Bell Labs Sets New Record for Internet Over Copper

1 Gbps without running fiber all the way to the home

2 min read
Bell Labs Sets New Record for Internet Over Copper
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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

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Metamaterials Could Solve One of 6G’s Big Problems

There’s plenty of bandwidth available if we use reconfigurable intelligent surfaces

12 min read
An illustration depicting cellphone users at street level in a city, with wireless signals reaching them via reflecting surfaces.

Ground level in a typical urban canyon, shielded by tall buildings, will be inaccessible to some 6G frequencies. Deft placement of reconfigurable intelligent surfaces [yellow] will enable the signals to pervade these areas.

Chris Philpot

For all the tumultuous revolution in wireless technology over the past several decades, there have been a couple of constants. One is the overcrowding of radio bands, and the other is the move to escape that congestion by exploiting higher and higher frequencies. And today, as engineers roll out 5G and plan for 6G wireless, they find themselves at a crossroads: After years of designing superefficient transmitters and receivers, and of compensating for the signal losses at the end points of a radio channel, they’re beginning to realize that they are approaching the practical limits of transmitter and receiver efficiency. From now on, to get high performance as we go to higher frequencies, we will need to engineer the wireless channel itself. But how can we possibly engineer and control a wireless environment, which is determined by a host of factors, many of them random and therefore unpredictable?

Perhaps the most promising solution, right now, is to use reconfigurable intelligent surfaces. These are planar structures typically ranging in size from about 100 square centimeters to about 5 square meters or more, depending on the frequency and other factors. These surfaces use advanced substances called metamaterials to reflect and refract electromagnetic waves. Thin two-dimensional metamaterials, known as metasurfaces, can be designed to sense the local electromagnetic environment and tune the wave’s key properties, such as its amplitude, phase, and polarization, as the wave is reflected or refracted by the surface. So as the waves fall on such a surface, it can alter the incident waves’ direction so as to strengthen the channel. In fact, these metasurfaces can be programmed to make these changes dynamically, reconfiguring the signal in real time in response to changes in the wireless channel. Think of reconfigurable intelligent surfaces as the next evolution of the repeater concept.

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