Soon cable operators will be able to fire up scads of bandwidth for subscribers, with even faster next-generation DOCSIS 3.0 gear in the pipeline. And beyond just raw speed, the technology may provide the industry a clean path to Internet protocol-based video services.
Two key suppliers of cable modem silicon components, Broadcom and Texas Instruments, are now delivering chips that can bond eight downstream channels together in a single DOCSIS 3.0 device.
What that means: The industry could soon see cable modems capable of transmitting upward of 400 Megabits per second to a single subscriber.
But the oodles of bandwidth won't necessarily be for Internet access alone. First, that's because there isn't likely to be much consumer demand for a broadband service with that kind of speed within the next several years, given the top bandwidth tiers available today are 50-Mbps downstream services from Verizon Communications and Comcast.
To wit, video over IP is one of the more intriguing applications for “8-by-4” DOCSIS 3.0 consumer-premises equipment (meaning it provides up to eight downstream and four upstream channels).
The DOCSIS 3.0 space is moving away from a “two-product market” — i.e., cable modems and embedded multimedia terminal adapters — to universal services gateways, said Peter Percosan, executive director of broadband strategy for Texas Instruments' Digital Connected Home business.
“We're moving toward a universal services gateway that handles everything: voice, video, data and other IP services,” he said. “Everything that sits in the digital realm that goes out over the network comes to the gateway in the home.”
Motorola has developed a DOCSIS 3.0-based transport gateway that will use eight downstream channels and allow an operator to split those between video and data to “mix and match any way you choose,” said Chris Kohler, director of engineering for Motorola's broadband home solutions group. The gateway device tunes to MPEG-2 video and then encapsulates it in IP for delivery over the home network — to either IPTV set-top boxes, a personal computer or some other device.
According to Kohler, on most dual-tuner cable set-top boxes, both tuners are in use less than 50% of the time. “So it makes sense to take those underutilized resources and move them into a gateway,” he said. “That's when we really see the need for eight downstream bonded channels.”
Motorola has also developed a version of its transport gateway built to the specifications of Time Warner Cable's Santa Monica project, which provides a gateway with storage for personal content, such as music and photos.
In Motorola's implementation, the gateway shares content using the Multimedia over Coax Alliance (MoCA) protocols and provides media sharing using Digital Living Network Alliance (DLNA) standards.
“We've been working with major MSOs on these kinds of projects,” Kohler said.
Arris has DOCSIS 3.0 gateway prototypes of its own. “Over time there will be markets for all permutations of gateways as the operators in our space are addressing multiple screens in the home,” said Bruce McClelland, president of Arris's broadband communications systems group.
On the other hand, there's a school of thought that if an 8-by-4 cable modem is approximately the same cost as a 4-by-4 modem, deploying the higher-capacity device is a no-brainer.
Cisco has gateway designs, but it's also developing a cable voice modem that will use Broadcom's recently announced DOCSIS 3.0 integrated CPE chip. Cisco hopes to submit the first DPC3212 eMTA to CableLabs for qualification in the first quarter of 2009, and the unit is expected to be shipping in volume by the middle of 2010, Cisco cable solutions marketing manager Ben Bekele said.
The DPC3212 will support two phone lines and provide data rates of more than 300 Mbps downstream and about 120 Mbps upstream. Cisco is currently shipping two DOCSIS 3.0 CPE products, the DPC3000 cable modem and DPC3202 eMTA, which both use Texas Instruments' Puma 5 chip set.
While a cable operator wouldn't necessarily introduce a 300- or 350-Mbps Internet tier initially, that latent capacity would be available down the line, Bekele noted. “As long as the cost is comparable, you'll see a lot of operators gravitate toward 8 by 4,” he said.
He added, however, that right now Cisco is not exactly sure how the cost of the DPC3212 would compare with current DOCSIS 3.0 models.
The forthcoming Cisco DPC3212 would be among the first to use Broadcom's BCM3380 DOCSIS 3.0 modem chip. Cisco also plans to incorporate Broadcom's DOCSIS 3.0 physical layer (PHY) component in its next-generation cable modem termination system.
Jay Kirchoff, senior director of product marketing for Broadcom, acknowledged that the company took longer than expected to deliver its DOCSIS 3.0 silicon. But, he said, the company spent the time to provide a highly integrated product, which includes the upstream power amplifier, Gigabit Ethernet physical layer and the tuners on a single chip.
“We've created a design that has a very low component count,” Kirchoff said. As a result, Broadcom claims, the bill of materials is much smaller, resulting in a modem whose cost is comparable to a 4-by-4 unit.
“If it's not a cost-premium, why wouldn't you buy the best?” Kirchoff said.
Motorola's Kohler, however, believes there's going to be a very long lifespan for 4-by-4 cable modems and eMTAs, which provide a theoretical maximum of 160 Mbps downstream bandwidth.
“Most of the MSOs looking at DOCSIS 3.0 data modems are going to max out around 50 Mbps service, at least in the short term,” he said.
To be sure, the driving force in the future for higher-speed broadband will be video over DOCSIS, whether that's managed video content or unmanaged content going over the top, Bekele said.
Cisco has predicted that the annual bandwidth demand on the world's Internet networks will nearly double every two years — reaching 522 Exabytes annually in 2012 (the equivalent of 250 million DVDs) — and that half of that will be video traffic.
“That's going to make it more likely that operators will push the tiers higher,” Bekele said. “That ability to leapfrog to eight channels definitely becomes an advantage.”
At some point, there could be a 16-downstream-channel DOCSIS 3.0 device, or perhaps even more. Microtune's MT2170 tuner already supports 96 MHz of bandwidth, or 16 6-MHz channels.
Microtune cable marketing manager Cliff Anderson said the issue right now is that the demodulator chips can't process that much bandwidth yet. “But if you want to get to 1 Gigabit per second,” he said, “the technology supports that.”