VDSL2 (Very-High-Bit-Rate Digital Subscriber Line 2) is a digital subscriber line with high transfer rate, which leverages existing telephony infrastructure. Previously, we wrote about VDSL or Very High Bit Rate Digital Subscriber Line, where we wrote about the basic technical details of the underlying technology. In this article, we will only focus on the second version of the technology; i.e. VDSL2. ITU-T G.993.2 is the standard for VDSL2. It is designed to support services known as Triple Play, including voice, video, data, high definition television ( HDTV ) and interactive gaming. Most ISPs have own offerings for video, voice and data on one line. VDSL2 enables operators and carriers to gradually upgrade existing xDSL lines, without a high cost.
Basics About VDSL2
ITU-T G.993.2 enables symmetrical or asymmetrical data transmission reaching bandwidths above 200 Mbit/s. This bandwidth depends on the transmission distance to the distribution center. Thus, the 250 Mbit/s speed which is leaving the production plant is reduced to 100 Mbit/s within 1 km and 50 Mbit/s after 2 Km radius away. 1.6 km radius performance is equal to ADSL2 +. 4 or 5 miles away bandwidth is of 1-4 Mbit / s. As the loop length shortens, it raises the ratio of symmetry, reaching more than 100 Mbit / s (both upstream and downstream), given the right conditions. Thus VDSL2 technology is not merely limited to short loops, but can be used with quality in medium distances.
Vectoring is a transmission method that uses the coordination of line signals to reduce crosstalk levels and offers performance improvement. It is based on the concept of noise-canceling headphones. Since 2010, ITU-T G.993.5, self-FEXT cancellation is in use with VDSL2 Transceivers. The scope of ITU-T G.993.5 is specifically limited to self-FEXT cancellation (far-end crosstalk) in the direction of lowering and raising.
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VDSL2 is the newest and most advanced standard of digital subscriber line (DSL) broadband wireline communications, in short. It has been announced as finalized on 27 May 2005 and first published on 17 February 2006. Several corrections and amendments have been published in 2007 through 2011.
Deployment of VDSL2
The Countries where VDSL2 is used or is available is listed in Wikipedia :
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http://en.wikipedia.org/wiki/Very-high-bit-rate_digital_subscriber_line_2#Deployment |
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