Data Over Cable Service Interface Specification (DOCSIS)
DOCSIS is an international standard developed by CableLabs and contributing companies that include ARRIS, BigBand Networks, Broadcom, Cisco, Conexant, Correlant, Harmonic, Intel, Motorola, Netgear, Terayon, and Texas Instruments. DOCSIS defines the communications and operation support interface requirements for a data over cable system. It permits the addition of high-speed data transfer to an existing Cable TV (CATV) system. It is employed by many cable television operators to provide Internet access (see cable internet) over their existing hybrid fibre coaxial (HFC) infrastructure.
As frequency allocation band plans differ between U.S. and European CATV systems, DOCSIS standards have been modified for use in Europe. These changes were published under the name of "EuroDOCSIS". The main differences account for differing TV channel bandwidths; European cable channels conform to PAL TV standards and are 8 MHz wide, whereas in North-America cable channels conform to NTSC standards which specify 6 MHz. The wider bandwidth in EuroDOCSIS architectures permits more bandwidth to be allocated to the downstream data path (toward the user). EuroDOCSIS certification testing is executed by Excentis (formerly known as tComLabs), while DOCSIS certification testing is executed by CableLabs. Typically, CPE gear receives "Certification", while CMTS equipment receives "Qualification".
Japan employs other variants of DOCSIS.
Speed Table
Maximum synchronization speed (Maximum usable speed)
Direction Downstream Upstream Version DOCSIS EuroDOCSIS Both 1.x 42.88 (38) Mbit/s 55.62 (50) Mbit/s 10.24 (9) Mbit/s 2.0 42.88 (38) Mbit/s 55.62 (50) Mbit/s 30.72 (27) Mbit/s 3.0 4channel +171.52 (+152) Mbit/s +222.48 (+200) Mbit/s +122.88 (+108) Mbit/s 3.0 8channel +343.04 (+304) Mbit/s +444.96 (+400) Mbit/s +122.88 (+108) Mbit/s Note: NTSC 6 MHz channel spacing will allow 10 bonded 6 MHz channels as MAX spectrum allocation for DOCSIS3.0 data, 60 MHz spectrum allocation could increase with consumer needs and re-allocation of analog TV channels into compressed digital space, leveraging the capability of DOCSIS 3.0 infrastructure to allow for 1 Gbit/s speeds in the future
DOCSIS 3.0 Cable Modem Information
I will post information on the DOCSIS 3.0 Cable Modems as it is made available to me.
DOCSIS Specification Succession
Motorola SB6120 (Currently available)
Cisco DPC3000 (Currently available)
Linksys WCM300 (Availability unknown)
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