Full Duplex DOCSISYears away, while DOCSIS 3.1 can do an upstream gigabit today. If the wireless guys think they can go both upstream and downstream on the same frequency, why can't cable? Alcatel has already demonstrated a DSL full duplex prototype. Belal Hamzeh at CableLabs believes the answer is probably yes. (Blog below.) Cable worldwide is excited, as the comments below from Australia's NBN CTO Dennis Steiger, demonstrate.

Full duplex cable won't be delivered to most customers soon, even if things go well. "If all signs remain positive, the project will transition from an innovation effort into an R&D project, open to all interested participants," Hamzeh reports. I expect it will take months even to begin the research project and more time after that for the research to yield a reliable standard. Upgrading the equipment, including the subscriber boxes, will take additional years. We all know projects like this often take longer than hoped.

Meanwhile, Verizon is winning away customers with 50 and 100 megabit upstreams. BT has begun deploying 15M lines of G.fast, also capable of hundreds of megabits. AT&T is deploying 12M lines of fiber home or G.fast. France, Spain, Korea and Taiwan are moving rapidly to G.fast and fiber home.

Google's gigabit symmetrical is finally coming to more cities of little more than cable charges for 5% of that speed.

Fast DOCSIS 3.1 upstream is available from all major suppliers today. Four years ago, Balin Nair & Mike Fries at Liberty didn't believe there was much demand. Today, I bet they've changed their mind. Tony Werner doesn't want to wait; his boss, Brian Roberts, told D.C. high upstream speeds were coming by 2015. Brian's team also told the U.S. Broadband Plan they would deploy AllVid. They wanted to make sure the Broadband Plan didn't restrict U.S. cable prices, already 50% or more than the prices in Western Europe. They haven't delivered on either.

Full gigabit cable upstream requires replacing amplifiers and other gear in the field. I believe Comcast has been doing that aggressively but most cable companies having been stingy with capes. That includes Numericable/Altice, Time Warner and Charter. The (moderate) upgrade cost for faster speeds would pay off for the cablecos, but Altice and Charter are keeping capes down to keep the stock price up. Cable is doing very well in the business market, which wants upstream. Brian Roberts just told the street, "Business Services under Bill Stemper has now exceeded a $5 billion revenue run rate while maintaining a growth of 20%." 

Going full duplex is not new. 30+ years ago, full duplex technology and echo cancelation were used to create 9600 baud modems. Moore's Law allows faster processing today and some engineers are optimistic. (At least one I respect remains unconvinced.)

Stanford and Columbia teams are looking to bring FD to market for wireless. Kumu Networks is extremely hopeful that full duplex is ready to work in wireless networks, although fitting into a mobile phone will be a challenge. It's a spinoff from the labs of Stanford Professors Sachin Katti and Phil Levis. Harish Krishnaswamy at Columbia has developed chips.

I fear full duplex technology will hold back upstream speeds for too many tears.

Thanks to Doug Fraser for pointing me to this story.

Here're the comments from the NBN CTO and the CableLabs Blog

From Corinne Reichert, ZDNET Australia 

NBN CTO Dennis Steiger, who is currently in the US with CableLabs for the announcement.

"We will be working closely with CableLabs to track the development of this technology, and are excited about the potential this offers for the 4 million premises that will receive their NBN services via our HFC network.

"Previously, it was only possible to deliver multi-gigabit symmetrical broadband if you deployed an FttP network -- but HFC is now right up there in terms of being able to deliver these kinds of speeds.

"We now have the pathway to deliver these ultra-fast symmetrical speeds to our HFC end users both very cost effectively and far more conveniently than we could if we had to deliver fibre all the way to their homes.

Full Duplex DOCSIS® 3.1 Technology: Raising the Ante with Symmetric Gigabit Service

By Belal Hamzeh, VP Wireless, R&D and Dan Rice, SVP, R&D, CableLabs —

Building on state of the art technology, ongoing DOCSIS 3.1 technology deployments have squarely set the cable industry on the path to deliver Gigabit services over HFC networks.

But there’s more to come! A newly unveiled project at CableLabs illustrates how DOCSIS 3.1 technology provides the basis for continued evolution of system capacities by supporting symmetric multi-Gigabit service over the cable network. During its recent 2016 Winter Conference, CableLabs unveiled a Full Duplex DOCSIS technology which applies emerging techniques from wireless networks to achieve a breakthrough increase in the upstream speeds for DOCSIS delivered broadband service. A Full Duplex DOCSIS network is a prime example of the CableLabs 2.0 vision using its rich innovation funnel of technologies to transform the industry.


How is full duplex different from existing technologies?

Existing technologies mostly use either Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD). In FDD, upstream and downstream (or uplink and downlink in the terms of the wireless world) traffic operate separately in dedicated parts of the spectrum. In current DOCSIS network deployments, the lower part of the spectrum is dedicated for upstream traffic and the upper part of the spectrum is dedicated for downstream traffic. In TDD, the upstream and downstream traffic share the same spectrum, but take turns in using the spectrum, similar to how Wi-Fi, or DSL, operate. In Full Duplex communication, the upstream and downstream traffic use the same spectrum at the same time, doubling the efficiency of spectrum use. A DOCSIS 3.1 Full Duplex network provides the peak speeds and flexibility of TDD solutions, but one-ups both TDD and FDD with double the capacity.

Using a combination of Passive HFC and the self-interference cancellation and intelligent scheduling of DOCSIS 3.1 technology, CableLabs has built a solution that proves the viability of full duplex communication. Its approach significantly increases upstream data capacity in order to enable symmetric multi-Gigabit broadband data services for consumers and the enterprise. These developments are expected to yield DOCSIS 3.1 network performance of up to 10 Gbps symmetrical on 1 GHz HFC networks, with the potential for even higher performance by utilizing spectrum that is currently available for future expansion above 1 GHz.

One of the compelling attributes of a Full Duplex DOCSIS 3.1 network for the next evolution in HFC delivery is the strong foundation DOCSIS 3.1 technology provides. Our design and analysis shows that the existing Physical and MAC layer protocols in DOCSIS 3.1 technology can largely support this new symmetric service. The evolution to a DOCSIS 3.1 Full Duplex network is an incremental evolution of DOCSIS 3.1 technology and will support both backward compatibility and coexistence with previous generations of DOCSIS network deployments.

So what’s next for the Full Duplex DOCSIS 3.1 technology?

Over the next few months, we will engage with a team composed of our members and vendors who can help us further validate and mature the technology. Following which, if all signs remain positive, the project will transition from an innovation effort into an R&D project, open to all interested participants.

We are excited about this development effort, and look forward to its further evolution. Stay tuned to this blog for more exciting news from CableLabs.