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A Wider Upstream Path: 2018?

A surefire way to fire up cable technologists used to involve smiling broadly while asking : “When will you need to widen the upstream path?”

For decades, the answer, usually harrumphed, was this: “Never!”

Why: It’s a pretty big hassle. Very plant-intensive, possibly to the point of having to revisit or replace gear at the tap level. (Taps are expressed in number of ports — 4-port, 8-port — and exist to adjoin fatter cable, like feeder cables, to the thinner, coaxial cable that drops into homes. So there’s tons of them.)

The upstream is a very skinny portion of the total available capacity of a cable system. “Very skinny” meaning five percent or less, occupying a slender spectral spot from 5-42 MHz.

Then broadband happened. Right now, the growth of downstream (home-facing) broadband consumption still far outpaces the growth of upstream (network facing) bandwidth usage. But think about how many things come with a built-in video camera — your phone, for instance, or any of the webcams monitoring any of the things in your life.

Video is big. Sending it upstream, live, chews up bandwidth.

Think, too, about the fact that more Wi-Fi traffic is happening right now than mobile or wired, combined. Offloading some of that onto the wired network in the house is a plausible reality.

Which brings us to the latest round of responses to the age-old question of when the industry might consider a wider upstream. Last week, specifically, during a panel of technologists at Light Reading’s annual “Cable Next-Gen Technologies & Strategies” event, the answer extrapolated from the guts of the panel and not expressed directly: 2018-ish.

“We’re all exploring it,” said Jorge Salinger, vice president, access architectures for Comcast, to the point of an organized, weekly call among technologists at several MSOs.

Here’s where the 2018-ish prediction comes from: DOCSIS 3.1 includes language supporting a “mid-split,” which is tech talk for widening the upstream.

The silicon for DOCSIS 3.1-based gear is expected this year. The cable modems and gateways that use it will follow in 2015. Then interops, then trials — which makes 2016 plausible as “the golden year” for widespread DOCSIS 3.1 deployments.

After that, 3.1-based headend gear (known industrially as “CMTS,” for “Cable Modem Termination System”) catches up. Let’s say that happens in a big way in 2017.

After all of that — and should we continue to see gadgetry in our homes that streams video constantly — it will probably make sense to move the upper boundary of the upstream spectrum, from 42 MHz to 65 MHz or higher.

That’s why we’re putting a 2018-ish stamp on it. (Heavy on the -ish.)

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