CableLabs Pushes Full Duplex Forward

Making good on its promise to fast-track next-gen broadband standards this year, CableLabs has released the critical physical layer specifications for its new Full Duplex (FDX) DOCSIS spec.

As has become typical for the cable R&D group, CableLabs announced the release in a short blog post Wednesday penned by Belal Hamzeh, vice president of wireless technologies for the organization. In his post, Hamzeh hailed the move as another step along the way in the evolution of the industry's flagship DOCSIS family of specs. (See Full Duplex, Coherent Optics Specs Advance .)

Considered a next-gen version of the still-new DOCSIS 3.1 spec, Full Duplex will enable cable operators to leverage the same spectrum to carry both upstream and downstream traffic over the last mile of coaxial plant running to broadband subscribers. Using echo cancellation technology, cable fiber nodes will send and receive traffic at the same time by filtering out transmission noise so the devices can simultaneously "hear" incoming signals while sending out their own messages. As a result, operators will be able to offer up to symmetrical 10-gigabit speeds without needing to replace every piece of coax cable in their networks with fiber. (See Full Duplex Is a Go; Cable Aims for 10 Gig.)

The issuing of the PHY layer specs for FDX comes just over a year after CableLabs launched the specification writing process in the summer of 2016, and less than two years after the organization introduced the concept in February 2016. But more work still needs to be done until the entire FDX spec is competed. As Hazmeh told Multichannel News, the MAC layer specs for FDX are still in the working group stage. While Hazmeh couldn’t say when they would be completed, he said he expects that to occur “in the near future.”

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Reflecting this progress, there should be plenty of demos of FDX-facing technologies and products at the SCTE•ISBE Cable-Tec Expo show in Denver next week. In a key sign of vendor preparation for the coming FDX era, Cisco Systems Inc. (Nasdaq: CSCO) staged a proof-of-concept demo of the technology at the ANGACOM show in Cologne, Germany in May. Although the display didn't show true FDX performance because today's cable modems can't support it, the demo did showcase a critical enabling component -- the FDX echo canceler. Recently, Cisco further advanced its work on echo cancellation with technology aimed at the cable-specific challenge of operating in a point-to-multipoint architecture. (See Cisco Demos Full Duplex and Cisco Makes the Case for FDX Over FTTH.)

Previously, Nokia Corp. (NYSE: NOK) staged its own PoC demo of FDX's potential to deliver symmetrical 10-gig speeds over a coaxial connection. (See Nokia Demos 10-Gig Over HFC.)

If the FDX spec continues to proceed as planned, CableLabs officials expect to see cable operators and vendors conduct the first field trials of FDX modems, nodes and other devices sometime next year. In turn, that could lead to the first commercial deployments of FDX products as soon as late 2018 and early 2019, although 2020 seems to be the more likely breakout year for the technology.

— Alan Breznick, Cable/Video Practice Leader, Light Reading

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