DOCSIS 3.0 arrives

Wed, 04/30/2008 - 8:40pm
Mike Robuck, Senior Editor

Better. Stronger. Faster.

In the high-stakes broadband game, DOCSIS 3.0 has been an ace in the hole for the cable industry, and this year that card will be on the table as MSOs start to roll out faster broadband services by using DOCSIS 3.0’s wideband downstream channel bonding.

DOCSIS 3.0 arrives - Better. Stronger. Faster.The DOCSIS 3.0 specification first came to light in August, 2006 when CableLabs outlined the methodology for downstream and upstream channel bonding, along with other features such as IPv6, IP multicasting and AES encryption.

DOCSIS 3.0 can achieve downstream speeds of up to 160 Mbps by bonding 6 MHz channels together (or in the case of Europe and some parts of Asia and Latin America, 8 MHz channels). DOCSIS upstream channel bonding can provide up to 120 Mbps of shared throughput for cable operators.

While there’s more to the DOCSIS 3.0 specification than just increased downstream speeds into customers’ homes, increased downstream speeds through wideband deployments allow cable operators to better compete against fiber-optic providers while providing a better service to subscribers.

Up until this year, wideband downstream channel bonding wasn’t much of a factor in North America, but cable operators overseas have gotten their feet wet by using products from companies such as Arris, Cisco and Motorola in order to beat back the competition from fiber optic-based service providers.

Expect cable operators to aggressively deploy downstream wideband services in areas where they compete with Verizon’s FiOS service. FiOS has deployed its 50 Mbps downstream and 20 Mbps upstream service in six markets to date.

While both Videotron and Comcast punched through the wideband barrier with their rollouts earlier this year, neither is using true DOCSIS 3.0 modems in their deployments. DOCSIS 3.0 specifies that a cable modem be able to bond up to four channels (four channels times 40 Mbps to achieve a total of 160 Mbps), but models deployed so far are bonding only three channels.

None of the cable modem vendors, who were all using silicon from Texas Instruments, received 3.0 certification in the wave that was announced late last year, but another wave is underway with the results expected to be announced May 16.

On the cable modem termination system side, CableLabs has awarded bronze certification, which covers downstream channel bonding and IPv6, to Arris and Cisco, while Casa Systems garnered silver in the tiered testing system.

Both Videotron and Comcast are using Cisco CMTSs and modems to bond three downstream channels, although each operator can bond as many or as few of the four channels as they see fit.

After a year-long trial, Videotron is serving up two tiers of the wideband service with speeds of 30 Mbps and 50 Mbps. The slower “Ultimate Speed” costs $64.95 a month while the faster speed checks in at $79.95 a month.

Currently, Videotron’s Ultimate Speed services are available to 112,000 homes in Quebec, with the goal of offering the service to Videotron’s entire footprint of 933,000 homes by next year.

While it sounds overly simple, the first step for downstream channel bonding is carving out the additional DOCSIS channels because up until this year most cable operators had just one upstream and one downstream DOCSIS channel.

Fred Davies

Charter’s Fred Davies, senior director of engineering, said along with channels for bonding, an additional frequency or channel may be needed for narrowband load balancing of legacy services.

Some MSOs will need to make room for the additional spectrum by using switched digital video or analog reclamation, but that wasn’t the case for Videotron.

“In terms of the HFC, we really had nothing to do,” said Pierre Roy, Videotron’s VP of engineering, IP technologies. “We were already transmitting DOCSIS channels at 256 QAM, so the quality of the plant didn’t change. The only thing we did do was allocate more channels to DOCSIS.

“The only thing we had to do with our CMTSs – and compared to other technologies that was the beauty of it – was insert a card into a CMTS. We added an external edge QAM and we changed the DOCSIS equipment at our customer premises, but by installing the cards and the edge QAM, the system was up and running.”

Roy said one of the lessons gleaned from the year-long trial was making software available to customers to enhance the IP stack in customers’ computers. The software allows Videotron to modify some stack IP parameters in Microsoft Windows in order to optimize them for the new speeds.

Comcast also picked a system where it wouldn’t need to clear room for more spectrum when it unveiled its first wideband deployment last month in the Minneapolis/St. Paul area with speeds of 50 Mbps on the downstream and 5 Mbps on the upstream.

The service is available to residential customers for $149.95 a month while small to medium-sized businesses can get the increased speeds for $199.95 a month.

Comcast, like other cable operators, is looking at the speeds of DOCSIS 3.0 in small-to-medium sized business settings as well.

In comparison, the cost of Verizon’s 50 Mbps service is $89.95 in New York and $139.95 in Massachusetts, New Jersey, Florida, Rhode Island and Connecticut.

