ITU-T Recommendations

Recommendation ITU-T J.224 specifies the fifth generation of high-speed data-over-cable systems.
Fifth generation transmission systems introduce a number of new features that build upon what was
present in previous ITU-T Recommendations, namely ITU-T J.112, ITU-T J.122, the ITU-T J.222.x-
series and the ITU-T J.223.x-series. Recommendation ITU-T J.224 includes key new features for the
physical (PHY) layer and establishes a full duplex data-over-cable service interface specification
(DOCSIS) mode of operation, including enhancements to media access control (MAC) layer protocols,
as well as requirements for those in the upper layer, e.g., the Internet protocol (IP) and dynamic host
configuration protocol (DHCP). Fifth generation cable modem specifications fully incorporate those
of the fourth generation.
NOTE – The structure and content of Recommendation ITU-T J.224 have been organized for ease of use
through direct reference to the original source material, based on the recognition of CableLabs by ITU in
accordance with Recommendation ITU-T A.5. 1 Recommendation ITU-T A.5 (2019), Generic procedures for including references to documents of other organizations in ITU-T Recommendations. See: https://www.itu.int/en/ITU-T/extcoop/Pages/sdo.aspx