Charter Communications took frequency division duplex (FDD) DOCSIS 4.0 out for a spin, achieving speeds of more than 8.5 Gbps downstream and 6 Gbps upstream in a trial conducted with Vecima Networks.
The experiment setup included a DOCSIS 4.0 system-on-chip for Remote MAC-PHY and cable modem devices, a single reference cable modem and downstream capacity dialed to 1.8 Ghz.
“This provides proof that our network is capable of offering multi-gig speeds bi-directionally,” Charter SVP of Network Engineering and Technology Joe Godas said in a statement. “Having this technology offers an option for future improvements and continuing to evolve our leading service for years to come.”
Vecima CEO Sumit Kumar added the testing “validates the performance and viability of DOCSIS 4.0 and the inherent multi-gig symmetrical capacity of the cable plant.”
FDD (also known as extended spectrum DOCSIS or ESD) is one of two flavors of DOCSIS 4.0, the other being full duplex (FDX) DOCSIS. While full duplex allows operators to transmit upstream and downstream in the same spectrum simultaneously, FDD/ESD is focused on enabling operators to use larger spectrum channels for upstream- and downstream-only transmissions.
Where DOCSIS 3.1 maxed out at 204 MHz upstream and 1218 MHz downstream, DOCSIS 4.0 bumps those spectrum channels up to 684 MHz upstream and 1.8 GHz downstream.
Over the past year, operators have begun publicly mapping out their DOCSIS 4.0 plans, with Comcast touting work on FDX and hitting symmetrical speeds of 4 Gbps in a trial conducted in April 2021. Others, including Cable One and Canadian operator Shaw Communications are choosing to take the same FDD road Charter is following.
A shift to DOCSIS 4.0 goes hand in hand with the adoption of distributed access architecture, with Remote PHY and Remote MAC-PHY the two main variants of that approach. While Comcast’s path to DOCSIS 4.0 will likely see it press ahead with Remote PHY technology, Charter is expected to pursue Remote MAC-PHY.
Last month, Charter invested in open DAA company Falcon V Systems, a move Dell’Oro Group VP Jeff Heynen said at the time indicated the operator wants “to set the standard for how cable operators should move forward with Remote MAC-PHY, DOCSIS 4.0 and flexible MAC architecture.”
This story has been corrected to reflect the trial achieved 6 Gbps upstream, not downstream.