VDSL2 (Very High Speed Digital Subscriber Line 2) is an access technology that exploits the existing infrastructure of copper wires that were originally deployed for POTS services. It can be deployed from central offices, from fibre-fed cabinets located near the customer premises, or within buildings.
VDSL2 is the newest and most advanced standard of DSL broadband wireline communications. Designed to support the wide deployment of Triple Play services such as voice, video, data, high definition television (HDTV) and interactive gaming, VDSL2 enables operators and carriers to gradually, flexibly, and cost efficiently upgrade existing xDSL-infrastructure.
It has been standardized as ITU G.993.2 in February, 2006.
ITU-T G.993.2 (VDSL2) is an enhancement to G.993.1 (VDSL) that permits the transmission of asymmetric and symmetric (Full-Duplex) aggregate data rates up to 200 Mbit/s on twisted pairs using a bandwidth up to 30 MHz.
VDSL2 deteriorates quickly from a theoretical maximum of 250 Mbit/s at 'source' to 100 Mbit/s at 0.5 km (1640 ft) and 50 Mbit/s at 1 km (3280 ft), but degrades at a much slower rate from there, and still outperforms VDSL. Starting from 1.6 km (1 mile) its performance is equal to ADSL2+.
ADSL-like long reach performance is one of the key advantages of VDSL2. LR-VDSL2 enabled systems are capable of supporting speeds of around 1-4 Mbit/s (downstream) over distances of 4 to 5 km (2 ½ to 3 miles), gradually increasing the bit rate up to symmetric 100 Mbit/s as loop-length shortens. This means that VDSL2-based systems, unlike VDSL1 systems, are not limited to short local loops or MTU/MDUs only, but can also be used for medium range applications.
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Very High Speed Digital Subscriber Line 2
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VDSL2, 100 MBPS over Copper Next
Very High Bit Rate DSL 2 (VDSL2), a new standard is likely to be ratified by next week, making it possible for carriers to provide upto 100 megabits per second connections (both up and down) over copper lines. VDSL2 standard has been under review with the International Telecommunications Union for sometime now, and the decision on the standard could come early next week.
VDSL2 is really really fast. How fast? According to Ikanos estimates, it takes an “ADSL network more than 45 minutes to transmit up to 50 high-resolution photos at 3 Mb per photo. Sending the same number of photos can take less than a minute over VDSL/VDSL2 networks.”
VDSL, though once thought of as a good solution for bringing more bandwidth to the home has lagged because of its lack of reach. It has become popular in the overseas markets because densely populated countries like China and Korea have central offices that are much closer to consumer premises. VDSL2 standard, which uses about 30 MHz of spectrum (versus 12 MHz in VDSL) allows more data to be sent at higher speeds and over longer distances. BellSouth and SBC have plans to use super-fast DSL to connect their fiber nodes to consumer homes. Qwest for instance has about 40,000 customers who are using VDSL technologies.
But eventually if they want to offer true triple play with high-definition streams, they will eventually have to migrate to VDSL2 technology which can handle three HDTV streams with relative ease. (Three HD streams at the very least because at present average American home has 3.1 televisions.) Of course there is that whole issue of US homes being too far from the Central office. The good news is that VDSL2 is going to be backward compatible with ADSL, ADSL2 and VDSL.
Here is a little comparison of more recent flavors of DSL
* ADSL has speeds up to 8 Mbps downstream and 1 Mbps upstream. Can be deployed from Central office and has a range of 15,000 feet and longer.
* ADSL2+ has a maximum speed of 25 Mbps downstream and 1 Mbps upstream. Can be deployed from Central office and has a range of 15,000 feet and longer
* VDSL , some chipsets that use the optional spectrum of 30 MHz can do 100 Mbps downstream and 50 Mbps upstream. Current carriers include NTT, KDDI, Korea Telecom, and Softbank BB of Japan. Has a range of about 5,000 feet
* VDSL2 has speeds of 100 Mbps downstream and 100 Mbps upstream. Has a range of about 12000
VDSL2 is expected to be a fiercely contested market place, with early leader Ikanos like to fend off challengers like Infineon, which is expected to announce new VDSL2 chipsets at SuperComm trade show. Other players competing for the VDSL2 pie could include Broadcom, TI, and existing VDSL chip maker, Metalink. Santa Clara-based Electriphy is another recent entrant in the VDSL space.
source: gigaom.com
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