scope:

The present document is part of a multi-part deliverable that defines the sixth generation of high-speed data-over-cable systems and is based on a set of specifications commonly referred to as DOCSIS 4.0 specifications.

This generation of the DOCSIS specifications [i.1] to [i.5] builds upon the previous generations of DOCSIS specifications (commonly referred to as the DOCSIS 3.1 and earlier specifications), leveraging the existing Media Access Control (MAC) and Physical (PHY) layers. It includes backward compatibility for the existing PHY layers in order to enable a seamless migration to the new technology. Further, the DOCSIS 4.0 specifications introduce Full Duplex (FDX) DOCSIS PHY layer technology as an expansion of the OFDM PHY layer introduced in the DOCSIS 3.1 PHY specification to increase upstream capacity without significant loss of downstream capacity versus DOCSIS 3.1. The DOCSIS 4.0 specification also builds upon DOCSIS 3.1 OFDM and OFDMA technology with an extended Frequency Division Duplex (FDD) DOCSIS alternative. DOCSIS 4.0 FDD supports legacy high split and also provides extended splits up to 684 MHz in an operational band plan which is referred to as Ultra-High Split (UHS). DOCSIS 4.0 FDD also introduces expansion of usable downstream spectrum up to 1 794 MHz. Both the FDX and FDD DOCSIS 4.0 alternatives are based on OFDM PHY. The DOCSIS 4.0 specifications also define appropriate updates to the MAC and management layers to support new PHY functionality.