Broadband Access Networks and Services

Broadband Access Networks and Services Chapter 1 INTRODUCTION Byeong Gi Lee Seoul National University EE 4541.759 Spring 2004

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/optics Access Node Network Termination

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) HOME NETWORK -xDSL -Cable -FTTx -Wireless Contents Provider BROADBAND SERVICES

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

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

“ 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)

Broadband Access Network (2) A9 A4 A3 A2 A1 A0 Access Network Reference model for BAN A0~A9: Interface S1~S3: Server NIU: Network Interface Unit STU: Set-Top Unit NT: Network Termination TE: Terminal Equipment RG: Residential Gateway Content Provider ----------------- Internet Transport Network Fiber Network Distribution Network Access Node Optical Network Unit (ONU) NT NIU RG STU TE STU Home Network TE TE TE S 1 S 2 S 3

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

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

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

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 Fiber ONU Coax or Copper Fiber 52Mbps 3Mbps 30Mbps 3Mbps 64Kbps LMDS only Home Terminal MSO /CO Hub Station Fiber or Wireless

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 transmission
Replace TP-based subscriber loops with optical fibers
Wireless-based supplement and renovation
Evolution of Subscriber Lines

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

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

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

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

*Reference Architecture

Access Networks and Standards (1) Access Network Telephony Standards Data Standards Video Standards Broadcast DTV - ATSC/DASE ATVEF Analog TV (NTSC, PAL, SECA M), digital TV using ATSC or DVB Cable Packet Cable Data Over Cable Service Interface Specification (DOCSIS), DAVIC/DVB Open Cable SCTE DVS ADSL/G.Lite Analog IP/PPP/ATM (ADSL Forum) Switched Digital Video (TBD) Other DSLs Voice over ATM (VoATM) or Voice over IP (VoIP) Various packet mode protocols such as the Point-to-Point Protocol Over Ethernet (PPPoE) Switched Digital Video (TBD)

Access Networks and Standards (2) FTTx VoATM/VoIP FSAN and other initiatives Switched Digital Video (TBD) 3G Wireless IMT-2000 IMT-2000 - LMDS VoIP/VoATM TBD TBD MMDS - DOCSIS Analog TV, digital TV using 8-VSB High Altitude Long Operation (HALO) aircraft TBD TBD - Blimps TBD TBD - Powerline, use of electric power lines for data transmission TBD TBD -

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-256 US Digital Cable Forward Channels QPSK US Digital Cable Return Channels OFDM European Digital Over-the-Air Broadcast 2B1Q HDSL DMT, CAP ADSL QAM, DMT VDSL

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)

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)

Transmission Media Summary Medium Modulation Techniques Bit Rate Bandwidth 750 MHz Distance Coaxial cable in downstream QAM-64/ 256 3.75 Gbps < 1.6 km 200kHz- 3.2MHz Coaxial cable in upstream QPSK 400Kbps- 5Mbps < 1.6 km 1 MHz TP pair (ADSL) DMT, CAP ~6 Mbps ~5 km 30 MHz TP pair (VDSL) QAM, DMT ~52 Mbps ~1.5 km 16 freq. of 2.4 Gbps each Single-mode fiber OOK, DWDM 40 Gbps 500 km 6 MHz Broadcast TV spectrum 8-VSB 19.39 Mbps >80 km 1.1 MHz LMDS spectrum QPSK, OFDM 2 Gbps < 5 km

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