final docsis

  • View
    226

  • Download
    0

Embed Size (px)

Text of final docsis

  • 8/7/2019 final docsis

    1/72

  • 8/7/2019 final docsis

    2/72

  • 8/7/2019 final docsis

    3/72

    DOCSIS : DATA OVER CABLE SERVICE INTERFACE SPECIFICATIONS

    International Standard developed by Cable Labs

    A set of standards for sending data over cable and managing

    the supporting equipment

    It is used for transporting data over a cable (CATV) plantutilizing QAM &/ or QPSK RF Modulation.

  • 8/7/2019 final docsis

    4/72

    CableLabs is a non-profit research and development

    consortium founded in 1988 by cable operatingcompanies.

    It is dedicated to pursuing new cabletelecommunications technologies and to helping its

    cable operator members integrate those technicaladvancements into their business objectives.

  • 8/7/2019 final docsis

    5/72

    1984: DICK LEGHORN (FATHER OF CableLabs)

    Wrote a memorandum entitledAn R&D Entity for the CableIndustry?

    (~1994 1998) 1st generation were

    Proprietary systems

    Lancity

    Terayon

    Motorola (1998 Present) 2nd generation moved to open standard

    (DOCSIS)

    Contributing companies include ARRIS, BigBand Networks,

    Broadcom, Cisco, Conexant, Correlant, Harmonic, Intel, Motorola,Net ear, Tera on, and Texas Instruments

  • 8/7/2019 final docsis

    6/72

    Simplification to cable Technology.

    Offers communication and operation support

    Addition of High Speed data over existing cable Tv(CATV).

    Employed by Cable operators over the existing Hybrid

    Fiber Coaxial.

    Multiple suppliers

    85+ Vendors to date have received certification or

    qualification

  • 8/7/2019 final docsis

    7/72

  • 8/7/2019 final docsis

    8/72

    DOCSIS 1.0 DOCSIS 1.1 DOCSIS 2.0 DOCSIS 3.0

    March 1997 April 1999 Jan 2002 Aug 2007

    Data

    transmission was

    asymmetric.

    Improved

    operational

    flexibility.

    Increased upstream

    reliability and

    throughput.

    It provides

    channel

    bonding

    - Improved

    security.

    - Support for

    IPTV.

  • 8/7/2019 final docsis

    9/72

  • 8/7/2019 final docsis

    10/72

  • 8/7/2019 final docsis

    11/72

    Modem in the true sense of the word

    Modulates and demodulates signals

    It simply uses the increased bandwidth of the TV cable

    instead of an ordinary phone line

    Cable modem

    Client device for providing 2 way communication(data,voice and video) over the ordinary cable TV networkcables

    Downstream - Data flowing from the CMTS to the cablemodem

    Upstream - Data flowing from the cable modem to theCMTS

  • 8/7/2019 final docsis

    12/72

    They typically have two connections

    One to the cable wall outlet and the other to a PC

    Online access via cable modems provides PC users faster

    access to online information

    Up to 1000 times faster than todays fastest telephone

    modems

    Cable modem speeds range from 500 Kbps (500,000 bitsper second) to 10 Mbps (10 million bits per second)

  • 8/7/2019 final docsis

    13/72

    Connect the Cable Modem to the TV outlet for your cableTV

    The cable TV operator connects a Cable ModemTermination System (CMTS) at their end (the Head-End)

    The CMTS is a central device for connecting thecable TV network to a data network like the Internet

  • 8/7/2019 final docsis

    14/72

  • 8/7/2019 final docsis

    15/72

    DOCSIS - Data Over Cable Service Interface Specification

    The dominating cable modem spec that defines thetechnical specs for both the cable modem and the CMTS

    Architecture Tuner, transceiver (modulator/demodulator), MAC, CPU,interface

  • 8/7/2019 final docsis

    16/72

    Tuner

    Connects directly to the CATV outlet

    Converts TV channel to a fixed lower frequency (6-40

    MHz)

    Normally a tuner with build-in diplexer is used, to provideboth upstream and downstream signals through the same

    tuner

    Must be of sufficiently good quality to be able to receivethe digitally modulated QAM signals

    A new concept of a silicon tuner is in the works

    Tuner on a chip

    Expected to cut the cost down quite a bit compared toa more conventional tuner module

    Companies (Sharp, Temic, Panasonic)

  • 8/7/2019 final docsis

    17/72

    Demodulator

    Performs analog-to-digital (A/D)conversion,demodulation (QAM-64/256), Reed Solomon

    error correction and MPEG frame synchronization

    In the receive direction, the interface signal feeds a

    demodulator

    Companies

    Broadcom, Conexant Systems, SGS Thomson, VLSITechnologies/Philips, LSI Logic, Fujitsu

