Docsis 3.1 to Be Revealed at Cable-Tec Expo

The veil is about to lift on Docsis 3.1.

The new CableLabs spec is indeed being called "Docsis 3.1" -- there was some doubt about that -- and it's being publicly discussed for the first time on Oct. 18 at the Society of Cable Telecommunications Engineers (SCTE) Cable-Tec Expo in Orlando. (See CableLabs, SCTE to Shine Light on Docsis 3.1.)

The 90-minute session, aptly titled "Docsis 3.1 Specification and Standard Development," is slated to start at 11 a.m. Eastern time that day, moderated by CableLabs VP of Access Network Technologies Dan Rice. He'll be joined by:
  • Jeff Finkelstein, senior director of network architecture, Cox Communications Inc. ;
  • Howard Pfeffer, senior vice president of broadband engineering and technology, Time Warner Cable Inc. (NYSE: TWC);
  • Jorge Salinger, vice president of Access Architecture, Comcast Corp. (Nasdaq: CMCSA, CMCSK); and
  • Matt Schmitt, director of Docsis specifications, CableLabs.

After the roundtable, SCTE Senior Vice President of Engineering and CTO Daniel Howard will come on to explain how the Society will do its part to put Docsis 3.1 on a fast track.

It's expected that the roundtable will cover the technical goals of Docsis 3.1 and will explain how far developed the specs are.

But some details about what the industry has in mind for Docsis's next chapter have been circulating for months.

Kicking out QAM
At The Cable Show in May, engineers from Arris Group Inc. (Nasdaq: ARRS), Cisco Systems Inc. (Nasdaq: CSCO) and Motorola Mobility outlined several ideas on how to refresh Docsis and put it on the road toward capacities of 10Gbit/s in the downstream and 2Gbit/s in the upstream by, in part, expanding the spectrum in both directions. Multiple industry sources say the 3.1 project will look to change the Docsis PHY.

Those discussions appear to be rallying around more efficient, non-QAM modulation technologies, including orthogonal frequency-division multiplexing (OFDM), a scheme that's popular in the wireless world. It relies on small (on the order of 10KHz-wide) subcarriers that should perform better than QAM in noisy conditions, which tend to plague the lower portion of cable's upstream spectrum.

Mixed approach
OFDM could be used in the downstream and upstream, but the industry is believed to be chewing on a hybrid approach in which OFDM is applied just to the upstream, while the downstream continues to be based on QAM modulation, so operators can preserve the investments they've made in new edge QAMs. OFDM, by the way, is also being considered for EPON Protocol Over Coax (EPoC), an Institute of Electrical and Electronics Engineers Inc. (IEEE) standard-in-the-making. (See Countdown's on for EPON Protocol Over Coax and EPON-Over-Coax Starts Its Standards Journey .)

FEC steps in
Another technology on the table is low density parity-check (LDPC), a forward error correction (FEC) technique that would also help data transmissions overcome noise, at a bandwidth overhead smaller than that of the current Reed-Solomon approach. The hope is that a combination of OFDM modulation and LDPC could improve spectral efficiency by 24 percent or more.

History lesson
One possible item of debate is whether Docsis 3.1 will be completely backwards-compatible with Docsis 3.0 (the desired goal), or simply coexist with it. Every previous Docsis spec has been compatible with the versions that preceded it, and that appears to be the direction in which many engineers would like to see for Docsis 3.1. If only coexistence is possible, that could require operators to carve out precious spectrum just for the new Docsis 3.1 platform.

And when will it all come together? "There's a desire to have it happen sooner than reality would let it," says a cable industry source, who doesn't expect initial Docsis 3.1 drafts to appear until sometime next year.

An executive with a vendor familiar with the project agreed that the cable operators are pushing the 3.1 project forward anxiously. "I've never seen the MSOs this united about wanting to do something," he tells Light Reading Cable in a recent interview about the topic.

Until the specs are frozen, expect Docsis 3.1 to morph and change like an amoeba during the next year. But the upcoming roundtable will offer the most solid details on the project yet.

For more

— Jeff Baumgartner, Site Editor, Light Reading Cable

AESerm 12/5/2012 | 5:19:49 PM
re: Docsis 3.1 to Be Revealed at Cable-Tec Expo

Yes, that modulation scheme will be kicking around for a while. But only (or at least) 24% efficiency gain improvement? Sounds like Mucho trabajo, pocito el espectro. 

Jeff Baumgartner 12/5/2012 | 5:19:49 PM
re: Docsis 3.1 to Be Revealed at Cable-Tec Expo

Okay, I'll admit that "Kicking Out QAM" is a bit of an overstatement since there's an apparent desire to continue using that modulation in the downstream because there's so much investment being made there.  But looks like a great opportunity to make some big changes on the upstream, which could probably benefit from a change sooner than the cable downstream. JB

Jeff Baumgartner 12/5/2012 | 5:19:48 PM
re: Docsis 3.1 to Be Revealed at Cable-Tec Expo

That's the number that was being kicked around a few months ago.. i believe they are thinking it'll be even better than that...way better, like 2X. JB

craigleddy 12/5/2012 | 5:19:46 PM
re: Docsis 3.1 to Be Revealed at Cable-Tec Expo

So if they didn't call it Docsis 3.1, what were they going to call it? I suppose they could take a page from Apple's iPhone 4S and call it Docsis 3S, but then it would leave people wanting more, just like all those who are holding their 4S right now and wishing they had an iPhone 5. And if you called it Docsis 4, then people might expect more than the spec delivers, like that maybe that you'd get Siri with your broadband service or something.

Let's face it, Docsis is one of the clunkiest acronyms to come down the pike (and we at Light Reading/Heavy Reading give it extra validity by writing it in lower case as if it's an actual word).

So maybe some smart cable marketer needs to come up with a new term. Wideband wasn't too bad but it didn't really take off and just calling it D3 isn't as cool as it should be.

How about Quantum? Oh yea, Verizon FiOS just took that name, years after Time Warner Cable used it for their 1 GHz cable system in New York.      

AESerm 12/5/2012 | 5:19:45 PM
re: Docsis 3.1 to Be Revealed at Cable-Tec Expo

These days it seems to take orders of magnitude to get anyone's attention -- 2x sounds better.

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