Alcatel-Lucent boosts broadband over copper to 300M bps

bealtine

Alcatel-Lucent has found a way to move data at 300Mbps over two copper lines, the company said on Wednesday. However, so far it is only in a lab environment -- real products and services won't show up until next year. Researchers at the company's Bell Labs demonstrated the 300Mbps technology over a distance of 400 meters using VDSL2 (Very high bitrate Digital Subscriber Line), according to Stefaan Vanhastel, director of product marketing at Alcatel-Lucent Wireline Networks. The test showed that it can also do 100M bps over a distance of 1,000 meters, he said.

On its own VDSL2 tops out at about 100Mbps over a distance of 400 meters, so to get to three times that capacity Alcatel-Lucent combines a number of different technologies. Alcatel-Lucent's first trick is to use two copper pairs at the same time, a technology called bonding. Next Alcatel-Lucent uses a feature it has developed called Phantom Mode to create a third virtual copper pair that sends data over a combination of the two physical ones.


The problem is that when you use bonding and Phantom Mode you also get a lot of crosstalk, a form of noise that degrades the signal quality and decreases the bandwidth. So instead of 300Mbps you only get about 200Mbps. To solve this Alcatel-Lucent uses vectoring, a technology that works like noise-cancelling headphones, according to Vanhastel. It continuously analyzes the noise conditions on the copper cables, and then creates a new signal to cancel it out, he said.

"It is a really complex technology that requires ... you to process gigabytes of signal data just to calculate the noise patterns," Vanhastel said.

Fiber to the home is the ideal long-term solution for fast broadband, and in 15 to 20 years all homes will have it, according to Vanhastel. But in the meantime operators should be able to use existing copper networks to offer faster speeds to households that don't have a fiber connection, he said.

Currently, copper is the most common broadband medium. About 65% of subscribers have a broadband connection that's based on DSL, compared to 20% for cable and 12% for fiber, according to market research company Point Topic. Today, the average advertised DSL speeds for residential users vary between 9.2Mbps in Western Europe and Asia Pacific and 1.9Mbps in South and East Asia, Point Topic said.

The use of vectoring on VDSL2 is currently being standardized by the International Telecommunication Union (ITU). The final review of the standard ends today, and if there are no further comments it will be approved by the end of April, according to Alcatel-Lucent. At the latest, it will arrive by July, according to Ericsson, which is also working on products that will support vectoring.

Alcatel-Lucent and Ericsson expect field trials using vectoring to start during 2010, and the technology will become commercially available in 2011, according to the two vendors.

Even higher speeds than 300Mbps can be achieved by using more copper pairs. However, Alcatel-Lucent settled on two copper pairs because it is a more realistic scenario for when the technology is rolled out to residential users in the future, according to Vanhastel. You might find six pairs in the field, but just for businesses and maybe mobile backhaul applications, he said.
"We could have made an announcement talking about 1Gbps or 2Gbps, but on purpose we chose not to do that because it is not a realistic scenario," said Vanhastel.

Sponge Bob

Frankly that is tech for the basement in a tower block not outdoor and certainly not outdoor in Ireland given the decrepit copper:(

Bonded VDSL is years ( 8?) old albeit at 100mbit rates and max two pairs.

watty

Combine two phantoms you get a ghost
combine two ghosts and get a spirit.

Done with audio/voice 80 years ago I think. We used the real copper for program and the phantom for studio "talkback" in the BBC analogue days...

Well known technique with balance circuits. The performance, interference and crosstalk is bad.

nice picture here of how you get a "phantom" circuit from two real circuits. http://en.wikipedia.org/wiki/Phantom_circuit

Indeed, not much use in real world outdoor for ADSL/VDSL. Bonding does work. I mentioned it yesterday. But uses multiple pairs.

bealtine

spotted this one:

http://www.bondeddslrings.com

lucernarian

Noise vectoring wouldn't be so effective for crosstalk surely?

If it was simple thermal noise or spurious noise entering the cable, it would be useful. But I assume that as the "noise" involved would be a weak but valid signal of an adjoining pair, the cancellation efforts of one line may cause more detrimental noise for the nearby line than would otherwise be the case. Am I missing something here?

cgarvey

My thoughts exactly, TBC!

Also, Ireland (rural, or urban) isn't exactly flush with spare pairs!