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BT’s G.fast gigabit broadband over copper trials achieve 700Mbps download speeds

BT trials of next-gen G.fast technology have proven that triple digit download speeds are possible over its current superfast broadband connections. 

The G.fast trials demonstrate that BT’s FTTC (Fibre to the Cabinet) connections can deliver a service that’s nearly ten times faster than the current 80Mbps and 20Mbps top download and upload speeds possible. The technology can in theory deliver 1Gbps (1,000Mbps) download speeds over FTTC lines and BT has been extensively testing it out. 

The results of this initial trial of Phase 1 G.fast technology show that 80 per cent of people able to get FTTC now should get download and upload speeds of around 700Mbps and 200Mbps, if G.fast was rolled out tomorrow. 

Copper bottomed plans: An Openreach engineer prepares to install several meters of fibre optic cable
Copper bottomed plans: An Openreach engineer prepares to install several meters of fibre optic cable

This is great news for customers worried that FTTC wouldn’t given them download speeds any faster than 80Mbps. 

FTTC uses a mix of fibre optic cable and old telephone copper connections to deliver superfast broadband services to homes and businesses. 

While BT’s FTTC lines provide much faster speeds than old ADSL broadband, the actual speeds you’ll get depend greatly on the distance between your house and the street cabinet – the further away you are the slower your broadband speeds will be

Over distances of over 1.6 kilometers, there’s little difference beten FTTC and ADSL in terms of the speeds you’ll get. BT hasn’t said what the effective range of G.fast is, as it’s only experimented wirth 19 and 66 meter lines so far. 

This rule of thumb still applies with G.fast, but the headline speeds are greatly increased. With G.fast, BT has been able to deliver download and upload speeds of 786Mbps and 231Mbps over an FTTC line where the copper line is 19 meters long using G.fast technology. 

BT also tested out G.fast with a 66 meter long copper line and found that the download speed fell to 696Mbps while top uploads weighed in at 200Mbps. 

Copper Line Length Download Uploads
Short (19m) 786Mbps 231Mbps
Long (66m) 696Mbps 200Mbps

A separate trial of the same technology by Alcatel-Lucent revealed that over 100 meters of copper, speeds decreased even further. 

The reason BT picked 66 meters for its trial is that 80 per cent of final copper links on its network right now are 66 meters or shorter. In other words, if you can get FTTC from BT right now, there’s a good chance you’d be able to get the sort of speeds depicted above. 

G.fast: Great for the cities, not so great for the sticks

For customers in some areas, particularly rural locations, G.fast won’t change much as the so-called copper ‘last mile’ is significantly longer. 

BT says that it’s investing in FTTdp (Fibre to the Distribution Point), which could mitigate this distance difference.  

FTTdp is an extension of FTTC, in that it rolls fibre out to telephone poles and junction boxes instead of street cabinets. As these are typically much closer to homes than cabinets, this closes the last mile distance, meaning headline speeds should increase. 

Dr Tim Whitley, MD of Research and Innovation, BT Group said: “We see G.fast as a very promising technology with significant potential – that’s why we’re putting some of our best minds on the case to assess it fully in a purpose-built facility.
       
“BT has a long history of pushing the boundaries in telecommunications, from the earliest days of the electric telegraph to today’s global fibre networks, and it’s crucial that we stay ahead of the curve for the benefit of our customers and shareholders.”

In some cases the distances would make building FTTdp out to remote areas uneconomical. Building full FTTP (Fibre to the Premises) lines might make more sense in some areas.  

As for when G.fast and FTTdp might roll out, there’s no firm dates yet. It’s still early days for the technology, which BT describes as “immature”. While the ITU (International Telecomunication Union) has speculated that we could see G.fast-based products arriving in 2015, it’s arrival in the UK will greatly depend on the findings of BT’s research teams. 

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