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BT researchers show how G.fast technology could hasten arrival of 5G

15 February 2016


In an experiment that’s believed to be a world first, BT has demonstrated how G.fast broadband technology can be used as a viable alternative to fibre optic mobile backhaul.

The company successfully used G.fast technology to deliver a ‘Cloud Radio Access Network’ (C-RAN) cellular network service over copper,

C-RAN is a new network architecture that can connect cellular base-stations to mobile operators’ core networks.

A traditional approach to C-RAN requires a dedicated fibre link to link transmitters at the top of a cell tower to complex signal-processing equipment deeper in the network. This can often involve intricate and costly engineering work if no fibre is present in the ground to carry the signal.

However, researchers at BT’s Adastral Park Labs in Ipswich, in collaboration with US-based semiconductor manufacturer Cavium, Inc. have showed that they can use G.fast technology to deliver cellular data over copper lines at speeds of 150 – 200Mbps.

Cost cutting

This removes the need for mobile operators to invest in costly, high capacity backhaul links over dedicated fibre connections.

By providing a far more economic ‘fronthaul’ connection between the base station and the mobile operators’ core network, a C-RAN service delivered over G.fast would significantly lower the cost of deployment for mobile operators building out 4G networks today and 5G architectures in the future.

Major advance

Dr Tim Whitley, managing director for Research & Innovation at BT said: “Using G.fast to deliver a cellular network is an exciting breakthrough for C-RAN and yet another world first for our team of researchers at Adastral Park.”

“These technologies will play a key role in 4G networks and will be fundamental to 5G architectures. The trials are another step towards a fixed and mobile network which will support customers’ increasing demands for data.”

Raj Singh, General Manager of Cavium’s Wireless Broadband Group, said: “We are very excited to collaborate with BT, using Cavium OCTEON Fusion-M™ basestation and ThunderX server processor technology to validate this new class of Radio Access application with G.fast technology.”

Successful testing

He added: “Our successful testing has laid the groundwork for enabling LTE deployments today and 5G deployments in the future using G.fast.”

As well as exploring the role that G.fast may play in helping operators to roll out their 4G/5G networks, Openreach, BT’s local access network division, is also trialling G.fast as an access technology in Huntingdon and Gosforth, alongside a further BT technical trial in Swansea.

G.fast is significant because by building on current Fibre-to-the-Cabinet (FTTC) technology, it allows Openreach to bring ultrafast speeds to a wide footprint far more rapidly and without the expense and disruption of running fibre directly into a home or business.

If the trials prove successful – and if UK regulation continues to encourage investment – the company has pledged to provide ultrafast speeds to ten million homes by 2020 and to the majority of the UK within a decade.