Cranking Up Copper: Bell Labs Demos DSL at 300 Mbps

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Is there still a ton of bandwidth left to wring out of DSL?

Bell Labs, the R&D arm of Alcatel-Lucent, says it has successfully demonstrated a technology — with the spooky code name “DSL Phantom Mode” — that boosts the transmission speeds achievable over one pair of digital subscriber lines (DSL) to 300 Megabits per second downstream.

The caveat: That’s at a distance of 400 meters between the customer endpoint and central office. At 1 kilometer, the technology allegedly provides 100 Mbps.

Meanwhile, the cable industry’s DOCSIS 3.0 is already capable of 300 Mbps down, and could go even higher (see Cisco To Take DOCSIS 3.0 Modems Over 300 Mbps and In the Box: Hot Chips).

Still, Bell Labs’ DSL Phantom Mode (sounds like a Six Flags roller coaster!) apparently beats Very High Bit-Rate DSL 2 (VDSL2), the flavor that AT&T U-verse uses, which provides a theoretical maximum of 50 Mbps at 1 kilometer.

Alcatel-Lucent touts DSL Phantom Mode as a major breakthrough: “At these speeds, service providers will be able to maximize the ability of the existing copper infrastructure — widely deployed around the world — to satisfy demand for bandwidth-intense residential triple-play and business services, for years to come.”

Maybe. The company acknowledged that “further research is being conducted to refine deployment models and determine a specific set of customer premises equipment [CPE]-models compatible with the DSL Phantom Mode technology.”

But the development may, at some point, give telcos the ammo to super-charge DSL — rather than undertaking expensive fiber-to-the-home builds — to fight cable’s DOCSIS 3.0.

Here’s how DSL Phantom Mode works, according to Bell Labs:

At its core, DSL Phantom Mode involves the creation of a virtual or “phantom” channel that supplements the two physical wires that are the standard configuration for copper transmission lines. Bell Labs’ innovation and the source of DSL Phantom Mode’s dramatic increase in transmission capacity lies in its application of analogue phantom mode technology in combination with industry-standard techniques: vectoring that eliminates interference or “crosstalk” between copper wires, and bonding that makes it possible to take individual lines and aggregate them.

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