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G.fast: The Dawn of Gigabit Copper?

Iain Morris
UBB Forum News
Iain Morris
9/1/2014
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Supercharging copper lines using vectoring technology should boost broadband connection speeds up to 100 Mbit/s, but that's unlikely to be enough for the deluge of high-definition video and other advanced services that will soon be heading to a neighborhood near you. (See Vectoring: Some Va-Va-Voom for VDSL.)

For that, the long-held assumption was that operators would have to bite the investment bullet and roll their fiber networks out to customers' homes. Then another copper-fortifying technology called G.fast came along.

Still very much at the trial stage, G.fast works largely by extending the range of frequencies over which broadband signals travel. According to Chinese equipment maker Huawei Technologies Co. Ltd. , VDSL2 -- a very high-speed copper-based technology -- uses either 17MHz or 30MHz frequencies, but G.fast will work on 106MHz or even 212MHz. By fattening up the frequency pipe, operators can pump more bandwidth down the line. During tests carried out by Huawei as far back as 2011, G.fast reached speeds of 1 Gbit/s -- ten times as much as vectoring-enabled VDSL2 can offer in the choicest conditions -- though real-world speeds are likely to peak below that headline speed.

Yet even more so than vectoring (which is also used with G.fast to reduce interference), G.fast is at its most effective over very short distances. Huawei's trial was over a loop length of just 100 meters. As acknowledged by Huawei rival Alcatel-Lucent (NYSE: ALU), the high frequencies used with G.fast cause signal strength to deteriorate badly over distances of several hundred meters. Indeed, the French equipment maker insists that vectoring-enabled VDSL2 is preferable to G.fast for longer loops.

Due to this problem of attenuation, G.fast is intended for use in broadband deployments where fiber has been deployed as far as the local distribution point, meaning copper is retained only for the last 100 or so meters to the customer's premises. No doubt, this is far less costly than rolling out fiber-to-the-home (FTTH). According to Sckipio Corp., an Israeli semiconductor company focused on G.fast development, if the cost of deploying FTTH is currently about US$1,500 per home, that of building fiber to the distribution point and using G.fast over "the last 200 meters" is just $300.

But this still means dipping into the coffers, and others have expressed concern about the overall investments needed for G.fast. Point Topic, a market-research company, said "the extra cost will be significant" in a white paper published last year, while noting that it was "not yet clear how much contribution G.fast will be making by 2020."

Clearly, progress has been halting. The industry reached agreement on the G.fast standard in December 2013, and the International Telecommunications Union was expected to ratify it in April, but that now seems unlikely to happen until the end of the year. Alcatel-Lucent expects field trials to follow in 2015, with "volume deployment-ready G.fast products" appearing by 2016. No wonder Point Topic doubts the impact G.fast will have before 2020.

Nevertheless, some prominent operators have the technology in their sights. Swisscom AG (NYSE: SCM) is working with Huawei, its main fiber-to-the-street (FTTS) partner, on G.fast, while Telekom Austria AG (NYSE: TKA; Vienna: TKA) has been conducting trials with Alcatel-Lucent, and last year claimed to have recorded speeds of 800 Mbit/s over loop lengths of 100 meters. In addition, Germany's Deutsche Telekom AG (NYSE: DT) was reported in February to be planning its own G.fast trials later this year. (See Swisscom Boasts FTTX Milestone and Telekom Austria Tests G.fast.)

Regardless of standardization and equipment availability, the strategy that operators pursue will largely determine how soon commercial G.fast services appear. Presenting G.fast as a kind of stepping-stone to FTTH, Alcatel-Lucent unsurprisingly urges operators to push fiber out to local distribution points immediately, instead of waiting for G.fast equipment to materialize. Yet it's true that investments required for this move could support subsequent planning for an all-fiber future. With vectoring merely a stopgap, and the cable community planning its own move to the bandwidth-boosting DOCSIS 3.1 standard, the pressure to act is mounting. (See DOCSIS 3.1: What's Next?)

Iain Morris, Site Editor, Ultra-Broadband

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kq4ym
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kq4ym,
User Rank: Light Sabre
9/18/2014 | 2:22:54 PM
Re: What will be the tipping point for fiber deployments?
If copper lines can be used for the last 100 meters of the installation that would seem to be a good deal even if there's some limiting on what is really a pretty fine speed. But balancing the cost vs fiber all the way may be the real deal maker or breaker. 
brooks7
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brooks7,
User Rank: Light Sabre
9/5/2014 | 9:10:41 AM
Re: What will be the tipping point for fiber deployments?
mhhf1ve,

I can tell you that both Verizon and NTT did FTTP for the same reason - to stop customer loss.  People forget that NTT was getting crushed in DSL.  Verizon was bleeding customers at a rapid rate to cable.

