Broadband Access Networks and Services

Chapter 1

INTRODUCTION

Byeong Gi LeeSeoul National University

EE4541.759 Spring 2004

BGL 2

Core, Access & Home Networks

CORE NETWORK

-TCP/IP

ACCESS NETWORK

-xDSL

-Cable

-FTTx

-Wireless

Contents Provider

Radio, Fiber, Coax, Internet

HOME NETWORK

-ATM

-SDH/SONET

-WDM/opticsAccess Node

Network Termination

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Broadband Access Networks & Services - The Scope of

Service Processing

Transport Processing

Network Access

-Streaming Video-Conversational

-Interactive Video -Other services

Service Processing

Transport Processing

Network Access

CORE NETWORK (420.594)

-TCP/IP

-ATM

-SDH/SONET

-WDM/optics

ACCESS NETWORK (4541,759)

HO

ME

N

ET

WO

RK

-xDSL -Cable

-FTTx-Wireless

Contents Provider

BROADBAND SERVICES

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TABLE OF CONTENTS

• Chap 1. Introduction

• Chap 2. Twisted-pair based Access Network

• Chap 3. Cable based Access Network

• Chap 4. Fiber based Access Network

• Chap 5. Broadband Wireless Access Network

• Chap 6. Access Network Architecture

• Chap 7. Broadband Services

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I. INTRODUCTION• Broadband Access Network (BAN)• Broadband Services for BAN • Conventional Subscriber Lines• Multiplicity of Access Networks• Structure of Broadband Access • Evolution of Subscriber Lines• Technical Foundation of BAN• Access Network Standards• Communication Environments

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• “Subscriber loop” is the transmission and signaling facility that connects the subscriber terminal equipment (NT) to the central office (AN).

• Access networks is a bridge that connects subscribers (i.e. users) to service providers

• Information services’ demand– Conversational telecommunication (telephones)– Broadband video distribution services (TV)– Interactive data services (computers)

• Requires large bandwidth and high interactivity

Broadband Access Network (1)

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Broadband Access Network (2)

ContentProvider

-----------------Internet

TransportNetwork

Fiber Network

Distribution Network

AccessNode

OpticalNetwork

Unit (ONU)NT NIU RG STU TE

STU

HomeNetwork

TE

TE

TE

S1

S2

S3

A9A4

A3 A2

A1A0

AccessNetwork

Reference model for BAN

A0~A9: Interface S1~S3: ServerNIU: Network Interface Unit STU: Set-Top UnitNT: Network Termination TE: TerminalEquipmentRG: Residential Gateway

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• Television (analog, digital, interactive TV)

• Video on Demand (VoD)

• Near Video on Demand ( nVoD)

• World Wide Web

• Datacasting

• Video Streaming

• Games

Broadband Services for BAN

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• Central office (CO):access node(AN)- remote node (RN)- network termination (NT):Home network

• Feeder, distribution network• Digital loop carrier(DLC), fiber loop carrier (FLC)• Conventional subscriber lines

– enormous asset- 700 million subscriber lines worldwide – twisted-pair (TP) dominant – 90% of subscriber lines, 5 to

10-km of distance – so far, mainly for POTS(plain ordinary telephone service)– 4 kHz bandwidth

Conventional Subscriber Lines

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• Embedded base – twisted pairs• Different characteristics – copper, coax, fiber,

wireless• Different applications – point-to-pt, point-to-multipt• Different population densities – urban vs. rural• Different geography – ocean, hills, buildings, etc.• Different business conditions – infra, regulation• Entrepreneurship – investment, development• => Matter of trade-in between investment and

performance (bandwidth, loss, delay)

Multiplicity of Access Networks

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Structure of Broadband Access• ADSL : Asymmetric Digital Subscriber Line• DBS : Direct Broadcast Satellite• FTTC : Fiber To The Curb• HFC : Hybrid Fiber Coaxial• LMDS : Local Multipoint Distribution System• MMDS : Multi-channel Multipoint Distribution System• MSO : Multiple Service Operator

Digital DBS

HFC

FTTC/FTTO

ISDN Line

VDSL Modem

ADSL Modem

Cable Modem

Analog Modem

ISDN Adaptor

DBS STB/MMDS/LMDS STB

Coax

MMDS/LMDS

56Kbps

6Mbps 640Kbps

FiberONU Coax or

CopperFiber 52Mbps

3Mbps

30Mbps

3Mbps

64Kbps

LMDS only

HomeTerminal

MSO /CO

Hub Station

Fiber orWireless

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• Special treatments needed depending on

– the physical characteristics,

– the distance from the serving core network,

– the type of desired communication services.

