Technology - Infrastructure - Last Mile 4 - ADSL Principles

Synopsis

We discuss the principles ADSL and ADSL2, including frequency allocations, modulation schemes, line splitters, modems, DSLAMs (Digital Subscriber Line Access Multiplexers) and ATM transport of data. We also discuss barriers to installation, including twisted pair line characteristics, pair-gain systems and RIMs/DLCs (Remote Integrated Multiplexers / Digital Loop Carriers).

Table of Contents

• 1. Synopsis
• 2. Common characteristics of xDSL
  • 2.1 Broadband access technology
  • 2.2 Maximising copper cable network
  • 2.3 Technical challenges
• 3. Frequency allocations
  • 3.1 Coexistence with POTS and BR-ISDN
    • 3.1.1 Annex A
    • 3.1.2 Annex B
    • 3.1.3 Annex C
    • 3.1.4 Annexes I and J
    • 3.1.5 Annex L
    • 3.1.6 Annex M
• 4. ADSL modems and DSLAMs
  • 4.1 ‘Single-chip’ modems
  • 4.2 Splitters and micro-filters
  • 4.3 DSLAM
  • 4.4 Moving DSLAMs closer to the customers
• 5. Obstacles to deployment
  • 5.1 Pair gain systems
  • 5.2 RIMs and DLCs
  • 5.3 Taps and loading coils
• 6. Modulation schemes
  • 6.1 CAP
  • 6.2 DMT / OFDM
  • 6.3 Digital Duplexing
  • 6.4 ATM carriage of data
  • 6.5 Latency – delay
  • 6.6 Classes of Service
• 7. Related reports