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DOCSIS
Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide cable Internet access over their existing hybrid fiber-coaxial (HFC) infrastructure.
DOCSIS was originally developed by CableLabs and contributing companies, including Broadcom, Comcast, Cox, General Instrument, Motorola, Terayon, and Time Warner Cable.
Several DOCSIS versions can co exist by using frequency division multiplexing and separating new DOCSIS versions from old ones according to their operation frequencies.
As frequency allocation bandwidth plans differ between United States and European CATV systems, DOCSIS standards earlier than 3.1 have been modified for use in Europe. These modifications were published under the name EuroDOCSIS. The differences between the bandwidths exist because European cable TV conforms to PAL/DVB-C standards of 8 MHz RF channel bandwidth and North American cable TV conforms to NTSC/ATSC standards which specify 6 MHz per channel. The wider channel bandwidth in EuroDOCSIS architectures permits more bandwidth to be allocated to the downstream data path (toward the user). EuroDOCSIS certification testing is executed by Belgian company Excentis (formerly known as tComLabs), while DOCSIS certification testing is executed by CableLabs. Typically, customer premises equipment receives "certification", while CMTS equipment receives "qualification".
The ITU Telecommunication Standardization Sector (ITU-T) has approved the various versions of DOCSIS as international standards. DOCSIS 1.0 was ratified as ITU-T Recommendation J.112 Annex B (1998), but it was superseded by DOCSIS 1.1 which was ratified as ITU-T Recommendation J.112 Annex B (2001). Subsequently, DOCSIS 2.0 was ratified as ITU-T Recommendation J.122. Most recently, DOCSIS 3.0 was ratified as ITU-T Recommendation J.222 (J.222.0, J.222.1, J.222.2, J.222.3).
Note: While ITU-T Recommendation J.112 Annex B corresponds to DOCSIS/EuroDOCSIS 1.1, Annex A describes an earlier European cable modem system ("DVB EuroModem") based on ATM transmission standards. Annex C describes a variant of DOCSIS 1.1 that is designed to operate in Japanese cable systems. The ITU-T Recommendation J.122 main body corresponds to DOCSIS 2.0, J.122 Annex F corresponds to EuroDOCSIS 2.0, and J.122 Annex J describes the Japanese variant of DOCSIS 2.0 (analogous to Annex C of J.112).
DOCSIS provides a variety of options available at Open Systems Interconnection (OSI) layers 1 and 2—the physical and data link layers.
Bandwidth is shared among users of an HFC, within service groups which are groups of customers that share RF channels.
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DOCSIS
Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide cable Internet access over their existing hybrid fiber-coaxial (HFC) infrastructure.
DOCSIS was originally developed by CableLabs and contributing companies, including Broadcom, Comcast, Cox, General Instrument, Motorola, Terayon, and Time Warner Cable.
Several DOCSIS versions can co exist by using frequency division multiplexing and separating new DOCSIS versions from old ones according to their operation frequencies.
As frequency allocation bandwidth plans differ between United States and European CATV systems, DOCSIS standards earlier than 3.1 have been modified for use in Europe. These modifications were published under the name EuroDOCSIS. The differences between the bandwidths exist because European cable TV conforms to PAL/DVB-C standards of 8 MHz RF channel bandwidth and North American cable TV conforms to NTSC/ATSC standards which specify 6 MHz per channel. The wider channel bandwidth in EuroDOCSIS architectures permits more bandwidth to be allocated to the downstream data path (toward the user). EuroDOCSIS certification testing is executed by Belgian company Excentis (formerly known as tComLabs), while DOCSIS certification testing is executed by CableLabs. Typically, customer premises equipment receives "certification", while CMTS equipment receives "qualification".
The ITU Telecommunication Standardization Sector (ITU-T) has approved the various versions of DOCSIS as international standards. DOCSIS 1.0 was ratified as ITU-T Recommendation J.112 Annex B (1998), but it was superseded by DOCSIS 1.1 which was ratified as ITU-T Recommendation J.112 Annex B (2001). Subsequently, DOCSIS 2.0 was ratified as ITU-T Recommendation J.122. Most recently, DOCSIS 3.0 was ratified as ITU-T Recommendation J.222 (J.222.0, J.222.1, J.222.2, J.222.3).
Note: While ITU-T Recommendation J.112 Annex B corresponds to DOCSIS/EuroDOCSIS 1.1, Annex A describes an earlier European cable modem system ("DVB EuroModem") based on ATM transmission standards. Annex C describes a variant of DOCSIS 1.1 that is designed to operate in Japanese cable systems. The ITU-T Recommendation J.122 main body corresponds to DOCSIS 2.0, J.122 Annex F corresponds to EuroDOCSIS 2.0, and J.122 Annex J describes the Japanese variant of DOCSIS 2.0 (analogous to Annex C of J.112).
DOCSIS provides a variety of options available at Open Systems Interconnection (OSI) layers 1 and 2—the physical and data link layers.
Bandwidth is shared among users of an HFC, within service groups which are groups of customers that share RF channels.