Traditional copper telephone lines can now run ultra-fast broadband service, at least in the lab.
Bell Labs, the research arm of Alcatel-Lucent, has developed a prototype technology that can deliver upload and download speeds of up to 10 gigabits per second (Gbps) simultaneously.
The technology, XG-FAST, is an extension of a new broadband standard, G.fast, which will be commercially available next year. XG-FAST uses an increased frequency range (up to 500 MHz) compared to G.fast to deliver higher speeds, but over shorter distances. In the lab, researchers achieved speeds topping 1 Gbps on a single copper pair over a distance of 70 meters. The eye-popping 10-Gbps rate was achieved over 30 meters using two pairs of lines, a technique referred to as bonding.
For some Internet providers, 70 meters may be enough to expand coverage. Many service providers have laid fiber across their networks, but getting it to every last home is an expensive additional cost.
Alcatel-Lucent said the new technology should allow for Internet connections over cable that are “indistinguishable” from fiber-to-the-home in places where it’s not “physically, economically or aesthetically viable to lay new fiber cables all the way into residences.”
“XG-FAST can help operators accelerate [fiber-to-the-home] deployments, taking fiber very close to customers without the major expense and delays associated with entering every home.” Federico Guillén, President of Alcatel-Lucent’s Fixed Networks business, said in a statement.
For the past few years, Alcatel-Lucent has also been working on other ways to improve the speed of fast Internet over copper. Another nagging issue they've been wrestling with is the cross talk that can leak between customers' copper wires. Alcatel-Lucent has introduced vectoring, which adjusts signals from the home that are sent back to the hardware in the street cabinet in order to minimize the interference. However, with G.fast, cross-talk "is more like cross-shouting," according to Alcatel's TechZine blog, and will require even more innovation if it's to be overcome.
Vectoring was paired with Alcatel-Lucent’s very-high-speed DSL technology (VDSL2) starting in 2011, but the latest breakthrough at Bell Labs considerably dwarfs the speeds achieved with VDSL2, albeit over a far shorter distance. Earlier this year, Alcatel-Lucent set a new world record for real-world fiber speeds of 1.4 terabits per second.
“Our demonstration of 10 Gbps over copper is a prime example: by pushing broadband technology to its limits, operators can determine how they could deliver gigabit services over their existing networks, ensuring the availability of ultra-broadband access as widely and as economically as possible,” Marcus Weldon, president of Bell Labs, said in a statement.
But the short distances over which XG-FAST operates in the lab may not be enough to deliver faster Internet over copper to those outside of dense, urban environments. Chris Green, a principal technology analyst at the Davies Murphy Group consultancy, told BBCNews that in small towns and especially rural locations, the distance from the street cabinet to the home would still likely render this latest breakthrough impractical.
“The problem that rural properties have is that they are usually very far away from the nearest telephone exchange,” he told BBCNews. “You can usually measure it in miles.”
Graphic: Bell Labs