VDSL Guide, Meaning , Facts, Information and Description
VDSL (very high data rate DSL) is an xDSL technology providing data transmission up to a theoretical limit of 52 Mbit/s over a single twisted pair of wires. Compare HDSL (High Data Rate Digital Subscriber Line).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 available bit rates ranges from about 26 Mbit/s symmetric for a loop of about 1500 m, up to 100 Mbit/s symmetric for a few hundred metres.
As of 2004, the market is still small, most of it in South Korea. In the US, Qwest is offering both internet and television services over VDSL in Denver, Colorado and Phoenix, Arizona. In Canada, VDSL is offered in urban areas by SaskTel in Saskatchewan, MTS in Manitoba, and Bell ExpressVu in Ontario and Quebec. In Hong Kong, VDSL is offered by HGC. In Finland it's provided in Oulu by Finnet. In Australia, the sole VDSL supplier is TransACT, who use VDSL for Digital TV, Internet and WAN applications over their Fibre-To-The-Curb network. (VDSL is not ratified for use on Telstra supplied copper lines in Australia yet, and Telstra has publically voiced opposition to VDSL)
VDSL is capable of supporting high bandwidth applications such as HDTV. Qwest is currently prototyping the service and may offer a HDTV package as early as 1Q05.
The current mostly used technology is QAM (the same technology used in cable modems). opposition
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