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DOCSIS

DOCSIS 4.0 prototypes could be here in less than a year

CABLE NEXT-GEN TECHNOLOGIES & STRATEGIES – Precise product delivery timelines are up to suppliers, but CableLabs expects to see prototypes of DOCSIS 4.0-based cable modems for lab testing surface in less than a year, an exec said at Light Reading's virtual event this week.

CableLabs wrapped up the D4.0 specs about six months ago. Meanwhile, word has spread that two key chip suppliers – MaxLinear and Broadcom – are developing silicon for a new platform that will support more capacity on widely deployed hybrid fiber/coax (HFC) networks along with improved latency and security.

DOCSIS 4.0 is one path of many in the access network that will be used to fulfill the cable industry's vision of '10G,' an initiative focused on 10-gig speeds along with improved network security, latency and  reliability.
DOCSIS 4.0 is one path of many in the access network that will be used to fulfill the cable industry's vision of "10G," an initiative focused on 10-gig speeds along with improved network security, latency and reliability.

The need for D4.0 is still years away as cable operators put DOCSIS 3.1 through the wringer, but suppliers are already "innovating," and initial prototypes are expected to show up at CableLabs' doorstep for testing before this time next year, Doug Jones, principal architect at CableLabs, predicted Wednesday on a panel focused on the industry's broader "10G" initiative.

Meanwhile, CableLabs is planning to be ready for DOCSIS 4.0 product certification testing by early 2022. When those products ultimately emerge is up to the vendor community, "but I've got internal schedules," Jones said. Meanwhile, he expects CableLabs to begin some initial interoperability work – a precursor to certification testing – in 2021.

There are two paths to DOCSIS 4.0 – Full Duplex DOCSIS (FDX), which delivers upstream and downstream traffic in the same block of spectrum; and Extended Spectrum DOCSIS (ESD), a path that could see the spectrum ceiling raised to 1.8GHz while keeping downstream and upstream traffic separate as it has been with all previous generations of DOCSIS.

MaxLinear and Broadcom haven't outlined their D4.0 roadmaps yet. But it's anticipated that the first wave of chips will support either FDX or ESD, not both in the same chipset. At the same time, there's also a technical path to a combined FDX/ESD chipset.

"The specifications are written such that it could be a single chipset," Jones said. "How the suppliers innovate and create their chipsets and products around that, that's up to the suppliers."

But however it's done, it's important that vendors support both options so that the product ecosystem can be vibrant, said industry consultant Brady Volpe, founder and president of The Volpe Firm.

Paul Broadhurst, CEO of Technetix, believes that both FDX and ESD will have strong roles to play. Although FDX has faced economic challenges because of the initial belief that it would require a fiber-deep, N+0 architecture (zero amplifiers between the node and the home), new Distributed Gain Architecture (DGA) technologies show that FDX can also be done in N+1 and N+2 scenarios.

"I think the economics of FDX is now very, very possible," he said. He noted that DGA will also aid cable operators taking the ESD path to DOCSIS 4.0 because it helps to nullify the power losses they will face when expanding plant spectrum up to 1.8GHz.

Both FDX and ESD present new challenges, Volpe stressed. But he likewise noted that the work being done by companies such as Technetix in the area of distributed gain architectures could present a clearer path to both versions of DOCSIS 4.0.

Several paths to '10G'
There are multiple paths to DOCSIS 4.0, and DOCSIS 4.0 is just one path of many to "10G," the cable industry's vision for access networks that can support capacities of 10 Gbit/s or more. That vision is agnostic in the sense that MSOs expect to get there via a mix of HFC, all-fiber/PON, and mobile and wireless technologies.

Symmetrical 10-Gig remains a "goal or a focal point" for 10G, but the initial DOCSIS 4.0 platform should be capable of supporting up to 10 Gbit/s down and as much as 6 Gbit/s in the upstream, Jay Lee, chief technology and strategy officer, broadband access, at ATX Networks, points out.

And those target capacities are for the backbone of the access network, not for each individual sub, Volpe said. He noted that the industry will need to be clear on how it's marketing that point and with "10G" in general.

Speed/capacity is just one "pillar" of 10G. Others include improved reliability, latency and security, Jones said.

Work is also underway for future cable networks that push spectrum to 3GHz, though that future is well out on the horizon – "At least a decade out there, if not further," Lee suggests.

But Broadhurst is confident that HFC has enough gas left in the tank to fulfill the promise of 10G.

"My belief is that HFC has all of the capacity [it needs] to get to 10G," he said. "The evolutionary investments in upgrading the HFC network, I believe, will keep it going for another 20 years, at least."

Broadhurst said new 1.8GHz technologies are coming with 3GHz connectors as a future-proofing move. "It will be module changes, not rewiring. We don't want to be playing around in wires."

But operators will use a range of technologies to get to 10G, and what is used will depend on whether it's for brownfields or greenfields and the costs involved, said Bill Warga, VP, strategy and technology at Liberty Global.

10G "is something we can drive to," he said, noting that operators will have a variety of tools to apply to every situation. "We're all in on fixed mobile convergence."

There are also some mixed views on how 5G and fixed wireless will play in these coming scenarios.

5G on lower-band spectrum won't compete head-on, capacity-wise, with a wireline network, but millimeter wave spectrum can do the job where there's good line of sight and the radios are close to the customer, said Robert Conger, CTO, Americas and head of product management and solutions marketing at Adtran.

While Volpe said cable should keep an eye on 5G as a potential competitive threat, Broadhurst sees 5G and its fixed backhaul needs as a major opportunity for MSOs.

"If you go down any street, the only guy that's got a big broadband pipe and power is the cableco. Nobody else has got it," Broadhurst said.

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— Jeff Baumgartner, Senior Editor, Light Reading

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