Last week, Telekom Austria announced that its domestic fixed-line subsidiary, A1, would be the first operator in the world to offer commercial DSL services using vectoring technology. By doing so, it extends both the reach and the top speed of its FTTC/VDSL deployments. Several other national fixed operators, including Belgacom, BT, KPN, Swisscom and Türk Telekom, are conducting advanced trials of the technology.
Vectoring mitigates cross-talk on a group of lines using an advanced signal-processing technique at the DSLAM, improving both the speed and the stability of an xDSL line. Vectoring is itself one of a number of tools, which have come collectively to be known as 'accelerated DSL', that are available to operators as methods of improving the performance of DSL – especially of VDSL2. The other main tools are:
- modification of the band plan for copper access networks: BT has got the go-ahead to launch faster FTTC/VDSL2 services on higher frequencies this year
- pair-bonding – effectively using one or more spare copper pairs to multiply speeds: AT&T and PTCL (Pakistan) already use this technology and KPN has signalled its intention to commercialise it
- 'phantom-mode': an as yet uncommercialised technology in which only one of the four wires in a bonded pair is made to act as a ground wire (instead of two), thereby releasing a third wire to act as a signal wire.
Accelerated DSL technologies are important because they can be rolled out quickly and are much less expensive than FTTH. Hence they enable telcos to compete more effectively against cable operators and to differentiate their data services from emerging LTE services. The potential headline downstream speeds exceed 100Mbps, and could be far higher where bonding is used, and vectoring provides a far more stable line environment for multiple managed services.
They are also important – commercially and politically – because they expand the addressable market for superfast broadband into areas that would otherwise be without coverage. The European Commission has set 100% coverage at speeds of at least 30Mbps (superfast broadband) as a target for 2020.
Analysys Mason's forthcoming Viewpoint, The impact of accelerated DSL technologies on meeting European Digital Agenda targets, highlights the potential coverage gains from using vectoring, pair bonding and phantom mode in cabinet and exchange deployments of VDSL2 in a number of national copper networks. Among the countries studied, France and the UK are the countries that stand to gain the most.
Figure 1: Additional percentage of total copper lines that could be enabled for greater than 30Mbps services with accelerated DSL technologies, France and the UK [Source: Analysys Mason, 2012]
![Figure 1: Additional percentage of total copper lines that could be enabled for greater than 30Mbps services with accelerated DSL technologies, France and the UK [Source: Analysys Mason, 2012]](/PageFiles/24487/Figure_1.png)
The stark difference between urban and rural population density in France means that a high proportion of subscribers in rural areas – who would be unlikely to be covered by a commercial FTTH service from one of the four main fixed operators – live on long cabinet loops. The study indicates that potentially one third of copper lines in France would, assuming availability of spare pairs, be enabled to get at least a 30Mbps service by a combination of vectoring and bonding, whereas they would otherwise get none on copper. This is broadly comparable with AT&T's claims that its addressable market for its FTTC/VDSL2 triple-play U-verse is increased by one third through the use of pair-bonding alone. It is therefore ironic that VDSL has still not been mandated on the French copper network.
In the UK, the potential gains are significant, but smaller. BT has already publicly indicated that a combination of band-plan changes, vectoring and public funding could extend the reach of non-cable 50Mbps services to over three quarters of UK premises. Analysys Mason's Viewpoint report, which draws on our work for the UK's Broadband Stakeholder Group, calculates that about 8% of lines could be enabled for at least 30Mbps services over and above those covered by the band-plan changes.