CableLabs is working on a new specification that will succeed Docsis 3.0 and pack some muscle onto cable's relatively weak upstream path, Cisco Systems Inc. (Nasdaq: CSCO) executives said Monday during a video Webcast ahead of The Cable Show, set for next week in Boston.

That spec has no number yet, but execs made reference to the project as "Docsis 3.x" and "Docsis 3.1" during the webcast, noting that part of the project involves using more effective modulation schemes.

While word of a new spec is, itself, new, cable's interest in dilating the upstream is not. Light Reading Cable reported in 2010 that a small group of engineers was weighing long-term technical options to approach 1Gbit/s upstream. Today, they'd be lucky to get 100Mbit/s out of Docsis 3.0.

It seems that those early efforts have reached the spec-development stage at cable's Louisville, Colo.-based R&D house. [Ed. note: We've asked CableLabs for more detail on the project.] (See CableLabs Eyes a Super-Sized Upstream .)

Part of the problem ahead is how to expand on the relatively limited amount of capacity that cable has set aside for the upstream. For North America Docsis, the upstream pipe is typically in the 5MHz to 54MHz range; for EuroDocsis, it's 5MHz to 65MHz. And there's typically a lot of noise at the lower end of that spectrum, which makes it unusable without the use of technology such as S-CDMA (Synchronous Code Division Multiple Access). (See Moto: S-CDMA Starting to Spread and Moto Preaches Cable's Upstream Savior .)

Ideas on how to address that include a High-Split, which would expand the upstream range to 200MHz, and a Top-Split, which would place additional upstream capacity above 1GHz. A potential short-term option is the Mid-Split, which would expand the upstream to the neighborhood of 85MHz.

And some newer ones are emerging. On Monday, Motorola Mobility LLC posted a blog pitching "Mid-Split Plus," an approach that would extend the upstream to 85MHz, and then add new bandwidth on-demand up to 200MHz or more. That strategy, Moto insists, would present less risk than a Top-Split and still achieve 1Gbit/s or more upstream.

Cisco's CCAP building block
During the webcast, Cisco also offered an update on its Converged Cable Access Platform (CCAP) strategy, noting that at next week's show, it will display its vision of a modular version of the super-dense, unified cable services architecture. Central to that is the DS384, a new line card for its RF Gateway-10 "universal" (because it's for cable services that use both MPEG and IP transport pipes) edge QAM. (See CCAP Market Is Cisco's & Arris's to Lose .)

Light Reading Cable reported about the new edge QAM card in April. The DS384 supports eight times the capacity of its current generation edge QAM cards. Cisco says an RF Gateway-10 fully loaded with DS384 line cards supplies about 160Gbit/s of capacity. (See Cisco Bulks Up for Cable's Next Platform.)

The new QAM technology and Cisco's 3G60 cable modem termination system (CMTS) cards will help cable operators begin the migration to CCAP, using denser versions of already-deployed gear until new, more tightly converged hardware arrives during the next two to three years, said Mark Palazzo, vice president of Cisco's Cable Access business.

Update: Cisco on Friday (May 18) issued an emailed statement seeking to clarify what the company said with respect to the purported Docsis 3.x project:

— Jeff Baumgartner, Site Editor, Light Reading Cable