Broadband on Fixed Services, ADSL Presentation by Dale N. Hatfield Adjunct Professor, University of Colorado at Boulder At the Access to Broadband “Universal Service Opportunities and Challenges” An ARNET Professional Development Workshop In collaboration with the International Telecommunications Union Sharm El Sheikh, Egypt 5 March 2005

Outline Background and Introduction Digital Subscriber Line (DSL) Technology DSL Position in the Broadband Market Opportunities and Challenges for DSL Technology in Achieving Universal Service Selected Policy Issues Relating to DSL Summary and Conclusions

Background and Introduction Notion of Bandwidth (Review) In simple terms, bandwidth is an analog concept which refers to the range of signal frequencies that a circuit (channel) will pass The larger the bandwidth, the more information that can be transmitted in a given amount of time In the digital world, bandwidth is measured in bits per second Analogous measures: vehicles per hour or liters per minute

Background and Introduction Notion of Bandwidth (Review) Computer Monitor Illustration of the Importance of Bandwidth

Background and Introduction Bandwidth of Different Transmission Media Twisted-pair copper cable Coaxial cable Fiber optic cable Radio

Background and Introduction Applications and Required Bit-rates Application Bit-rate Required VoIP 16 kbps Full screen video conferencing (H.263) 384 kbps Basic web browsing 1 Mbps 5 Mpixel JPEG photo in 10 seconds 1.5 Mbps SDTV (MPEG2) 4 Mbps SDTV (MPEG4) HDTV (MPEG2) 15 Mbps HDTV (MPEG4) 7 to 9 Mbps Uncompressed medical X-ray in 2.5 seconds 25 Mbps Source: Adopted from DSL Forum; rates include overhead

Background and Introduction The Traditional Local Telephone Network Trunks PBX Exchange Switch Feeder Distribution Inside Wiring Lines or Local Loops Drop/Service Wire Feeder-Distribution Interface

DSL Technology Asymmetrical DSL (ADSL) Systems (Notional) Frequency Response or “Bandwidth” Of the Local Loop Existing Telephone Service Amplitude Downstream Channel To Residence/Business Upstream Channel To Network 4 30 Frequency (kHz)

DSL Technology Varieties of DSL Asymmetrical Digital Subscriber Line - ADSL High bit-rate Digital Subscriber Line - HDSL Single-pair HDSL – SHDSL Very high bit-rate DSL - VDSL Others

DSL Technology ADSL Circuit Switch DSLAM Voice & Voice Band Data Analog Voice Analog Voice Circuit Switch Splitter DSLAM Data Splitter Data Residence Data to ISP or Corporate Network* Central Office DSLAM=Digital Subscriber Line Access Multiplexer

DSL Technology Unbundled Loop with ADSL ILEC Central Office Loop PSTN Splitter Splitter ISP/Internet DSLAM Line sharing Unbundled Loop with ADSL MX CLEC Network Unbundled Loop

DSL Technology ADSL bit-rates: ADLS2+ bit-rates up to 20 Mbps Up to 8 Mbps downstream over 2 km of copper wires; longer lengths less (e.g., 384 kbps downstream at 5.5 km) Typical offerings 1.5 Mbps down and 384 kbps up or 3.0 Mbps down and 768 kbps up ADLS2+ bit-rates up to 20 Mbps VDSL2 bit-rates up to 50 Mbps

DSL Position in the Worldwide Market Notes: Number of DSL lines worldwide on the order of 100 million at EOY 2004; growing rapidly In the US, DSL to cable modem service is about 1:2 but recently, in terms of new lines, competition is about even Even better success in many other markets; technological characteristics of existing network have an important influence on the speed of rollout

DSL Position in the Worldwide Market No. of Lines in 1,000s 1999 2000 2001 2002 2003 2004(3rdQtr) Source: DSL Forum and Point Topic

ADSL Position in the Broadband Market Percentage DSL Subscribers by Region Source: DSL Forum and Point Topic

ADSL Position in the Broadband Market

Opportunities and Challenges for DSL Technology in Achieving Universal Service Advantages Comparative low incremental cost over an existing copper based telephone infrastructure Standardization and large volumes in developed countries drive down costs Competition with cable company provided cable modem service and licensed and unlicensed wireless service drives technological advances

Opportunities and Challenges Advantages (Continued) Can provide convenient backhaul for WLANs and Wireless ISPs (WISPs) in low density environments Challenges May not be the technology of choice where telephone infrastructure does not already exist Despite rapid development, loop distance limitations still a factor in low density environments

Opportunities and Challenges Challenges (Continued) In addition to the loop length constraint, problems may still arise depending upon loop quality (e.g., faults) and architecture (e.g., presence of loading coils or Digital Loop Carrier systems) Very high data-rate versions (e.g., VDSL) may require a change in architecture (e.g., FTTx) and, hence, additional investment

Selected Policy Issues Loop Unbundling Price of Unbundled Loop Collocation and Collocation Pricing Loop Sharing (Different Providers for Voice and Data on Common Loop) DSL Service Without Voice Service on Loop

Summary and Conclusions

Contact Information Dale N. Hatfield Adjunct Professor Interdisciplinary Telecommunications Program University of Colorado at Boulder Engineering Center - ECOT-317 Campus Box 530 Boulder, CO 80309-0530 Main Tel: +1-303-492-8916 Direct Dial: +1-303-492-6648 Fax: +1-303-492-1112 Cell Phone: +1-303-589-4546 Email: dale.hatfield@ieee.org or hatfield@spot.colorado.edu