Very High Speed Digital Subscriber Line
From Wikipedia, the free encyclopedia
| DSL technologies | |
|---|---|
| Technology | ITU-standard |
| ADSL | ANSI T1.413 Issue 2 ITU G.992.1 (G.DMT) ITU G.992.2 (G.Lite) |
| ADSL2 | ITU G.992.3/4 ITU G.992.3 Annex J ITU G.992.3 Annex L |
| ADSL2+ | ITU G.992.5 ITU G.992.5 Annex L ITU G.992.5 Annex M |
| HDSL | ITU G.991.1 |
| HDSL2 | |
| IDSL | |
| MSDSL | |
| PDSL | |
| RADSL | |
| SDSL | |
| SHDSL | ITU G.991.2 |
| UDSL | |
| VDSL | ITU G.993.1 |
| VDSL2 | ITU G.993.2 |
VDSL or VHDSL (Very High Speed DSL) is a DSL technology providing faster data transmission over a single twisted pair of copper wires. 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. VDSL is deployed over existing wiring used for POTS (Plain Old Telephone System) and lower-speed DSL connections.
Second-generation VDSL2 systems (ITU-T G.993.2) utilize bandwidth of up to 30 MHz to provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. The maximum available bit rate is achieved at a range of about 300 meters; performance degrades as the loop attenuation increases.
Currently, the standard VDSL uses up to 7 different frequency bands, which enables customization of data rate between upstream and downstream depending on the service offering and spectrum regulations. First generation VDSL standard specified both QAM (Quadrature amplitude modulation) and DMT (Discrete Multi-Tone modulation.) In 2006, ITU-T standardized VDSL in recommendation G.993.2 which specified only DMT modulation for VDSL2.
[edit] Supply
As of 2006, the market is still small, except in Japan and South Korea, where VDSL is predominant.
- Australia
- The sole VDSL supplier is TransACT, who use VDSL for Digital TV, Internet and WAN applications over their Fibre-To-The-Curb network in Canberra.
- Belgium
- Belgacom is providing VDSL in parts of the country (about 6% coverage), but limited to 17 Mbit/s down and 400 kbit/s up, with a monthly download limit of 35 GB.
- Canada
- VDSL is offered in urban areas by SaskTel in Saskatchewan, MTS in Manitoba, and Bell Sympatico in Ontario and Quebec.
- Germany
- VDSL is currently available in 28 major cities with 25/5Mbit downstream/upstream or 50/10Mbit downstream/upstream. The infrastructure is owned by T-Home, subsidiary of Deutsche Telekom who is planning to invest approximately € 3 billion to set up the requisite VDSL infrastructure in 50 cities until approximately 2007; despite a ruling by the European Commission in December 2004 that would force the company to make parts of this new infrastructure immediately available to competitors, deployment is ongoing. The extent and the terms of infrastructure access areh still to be determined. The theoretical bandwidth right now is 100/100Mbit (synchronous line) downstream/upstream but is limited by T-Home to 50/10Mbit downstream/upstream. Cost for the 25/5Mbit VDSL service is set at €69,95 and for the 50/10Mbit VDSL service €74.95, both prices are basic (70 TV channels including some HDTV channels) IPTV channel package, for the premium (100 TV channelsincluding some HDTV channels) IPTV package T-Home is asking an additional €15 which also includes some Pay-TV perks like soccer and movie packages. There no additional charge for data throughput. VDSL from T-Home is bundled with a flat rate.
- Hong Kong
- VDSL is offered by HGC. A 10 Mbit/s up and down connection costs less than $15 USD/month with a 12-month contract and $20 USD/month without any contract, both with unlimited traffic.
- Netherlands
- VDSL roll-out is being tested by the company KPN. KPN hardly invested in ADSL2+ in 2006, despite the current coverage of only 57% (2007), because they see a better future in VDSL.
- Russia
- VDSL appeared on 8 February 2005. It is provided by SCTS, offers internet speeds ranging from 4 Mbit/s / 1.5 Mbit/s to 12 Mbit/s / 6 Mbit/s at Saratov city. Connection costs around €7-50 per month (including 125-1024 Mbytes of external incoming traffic). Traffic costs around €0,03-0,05 per Mbyte.
- 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 60 Mbit/s / 25 Mbit/s at more than 120 locations across the country (75% coverage). A 10 Mbit/s / 10 Mbit/s connection costs €46 per month.
- South Korea
- VDSL is offered in apartments by KT and other several providers, costing about $25-$40 USD/month.
- Spain
- VDSL roll-out by Telefonica began in 2005 in selected places in Madrid. Commercial launch up is planned for 2007.
- Sweden
- Bredbandsbolaget AB supplies fiber-optic VDSL, but not officially.
- Switzerland
- Used in the Bluewin TV television-over-IP service and in the DSL service with 15Mbit/s downstream and 1 Mbit/s upstream, introduced in July 2007. The city of Zurich had a vote about putting VDSL infrastructure in place in 2007 which was approved by the voters. This "Fiber to the Home" network will be run by the cities power company and will offer maximum speeds of around 100Mbit bandwidth though it's not clear what the upload speeds or pricing will be. The swiss telecom giant Swisscom offers VDSL in most of switzerland.
- Taiwan
- VDSL is available in Taiwan in the Fiber To The Building (FTTB) service provided by Chunghwa Telecom, the largest telecommunication company in Taiwan. FTTB has a maximum connection speed of up to 100 Mbit/s downstream and 5 Mbit/s upstream.
- Turkey
- Turkish state-regulated monopoly Turk Telekom is said to begin VDSL trials in September 2007 with service planned for 2008 (per article in Turkish daily Hurriyet dated 19 March 2007, p. 10).
- United States
- Qwest provides Internet access and television service over VDSL in Denver, Colorado and Phoenix, Arizona.
- AT&T provides Internet and television service over VDSL in 25 cities under the trade-name U-Verse. The AT&T service is based on FTTN, Fiber to the Node and FTTP is also used.
- Verizon offers it's FiOS service in some metropolitan areas at speed of around 30Mbit or higher, depending on line quality. The Verizon service is based on FTTN, Fiber to the Node.
- Ikanos supplies VDSL chipsets.
