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DOCSIS 3.0: About more than bandwidth – Not!

Wed, 07/30/2008 - 8:30pm
Jim Barthold, Contributing Editor

Midcontinent, Comcast, Cox executives detail their plans for the technology

DOCSIS 3.0 is Viagra for cable’s HFC midlife crisis; one dose and existing equipment works better.

Despite its potential to bond channels and drive bandwidth into triple-digit megabits, DOCSIS 3.0 is “not all about bandwidth,” said Chris Kohler, senior director of engineering for Motorola’s Broadband Solutions Group during a panel discussion at SCTE Cable-Tec Expo 2008 in Philadelphia in June.

According to Kohler, DOCSIS 3.0 will move cable to IPv6 and all the IP addresses needed for new applications and services and will ensure better security to appease content providers worried about the Internet’s Wild West potential. Bandwidth is great, but there’s so much more.

This assertion left his fellow panelist, David Haigh, lead engineer of Midcontinent Communications, a bit flabbergasted.

“From my point-of-view, it’s bandwidth. Everybody I speak to in the industry [says it’s] bandwidth. You get all these other functions of IPv6 which you’re going to be able to use in the future and extra security and stuff, but that’s not the reason we’re going to it. Bandwidth is well beyond any other driver I can see,” he said.

That bandwidth is in the upstream as well as the downstream.

Comcast will be rolling out the service to about 20 percent of its footprint this year with a 50 Mbps “out the door” offer to battle Verizon’s fiber-to-the-home (FTTH) FiOS play and deliver a crushing blow to DSL, Tony Werner, the MSO’s executive vice president and CTO, said during the CTO panel at Cable-Tec.

When Comcast gets there, it will still be behind Midcontinent, which has been looking at DOCSIS 3.0 since before there were specifications and is the first MSO in the world to work with DOCSIS 3.0’s 64-QAM upstream channel bonding, said Haigh. Midcontinent was “looking at doing some of the pre-3.0 but waited until the certification came out with modems and the CMTS. We’re (now) ready to pull the trigger,” he said.

DOCSIS 3.0 is a potent elixir for the MSO, which has 500,000 subscribers scattered around the Dakotas, because it reduces the need to split nodes to deliver more bandwidth – although there will be a lot of slicing and dicing still going on.

RF bandwidth availability
Figure 1: Preparing for DOCSIS 3.0 – RF bandwidth availability

“You could grab 20 or 30 users and put them on a different (service) tier, but on the other hand, you can get video-on-demand and still require node splits,” he said. “You might have too many service groups or you might just have too many homes passed. I’m not sure DOCSIS 3.0 is going to save everything, but it’ll definitely help with a lot of the node splits.”

It will also help with some non-bandwidth specific needs such as IPv6 and delivering enhanced security across IP content, as Kohler suggested. But primarily, DOCSIS 3.0 lets Midcontinent better use a plant that is 20 to 30 years old “or more” and has been upgraded from 330 MHz to 750 or 860 MHz along with some new plant that’s been installed in the last six months.

“A lot of the 64-QAM stuff we’re doing is on the new plant,” Haigh said.

While DOCSIS 3.0, according to almost everyone, is the real deal, it’s not without its side effects. For one thing, it will still cost money to turn around some of the network and CPE devices to take full advantage of the new bandwidth and other features. While it’s backwards-compatible, it will still require new equipment and, surprisingly, it could strain the system in ways that Haigh has yet to fully determine.

“The biggest one is trying to make sure our provisioning system is going to be able to handle it,” he said. “We have no idea right now. It could be a little impact when we start and then give us some breathing room, but if 3.0 takes off and customers jump on board, it’s like any other data product – it’s going to draw a lot of the bandwidth whether it’s the Internet or between our headends. You have all this bandwidth going back to the headend but you have to make sure you have somewhere you can go.”

Just getting enough channels to bond is something of a dilemma. Everyone just assumes that MSOs will reclaim analog channels and compress them into digital but “right now some of the programmers have contracts in place for six to 12 months and they can’t go on the digital tier unless they’re in another package,” he said.

Still, Haigh said, “it shouldn’t be a problem to come up with four (channels), but if you want to put those four, five, six (analog) channels into digital, it takes another digital channel to do it.”

While the DOCSIS 3.0 spec says that at least four channels could be bonded, it doesn’t have to happen at once.
“You could start out with a two-channel bond. We might start out with three and only use two,” said Chris Bowick, Cox Communications’ CTO, speaking at the SCTE CTO panel.

DOCSIS 3.0 also provides the cable operator with one other nice feature: “there is no need to launch ubiquitously,” Bowick said.

That’s where everyone will probably learn something from the work Midcontinent’s doing. Haigh said that DOCSIS 3.0 will be part and parcel with the MSO’s normal upgrade policy: completely upgrade one area then link it to the next. It’s how operators, faced with Verizon’s FiOS and AT&T’s U-Verse, can best use the potent new spec.

“We would like to do it if we’re getting competitors, but it’s not always a driver,” Haigh, ever the contrarian, said. “If we have a market that looks like a better fit for initial deployment, it’s not like we’re going to choose somewhere else. We could be there in three to six months anyway.”

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