G.fast Could Use a Boost

Iain Morris
Prime Reading
Iain Morris, International Editor
10/13/2016



G.fast is under pressure to deliver. The copper-fortifying broadband technology, which many had expected to see in commercial deployment this year, is still at trial stage in several European markets as 2017 draws closer. Forthcoming "second-generation" chips and standards have been heralded as G.fast game-changers, but few European operators have announced big commitments to G.fast in the meantime. And in a troubling development for the G.fast community, European regulators are now said to harbor serious reservations about G.fast's ability to meet regional targets for high-speed broadband connectivity.

Among Europe's biggest fixed-line operators, BT Group plc (NYSE: BT; London: BTA) has quickly emerged as the main G.fast cheerleader. Using the technology, the UK operator aims to provide 300Mbit/s services to about 10 million UK premises by 2020. Having carried out G.fast trials this year, BT is now set to cover about 140,000 homes and businesses with the technology by March 2017. Others will be watching closely to see if it measures up. (See Long-Range, High-Speed Gfast Is Coming – BT)

Turning Copper Into Gold
Proponents of G.fast technology believe it can give fiber a run for its money.
Proponents of G.fast technology believe it can give fiber a run for its money.

The ambitious scheme would not have been possible had G.fast not already taken giant strides. The technology essentially works by extending the frequency range over which broadband signals travel. When it first appeared several years ago, it was designed to increase speeds over very short copper loops between homes and nearby distribution points, losing potency over longer distances. That meant rolling fiber out to those distribution points and equipping them with the necessary electronics. For an operator wanting a nationwide solution, it looked prohibitively expensive. (See G.fast: The Dawn of Gigabit Copper?.)


Want to know more about G.fast? Head to the Broadband World Forum
on October 18-20 in London.


Thanks to progress since then, BT is now confident that G.fast can be effective over much longer distances than was originally thought possible. Instead of introducing the technology at distribution points, BT plans to install it at street cabinets, usually around 300-350 meters from customer premises. Because BT maintains as many as 4 million distribution points, but just 90,000 street cabinets, the economics of a cabinet-based deployment clearly make sense.

The G.fast workout
To realize its vision, however, BT needs G.fast to hit the technology treadmill and become even fitter. Encouragingly, the G.fast industry is currently in the midst of epic workout that will "vastly change what G.fast looks like in the next 12 months," according to Eric Joyce, a systems engineer at broadband vendor Adtran Inc. (Nasdaq: ADTN), which has been heavily involved in BT's G.fast trials.

Even before an "Amendment 2" became fully standardized this year, the industry had started experimenting with a reduction in what is known as the SNR (for signal to noise ratio) margin to boost performance. With G.fast, the original recommendation was for an SNR margin of 6dB to provide a sufficient "buffer" against unwanted noise, as Joyce describes it. That margin has turned out to be surprisingly robust, though. By reducing the SNR margin to 3dB, and removing some of that buffer, Adtran has seen bandwidth improvements of between 50 Mbit/s and 100 Mbit/s, depending on loop length, with "negligible impact on stability."

Next page: Second generation



Second generation
Amendment 2 will usher in techniques such as higher bit loading and increasing the transit power to bring about further improvements. But the real prize is expected to come with Amendment 3 in 2017. Besides doubling the frequency range, from 106MHz to 212MHz, this iteration of the technology will also bolster vectoring, which cuts out crosstalk interference, and support the introduction of distribution point units featuring many more "ports" than today's models.

"At the moment we are stuck at 16-port vectoring," says Joyce. "That is fine for distribution points but with cabinets it's not really enough -- we want to be going into 48- and 96-port vectoring solutions for cabinet deployments."

The Road Ahead
Eric Joyce, a systems engineer at Adtran, thinks G.fast is set for a radical change over the next 12 months.
Eric Joyce, a systems engineer at Adtran, thinks G.fast is set for a radical change over the next 12 months.

While vendors seem confident they can support Amendment 2 using existing first-generation silicon, Amendment 3 will definitely require a new set of second-generation G.fast chips from Broadcom Corp. (Nasdaq: BRCM) and Sckipio Technologies , the market's two leading G.fast chip vendors. These second-generation chips seem likely to become available next year, but it remains unclear exactly when. "They are right around the corner in telco time," says Michael Weissman, Sckipio's vice president of marketing. "That doesn't mean next week but it doesn't mean in 2018, either."

BT will obviously be very keen to get delivery of technology based on those chips to pursue a more widespread cabinet-based deployment of G.fast technology. In the meantime, its current G.fast rollout plans, which involves connecting up to 140,000 premises by the end of March 2017, will rely on enhanced first-generation chips that support Amendment 2 of the G.fast standard, with new higher-power line drivers. For this stage of its access network upgrade, BT recently announced supplier deals with Huawei Technologies Co. Ltd. and Nokia Corp. (NYSE: NOK) for G.fast equipment. (See Huawei, Nokia Land Initial G.fast Deals at BT's Openreach.)


The rollout of gigabit broadband access networks is spreading. Find out what's happening where in our dedicated Gigabit Cities content channel here on Light Reading.


Broadband equipment vendors may also be keen to weigh up the differences between Broadcom and Sckipio once second-generation chips become available. Sckipio has long been regarded as the real G.fast pioneer, but there is a perception that Broadcom has been closing that gap during the past year.

