Ordinary copper telephone wire could carry gigabit broadband speeds

Matthew Sparkes is a writer.

Fibre-optic cable is being laid across the UK at great expense to speed up people's internet connections, but researchers claim that the copper telephone wire already in use across the country can achieve data rates three times higher than currently seen at a fraction of the price. Their technique to boost speeds may help to ease the transition to nationwide fibre optic, and may also be used in countries that use similar twisted-pair copper wire.

The University of Cambridge and their colleagues say that twisted pairs of copper wire can support a higher Frequency than is currently used, which would dramatically improve data transmission rates. The researchers found that the wire acts as an aerial and transforms any signal sent along it into radio waves that disappear before reaching their destination.

Alexander Graham Bell invented the cables, and since then no one has looked into the theoretical limits.

He and his colleagues believe that their findings may allow houses near fibre-optic cables to achieve higher speeds than they currently enjoy without the expense of running fibre all the way to their home.

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Fibre-optic cables carry groups of photons to represent data, and huge numbers of these groups can be sent along the line one after another without waiting for the first to arrive. Fibre connections in use today typically operate at 1 gigabit per second, but theoretical speeds could be many thousands of times higher.

The signal is sent by an electrical current running along the entire length of cable, and the data transmission rate is limited by how quickly the current can be changed.

The current of existing copper broadband connections can be changed a billion times a second, but the researchers discovered that a small and cheap component called a balun can be used to raise the current to 5 gigahertz.

The error rate increases at higher frequencies so Dinc doesn't believe this will translate to a fivefold increase in data transmission. Dinc estimates that 3 gigabits per second is feasible, but further research is needed to determine how much of a boost is really possible. Most people with copper wire broadband in the UK only achieve speeds of 80 megabits per second, which is triple the current theoretical maximum.

Nature Communications is a journal.