G.fast broadband standard approved and on the market
Compliant chips and equipment in the hands of service providers
Geneva, 05 December 2014 – ITU members today achieved final
approval of G.fast, the new ITU broadband standard designed to deliver access
speeds of up to 1Gbit/s over existing telephone wires. The standard answers to
service providers’ need for a complement to fibre to the home (FTTH)
technologies in scenarios where G.fast proves the more cost-efficient strategy.
G.fast, within the fibre to the distribution point (FTTdp) architecture,
combines the best aspects of fibre and DSL. Within 400 metres of a distribution
point, G.fast provides fibre-like speeds matched with the customer
self-installation of DSL, resulting in cost-savings for service providers and
improved customer experience.
Dr Hamadoun I. Touré, Secretary-General, ITU: “The time from G.fast’s
approval to its implementation looks set to be the fastest of any access
technology in recent memory. A range of vendors has begun shipping G.fast
silicon and equipment, and service providers’ lab and field trials are well
Today’s approval of the physical-layer protocol aspects of G.fast – defined
Recommendation ITU-T G.9701 “Fast Access to Subscriber Terminals (FAST) -
Physical layer specification” – follows the approval in April this year of
G.9700, a companion text specifying methods to ensure that G.fast equipment
will not interfere with broadcast services such as FM radio.
G.fast will increase the feasibility of implementing bandwidth-intensive
services such as Ultra-HD ‘4K’ or ‘8K’ streaming and next-generation IPTV,
advanced cloud-based storage, and communication via HD video. The standard will
comfortably serve the broadband access needs of small-to-medium enterprises,
with other envisioned applications including backhaul for small wireless cell
sites and WiFi hotspots.
G.fast’s ‘zero touch’ operations, administration and management will increase
the speed of new-service rollouts. This remote management of user connections
will simplify migrations to G.fast, and the standard’s coexistence with VDSL2
offers service providers the agility required to switch customers between G.fast
and VDSL2 as business operations demand.
The development of G.fast has been coordinated with the Broadband Forum’s
FTTdp system architecture project. ITU and the Broadband Forum have been working
in collaboration to ensure that G.fast solutions can be quickly placed into
“The Broadband Forum is working closely with the ITU to ensure compliance
with the G.fast standard and certify chipsets and equipment,” said Robin Mersh,
CEO of the Broadband Forum. “We have already set our first plugfest for
The Broadband Forum has begun developing a test suite and certification
programme for G.fast systems. The test suite will provide for interoperability,
functional and performance testing. A beta-trial of the certification programme
is planned for mid-2015, and certified G.fast implementations are expected to
appear on the market before the end of 2015.
Study Group 15 has initiated work on an extended set of features for G.fast,
targeting performance enhancements which will include additions to its range of
low-power states. These features are likely to be available for incorporation
into service providers’ G.fast deployments as early as 3 July 2015.
Note to Technical Editors in annex for a G.fast
feature list and standards timeline.
For more information, please contact:
Head, ITU Corporate Communications
Note to Technical Editors: G.fast features and timeline
Answering to business strategy requirements
G.fast delivers high-speed broadband access over copper telephone wires,
operating on lines up to 400-metres long
- G.fast enables service providers to capitalize on existing
infrastructure, achieving fibre-like speeds without rewiring urban areas already
equipped with copper.
- Despite G.fast’s leap forward in sophistication over DSL access
technology, it maintains the installation simplicity of ADSL. G.fast customer
equipment, in line with that of ADSL, will arrive in a box containing only a
G.fast-compliant modem and dongles to protect telephones.
‘Zero touch’ operations, administration and management
- Upgrading a customer to G.fast does not require the deployment
of a technician to a customer premises or capable distribution point to effect
- This remote management of user connections will simplify
migrations to G.fast, and the standard’s coexistence with VDSL2 offers service
providers the ability to switch customers between the two standards as business
Coexistence with xDSL
- G.fast’s spectrum compatibility with VDSL2 enables service
providers to play to the strengths of each standard in different environments.
