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Cable Modem : Technology Venkata C. Majeti 4343 Commerce Court Lisle, IL 60532 Tel: (630) 281 - 3152 Email: venkata@cada

Cable Modem : Technology Venkata C. Majeti 4343 Commerce Court Lisle, IL 60532 Tel: (630) 281 - 3152 Email: venkata@cadant.com. Outline. Cable television network architecture Migration of cable networks to hybrid fiber-coax networks Use of cable RF spectrum

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Cable Modem : Technology Venkata C. Majeti 4343 Commerce Court Lisle, IL 60532 Tel: (630) 281 - 3152 Email: venkata@cada

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  1. Cable Modem : Technology Venkata C. Majeti 4343 Commerce Court Lisle, IL 60532 Tel: (630) 281 - 3152 Email: venkata@cadant.com

  2. Outline • Cable television network architecture • Migration of cable networks to hybrid fiber-coax networks • Use of cable RF spectrum • Recent changes to the use of RF spectrum • Developments in cable modem technology • Cable modem details: • Physical (PHY) layer specification and design • Media Access Control (MAC) layer specification and design • Data encapsulation • Signaling & Control • Data Over Cable Services Interface Specification (DOCSIS) standard • Other related standards: PacketCable, OpenCable, & EuroDOCSIS

  3. Cable Television Network Architecture Cisco 2500 Cisco 2500 Summary - headend at a glance Ethernet switch Fiber Transmitter CMTS Passive combiner channel lineup video reception battery backup digital video storage

  4. Migration of CATV Networks to HFC Networks Community Antenna Television (CATV) network evolution : ( a ) “Tree and Branch” Architecture ( b ) Capacity increase via “fiber trunks” ( c ) Evolution to “Fiber Serving Areas”

  5. Migration of CATV Networks to HFC Networks main trunk main trunk Headend/ Hub (a) traditional tree-and-branch architecture

  6. Migration of CATV Networks to HFC Networks Headend/ Hub main trunk Node Headend/ Hub (b) traditional tree-and-branch with fiber trunks

  7. Migration of CATV Networks to HFC Networks main trunk Node Node Headend/ Hub (c) tree-and-branch with fiber-serving-areas

  8. Use of Cable RF Spectrum

  9. Use of Cable RF Spectrum Headend Downstream Upstream signaling . . . 550 MHz - 750 and up MHz 50 MHz - 550 MHz 5-40 MHz 1 NTSC Video Channel per 6 MHz RF Carrier Bandwidth Use in CATV Networks Cable distribution network has limited (shared) upstream capability in 5- 40 MHz range. Most cable systems use 50 - 550 MHz range for downstream broadcast video signal.

  10. Recent Changes to the Use of RF Spectrum . . . . Encoding schemes assume multiplexing of many DS0/MPEG channels to form one 6 MHz NTSC channel for distribution over existing facilities. 1 NTSC Video Channel per 6 MHz RF Carrier Increasing the Cable Distribution Capacity Downstream . . . Upstream 50 MHz - 550 MHz 550 MHz - 5-40 MHz

  11. Developments in Cable Modem Technology Products Zenith, LANcity, Hybrid Networks Proposals PHY Layer Scientific Atlanta Amati Alcatel CORTEC Stanford Telecom Zenith General Instrument AT&T / Lucent Microunity IBM Aware MAC Layer TDMA F-TDMA XDQRAP M3 ADAPt UPSTREAMS CDMA/S-CDMA SEMAP MLAP FPP Key Issues Modulation Techniques Upstream Noise Data Link Layer Format Loop length – propagation delay Privacy over shared media ----- Ranging, Registration Upstream Frame Format Timing Source & Uncertainties Superframe Frame Slot

  12. Cable Modem O/E Node Fiber Security Authentication Local Servers Cable Data Network architecture Router Interface Alternative telephone return interface

  13. Data Over Cable Service Interface Specifications (DOCSIS) Cable Modem Termination System - Network Side Interface Cable Modem - Customer Premise Equipment Interface Operation Support System Interface Cable Modem Telephony Return Interface Radio Frequency Interface Baseline Privacy Interface Security System Interface Removable Security Module Interface CMTS-NSIOSSIRFI CMCICMTRIBPI SSI RSMI

  14. RFI Downstream • 6 MHz spectrum • 64/256 QAM • Reed-Solomon block code and Trellis Code • Variable depth interleaving to support latency • Contiguous serial bit-stream w/ no implied framing Upstream • Frequency agile • QPSK/16 QAM • Multiple symbol rates, data rates • CM programmable by the CMTS • Supports fixed-frame and variable length PDUs • Programmable Reed-Solomon block coding • Time Division Multiple Access (TDMA)

  15. MAC (media access control) Layer • CMTS-controlled mix of contention and reservation • Stream of mini-slots in upstream • Fixed and variable-length packets • Extensions to support ATM PDUs • Support for multiple data rates • Support for multiple grades of service

  16. Routing DATA FORWARDING THROUGH THE CM AND CMTS

  17. Summary

  18. Resources Albert Azzam, “High-Speed Cable Modems,” McGraw-Hill Series on Computer Communications, Published in 1997. Venkata Majeti (Executive Editor), “Cable Modems: Current Technologies And Applications,” Published by the International Engineering Consortium And the IEEE Press, 1999. CableLabs: resource for DOCSIS, PacketCable and OpenCable initiatives. URL: www.cablelabs.com Market Information: www.cabledatcomnews.com Other market research information from various investment banks.

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