DOCSIS Data Over Cable Service Interface Specification Standard of high-speed data transmission

2017: DOCSIS 3.1 FD (Full Duplex, full duplex)

The American research consortium CableLabs submitted in the fall of 2017 the amendment to the standard of high-speed data transmission DOCSIS 3.1 determining standards of information transfer by coaxial i.e. television, to a cable. The amendment as reports^[1] will remove a communication channel asymmetry — the essential difference between speeds of receiving and transmitting data existing from the moment of emergence of the very first DOCSIS specification. After correction in the DOCSIS standard sending and data reception will be possible at a speed up to ten gigabits per second^[2].

The amendment to the DOCSIS 3.1 standard for the first time in 19 years of existence of a standard data transmission technology via the coaxial cable will allow to make speeds of direct and return channels equal. On development of the specified specification at consortium CableLabs one and a half years left. Increase in speed of a reverse channel up to ten gigabits per second within the DOCSIS 3.1 standard became possible thanks to sharing of all cable frequency range (from zero megahertz to 1.2 gigahertzes) both on sending, and on data reception. It allows to optimize also temporary slots.

As expected, commercial implementation of the new standard which received the name DOCSIS 3.1 FD (Full Duplex, a full duplex) will begin in 2019. Earlier some producers of cable modems for work in networks of the DOCSIS standard provided the devices capable to work with the full-duplex protocol. In particular, the Cisco company in May, 2017 demonstrated the cable modem with ravnoskorostny direct and the return channels. This device for joint sending and data reception allows to use 576 megahertz from all cable range (you watch Cisco DOCSIS) and also Any Media Giga Access Platform, Huawei D-CMTS (Distributed-cable Modem Termination System).

2013: DOCSIS 3.1

In 2013 CableLabs submitted the DOCSIS 3.1 standard. In this standard was for the first time decided to refuse data transmission on channels six and eight megahertz wide and to use so-called subcarrier frequencies from 20 to 50 kilohertzes wide. At the same time the standard permits multiple consolidation of these subcarriers that, finally, allows to provide the speed of forward channel in ten gigabits per second, and the return — in one gigabit per second.

The asymmetry between direct and return channels in all versions of the standard was defined by features of operation of the equipment. The matter is that the servicing systems work at the party of provider on the system of temporary slots, for certain time frames providing to users channels for sending and data transmission. At the same time all temporary slots cannot be selected to one user. Besides, transfer and data reception are made with the different frequency ranges. In more detail about work of DOCSIS it is possible to examine, for example, here.

DOCSIS 3.1 combines technologies of multiplexing with orthogonal frequency demultiplication of channels at the physical layer (Orthogonal Frequency Division Multiplexing, OFDM) and additional anticipatory error correction with a low density of check on parity (Low Density Parity Check, LDPC).

The combination of OFDM and LDPC technologies is capable to increase by one and a half times the capacity of the entering and outgoing channels when preserving backward compatibility with the big set base of the previous versions DOCSIS. If the operator of MSO wants to compete successfully with fiber-optical networks or aims to meet the user demand for bandwidth growing with a speed of 45-50 percent a year to it it is necessary to draw close attention to the new version of DOCSIS.

DOCSIS 3.1 is a stage of development of broadband technologies. The Cisco company participated in development of all specifications of DOCSIS, from very first (1.0) to the last (3.1) therefore we are complete of determination to help the cable industry to implement new release.

At the beginning of 2013 development of the PHY and MAC specifications will be complete, in 2014 there will be new processors, and in 2015 – cable modems and the CMTS systems.

1998

The DOCSIS standard was developed and entered by consortium CableLabs in 1998 within the large-scale program for increase in number of the subscribers connected to the Internet. So it developed that in the USA by the end of the 1990th years several dozens of cable cameramen and a share of houses with connection to a television cable acted it was very high. The DOCSIS standard allowed to organize connection to a global network using already existing infrastructure.

The first version of the new standard in the USA stipulated a possibility of data transmission to the subscriber (forward channel) at a speed up to 42 megabits per second and acceptance (return) at a speed up to 10.4 megabits per second. For information exchange channels six megahertz wide were used. A bit later in Europe the localized version of the standard which received the name EuroDOCSIS was developed. She uses channels eight megahertz wide for data transmission. In the European standard of the first version the speed of forward channel is 55.6 megabits per second, and the return — only 10.2.

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