DOCSIS

Data Over Cable Service Interface Specifications (abbreviated as DOCSIS) is a globally-recognized telecommunications standard that enables high-bandwidth data transfer via existing coaxial cable systems that were originally used in the transmission of cable television program signals (CATVS). The standard is now in its third generation, with market prospects for the future remaining bright.

DOCSIS 1.0

Devoted to the implementation of typical services related to Internet access, D1.0 allowed bandwidth of up to 40 Mbps in downstream and about 10 Mbps in upstream. Version D1.1 kept the same bit rates while becoming a long-standing basis for the implementation of VoIP services for cable TV subscribers. The standard, complemented with elements of QoS (Quality of Service), began to meet the extended security requirements for DES 56 data transmission, including the use of encryption.

DOCSIS 2.0

In January 2002 DOCSIS 2.0 was released, providing more symmetrical transport bandwidth (downstream and upstream), as a response to the increased demand for network bandwidth.

The maximum speeds achieved in this version were accordingly: 40 Mbps download and up to 30 Mbps upload.

This was made possible by making a wider band available in the upstream direction (e.g. 6.4 MHz channels) and by implementing more effective modulation schemes.

DOCSIS 3.0

DOCSIS 3.0 was introduced in 2006 to provide the possibility of combining downstream and upstream channels (channel bonding), IP multicast, IPv6 functionality, and AES encryption.

It is capable of connecting 6 or 8 MHz channels in downstream, achieving speeds of up to 340 Mb/s (DOCSIS) and 440 Mb/s (EuroDOCSIS).

In upstream the possible speed is about 120 Mbps.

DOCSIS 3.1

DOCSIS 3.1 allowed the implementation of GigabitEthernet services in existing HFC networks.

The D3.1 technology introduces a new generation of physical layer (PHY), which integrates the OFDM (Orthogonal Frequency Division Multiplexing) and FEC (Forward Error Correction) mechanisms. This combination increases efficiency by 50% in downstream and 66% in upstream, thanks to the use of improved modulation from 1024QAM to a maximum of 4096QAM.

The 3.1 version also uses the available channel bandwidth in other ways. The 6 or 8 MHz channel widths featured in previous iterations have been replaced by narrower (25 kHz or 50 kHz wide) orthogonal frequency-division multiplexing (OFDM) subcarriers, which combined form a block spectrum as wide as 200 MHz.

As a result, a staggering bandwidth of 1 or 2 Gbit/s upstream and 10 Gbit/s downstream is supported.