  • 8/7/2019 final docsis

    18/72

    Burst modulator Performs Reed Solomon encoding, modulation(QPSK/16-QAM), frequency conversion, digital-to-analogconversion

    In the transmit direction, a burst modulator feeds the tuner

    The output signal is fed through a driver with variableoutput level, so the signal level can be adjusted tocompensate for the unknown cable loss

    Companies

    Broadcom, Conexant Systems, Analog Devices, SGSThomson

    Combined demodulator and burst modulator chips are

    also available

  • 8/7/2019 final docsis

    19/72

    MAC (Media Access Control) sub-layer in the networkstack (runs on both the cable modem and head-end)

    Extracts data from MPEG frames, filters data, protocol

    execution, times transmission of upstream bursts Sits between the receive and transmit paths

    Can be implemented in hardware or split between

    hardware and software

    Assigns upstream frequency & data rate

    Allocates time-slots (upstream bandwidth)

    Requires CPU to handle MAC layer functions

    Companies: Broadcom, Texas Instruments, Conexant

  • 8/7/2019 final docsis

    20/72

    Interface

    Data passes through the MAC and goes into thecomputer interface of the cable modem

    PCI bus, USB, Ethernet, HomePNA

    CPU - microprocessor

    Required for external cable modems

    Single-chip cable modem are emerging

    Combines the MAC, demodulator, burst modulator,CPU,Ethernet/HomePNA/PCI/USB interfaces

    Additional parts such as memory, tuner, analog, powersupply will not be within the single-chip cable modem

  • 8/7/2019 final docsis

    21/72

  • 8/7/2019 final docsis

    22/72

    Cable Television Laboratories, Inc. 2005. All Rights Reserved. Proprietary/Confidential

    22

    CM

    CM

    CM

    CM

    CM

    CM

    CM

    CM

    Operator CoreBackbone

    CMTS

    CMTS

    CMTS

    Aggregation Network Access Network

    CM

    CM

    OperatorAggregation

    network

    Core Network

    Operator administered

    New Services

    Opportunities DOCSIS CableHome

    Remote filesharing

    Shared calendarUnifiedmessagingManagedservices

    CM

    HVAC controlFire sense & controlSecurityAir quality monitoringChild monitoring

    Energy management, etc.

    PacketCable

    MPEG Services

    IP Services

    CPEHeadendBackend

  • 8/7/2019 final docsis

    23/72

    Cable ModemTermination System(CMTS) and Cable

    Modem

  • 8/7/2019 final docsis

    24/72

    Transfer bi-directionaldata traffic betweenservice providers head

    end(CMTS) and

    customers cable modem CATV tree-and-branch

    infrastructure provides

    data conduit: fiber andcoax cables with

    amplifiers -- hybrid-fiber/coax (HFC)

    Wide BW and fast datarate for DS

    Allocated BW and lower

    data rate for US ascom ared to Euro e.

  • 8/7/2019 final docsis

    25/72

  • 8/7/2019 final docsis

    26/72

  • 8/7/2019 final docsis

    27/72

  • 8/7/2019 final docsis

    28/72

    IEEE 802.2 is the IEEE 802 standard defining Logical LinkControl (LLC), which is the upper portion of the data linklayer of the OSI Model.

    The LLC sub-layer acts as an interface between the MediaAccess Control (MAC) sub layer and the network layer.

  • 8/7/2019 final docsis

    29/72

  • 8/7/2019 final docsis

    30/72

    Physical Medium Dependent : Generates electrical or opticalsignals depending on the nature of the physical mediumconnected.

    In layer 1 of the (OSI) 7-layer internetworking model, PMDrepresents the part of the physical layer (PHY) that dictatesthe way bits are converted to physical signals, such as light inthe case of fiber.

  • 8/7/2019 final docsis

    31/72

  • 8/7/2019 final docsis

    32/72

    Medium Access Control, is a sublayer ofthe Data Link Layer.

    It provides addressing and channelaccess for several terminals, typically alocal area network (LAN) or metropolitanarea network (MAN).

  • 8/7/2019 final docsis

    33/72

    Registration of CM into Network

    Acquiring upstream and downstream channels and

    encryption keys from the CMTS and an IP address from theISP.

    CM also determines propagation time from the CMTS inorder to synchronize itself with the CMTS

    Multiple handshakes between the CMTS and each CM

  • 8/7/2019 final docsis

    34/72

    The upstream channel is divided into a stream of timedivision multiplexed mini-slots contain from 8 to 32 bytesof data.

    Each CM must learn its distance from the CMTS.

    This is called ranging.

    DATA RATE : 320 Kbps 10 Mbps

    Bandwidth/ Channel : 2 MHz for a 3Mbps QPSK Channel

    Frequency : 5-65 MHz

Search related