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Welsh researchers promise 40Gbps fibre speeds with low-cost components

Scientists at Bangor University have come up with a way of applying OOFDM techniques, already common in technologies such as Wi-Fi, to fibre. The result, they say, could allow speeds of up to 40Gbps - although that would need to be shared between neighbours.
Written by David Meyer, Contributor

Researchers at Bangor University in Wales have come up with a way to drastically speed up broadband access over fibre networks, while using relatively low-cost components.

The academics, who are working with companies such as Fujitsu in an EU-funded consortium called Ocean, said on Tuesday that their use of a technique called Optical Orthogonal Frequency Division Multiplexing (OOFDM) could demonstrably provide speeds of 20Gbps. In future, they said, it could even ratchet up to 40Gbps.

It is important to note that these speeds would be provided to clusters of people, so each connection would only get a proportion of the total, depending on how many people in the area are online at the same time.

However, even the 1Gbps average speed-per-user that the team is aiming for would be an improvement over the 330Mbps maximum that is available to some of those using current fibre-to-the-home (FTTH) technology now.

The technique only provides its big boost over FTTH connections. It can improve speeds over copper too, but only over a short distance.

How it works

OOFDM's core technology is not in itself new — it's used in Wi-Fi, for example — but its application over optical networks is fairly novel.

Bangor lecturer Roger Giddings explained to ZDNet how the technique helped overcome the problem of dispersion — when pulses of light are running so fast over fibre that they interfere with each other.

"The current systems basically use optical pulses: they turn the lasers on and off," he said. "The trouble is, as you try and send the data faster and faster, these pulses merge into each other, so there's a limit to how fast you can use them.

"We break the signals down and send them at different frequencies. On each frequency or sub-carrier, the data stream is running slower so we don't have this problem of dispersion. This modulation technique is very spectrally efficient, so we can get a lot of data in a certain amount of bandwidth."

Giddings said the cost of the components used by the team was fairly low, which made the technology ideal for the access part of a network.

"People are looking at using this in the core networks, but [the operators of those core networks] are not too concerned about cost," he explained. "In our case, the idea is to make it as cheap as possible. By doing a lot of processing in the electronics, then we can use lower-cost optical components."

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