


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The New Data Channel

High Speed Physical Downlink Shared Channel (HS-PDSCH)


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HS-PDSCH


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Adaptive Modulation and Coding


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Link Adaptation Versus Power Control


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Hybrid ARQ (HARQ)

• Scheme combining ARQ and Forward Error Correction

• FEC decoding based on all unsuccessful transmissions

• Stop-and-Wait (SAW) protocol

• Two basic schemes:

– Chase Combining

-Same data block is sent at each retransmission

– Incremental Redundancy (IR)

- Additional Redundant Information sent at each retransmission


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HARQ Example


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Comparison Summary

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Network Architecture with HSDPA

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Transport Channel

• High Speed Downlink Shared Channel (HS-DSCH)

– Downlink Transport Channel

Physical Channels

• High Speed Shared Control Channel (HS-SCCH)

– Downlink Control Channel

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

– Downlink Data Channel

• High Speed Dedicated Physical Control Channel (HS-DPCCH)

– Uplink Control Channel

HSDPA Channels


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HSDPA Channels


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HS-PDSCH and HS-SCCHSpreading and Modulation


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HSDPA Operation


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HSDPA Operation: Timeline

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HS-PDSCH

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HS-PDCCH

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HS-SCCH


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HSDPA Data Rate

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HSDPA Data Rate

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Theoretical HSDPA Data Rate

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Use of Multiple Codes


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Consecutive Assignment

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Going from QPSK to 16-QAM: 7.2Mbps X 2 = 14.4 Mbps

Code Puncturing and use of QAM

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Review

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OVSF Allocation


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High Speed Uplink Packet Access (HSUPA): Release 7

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Release 99 Uplink Packet Data

Reference: WCDMA (UMTS) HSUPA Protocols and Physical Layer, QUALCOMM UMTS University.

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Release 99 Uplink Limitations

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High Speed Uplink Packet Access (HSPA)

Enhanced Dedicated Physical Data Channel (E-DPDCH)

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HSUPA vs. HSDPA


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Rise-Over-Thermal Noise


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Node B Scheduler for HSUPA


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Rise-Over-Thermal Loading


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HSUPA Channel Operation


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HSUPA Channel Operation Contd.


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GRANT: E-AGCH (Absolute Grant CH)

76Data: E-DPDCH, Control: DPCCH


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ACK/NAK: E-HICH (Enhanced Hybrid ARQ Indicator Channel)


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HSUPA Uplink Channels

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HSUPA Uplink Channels Contd.

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Uplink Channels


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Downlink Channels


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HSUPA Channel Timing


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HSUPA Channel Mapping


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UMTS Network Architecture with HSUPA


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Theoretical HSUPA Maximum Data Rate

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E-DPDCH with SF4 and Puncturing


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Lower Spreading Factor SF2

Maximum payload for spreading factor of 2, TTI of 2 ms and coding rate of 1 is 3840 bits (for 1920 kpbs).


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Multi-code Transmission


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Timeline: For UMTS and CDMA2000

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Other Standards • Worlwide Interoperability Microwave Access

(WiMax)– Operate in the 2.5, 3.5, or 5.8 GHz bands.– Data Rates now close to 73 Mbps (in 20 MHz of

spectrum) – Versions: IEEE 802.16d and e with amendments

like: 802.16f, g, h, i, j and k– Uses OFDM

• IEEE 802.20: Mobile Broadband Wireless Access (MBWA) (Fast Low-latency Access with Seamless Handoff ) FLASH-OFDM. (suspended but being developed under the name of EVDO Rev C: UMB)

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Amendments to the IEEE 802.16 standardAn amendment to the standard, IEEE 802.16e addressing mobility, was concluded in 2005. This is sometimes called “Mobile WiMAX”, after theWiMAX forum for interoperability. Active amendments:

•802.16f – Management Information BaseAmendments in development:

•802.16g - Management Plane Procedures and ServicesAmendments at pre-draft stage:

•802.16h - Improved Coexistence Mechanisms for License-Exempt Operation •802.16i - Mobile Management Information Base •802.16j - Mobile Multihop Relay •802.16k - Bridging

Ref: http://www.reference.com/browse/wiki/IEEE_802.16

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Cellular Technology Roadmap

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Why are new services/mobile content required?Tough competitionLow ARPUNo differentiation in Service Offerings

Problem:What services will differentiate one operator from the other?How would these services be delivered?

Issues

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Technologies

2G: Mainly Voice & SMS

2.5G: Limited Data Capability

3G and Beyond: High Speed Data coupled with data centric applications and services

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Services Continue to Evolve With Enriched User Experiences

Wallpaper

Location BasedServices2D Gaming

Ringtones

Mobile TV

3D Gaming

Music & Video on Demand

Services Evolution

Paul,How

did the meeting go?

Send Options

Text Messaging MMS

Voice

Social Networking

Blogging

Mobile Commerce

RSS Feeds & Tagging

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1) WCDMA(UMTS) Overview, QUALCOMM UMTS University.

2) WCDMA for UMTS: Radio Access for Third Generation Mobile Communications, H. Holma and A. Toskla, Second Edition, John Wiley and Sons, 2002.

3) Scrambling Techniques for CDMA Communications, B. G. Lee and B. Kim, Kluwer Academic Publishers, 2001.

4) HSDPA: Protocol and Physical Layer, Qualcomm UMTS University.

5) HSUPA:Protocol and Physical Layer, Qualcomm UMTS University.

6) HSDPA/HSUPA for UMTS, Ed. Holma and A. Toskla, Second Edition, John Wiley and Sons, 2006.

References

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THANK YOU

E-mail:

[email protected]

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