BT has unveiled the results of new field trials that show 'ultrafast' broadband - with combined downstream and upstream speeds of up to one Gigabit per second (1000 Mbps) - can be delivered via a mix of fibre and copper. Previously it was thought such speeds would require a dedicated business line or a fibre optic cable to be laid all the way from a telephone exchange to a premises, a relatively expensive, disruptive and time consuming process.

BT, which is due to open a new ultrafast broadband lab at its Adastral Park R&D centre in Ipswich, says it is greatly encouraged by the potential of Fibre To The Distribution Point (FTTdp) 'G.FAST' technology - where fibre is instead rolled out to telephone poles or junction (footway) boxes located close to homes and businesses.

During the G.FAST trials, downstream speeds of around 800Mbps were achieved over a 19m length of copper, combined with upstream speeds of more than 200Mbps. Impressive speeds of around 700/200Mbps were also achieved over longer lines of 66m, a distance that encompasses around 80 per cent of such connections. As well as delivering ultrafast speeds, the technology also offers the flexibility to tailor the allocation of the total 1Gbps speed according to a users’ needs.

BT's fibre network - which is being rolled out by its local access network business Openreach – currently passes more than 20 million UK premises using a mix of Fibre to the Premises (FTTP) and Fibre to the Cabinet technology (FTTC).

FTTC, the more common of the two technologies, currently delivers downstream speeds of up to 80Mbps, giving residential customers plenty of capacity to enjoy the online world today. Openreach has doubled the speed of this product in recent years and BT believes potential enhancements such as vectoring can improve speeds further.

FTTP, where the fibre runs all the way to the premises, is capable of significantly faster speeds than FTTC but is considerably more expensive to deploy.

With FTTdp, the fibre is closer to the premises than with FTTC, meaning the copper link is much shorter. G.FAST technology is then used to maximise data capacity over the copper and uses much higher frequencies, plus advanced 'crosstalk' cancellation techniques, to make ultrafast speeds possible.

FTTdp is potentially a more cost effective and simpler solution than both FTTP and dedicated business lines such as Ethernet. This is because less fibre and civil engineering is required.

Over the coming months BT researchers will use the new laboratory to study the full technical capabilities of G.FAST hardware designed by system vendors such as Adtran, Alcatel Lucent and Huawei.

Whilst commercial G.FAST equipment is still immature, there have been determined efforts by the ITU to accelerate the standardisation of the technology, with the approval of the G.9701 recommendation expected in December.