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DSL/vectoring/G.fast

DT Looks to XG.FAST as Ultra-Fast Option

Deutsche Telekom has become the latest operator to carry out trials of XG.FAST, an experimental technology that is intended to boost connection speeds over very short copper loops.

During trials with Alcatel-Lucent (NYSE: ALU) late last year, the German incumbent managed to achieve a speed of 11 Gbit/s over two bonded pairs at a distance of about 50 meters, according to a statement from Finland's Nokia Corp. (NYSE: NOK), which acquired Alcatel-Lucent last month.

Tests using "standard drop cable" delivered more than 8 Gbit/s over 50 meters, and symmetrical speeds of more than 1 Gbit/s were possible over 70 meters, says Nokia.

UK incumbent BT Group plc (NYSE: BT; London: BTA) flagged trials of XG.FAST in October last year, when it claimed to have recorded speeds of 5 Gbit/s over a distance of 35 meters. (See Long-Range, High-Speed Gfast Is Coming – BT.)

BT aims to use ordinary G.fast technology to provide services of between 300 Mbit/s and 500 Mbit/s over distances of about 300 meters, but Deutsche Telekom AG (NYSE: DT) has yet to announce any G.fast plans whatsoever.

Instead, it is investing in a technology called vectoring, which improves the capability of copper connections by cutting out the interference between lines.

Spokespeople for Deutsche Telekom have previously told Light Reading the operator will not look to G.fast until it has first introduced vectoring, the rollout of which appears to have fallen behind schedule due to regulatory challenges. (See DT's $1.1B Vectoring Plans Thrown Into Doubt After New Ruling.)

Nevertheless, CEO Timotheus Höttges has suggested that G.fast could eventually be used to provide gigabit-speed connections to customers over bonded copper pairs.

Commenting on the XG.FAST trials, CTO Bruno Jacobfeuerborn said the technology would give Deutsche Telekom another option for prolonging the life of its copper assets.

"Working on this demonstration we can see the future possibilities of XG.FAST in maximizing existing assets," he said in a statement published on Nokia's website. "This will provide another technology option which could enable us to offer high-speed connectivity to our customers quickly and cost-effectively and, at the same time, move our fiber infrastructure closer to our customers."


The rollout of Gigabit broadband access networks is spreading. Find out what's happening where in our dedicated Gigabit Cities content channel here on Light Reading.


Despite the promise, the use of G.fast or XG.FAST is likely to meet with a backlash from Deutsche Telekom's critics, which have accused the operator of dragging its heels on the deployment of fiber.

Vodafone Group plc (NYSE: VOD) reckons the use of copper-fortifying technologies such as vectoring is "cementing the dominance of incumbents" in European telecom markets. (See Vodafone Calls for Broadband Regulation Shake-Up in Germany.)

It wants German authorities to overhaul broadband regulations and force Deutsche Telekom to provide better access to ducts and dark fiber, arguing this would spur fiber investments and bolster competition.

A major challenge for XG.FAST will be delivering ultra-fast services over longer distances: Because it works in very high frequency ranges, it is badly affected by signal attenuation.

"Given that it's a 500MHz system, I don't think it will be going too far away from the fiber," said Trevor Linney, BT's head of access network research, during a discussion with Light Reading about BT's XG.FAST trials in October.

— Iain Morris, Circle me on Google+ Follow me on TwitterVisit my LinkedIn profile, News Editor, Light Reading

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