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| Theory of 2 Gigabit Triple-V DSL |
| Tuesday, 08 February 2011 16:31 |
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They doubted when John Cioffi outlined in 2004 how four wires could deliver a gigabit one day. In 2010, Alcatel and others demonstrated 700+ megabits. Now, his ASSIA colleague Ken Kerpez shows a path to two gigabits. It requires 300 MHz, four wires and goes only a short distance. Presumably it's many years away. But Triple-V could deliver 2 gig to Jennie's 9th apartment from the basement. France Telecom is looking for an alternative for buildings they hope not to run fiber to each apartment. My mother in her old neighborhood and 20 attached homes could receive a gig and a half.
ADSL originally used only the first megahertz of spectrum and was limited to 6 megabit service. In VDSL2, as much as 30 megahertz is used and 100 megabits practical. Full DSM including vectoring doubles that speed to 200 megabits/copper pair, close to the 250 megabits John envisioned. Engineering to reliably modulate 30 megahertz of signal was a challenge initially but the chipmakers have solved it.
Ken's "Triple-V" proposes extending signal to 300 megahertz. He introduces it with a paper "Initial simulations of Very Short, Very Simple, Very Fast metallic access, 'Triple-V.'"
It will take first-rate engineering and several iterations of Moore's Law before it will be practical to vector that signal. The power levels need careful shaping to meet interference requirements, limiting the throughput.The full 300 megahertz travels less than 500 feet at -80 dBm/Hz I haven't heard of anyone even close to a lab test, much less deployable systems.
Copper continues amazing. |
| Last Updated on Wednesday, 16 February 2011 04:04 |