Bell Labs celebrates net speed record over copper lines
By Leo Kelion Technology desk editor
9 July 2014
Bell Labs hit speeds using copper cables previously only available to fibre optic links
A team of researchers has announced it has transmitted data over traditional copper telephone lines at a record speed of 10 gigabits per second (Gbps).
Bell Labs said it used two pairs of 30m (98.4ft)-long standard phone cables to achieve the speed in its laboratory.
It suggested the tech could eventually be adapted to offer 1 Gbps in real-world uses.
That could reduce the amount of expensive fibre optic cable needed to boost internet speeds in cities.
“It will enable operators to provide internet connection speeds that are indistinguishable from fibre-to-the-home services, a major business benefit in locations where it is not physically, economically or aesthetically viable to lay new fibre cables all the way into residences,” said Bell Labs’ owner, Alcatel-Lucent.
“Instead, fibre can be brought to the curbside, wall or basement of a building and the existing copper network used for the final few metres.”
However, one analyst noted that the tech would not solve the problem of slow net speeds for many other users.
“The problem that rural properties have is that they are usually very far away from the nearest telephone exchange – you can usually measure it in miles,” said Chris Green, principal technology analyst at the Davies Murphy Group consultancy.
“The speed jumps that Bell Labs have managed to achieve drop away at much shorter distances.
“In order to get any of these speeds you would need to be close enough to your exchange – or fibre optic cable connected to it – that you could pretty much throw a stone at it from your door.”
Mr Green added that even in many parts of major cities, BT often only provides “fibre to the cabinet”, rather than “fibre to the home” – and many properties would be too far away from a phone cabinet to benefit.
Even so, he acknowledged the tech could significantly cut the cost of offering ultrafast broadband to those who would qualify.
Bell Labs said a team of engineers at its Antwerp, Belgium offices developed a technology called XG-Fast to achieve the speed record, building on the existing G.fast specification.
To do this it developed kit that uses a wider frequency range of up to 500 MHz to transmit data, rather than the 106 MHz range used by G.fast.
The trade-off, however, is that XG-Fast only works over shorter distances than its predecessor.
So, while G.fast offers 700 megabits per second over 100m, XG-Fast can offer either a one-way data transfer of 10 Gbps over 30m or the prospect of a simultaneous 1 Gbps upload and 1 Gbps download over 70m.
While Alcatel-Lucent can claim this is a new record for copper cables, it is still a fraction of 1.4 terabits per second speed it achieved last November in a test carried out with BT over a fibre optic cable link running between London’s BT Tower and a research campus in Suffolk.
Data speeds are usually described in terms of bits:
1,000 bits = 1 Kilobit
1,000Kb = 1 Megabit
1,000Mb = 1 Gigabit
1,000Gb = 1 Terabit
Data storage is usually described in terms of bytes:
8 bits = 1 byte
1,024 bytes = 1 Kilobyte
1,024KB = 1 Megabyte
1,024MB = 1 Gigabyte
1,024GB = 1 Terabyte
So, a 10 Gbps connection would allow you to transfer 75GB of data over the course of a minute, or the equivalent of about 110 full CDs worth of music.