• Three paths of evolution– Apply advanced modulation techniques to TP- based tr

ansmission

– Replace TP-based subscriber loops with optical fibers

– Wireless-based supplement and renovation

Evolution of Subscriber Lines

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• TP-based evolution (1st stage of evolution)– Mod Schemes: QAM, CAP, DMT, DWMT– HDSL, ADSL, SDSL, VDSL stages– No requirement of any new deployments or changes to the

loop other than attachment of the converters

• Fiber-based evolution (2nd stage of evolution)– FTTO, FTTC, FTTH stages– CATV network: HFC enhanced with bi-directional capability

for interactivity

• Wireless-based evolution (3nd stage of evolution)– Limitation of bandwidth and security– Economical alternative– Mobility and network tractability

Evolution Paths

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• Without modulation, 4kHz

• Digital Subscriber Line (DSL), 144kbps

• High-speed DSL (HDSL), 784kbps-1.5Mbps

• Asymmetric DSL (ADSL), 1.5-8Mbps/16-820kbps (5.4-3.6km)

• Very-high-speed DSL (VDSL), 13-52M/1.5-2.3M (300-1500m)

*TP-based Bandwidth Expansion

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• Fiber-in-the-loop (FITL)– investment vs. demand, chicken-and-egg

• Fiber-to-the-office (FTTO) first

• Fiber-to-the-curb (FTTC) next

• Fiber-to-the-home (FTTH) final

• Hybrid-Fiber-Coaxial(HFC): contributes to evolution of CATV toward HTTH

*Optical Fiber-based Evolution

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• Advantages– Complements wireline access networks– Low initial investment, fast installation, flexibility

• Disadvantages– Limited bandwidth, information security

• Narrow band services– MPMP, cellular, cordless

• Broadband services– MMDS, LMDS

• Fixed and mobile services

*Wireless-based Evolution

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*Reference Architecture

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Access Networks and Standards (1)

Access Network Telephony Standards Data StandardsVideo Standards

Broadcast DTV - ATSC/DASEATVEF

Analog TV(NTSC, PAL, SECAM), digital TV usingATSC or DVB

Cable Packet Cable Data Over CableService InterfaceSpecification(DOCSIS), DAVIC/DVB

Open Cable SCTE DVS

ADSL/G.Lite AnalogIP/PPP/ATM(ADSL Forum)

Switched DigitalVideo (TBD)

Other DSLsVoice over ATM(VoATM) or Voice over IP

(VoIP)

Various packetmode protocolssuch as thePoint-to-PointProtocol OverEthernet(PPPoE)

Switched DigitalVideo (TBD)

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FTTx VoATM/VoIPFSAN and other

initiatives

Switched Digital

Video (TBD)

3G Wireless IMT-2000 IMT-2000-

LMDS VoIP/VoATM TBDTBD

MMDS - DOCSISAnalog TV, digital

TV using 8-VSB

High Altitude Long

Operation (HALO) aircraftTBD TBD-

Blimps TBD TBD-

Powerline, use of electric

power lines for data

transmission

TBD TBD-

Access Networks and Standards (2)

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Modulation Techniques

Service Modulation Techniques

ISDN (US) 2B1Q

US Direct Broadcast Satellite QPSK

Vestigial Sideband (VSB)US Digital Over-the-Air Broadcast

QAM-64, QAM-256US Digital Cable Forward Channels

QPSKUS Digital Cable Return Channels

OFDMEuropean Digital Over-the-Air Broadcast

2B1QHDSL

DMT, CAPADSL

QAM, DMTVDSL

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• Noise Mitigation Techniques– Forward Error Correction

– Interleaving

– Spread Spectrum/Code Division Multiple Access

• Metallic Transmission Media– Twisted-pair, Coaxial Cable

– Problems with High Frequency: Attenuation, crosstalk

– External Impairments: Leakage, impulse noise, loading coils, thermal noise, bridged taps

Communication Environment (1)

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• Fiber-Optic Transmission– Modulation: on/off keying (OOK), FM, AM

– Impairments: attenuation, dispersion, handling problems, cuts and other damages, bending, clipping

– Improvements: DWDM

• Wireless Transmission– The higher frequency, the less distance

– Modulation: QPSK, VSB, OFDM

– Impairments: LOS, multipath, absorption, interference

Communication Environment (2)

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Transmission Media Summary

MediumModulation

TechniquesBit RateBandwidth

750 MHz

Distance

Coaxial cable in

downstream

QAM-64/

2563.75 Gbps < 1.6 km

200kHz-

3.2MHzCoaxial cable in upstream

QPSK400Kbps-

5Mbps< 1.6 km

1 MHzTP pair (ADSL) DMT, CAP ~6 Mbps ~5 km

30 MHzTP pair (VDSL) QAM, DMT ~52 Mbps ~1.5 km

16 freq. of2.4 Gbps

each

Single-mode fiber OOK, DWDM 40 Gbps 500 km

6 MHzBroadcast TV spectrum 8-VSB 19.39 Mbps >80 km

1.1 MHzLMDS spectrum QPSK, OFDM 2 Gbps < 5 km