Comcast has been a big advocate of the increased downstream data speeds that are part of the DOCSIS 3.0 feature set. Comcast CEO Brian Roberts has stumped for the benefits of wideband at various events, including this year’s International Consumer Electronics show, and said the nation’s largest cable operator plans to have elements of DOCSIS 3.0 deployed in up to 20 percent of its footprint by the end of the year.

Roberts has said Comcast expects downstream channel bonding to increase download speeds up to 100 Mbps over the next two years and even reach speeds of up 160 Mbps farther down the road. Comcast has targeted the middle of 2010 for full DOCSIS 3.0 rollouts across its entire footprint.

Figure 1: Maximum synchronization speed (Maximum usable speed).

Texas Instrument’s Peter Percosan, executive director of broadband strategy, said he expects to see true 3.0 modems become available mid-year, once Wave 58 is completed this month at CableLabs.

“Worldwide we’ll see real 3.0 downstream channel-bonded services this year, for sure,” he said. “I think right off the bat we’re going to see 50 Mbps deployments, but then we’re going to have other operators who are doing the network planning for 100 Mbps.”

Cox Communications’ John Coppola, director, access technology and engineering, said his company has 3.0 modems in labs.

“Our goal is to go out the door with 3.0 modems,” Coppola said. “I don’t want to have to put non 3.0 modems out there and then have to worry about pulling them later. There will be some limited trials and deployments this year, but it is more of an ’09 thing system wide.”

Davies said Charter is also working with 3.0 software and hardware in its lab as it becomes certified by CableLabs with the goal of conducting trials in selected markets in the fourth quarter of this year.

Patrick Knorr, Sunflower Broadband’s general manager, said he is willing to wait until next year before deploying either wideband or DOCSIS 3.0 modems, especially since Sunflower isn’t facing any competition from fiber-optics services in its footprint. But aside of adding HD channels, increased broadband speeds are also top of mind with smaller cable operators.

“I think downstream channel bonding has a very universal appeal to all different sizes of operators and we’re seeing it deployed with the smaller operators as well as the big boys we normally talk about,” said John Mattson, Cisco’s senior director of marketing, CMTS products. “I don’t see any hesitation or limitations on their part. The actual incremental cost, from a CMTS standpoint, is relatively small, particularly if they have added capacity anyway. I would say a year to 18 months from now most subscribers will have access to DOCSIS 3.0 services.”

While it makes sense for cable operators to buy more DOCSIS 3.0 embedded multimedia terminal adapters (EMTAs) instead of just DOCSIS 3.0 modems, Mattson said there is a cost hurdle to overcome with the new 3.0 equipment.

“There’s a pretty good amount of new technology that requires more silicon and there are more gates and all of that kind of stuff which does have an incremental cost as well,” Mattson said. “ Once the volumes get up I think the cost will come down pretty close to where the 2.0 modems are and the only incremental cost point will be that little bit of extra raw silicon cost that is in there.

“The one thing that made the three-channel modems that are being shipped today so compelling from a cost standpoint was that they’re based on silicon for a set-top box, so the silicon is already kind of off-the-shelf. They (cable operators) had already gone down the volume cost curve, but that hasn’t happened with the 3.0 silicon yet and nobody wants to be the one to buy all of the modems at the higher cost point and let everyone else take advantage of them driving the cost curve down.”

Tom Cloonan, Arris’ chief strategy officer, said despite the cost of the new EMTAs or modems, the demand will be driven by customers and by competition from passive optical network (PON) providers.

“There’s a premium on the cost right now because they are new chips and they offer more bandwidth and capacity, but I think the MSOs have indicated to us that they’re more than willing to take that cost in order to keep their subscribers from jumping over to the competition,” Cloonan said. “We think a lot of it depends on how the competition rolls out, but DOCSIS 3.0 is definitely the weapon to use to fight back against the PON providers.”

Texas Instruments’ Percosan said the competition from fiber-optic providers will also drive the use of DOCSIS 3.0 upstream channel bonding, which he expects cable operators such as Comcast to start deploying this year.

Comcast, as well as Time Warner Cable, is also a good candidate to jump on the IPv6 bandwagon because of the number of IP devices the cable operator has.

“For us, IPv6 is a little ways out,” Cox’s Coppola said. “We’re thinking probably more 2010 and beyond because we don’t have the IP address constraints that some of the other MSOs have.”

Due to its better security, Coppola said 128-bit AES encryption was a high priority for Cox’s business services and will probably be deployed next year.

Some cable operators don’t see an immediate need for DOCSIS 3.0 IP multicasting, which lets operators offer broadcast-like services over a DOCSIS network based on subscriber demand that could be used in an IPTV architecture, but Cox could be an early adopter.

“IP multicasting becomes more important as we start delivering more and more IP-based video,” Coppola said. “We see that as more of an ’09 time frame as well.”



Share This Story

You may login with either your assigned username or your e-mail address.
The password field is case sensitive.