News

DOCSIS 3.0 + PacketCable 2.0 = Cross Platform

8/29/2008 8:00 PM Eastern

By now, the channel-bonding feature of the newest cable modem chapter, known in tech-speak as DOCSIS 3.0, should be pretty evident. Benefit: Ramming speed.

Channel-bonding is what lets you download a movie, or 40 pounds of encyclopedias, or anything else with bit bulk — in the time it takes to boil an egg.

The math of it goes like this: Each 6 MHz channel, slinging information using 256-QAM (quadrature amplitude modulation), can carry 38.8 Megabits per second of data. Bond two channels for 77.6 Mbps; three for 116.4 Mbps. A four-channel bond, at 256-QAM, yields a blistering 155.2 Mbps in downstream, toward-the-house speed.

And so on, all the way to the end. The end, in the case of a cable system built to 860 MHz, is 134 downstream 6 MHz channels. (The math: 860 minus the 54 MHz of the upstream path, divided by the 6 MHz channel width.)

If you bonded all 134 channels, you'd have a downstream pipe capable of 5.2 Gigabits per second. (Note: The channels need to be empty before you can do any kind of willy-nilly bonding.)

Even the most tricked-out home can't guzzle that much raw speed. Even if it contained 10 HDTVs, all on (and compressed with MPEG-4 at 8 Mbps per stream). And five cable modems, all streaming video at 6 Mbps. And 5 voice-over-Internet protocol phones, all “off-hook,” as it were.

Even that bit-storm only consumes around 90 Mbps. (Only.)

Here's the rundown of DOCSIS 3.0's other major attributes: Channel bonding, sure. A side benefit of channel bonding is that the wider, bonded channels can reap the benefits of better statistical multiplexing. That means more people sharing the same bandwidth, more efficiently.

Then there's the IPv6 support, which substantially lengthens the number of IP addresses an operator can dispense — which substantially increases the number of Internet-hungry gizmos it can support. Better security is part of the spec, too, but it's largely irrelevant — the existing cable modem security, known as BPI and BPI-plus, is unscathed.

And remember: Lots of cable modems are riding into people's homes today — nested inside digital set-top boxes. That's what tech-siders mean, in essence, when they say “DSG,” which stands for “DOCSIS Set-Top Gateway.” No, they're not based on DOCSIS 3.0 yet — trials are just now starting for standalone modems — but the trajectory is visible.

Product people: This is less dry than it seems. As a springboard into an IP smorgasbord, DOCSIS 3.0 is sensibly featured. It lets you walk into battle with a credible speed weapon, a sturdier defense, and reams of information and tools.

At some point, though, speed becomes overkill. Then what? To really juice the imagination, it's probably wise to start brushing up on the basics of PacketCable 2.0. The two together — DOCSIS 3.0 and PC 2.0, as it's often abbreviated — make for some striking product roadmap imaginings.

PC 2.0 is a CableLabs specification. It grew up on the voice-over-IP side of the house. It matters now because it's a tech sandbox for IP-based approaches that look plenty handy for cross-platform services.

A big part of daydreaming in PC 2.0 is getting your head around how to morph today's bundle constituents — voice, video, data — into applications, not just standalone services.

Example: Voice, as an application built into an online customer care portal. If you've ever used a chat room when you need help with a cable problem, you know that it's fine — but, in some cases, it's just easier to talk than type. Videoconferencing possibilities apply here, too.

And then there's the whole notion of FMC, for “Fixed Mobile Convergence.” It also grew out of mobile. It's what happens when you buy a new cell phone, and one of the many features it lists is “dual mode.” In this case, dual mode means it runs on the cellular network when that signal is best, and it flips over to (broadband-fed) WiFi when its signal is best.

The FMC application most discussed is the person who walks into the house, where the cell reception is not so good. The phone flips over to the WiFi network, which is fed by cable broadband, and bingo! The person she's talking to doesn't sound like the teacher from Peanuts anymore.

PC 2.0 is also big on IMS, the IP Multimedia Subsystem, which likewise grew up out of the cellular/telecom industry. It's all about treating the network as a holding pen for lots of different applications servers, capable of working across different types of networks.

The point is this: DOCSIS 3.0 will start out as a weapon in the speed battles. With PacketCable piled on, its core technical attributes can serve as a solid springboard for cross-platform activities: voice stuff first, video stuff likely.

Video stuff? Already, most major MSOs are using their growing expertise in online video (think Fancast, as one example) to figure out what can be leveraged on the set-top — and especially on that built-in cable modem.

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