G.fast chipmaker Sckipio hopes a new bandwidth technology will improve the business case for G.fast by giving telcos an edge over their cable rivals on upstream performance.

The Israeli startup has begun demonstrations with broadband equipment vendor Adtran Inc. (Nasdaq: ADTN) of a technology it calls dynamic bandwidth allocation (DBA), which is already being used in passive optical networks to share bandwidth between users.

In the G.fast case, however, DBA has been designed to boost the upstream bandwidth available to customers on copper-based telco networks.

Upstream speeds are still relatively low on this infrastructure, as well as the DOCSIS networks used by cable companies. In the UK, for instance, the premium residential service from telco incumbent BT Group plc (NYSE: BT; London: BTA) promises 76 Mbit/s on the downstream but does not go above 19 Mbit/s on the upstream. The best that cable competitor Virgin Media Inc. (Nasdaq: VMED) can offer is 200 Mbit/s on the downstream and 12 Mbit/s on the upstream.

BT has been an active proponent of G.fast, which extends the frequency range to boost connection speeds over last-mile copper links. Using G.fast, it hopes to increase downstream connections to as much as 500 Mbit/s. But without DBA, upstream speeds may continue to lag. (See BT to Cover 2M Homes With FTTP in $8.7B Plan.)

At the moment, the chief market requirement is for a good downstream connection that allows customers to watch movies and access more advanced Internet services. But this could soon change with the growing popularity of cloud computing, interactive gaming and other user-generated content services.

This is the opportunity that Sckipio Technologies is targeting. Rather than giving networks any kind of always-on "symmetric" capability, the DBA technology it has developed works by dedicating more capacity to either the upstream or the downstream as circumstances dictate. If, say, a user begins uploading a number of video files to the cloud, the upstream capability would automatically be increased to cope with that demand.

The trade-off in this example appears to be that downstream capability would diminish as upstream bandwidth is increased. In other words, watching a movie in high definition while the video files are being uploaded might not be a straightforward option.

That said, Sckipio is making some bold claims for the DBA technology, saying it could support connection speeds of up to 750 Mbit/s in each direction on today's chipsets.

It seems unlikely to be available anytime soon, though, or even exactly in its current form. Sckipio expects many elements of DBA to find their way into an International Telecommunication Union (ITU) standard called dynamic timeslot allocation (DTA). That technology will be the one intended for commercial deployment, rather than just demonstration purposes.

"[DTA] is being vigorously discussed now and may or may not make standardization this year," says Michael Weissman, Sckipio's vice president of marketing. "I'll be honest -- there are complexities in it and we want to take into consideration everyone's thought processes and create the perfect solution."

Nevertheless, Weissman argues the work that Sckipio has already done on DBA gives it a DTA head start of between six months and a year on Broadcom Corp. (Nasdaq: BRCM), which he evidently regards as Sckipio's biggest G.fast rival.

For more fixed broadband market coverage and insights, check out our dedicated Broadband content channel here on Light Reading.

What's clear is that, as a technology concept, DBA has already piqued the interest of telcos plotting G.fast deployments.

In a video interview about G.fast with Light Reading in April, Eddy Barker, the vice president of technical design and architecture for AT&T Inc. (NYSE: T), flagged interest in using DBA technology to provide much higher-speed upstream services to customers. (See AT&T's Big Plans for G.fast.)

Moreover, an endorsement of DBA from Canada's Telus Corp. (NYSE: TU; Toronto: T) is included in a Sckipio statement about demonstrations of the technology at the G.fast Summit in Paris this week. "DBA is a G.fast game-changer," said Tim Fell, the vice president of video and broadband services at Telus, in that statement. "In the race to deliver ultra-fast broadband, the ability to offer affordable symmetrical services will give telcos the flexibility required to meet our customers' evolving high-speed Internet needs."

None of this necessarily means that AT&T or Telus are making huge commitments to G.fast or Sckipio, but it could bolster the appeal of G.fast to operators weighing their broadband technology options.

Following recent improvements, G.fast already appears to have convinced a few big telcos they can sweat their legacy copper assets instead of rolling out new fiber. But critics have argued that G.fast is simply prolonging the life of a dying technology, and delaying an inevitable fiber upgrade in the years ahead. (See NBN Looks to G.Fast to Reduce Fiber 'Hassle'.)

Right now, the big question is whether DTA really will give telcos an upstream advantage over cable operators. Of this, Weissman sounds fairly confident. "DOCSIS 3.1 is the next three-year [cable] roadmap and so unless they can do something really quickly, this is going to catch them flatfooted," he says.

Yet even if DBA is not on the cable roadmap, symmetrical capability is. Indeed, Finland's Nokia Corp. (NYSE: NOK) today announced demonstrations of a symmetrical 10 Gbit/s service over a coax connection using Full Duplex technology. CableLabs and Kumu Networks have also been exploring Full Duplex, which shares the same frequency bands between upstream and downstream signals to support symmetrical services. (See Nokia Demos 10-Gig Over HFC.)

Given the real-world challenges surrounding Full Duplex, however, it will probably not see commercial deployment until at least 2020. If the G.fast community can bring DTA to market in the next couple of years, operators of copper-based networks may have something to shout about.

— Iain Morris, , News Editor, Light Reading