When we did our FTTP business cases for carriers, reducing a large customer loss was the most important element of the business plan.  Ability to lower construction costs was number 2.  Both NTT and Verizon did huge amounts of work on that subject (something we never talk about).  This second factor is why Verizon worked on aerial plant first.

seven
mhhf1ve
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mhhf1ve,
User Rank: Light Sabre
9/4/2014 | 7:47:29 PM
What will be the tipping point for fiber deployments?
These copper stopgaps sound nice, but they've got various practical problems -- and it just seems cleaner to start fresh with fiber, right? So... what is the tipping point that will make telcos dig into their investment pockets and start deploying large scale fiber networks? 

Are telcos waiting for the FCC to ensure that they'll be able to reap every last cent out of any fiber investment? Or is it really going to be a flood of consumer demand that ultimately pushes them to do it?
brooks7
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brooks7,
User Rank: Light Sabre
9/3/2014 | 10:42:14 AM
Re: Take the lead from Frankie
infostack,

Verizon has been installing FiOS where it can in NYC.  It started doing so back in 06 or so.  Many building owners have deals with Cablevision and have locked FiOS out of the buildings through conduit ownership.  You can not assume that you can run G.Fast out of a basement through the existing copper.  That has been the problem with VDSL2 based units inside Verizon.  Essentially you end up with a mess for optimizing configurations.  What they eventually did is reformat ONTs as indoor units and locating them in each apartment.

seven

 
Infostack
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Infostack,
User Rank: Moderator
9/3/2014 | 10:36:33 AM
Take the lead from Frankie

As Sinatra said if you can make it in NYC you can make it anywhere.

Seems like G-fast would be perfect for this market given density, availability of fiber laterals and issues with landlords and street permitting.

I see coax cables strung up the outside of brownstones (legally?) everywhere.  But MaBell has the wire in the building!

Hello Verizon?  Can you hear me now?
brooks7
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brooks7,
User Rank: Light Sabre
9/3/2014 | 12:22:31 AM
Re: Reverse powering - how well will that work?
jayja,

Reverse Powering works fine.  

It is just like power being carried from Central Offices to power phones.  So, its safe and fine at relatively low power delivery.  

There is nothing per se that prevents you from putting power on the end at the home.  There is no point to it and it can be a problem on a powered (aka wet) line.  G,Fast will disconnect the line from the CO and the line will be unpowered (aka dry) line.  

Power management will be rudimentary since you won't a priori be able to design system to match to the absolute number of subscribers.

Regulators are pretty much okay with it on FiOS.

seven

 
jayja
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jayja,
User Rank: Light Beer
9/2/2014 | 10:02:23 PM
Reverse powering - how well will that work?
I've never gotten a good answer to this question.  How effectively will installed telephony drop cable carry electrical current back to the ONU?  How safe is it?  Aren't there things installed in the PSTN outside plant to prevent electricity from the subscriber carrying back to the network?  How will powering (and costs) be split among multiple subscribers off a single ONU?  What will the regulators say?
brooks7
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brooks7,
User Rank: Light Sabre
9/2/2014 | 1:15:27 PM
Re: If the copper is quality...
 

Let's remember that to get these very high speeds that you are at 100M or less of copper loop.  In high density housing, this means that you would have a DSLAM on every floor and those DSLAMs would be fiber fed.  For Single Family homes that means that they need to run fiber into the neighborhood at the distribution boxes.

They are trying to fix the powering by back powering from the home, but that is going to be a challenge as well (How many pairs can be cut/out/unused before the DSLAM needs local AC power).  Imagine not having DSL and being required to power the DSLAM.  So, it seems likely that we will have thousands of power drops to do this.  If we are moving to VoIP as a replacement for POTS, it might mean that these small DSLAMs now have battery backup requirements.  

So, what you are saving is the drop cable installation.  The trade off on that is not the same even 2500' copper (Uverse) or 12Kft copper (standard DSL deployment).  You still have to dig up streets to do a high speed G,Fast installation.  Given all that, you still have problems with loops that are too long or of poor quality.

seven
KBode
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KBode,
User Rank: Light Sabre
9/2/2014 | 12:32:35 PM
Re: If the copper is quality...
Problem being I've been seeing these kinds of advancements in the labs for much of the last decade, yet you've got tens of millions of DSL customers still lucky to get 3 Mbps from their local phone company. You never seem to see these ultra-fast copper solutions get any real traction because so few telcos are seriously spending money on upgrades (no competition, no pressure).

And yes, even if the tech is deployed, it depends on copper quality and usually an extra pair (or more) being available...
iainmorris
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iainmorris,
User Rank: Blogger
9/2/2014 | 1:37:35 AM
Deutsche Telekom and G.fast
It will be interesting to see what Deutsche Telekom does in this area and how quickly it moves, given that it's already made a commitment to vectoring and has continued to express concern about the investments needed for FTTH.
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