Joseph Lechleider, a Father of the DSL Internet Technology, Dies at 82(nytimes.com)
nytimes.com
Joseph Lechleider, a Father of the DSL Internet Technology, Dies at 82
http://www.nytimes.com/2015/05/04/technology/joseph-lechleider-a-father-of-the-dsl-internet-technology-dies-at-82.html
5 comments
>> "When the data speeds in both directions — downloading and uploading — were the same, there was a lot of electrical interference that slowed data traffic to a crawl.
>> ... such meddlesome interference — known as electrical crosstalk — could be drastically reduced if the download speeds were far faster than the upload speeds."
Cool, so DSL is prevented from increasing the upstream traffic by the physics - not a matter of upgrading the 'boxes' at each end of the wire.
>> ... such meddlesome interference — known as electrical crosstalk — could be drastically reduced if the download speeds were far faster than the upload speeds."
Cool, so DSL is prevented from increasing the upstream traffic by the physics - not a matter of upgrading the 'boxes' at each end of the wire.
This problem has been solved by VDSL2 for quite a while: http://en.wikipedia.org/wiki/Very-high-bit-rate_digital_subs... - the ratio of downstream and upstream and be configured freely there. Using VDSL2 with vectoring you can now get connections with 100 Mpbs downstream and 40 Mbps upstream in Germany.
> LR-VDSL2 enabled systems are capable of supporting speeds of around 1–4 Mbit/s (downstream) over distances of 4–5 km (2.5–3 miles), gradually increasing the bit rate up to symmetric 100 Mbit/s as loop-length shortens.
You need to be quite close to the exchange to get the higher speeds. Sounds like it should be a solution to the last mile problem though - strategically place DSLAMS along the fiber where existing copper can be re-routed to it. I have no idea how much this is done.
You need to be quite close to the exchange to get the higher speeds. Sounds like it should be a solution to the last mile problem though - strategically place DSLAMS along the fiber where existing copper can be re-routed to it. I have no idea how much this is done.
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PaulHoule(3)
> Mr. Lechleider’s insight about how to increase data speed came when he was 55. He had spent decades studying signal processing, so he was deeply grounded in the field. But Mr. Lechleider, according to Mr. Cioffi, was something of an iconoclast in a large, often bureaucratic organization. “He was not afraid to take a risk and fight for a new idea,” Mr. Cioffi said.