The path to 10 Gbps downstream has been laid out with DOCSIS 3.1 using spectrum up to 1.2 GHz. DOCSIS 4.0 adds full duplex operation for a 5 Gbps upstream or an extended spectrum high-split option using 1.8 GHz. Both support similar 10 Gbps throughputs. Yet, the PON world is already 10 Gbps downstream and upstream, and due to deliver a 25 and 50 Gbps standard in 2020. What will cable’s response be?
The good news is that 25 Gbps DOCSIS can be built on the same wiring infrastructure of 10G DOCSIS 4.0 – the same digital Fiber to the Node, the trunk coax to the TAP, and drop coax to the Home. Furthermore, the transition from 10 Gbps speeds to 25 Gbps is not imposing that the fiber need to go any deeper. In DSL, the transition to higher speeds requires taking fiber deeper and making the copper link shorter whereas this is not the case for “25G” DOCSIS.
At the same time, extended spectrum DOCSIS (ESD) will require a complete product family refresh with CMTS/RPD - node - amp - tap - CM which will take time and investments from both vendors and operators. This paper shows how a roadmap to 3 GHz, 25 Gbps ESD is possible with 1.8 GHz ESD as a steppingstone. This paper explains the various techniques to get there and how the transition can be done. Considerations on power consumption, coexistence with FDX, spectrum plans and interference from MoCA, LTE and Wi-Fi are discussed.
