Summary

Annex B defines the radio-frequency interface specifications for high-speed data-over-cable systems.

There are two options for physical layer technology, which have equal priority and are not required to be interoperable. One technology option is based on the downstream multi-programme television distribution that is deployed using 6 MHz channelling, and supports upstream transmission in the 5‑42 MHz region. The second technology option is based on a multi-programme television distribution using 8 MHz channel spacing and supports upstream in the 5-65 MHz region. Both options have equal status. The first of these options is defined in clauses B.4, B.6 and B.7, whereas the second is defined by replacing the content of those clauses with the content of Annex B.N.

Annex B.O "Privacy for cable modem implementations" to the former Annex B/J.112 is removed because it became the stand-alone ITU-T Rec. J.125.