The Ultimate Cable Modem

Jeff Baumgartner
The Bauminator
Jeff Baumgartner, Senior Editor, Light Reading

5:40 PM -- DENVER -- CTAM Summit -- The CableLabs Docsis 3.0 specs call for a modem to be capable of bonding, at a minimum, four upstream channels and four downstream channels. There's not much actual upstream channel bonding occurring in the wild yet, but that 4x4 configuration ensures that MSOs can offer burst speeds of more than 100 Mbit/s in both directions.

Not lame. But not where things are heading.

These days, vendors are working on modem configurations that bond eight or 16 downstream channels, while maintaining a four-channel upstream, Carey Ritchey, general manager of Microtune Inc. (Nasdaq: TUNE)'s cable unit, mentioned to me yesterday. At full burst, a 16-channel downstream (using 6MHz-wide channels) would generate something like 640 Mbit/s.

Definitely not lame. But also not where some see this all going... at least among the mad scientists out there.

Ritchey said he's already seen some requests for Docsis modems that can bond 32 downstream channels. My cable math suggests that would put a burst speed in the neighborhood of 1.2 Gbit/s.

"But that's been the extreme," Ritchey says. It's the type of extreme Cisco Systems Inc. (Nasdaq: CSCO) openly conceptualized in January 2008 at the Society of Cable Telecommunications Engineers (SCTE) Conference on Emerging Technologies with a presentation titled "A proposal for Docsis 4.0."

Seems as though that vision has since taken a few steps closer to reality.

Of course, the question is what sort of extreme would require such a massively wide speed pipe. If I had to guess, it would have to be for something along the lines of a QAM-IP gateway that can do everything today's digital set-tops can now, but also help MSOs pursue a unicast video model in a big way. Someday.

Or maybe it's about something completely different. But what? I'll do more asking around here. Got an idea? Please share it on the message board.

— Jeff Baumgartner, Site Editor, Cable Digital News

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