The International Telecommunication Union (ITU) yesterday gave initial approval to a data transmission standard capable of 500Mbps speeds in both directions over existing telephone wires. The new standard, G.fast, can be used on phone lines within 250 meters of a distribution point, benefiting fiber-to-the-node deployments. With telcos not having to build fiber on the proverbial "last mile" (or, really, 250 meters), this could bring fiber-like speeds to many more homes.

The ITU describes G.fast as providing speeds up to 1Gbps over existing phone lines, but telecom equipment vendor Huawei notes that "Reports of G.fast bandwidth exceeding 1 Gbit/s generally refer to the sum of the upstream and downstream bandwidths," or 500Mbps in each direction. And although G.fast is usable within 250 meters of a node, the highest speeds aren't likely to be available on the top end of that range.

"G.fast is intended for typical applications of 500 megabits per second (Mbps) speeds at 100 meters or less," Alcatel-Lucent said in July of this year. "In recent demonstrations and under laboratory conditions, Alcatel-Lucent achieved 1.3 Gbps over 70 meters, making G.fast a promising option for service providers to complement their fiber deployments."

Alcatel-Lucent's 1.3Gbps speed was achieved on the downstream path alone, according to Informa telecom analyst Tony Brown. That won't be typical, but actual speeds should be a big improvement for many people. "[O]ne big advantage of G.Fast is that it allows operators to offer symmetrical speeds—so with 1Gbps of bandwidth an operator could offer 500Mbps downstream AND upstream to achieve—something other copper acceleration technologies cannot do," Brown wrote.

"G.fast, within the fibre to the distribution point (FTTdp) architecture, combines the best aspects of fibre and ADSL2," the ITU said. "Consumers will have an over-the-counter solution, self-installed without a technician’s assistance, but equipped to support bandwidth-intensive services such as Ultra-HD ‘4K’ or ‘8K’ streaming and IPTV, advanced cloud-based storage, and communication via HD video."

To follow on yesterday's vote, "Chip manufacturers will now scale-up G.fast chip design and testing efforts, feeding results of this work into ITU-T Study Group 15 in the interests of finalizing G.fast as early as April 2014," the ITU said. The ITU says it will specify methods to prevent interference with FM radio and other broadcast services.

G.fast operates on higher frequencies than DSL. "VDSL2 currently works on 17 MHz or 30 MHz, while G.fast will work on 106 MHz or even 212 MHz," Huawei says. The company notes that higher frequencies do result in "shorter transmission distances, higher costs, and greater power consumption."

Like VDSL2, "G.fast performance is affected by crosstalk between lines." But because of the higher frequency, crosstalk will cause bigger problems for G.fast than VDSL2. "Without the vectoring noise cancellation process, G.fast rates are severely degraded," Huawei said. "Therefore, G.fast must use a more advanced vectoring technology to cancel crosstalk between lines."

G.fast could be a boon to Internet services such as AT&T's U-verse, which typically brings fiber to the node (except when AT&T builds all the way to homes). AT&T says its nodes are typically 2,000 to 3,000 feet from homes, so more buildout would still be required to reach 500Mbps bandwidth.

The ITU said G.fast "is designed to coexist with VDSL2, enabling service providers to play to the strengths of each standard in different environments; switching customers between G.fast and VDSL2 in line with dynamic business models. The standard will complement FTTH [fiber-to-the-home] strategies, serving the many scenarios where G.fast is more cost-efficient than FTTH."

Huawei has been working on developing G.fast since 2010 and says it had a prototype delivering gigabit (combined upstream and downstream) speeds over 100 meters of copper by 2011. Huawei announced two months ago that BT is trialing its G.fast technology. Alcatel-Lucent and Telekom Austria Group announced a similar trial in July of this year.

The ITU's G.fast group has seen participation "from a large number of operators, chipset manufacturers, and equipment suppliers," Huawei said. D-Link says that it's "working today with selective Operators to achieve FTTdp deployment and trials" using G.fast.

A new company, called Sckipio, was founded last year to build G.fast chips, on the belief that it will become a booming business because it's more cost-effective than fiber-to-the-home. "[A]s fiber nodes move closer to the home, it is becoming obvious the cost to deploy fiber for the last 250 meters is prohibitive," Sckipio says. "According to some accounts, over 80 percent of the cost to deploy fiber is based upon this last segment. This is due to the high cost of trenching and installation for fiber optics. In fact, most fiber to the home deployments will take longer than 10 years to break even."

Sckipio Marketing VP Michael Weissman told The Register that field trials should be followed by live deployments in late 2014 or 2015. Other estimates have deployments expected for 2016.