Complements fibre to the home (FTTH) strategies
- In ‘greenfield’ scenarios, service providers will opt for FTTH.
- In ‘brownfield’ scenarios – for example, an urban environment
with an abundance of copper telephone wiring – G.fast will be more cost-efficient
The deployment advantages of the FTTdp architecture
- A key benefit of FTTdp is that the distribution point unit
(DPU) typically serves 1-20 lines, making it compact enough to place on a pole,
in a small underground enclosure or in a small pedestal.
Answering to service provider requirements
Low power, cost and complexity
‘Zero touch’ operations, administration and management
Support for both TR-156 and TR-167 Broadband Forum architectures
Service rate performance targets
- 500-1000 Mb/s for FTTB deployments at less than 100m, straight
- 500 Mb/s at 100m
- 200 Mb/s at 200m
- 150 Mb/s at 250m
- Aggregate service rates of equal to or more than 500 Mb/s with
start frequency of 23 MHz and VHF and DAB bands notches
Capitalizes on the advantages of FTTH and DSL
- FTTH bit-rates, with the customer self-installation of DSL
- Complements FTTH, and enhances fibre to the cabinet (FTTC)
Coexistence with xDSL
- Spectrum compatibility: G.fast operates at higher frequencies
than VDSL2 (start frequency: 2.2, 8.5, 17.664 or 30 MHz)
Reverse power feeding (RPF) for the DPU from the customer premises
- Persistent Management Agent (PMA) acts as management proxy in
the event of the DPU losing power
Control of upstream/downstream asymmetry ratio
- Flexible up/down data rate allocation
- Mandatory: 90/10 and 50/50
- Optional: from 50/50 to 10/90
Operates up to 106 MHz
- Maximum power spectral density (PSD) much lower than in VDSL2
- Configure PSD mask (e.g. start above VDSL2)
- Configure RFI/IAB notches (e.g. notch FM band)
Uses Time Division Duplexing (TDD)
- Can easily vary upstream/downstream asymmetry ratio
- Easily supports low-power states
- Discontinuous mode allows trade-off between power consumption
and user data throughput
- Point-to-point distribution
Mandatory support for vectoring
- Far-end crosstalk (FEXT) cancellation
PHY layer retransmission
- Mitigating the effects of impulsive noise while maintaining low
Supports Fast Rate Adaptation (FRA)
- Quickly adapts to changing channel or noise conditions
Timeline: Standardization, testing and certification of G.fast systems
At request of the Broadband Forum, ITU’s Standardization Sector (ITU-T)
issued a call for papers on the transceiver aspects of FTTdp, resulting in the
initiation of the G.fast project.
4 April 2014:
Approval of Recommendation ITU-T G.9700 “Fast access to subscriber terminals
(FAST) - Power spectral density specification”, a specification to ensure that
G.fast systems will not interfere with broadcast services such as FM radio.
5 December 2014:
Approval of Recommendation ITU-T G.9701 “Fast access to subscriber terminals
(FAST) - Physical layer specification”.
Expected approval of G.9701 Amendment 1, providing an extended set of
features for G.fast, which will include performance enhancements such as
additions to its range of low-power states.
Testing and Certification
The Broadband Forum’s operator survey found strong support for a G.fast
certification programme available to the industry before deployments take off,
with interoperability as a top priority.
The Broadband Forum has initiated the development of a G.fast certification
test plan (ID-337) and programme, and has chosen the University of New Hampshire
InterOperability Laboratory as its Certification Test Lab.
Beta-trial of the G.fast certification programme planned for mid-2015
- first plugfest planned for the end of January 2015
The G.fast certification test plan tests one DPU/CPE combination for
- Functional, performance, stability, throughput
The University of New Hampshire InterOperability Laboratory will certify
G.fast DPUs and CPEs independently
- Based on criteria defined by the Broadband Forum, e.g., how
many counterparts to interoperate with, etc.
Certified G.fast implementations expected before the end of 2015