DOCSIS 3.1

A Wider Upstream Path: 2018?

DENVER–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.)

Later, queries about a wider upstream softened into variations of “not in my lifetime.” Why: 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. Answer, extrapolated from the guts of the panel and not expressed directly: 2018-ish.

“We’re all exploring it,” said Jorge Salinger, VP/Access Architectures for Comcast, to the point of an organized, weekly call amongst involved 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.)

This column originally appeared in the Platforms section of Multichannel News.

 

 

 

 

 

DOCSIS 3.1 in ’13

By now, hopefully, you’ve heard that there’s a new chapter coming in cable modems. It’s the latest iteration in the specification known by technologists as “DOCSIS 3.1” for “Data Over Cable Service Interface Specification.”

DOCSIS 3.1 is a doozy — both in terms of what it will do for broadband capacity, and the sheer density of the tech talk that surrounds it.

Hey! Let’s face it. “QAM” is a little long in the tooth, as impressively nerdy industrial tech-talk goes. Not to worry. With 3.1, you too can impress your friends and colleagues by blurting out 3.1-speak like “Orthogonal Frequency Division Multiplexing with Low Density Parity Check.”

Feature-wise, DOCSIS 3.1 is so crammed with improvements that some of us wondered why it didn’t qualify as “DOCSIS 4.0.” (Answer: To thwart any misperceptions from the investor community about “forklift upgrades.”)

First off: DOCSIS 3.1 matters and was devised because of the billowing consumer demand for broadband usage — 50% and higher compound growth, since about 2009. Again: In the history of consumable goods, nothing has grown at a sustained rate of 50%, year over year.

DOCSIS 3.1 basics: When complete (2013) and in market (2014?), it will expand the industry’s downstream and upstream carrying capacity for digital, IP traffic by 50%.

“Half as much again” is always a big deal, especially for that spectrally anemic upstream signal path.

Also impressive about DOCSIS 3.1: It could enable connection speeds of 10 Gigabits per second (Gbps.) Note: Don’t inhale too deeply on this one. It’s 10 Gbps if and only if all other channels on a system are empty. No analog, no SD or HD video, no broadband, no voice.

Let’s get back to the tech-talk of 3.1. What makes for these enormous gains in IP capacity and speed is a new (to cable) form of modulation called “OFDM” (see above.) OFDM, when coupled with a new (to cable) form of forward error correction (LDPC), brings the 50% efficiency gains.

OFDM is widely used by mobile carriers, because they’re already pretty bandwidth-challenged (ship any video from your phone lately?). It works by chopping the typical 6 MHz digital cable channel into smaller “subcarriers,” in the lingo. That’s good for both transmission and dealing with impairments.

That’s the basics of DOCSIS 3.1 — why it matters, and how to talk about it with aplomb. Watch for it to be a major undercurrent of the 2013 cable-tech scene.

This column originally appeared in the Platforms section of Multichannel News.

On Widening Cable’s Upstream Path: All Eyes on YOU, Massillon Cable!

ORLANDO–Finally! Someone is going to see what it takes to widen cable’s upstream path.

At last week’s Society of Cable Telecommunications Engineers, burrowed into an opening session featuring engineers from mid-sized operators, Massillon Cable GM and technical operations manager Kelly Rehm made this understated but momentous declaration: “One of the projects we’re working on next year is to go to 85 MHz, to improve the return path.”

In the hall, an audible murmur: Did he say what I think he said?

Trust me: If ever you want to raise the energy level in a room full of cable engineers, ask them when they’re going to widen the upstream. Answers like “hopefully not in my lifetime” tend to follow.

It’s nearly a religious debate. Why: Widening the upstream is a big deal, operationally and technically. It’s not for the faint of heart, is the common refrain.

Plus, technologists and bandwidth watchers submit, the need for more upstream capacity isn’t as dire as the need for more room in the downstream, so far.  That 50% CAGR in broadband usage that we keep hearing about is a downstream phenomenon only.

