Broadband services based on the emerging G.fast standard will be used by nearly 30 million homes and businesses worldwide in 2021, according to new research from analyst firm Ovum.

Commissioned by the UK's BT Group plc (NYSE: BT; London: BTA) and Australia's NBN Co Ltd. , two of G.fast's strongest supporters, the report argues that take-up of G.fast will rise sharply following commercial launch next year to reach about 29 million subscribers in 2021, when it will account for about 3% of the global fixed broadband market.

G.fast technology is designed to boost the connection speeds available over copper lines by extending the frequency range over which broadband signals travel. (See G.fast Could Use a Boost.)

Operators such as BT see it as a way of prolonging the lifetime of their copper assets, but some critics have pointed out that it loses effectiveness over longer distances and that homes and businesses will sooner or later need hooking up to fiber.

Both BT and NBN, however, believe technology improvements over the next few months will allow them to use G.fast over much longer distances than was originally thought possible.

Instead of deploying G.fast at distribution points near customer premises, as developers originally intended, BT plans to introduce it at street cabinets, typically 300-350 meters from homes and businesses. Taking this approach, the operator aims to connect 10 million premises to services of at least 300 Mbit/s by 2020. (See Long-Range, High-Speed Gfast Is Coming – BT.)

NBN has also previously flagged interest in using G.fast over longer distances if technology challenges can be overcome. (See NBN Looks to G.Fast to Reduce Fiber 'Hassle'.)

The wholesale-only operator recently announced plans for a fiber-to-the-curb deployment covering about 700,000 Australian premises. According to a joint press release issued by BT, NBN and Ovum Ltd. , that network could provide an "ideal platform" for the future rollout of both G.fast and XG.FAST, an even higher-speed technology that NBN has been testing.

Ovum expects G.fast to garner about 330,000 customers next year and then quickly take off, attracting as many as 11.5 million subscribers in 2021 alone.

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.

Despite interest in Australia and other parts of the world, the market research company reckons most G.fast interest will come from Europe, where the technology figures to at least some extent in the plans of Deutsche Telekom AG (NYSE: DT) (Germany), Proximus (Belgium), Swisscom AG (NYSE: SCM) (Switzerland) and Telekom Austria AG (NYSE: TKA; Vienna: TKA) (Austria).

"About 11% of broadband services in Western Europe may be delivered via G.fast within five years, with a number of major markets already including the technology in their upgrade plans," say the report authors.

Much is riding on the experience of BT, which has already carried out several G.fast trials and now aims to connect 140,000 premises to the technology by March during the next phase of its project. (See Huawei, Nokia Land Initial G.fast Deals at BT's Openreach.)

If BT can demonstrate that G.fast works effectively over longer distances in a commercial setting, it will deliver a huge boost to G.fast's prospects.

Not everyone is convinced by the technology. Indeed, European regulatory authorities are said to have doubts that cabinet-based G.fast will be up to the task of meeting regional broadband targets over the next few years. (See EC Rules to Narrow Tech Options for Telcos.)

That could still leave a major role for G.fast from distribution points, although such deployments could prove far costlier than cabinet-based ones over large areas: Operators would need to extend fiber networks to those distribution points and equip them with the necessary electronics.

With an eye on the economics of G.fast rollout, BT has indicated that it maintains about 4 million distribution points across the UK but just 90,000 street cabinets.

Other service providers could be dissuaded from investing in G.fast by competitive circumstances. In each of the markets of France, Spain and Portugal, for example, several operators are now rolling out fiber-based networks. Any G.fast investor would therefore appear to be a relative laggard in the high-speed broadband race.

— Iain Morris, , News Editor, Light Reading