ITU standards experts have achieved another leap forward in broadband access over telephone wires and coaxial cable with MGfast, a new access technology capable of transmission at an aggregate bit rate up to 8 Gbit/s if in Full Duplex (FDX) mode, and up to 4 Gbit/s if in Time Division Duplexing (TDD) mode.
The MGfast standard, ITU G.9711, not only promises higher bit rates than ever, but also ultra-low latency for highly interactive applications, the capability to optimize Quality of Service (QoS) in line with the needs of different applications, and point-to-multipoint operation enabling better coverage within the premises.
This work is led by the Q4/15 working group (Broadband access over metallic conductors) of ITU-T Study Group 15 (Transport, access and home). See the graphic below for an overview of the bit rate and reach capabilities of ITU-standardized access solutions from the Q4/15 working group, and more on key application features of MGfast in an MGfast technical flyer.
Fibre to the most economical point
MGfast is the successor to Gfast (ITU G.9701), an ITU standard released in 2014. Both technologies intend to meet service providers' need for a complement to the Fibre to the Home technologies in scenarios where Gfast or MGfast prove the more cost-efficient strategy.
Within the Broadband Forum's Fibre to the Extension Point (FTTep) architecture - bringing fibre very close to the home - gigabit-class service is possible with Gfast and MGfast with significant cost-savings for service providers and convenience attractive to their customers.
With no need for technicians to replace existing wiring, and customers able to install equipment themselves, Gfast and MGfast combine the best aspects of fibre and DSL to keep pace with growing demand for bandwidth as economically as possible.
'Zero touch' operations, administration and management increase the speed of new-service rollouts, and coexistence with VDSL2 offers service providers the agility required to switch customers between VDSL2, Gfast and MGfast as business operations demand.
MGfast is Multi-Gigabit fast
MGfast achieves aggregate bit rates up to 4 Gbit/s over telephone wires using TDD, doubling the rates achievable with Gfast. Support for FDX transmission - best suited to coaxial cable and CAT5-type wiring - enables MGfast to achieve aggregate bit rates up to 8 Gbit/s. And by enabling full-speed transmission simultaneously in both directions, FDX transmission is a compelling means to provide symmetric bit rate services.
The higher bit rates of MGfast are enabled by expanding the frequency band to 424 MHz from Gfast's 212 MHz, and introducing advanced forward error correction based on Low-Density Parity-Check coded modulation. A future version of MGfast may expand the frequency band to 848 MHz for yet higher bit rates.
Alongside the higher throughput necessary to support Ultra-High Definition '4K' and '8K' video, improvements including proactive retransmission enable MGfast to achieve the ultra-low latency necessary to highly interactive services such as cloud-based Virtual Reality and online gaming. Latency, jitter, and error protection can be better tuned to the needs of each application, thanks to MGfast's support of up to four simultaneous QoS classes.
More efficient, more dynamic
While Gfast and xDSL support direct communication to just one access point in premises, MGfast's Point-to-Multipoint operation enables direct wired communication to multiple devices - to the benefit of homes and businesses needing multiple Wi-Fi access points to cover the entire premises.
MGfast conserves electrical power and processing capacity by transmitting data only at the times and frequencies necessary to meet the customer's traffic demand. This Discontinuous Time and Frequency Operation reduces both crosstalk and vectoring complexity. MGfast also retains the Dynamic Time Assignment functionality of Gfast, enabling transmission capacity to be allocated to the upstream or downstream direction right at the time the customer needs it.
Reverse Power Feeding from the customer premises to the distribution point is another feature that MGfast shares with Gfast.
Certification verifies interoperability
The development of Gfast and MGfast is closely coordinated with the Broadband Forum's FTTep system architecture project.
The associated certification programme run by the Broadband Forum and the University of New Hampshire InterOperability Laboratory has made a key contribution to industry confidence in Gfast. By verifying solutions' functional interoperability, the certification programme helps to ensure a wide choice of interoperable Gfast solutions and smooth evolution to new solutions. Similar to Gfast, ITU-T coordinates with the Broadband Forum on MGfast certification and development of data models for management, facilitating MGfast introduction in the Software Defined Access Network.