Currently, the headline difference between the two silicon vendors is that Sckipio does not support fallback to VDSL, an older copper-based broadband technology, while Broadcom does. Sckipio insists this is not an issue, and that it supports "co-existence" with VDSL, but it also acknowledges that some operators have seen the lack of VDSL fallback as a potential problem. Nevertheless, it denies this has driven BT towards Huawei and Nokia, which are using Broadcom chips, and away from Adtran, which has worked closely with Sckipio during BT trials. (Both Adtran and Sckipio are still involved in those trials, it should be noted.)

With second-generation silicon, Broadcom has a dual-chip strategy, according to Adtran's Joyce, whereby a second chip handles vectoring needs when more than 24 ports are in use. Sckipio, by contrast, does not rely on this dedicated "vectoring engine" but can instead link chips together to provide so-called "distributed vectoring." There is a possibility that Broadcom's dual-chip approach drives up space requirements and costs. Joyce reckons this is unlikely because larger "pizza box" units would, in any case, be used to support 96-port deployments. But until physical chips materialize, Adtran cannot verify any of the differences between Broadcom and Sckipio.

Next page: Regulatory and competitive heat



Regulatory heat
There are other reasons G.fast chip vendors may be feeling the heat. Tony Shortall, a director at consulting group Telage and former advisor to the European Commission (EC), reckons the latest EC framework is driving service providers towards a narrower selection of high-speed technologies to meet future broadband targets.

That has not gone unnoticed in the broadband systems vendor community. "From a capacity point of view, cabinet-launched G.fast would probably fall short of requirements for the majority of the serving area," concurs Ronan Kelly, Adtran's chief technology officer for the EMEA and APAC regions. (See EC Rules to Narrow Tech Options for Telcos.)

Sckipio's Weissman expresses surprise at this development. "Sure, if cabinets are very far away then it's more challenging, but the reality is that G.fast is working in cabinets," he says. Regardless, if regulators are leaning on operators to use specific technologies, and broadband vendors such as Adtran are taking heed, the alternatives could naturally lose out.

Even before that framework was published, no European service providers of BT's size appeared to be giving serious consideration to a cabinet-based G.fast deployment. Deutsche Telekom AG (NYSE: DT) has been thinking about "bringing it to the basement of houses," according to Niek Jan van Damme, the managing director of the German operator's domestic business. France's Orange (NYSE: FTE) and Spain's Telefónica are focused on the deployment of fiber-to-the-home technology in their own domestic markets. (See DT's Jan van Damme Flexes Quads and Telefónica's Fiber Fix.)

Weighing up the Copper Options
Source: Nokia.
Source: Nokia.

Aside from BT, Swisscom AG (NYSE: SCM) has arguably been the most vocal proponent of G.fast among Europe's former state-owned telecom monopolies. But Swisscom is obviously a much smaller company than BT, operating in a market of just 3.4 million households. Moreover, while it is working on a widespread deployment of G.fast, covering about two thirds of the population, Swisscom appears to be using the technology in building basements and so-called fiber-to-the-street deployments, where units are installed in manholes about 100-200 meters away from customer premises. Speaking at Huawei's Ultra-Broadband Forum in Frankfurt last month, Daniel Burri, a senior project director with Swisscom, said the operator's plan was to launch services in November.

But when it comes to the broadband technology roadmap, uncertainty about G.fast development and regulatory aversion to cabinet-based G.fast are perhaps less important than competitive realities and service evolution.

No doubt, G.fast's bandwidth capability seems to be improving all the time. With another forthcoming tweak called dynamic time allocation, which Sckipio claims to have pioneered, overall bandwidth could be temporarily apportioned between the downlink and the uplink to suit the needs of a specific circumstance (such as heavy streaming of 4K video services). Over certain types of infrastructure and in ideal conditions, G.fast might ultimately be capable of supporting gigabit-speed connections. As Sckipio's Weissman points out, that is far more than any customer really needs. "The only application that requires 1 Gbit/s is a speed test," he says. (See Swisscom Boasts FTTX Milestone and Sckipio Pitches G.fast Boost as Telco Weapon Against Cable.)

True as that may be, incumbent telcos in some of western Europe's biggest markets are battling rivals investing in much higher-speed fiber connections nationally. France is home to four such players, including Orange, while in Spain both Orange and Vodafone Group plc (NYSE: VOD) are now competing against Telefónica in the ultra-fast broadband market. Whether or not G.fast meets all service requirements, operators do not want to be in the position of marketing a lower-speed service than other players.

As far as Orange is concerned, subscribers' thirst for bandwidth has become truly insatiable. "Customers still ask for more," said Yves Bellego, the director of technical strategy for Orange, at Huawei's Ultra-Fast Broadband Forum in Frankfurt. "That is why we need to continue investing and developing capabilities, even though we don't know exactly what for." (See Orange Forecasts 'Common' Gigabit by 2018.)

Gigabit Vision
Yves Bellego, Orange's director of technical strategy, says customer thirst for high-speed connectivity is insatiable.
Yves Bellego, Orange's director of technical strategy, says customer thirst for high-speed connectivity is insatiable.

Even in the best-case scenario, G.fast's days are numbered. Just a decade ago, BT exhibited zero interest in even extending fiber to street cabinets, commenting that 24 Mbit/s over ADSL2+, a legacy broadband technology, was sufficient for the foreseeable future. Yet circumstances soon made ADSL2+ look obsolete. The strategy, clearly, is to sweat those copper assets for as long as possible, taking advantage of the broadband innovations that Sckipio and others are developing. G.fast may be around for many years to come, in a variety of deployment scenarios, but the long-term future is one that is ultimately based on the ubiquity of fiber.

— Iain Morris, Circle me on Google+ Follow me on TwitterVisit my LinkedIn profile, News Editor, Light Reading

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