Broadband on Fixed Services, ADSL

1. 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

2. 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

3. 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

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

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

6. Background and Introduction • Applications and Required Bit-rates Source: Adopted from DSL Forum; rates include overhead

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

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

9. 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

10. ADSL DSL Technology 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

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

12. DSL Technology • ADSL bit-rates: • 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

13. 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

14. 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

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

16. ADSL Position in the Broadband Market

17. 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

18. 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

19. 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

20. 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

21. Summary and Conclusions

22. 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