Currently, the standard VDSL uses up to 4 different frequency bands, two for upstream (from the client to the telco) and two for downstream.
The standard modulation technique is either QAM ( Quadrature Amplitude Modulation ) or DMT ( Discrete Multitone Modulation ) which are not compatible, but have similar performance. The current mostly used technology is DMT.
The available bit rates range from about 26 Mbit/s symmetric for a loop of about 1500 m, up to 100 Mbit/s symmetric for a few hundred metres.
These fast speeds mean that VDSL is capable of supporting new high bandwidth applications such as HDTV, as well as telephone services ( Voice Over IP ) and general Internet access, over a single connection.
A new VDSL standard is now available, named VDSL2 ; no current rollouts are known.
As of 2006 , the market is still small, except in Japan and South Korea , where VDSL is predominant.
- Belgium
- --- Belgacom is providing VDSL in parts of the country (about 6% coverage), but limited to 17 Mbit/s down, 400 kbit/s up and with a monthly download limit of 30 GiB.
- Germany
- ---VDSL currently unavailable; the technology was being championed by market leader Deutsche Telekom who originally planned to invest ca. € 3 billion to set up the requisite infrastructure in 50 cities until ca. 2007 ; however, in the wake of a ruling by the European Commission in December 2004 that would force the company to make this new infrastructure immediately available to competitors, a strategic switch to the cheaper ADSL2+ may be imminent.
- Japan
- ---VDSL is indirectly offered in many areas by NTT , Japan's largest telco in conjunction with FTTH service. It is used as a mechanism to wire apartments and other existing construction as a lower cost alternative to pulling optical fiber to each unit.
- Netherlands
- ---VDSL Roll-out is tested by the company KPN and is expected in Q2 2006 to be used. ADSL2+ is already being used on large parts of the network.
- Slovenia
- --- VDSL appeared on 1 October , 2005 . It is provided by T-2.net , offering Triple Play services with internet speeds ranging from 1 Mbit/s/256 kbit/s to 40 Mbit/s/15 Mbit/s at more than 120 locations across the country. A 10 Mbit/s/10 Mbit/s connection costs around US$65 per month. There is no fair-use policy (uncapped downloads).
- South Korea
- ---VDSL is offered in apartments by several providers, costing about $20-$40 USD/month.
- Spain
- ---VDSL Roll-out by Telefonica began in 2005 in selected places in Madrid. Commercial launch up is planned for 2007.
|
