Digital Subscriber Lines

1
Digital Subscriber Lines

• Tisha McDermott
• Ed Tignor

2
Agenda

• Technology Overview
• So What?
• Questions

3
Plain Old Telephone Service

• Voice
• Analog
• Baseband - 300 to 4,000 Hz
• 24 - 26 Gauge Wire
• Data
• Digital
• Baseband - 300 to 4,000 Hz
• 56 kbs max

4
High(er) Data Rate Alternatives

• ISDN - requires upgrade of local loop to four
  wire lines and digital switches
• T1\E1 leased line - requires specially
  conditioned circuits
• Relatively expensive and not universally
  available.

Frankly, not very fast.
5
Alphabet Soup

• DSL Digital Subscriber Line
• HDSL High bit rate DSL
• SDSL Symmetric DSL
• ADSL Asymmetric DSL
• Universal ADSL
• RADSL Rate Adaptive DSL
• IDSL ISDN DSL

6
Distinguishing Features of DSL

• Can use existing two-wire copper infrastructure
• Does not go through switched network
• Frankly, Fast

7
Data Rates

• Modem 56 Kbs
• ISDN 128 Kbs
• T1 1.5 Mbs
• ADSL up to 8 Mbs downstream
  up to 640 Kbs upstream
• Universal ADSL 1.5 Mbs downstream
  384 Kbs upstream

8
Higher Data Density Signaling Protocols

• More data per cycle
• Lower frequencies Longer loops
• Higher bit rates
• Protocols
• Discrete MultiTone (DMT)
• Carrierless Amplitude Phase (CAP) Modulation

9
Why doesnt ADSL interfere with phone calls?
POTS
Upstream
Downstream
F(kHz)
4
30
10
Reference Diagram
11
Universal ADSL

• Less Complex
• Lower Frequencies equal Longer Loops
• Lower bit rate - 1.5 Mbs / 384 Kbs
• Less equipment - no POTS splitter
• Less expensive
• Can run on 70 to 90 of existing infrastructure

12
So What?

• Data communications fastest growing segment of
  communications
• Growth 7x faster than voice communications
• By end of 2000, 77 of network traffic
• Possibilities ? Realities
• Real-time Video Conferencing Web Hosting
• Video Streaming Video
  on Demand

13
Forces Driving ADSL

• Businesses - Small, Medium and Large
• By 2002 ? 66 million teleworkers
• Currently, 88 of businesses use dial-up
  connections for site-to-site connectivity

14
Primary Uses of ADSL

• Branch Office Connectivity
• Telecommuting Services
• Virtual office experience
• Reduction in facility expenses
• Business to Business Services
• Internet Connectivity Services
• Content Delivery Services
• Shopping catalogs, real estate listing, yellow
  pages

15
Universal ADSL Working Group

• Leaders Microsoft, Intel, BellSouth, SBC
  Communications
• Goal Provide consumers with assurance that
  products and services will work together
• Universal, single standard
• Simple plug and play
• Performance ? 25x faster than standard modem
• Always On

16
Who Supplies ADSL?

• Hardware
• Alcatel
• 30 of market
• 3Com
• Texas Instuments
• Lucent Technologies

• Service
• PairGain
• SBC Communications
• Rhythms NetConnections
• Bell Atlantic-AOL

17
ADSL Now

• SBC Communications
• ADSL Service in Texas, Missouri, Oklahoma,
  Arkansas, Kansas and possible New England
• Package price
• Hardware - 198 Connection - 39-49/mon
• Goal by the end of 1999
• 8.2 million residential customers
• 1.3 million business customers

18
ADSL Now Locally

• Bell Atlantic - AOL Partnership
• AOL Premium Service - DSL Connection
• When? Available by the end of 1999
• Where? Bell Atlantic region
• Who? 7.5 million AOL customers
• How much? Additional 20/month on top of
  regular service

19
Questions?