Think about it: Of all the IP-connected devices you use (smart phones, tablets, PCs, connected TVs), most activities that eat up bandwidth are downstream – towards you. Streaming video is a classic example. Until we’re using our digital, IP gadgetry to, say, videoconference through the cable modem (as opposed to Facetiming through the cellular network), or to send live video streams, it’s less of an issue.

Cable upstream basics: Spectrally slender, cable’s upstream path (which also goes by the “return” or “reverse” path) represents a scant 5% of total available bandwidth. Because of where it sits (between 5-42 MHz), it’s riddled with different types of noise – much of it generated inside the home.

Just as you slow down when driving on a road pocked with potholes, transmitting upstream traditionally required modulation sturdiness, more so than boffo speeds.

In Expo conversations about the new DOCSIS 3.1 specification, also unveiled here, MSOs said they’ll phase new, higher-order modulation and forward error correction techniques into the downstream first. Then, if the need arises, they’ll have the tools they need to expand the upstream too.

That’s why Massillon’s decision to experiment with widening the upper boundary of the reverse path, to an 85 MHz “mid-split,” is a big deal. Finally, we’ll see what it really takes to get ready for a wider upstream, if and when needed. Go Massillon!

This column originally appeared in the Platforms section of Multichannel News.

 

 

Preview: CTAM Summit, SCTE Cable-Tec Expo, Orlando

For someone passionate about making technology approachable to non-technical people, this week is a grand slam of cable conventions: CTAM Summit and the SCTE Cable Tec-Expo. Marketers and engineers, all in one place! Nirvana!

And hello again, Orlando. This location means one thing right off the bat: Brush up on your Full Service Network history (see Craig Leddy’s take on this here: http://www.multichannel.com/archive/orlando-revisited/139794), because you’ll likely hear more than a few nostalgic and/or instructive anecdotes about it.

For the tech-interested at CTAM Summit, check out self-professed gadget guru, author (“Beyond the Obvious: Killer Questions That Spark Game-Changing Innovation”) and new-ish CEO of CableLabs, Phil McKinney, who kicks off a “Products Consumers Crave” panel on Tuesday at 9.  The session features chief technologists from Comcast, Cox and Charter (full disclosure: moderated by yours truly.)

In the topic mix: What technologists want from marketers; the operational impact of “service velocity;” maneuvering a software-heavy workplace, and the parallel industrial shift to “agile” development; cable’s changing role in innovation.

That’s all on the front part of the week. Then, on Wednesday, the marketers pull out, and the techies pull in.

What to watch for, news-wise, at this year’s SCTE Cable Tec Expo: Lots of detail about the next chapter in cable modems, now officially named “DOCSIS 3.1.”

Why: A session added to the Thursday morning schedule (11-12:30) aims to go long on the constituent components of DOCSIS 3.1. It’s all about wringing more capacity out of existing hybrid fiber-coax (HFC) networks, by tweaking things like modulation and error correction. (Yes, you can expect a full translation in a future edition.)

One of the great things about Cable Tec-Expo: Session repetition. This year’s technical workshops look chewy, and many of them repeat throughout the three-day tech-fest. Even with the session repeats, though, the 2012 lineup makes one want a clone.

On my short-list: “Is Your Network Capable of Handling the Next Generation of Services?”, “Slaying the Bandwidth Consumption Monster,” “Fast Times: Speed Tiers and Their Impact on Your Network,” and “Take 5: HTML5 in Cable.”

Also hot-looking (as hot goes): “Advanced Encoding for an Untethered World,” “CCAP Trial: The Verdict,” and “Springing New Leaks: A Look at New Sources of Interference.”

If there was an award for best session title (because that’s what the industry needs! More awards! ;-), it’d have to go to “Bandwidth Hunger Games.” Best acronym overload: “EPON, EPoC, DPoE, RFoG, DOCSIS – Beyond the Alphabet Soup.” (A typo in the online agenda makes it all the better: “FRoG.”)

Hope to see you there!

This column originally appeared in the Platforms section of Multichannel News.