ITU standards deliver 2 Gbit/s G.fast broadband, SDN management-control, timing and synch for 5G, and state-of-the-art optical fibre

ITU standards experts have doubled the access speeds achievable with the ITU G.fast broadband standard. G.fast is now capable of enabling data rates up to 2 Gbit/s over traditional telephone lines, providing operators with a valuable complement to fibre to the home (FTTH) technologies in scenarios where G.fast proves the more cost-efficient strategy.

This achievement comes in parallel with the completion of ITU standards detailing commonalities in software-defined networking (SDN) and automatically switched optical networks (ASON); tools to meet the expected synchronization demands of 5G systems; and the characteristics of state-of-the-art optical fibre.

These standards have achieved first-stage approval (‘consent’) and are expected to see final approval before the close of 2016. They are products of the ITU standardization expert group responsible for ‘Networks, Technologies and Infrastructures for Transport, Access and Home’, ITU-T Study Group 15.

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.

The third amendment of ITU-T G.9701 doubles the aggregate net data rate achievable with G.fast, increasing its capacity to 2Gbit/s using spectrum up to 212 MHz. The update to the standard maintains spectral compatibility with VDSL2. The coexistence of G.fast and VDSL2 offers service providers the agility required to switch customers between G.fast and VDSL2 as business operations demand.

The amendment extends G.fast’s application to coaxial cable, enabling the coexistence of G.fast and satellite signals in coaxial cable infrastructure. The amendment also specifies a mechanism for dynamic time assessment, functionality that enables upstream or downstream transmission to exploit G.fast’s full aggregate net data rate. This functionality will improve users’ broadband experience by increasing upload or download speeds in line with the demands of the applications in use.

SDN is a promising route towards more dynamic network management-control, enabling operators to establish and manage-control virtual network resources without introducing new specialized hardware.

The new ITU-T G.7701 “Common Control Aspects” describes commonalities in SDN and ASON network management-control, covering common SDN and ASON control approaches as they relate to transport resources and their representation, control components, control communications, and naming and addressing.

ITU-T Study Group 15’s study of SDN is a natural progression of the group’s work on Operation Support Systems (OSS) and ASON.

The new ITU-T G.7701 follows the 2015 approval of ITU-T G.7711/Y.1702 “Generic protocol-neutral information model for transport resources”, which provides a core information model for transport resources to enable smooth transitions to SDN architectures from traditional management using OSS. ITU-T G.7711/Y.1702 gives operators the ability to deploy SDN selectively, migrating parts of the infrastructure to SDN without nullifying the value of investments in legacy OSS infrastructure.

Timing and synchronization is crucial to the efficient operation of advanced mobile-wireless technologies. Industry looks to ITU for standards to support the synchronized mobile backhaul essential to the success of wireless systems through 4G, 5G and beyond.

The new ITU-T G.8272.1/Y.1367.1 “Timing characteristics of enhanced primary reference time clocks” specifies the requirements of enhanced primary reference time clocks (ePRTCs) suitable for time and phase synchronization in packet networks. The new standard will enable highly accurate time synchronization and levels of reliability translating into holdover capabilities up to several days, with technology typically based on a combination of GNSS (Global Navigation Satellite Systems, such as GPS) and atomic clocks (e.g. cesium clocks).

The ePTRCs provided for by ITU-T G.8272.1/Y.1367.1 will make it possible to design synchronization networks where the prolonged loss of GNSS would not impact the performance of the network, an important consideration amid increasing concerns around GNSS vulnerability. A planned future edition of ITU-T G.8272.1/Y.1367.1, based on the further development of atomic clock technology, will include an option for holdover periods potentially as long as 80 days.

Demand for optical fibre continues to display steady growth. In 2014, the volume of fibre produced worldwide exceeded 300 million kilometres, and estimates suggest that 2016 will yield over 400 million kilometres. Built in conformance with ITU standards, these fibres are at the core of the ultra-high-speed optical networks that form the backbone of the Information Society.

Revisions to ITU-T G.652 and G.657 extend and optimize the use of these optical fibres beyond their current capabilities. ITU-T G.652 was released in 1984 as the first standard for single-mode fibres, leading to these fibres becoming known as “standard single-mode fibres”. ITU-T G.652 fibres were the first to be deployed in public networks and still account for the vast majority of the fibres installed worldwide. ITU-T G.657 is a standard for single-mode fibres created in 2006 specifically for optical access networks, networks which are more demanding of fibre and fibre-optic cabling with respect to macrobending sensitivity and connectivity.

ITU-T G.654, which traditionally dealt with the characteristics of fibres for submarine cables, has been revised to include a new subcategory of fibre (G.654.E fibre) to support coherent digital transmission systems in terrestrial optical networks at rates beyond 100 Gbit/s.

The new G Supplement 59 provides guidance relevant to the long-term reliability of cabled optical fibres. The supplement describes the factors that impact the performance of an optical fibre over time, looking at fibres’ optical and mechanical reliability and how this can be impacted by the cabling process.

For more information on ITU-T Study Group 15, see the group’s homepage.

 

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