A 100-year-old networking trick could boost transmissions over telephone infrastructure.
Alcatel-Lucent has developed a prototype technology that could dramatically increase the speed of data communications over the copper wires that make up the majority of the world's telephone infrastructure. The technology combines three existing techniques, known as bonding, vectoring, and DSL phantom mode. It can reach speeds of 300 megabits per second at a distance of 400 meters from a communications hub, and 100 megabits per second at one kilometer.
Squeezing more speed out of copper connections is an important goal for telecommunications companies in the United States. They want to compete with the 50-megabit-per-second speeds offered by cable providers, but DSL connections transmit data through telephone lines--a fundamentally different technology from that used by cable companies. Alcatel-Lucent's technology could help these companies extend high-speed Internet access before next-generation fiber-optic networks become widely available.
The first two components of the prototype system, vectoring and bonding, are standard ways to increase the speed of DSL broadband connections: vectoring cancels out noise in a DSL line, and bonding treats multiple lines as if they were a single cable, which increases bandwidth by a multiple almost equal to the number of cables involved. Neither technique is widely used in the United States, but bonding is deployed to a limited extent in both Asia and Europe, where high urban density makes it more economical.
The third component, "phantom mode," is based on a networking trick invented in 1886 by electrical engineer and telephony pioneer John J. Carty, who later became a vice president at AT&T.
A digital signal is normally transmitted through two wires twisted together--one positive and the other negative. Carty realized that it is possible to send a third signal on top of four wires separated into two twisted pairs. The negative half of this "phantom" connection is sent down one twisted pair (which is already carrying a conventional signal), and the positive half down is sent down other twisted pair. At the destination, analog processors are used to extract all three signals--two real and one "phantom"--from the two pairs.
The challenge, says Stefaan Vanhastel, director of product marketing at Alcatel-Lucent, is that any additional bandwidth gained by creating a phantom channel can easily be swamped by the increased noise that the technique introduces. The noise arises because telephone wires are often bundled tightly into a single cable, allowing for electrical induction, or "cross-talk", between them.
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This scheme will probably work, but like all similar schemes depends on extremely fast DSP - digital signal processing - and that takes (electrical) power. That's why a fiber optic network link at high speeds uses about 20-25% as much power as a fiber link - it needs no DSP. This has become a major issue in data centers, but think of the implications of millions of links consuming large amounts of power!
We'll never see the end of these schemes to use copper, but fiber to the home/subscriber is really the logical solution. Even the reduction in maintenance required by fiber over old copper pays for the cost in a few years.
Bonding was developed by AT&T in 1886??? AT&T didn't even exist then.
Re: Fiber optic speeds over DSL
A guy who later worked for AT&T created it in 1886, he wasn't at AT&T when he created it. He later became Vice President at AT&T.
They think they'll be able to roll out 100mb connections to only residences 1km or less from the switching office in 5 to 10 years? How many people are that close to their switch except in NYC? Not many me thinks. And almost no one is 400 meters away for 300mb. I live in urban Dallas and I am over 3km away from my switch. Obviously I use cable internet and not DSL.
They could and should do this in 3 to 4 years, then they might get some customers. Cable will have 100mb connections for most residences they service in that amount of time or less. Given cable's current upgrade cycle, I'd expect at least 300mb to all of those residences in less than 10 years.
If I don't have FTTN, and preferrably FTTH in less than 10 years, I wouldn't be surprised if I move to a more progressive area in the US or internationally.
Well, you could move to a suburb such as Carrollton where FIOS is available.
Yes, but Carrollton is probably not progressive in any way other than fiber deployment. I grew up in The Woodlands. I have a name for places like it and Carrollton... Suburban Hells ;)
Unless you live in a very remote area, you're more than likely not more than 12Kft from your "central office".
Phone companies utilize an engineering system called carrier service areas (CSA's) to distribute remote carrier units (miniature CO's) fed by fiber optic links into areas greater than 30Kft from the main CO. From these remote nodes they service customers in a 12Kft radius around the node. As such, you are more than likely to have a very decent chance of having a relatively fast network connection.
That said, the cable companies DOCSIS 3.0 technology is definitely pushing telcos to up their game to provide better access speeds to their customers. In return, the telcos are pushing cable operators to up their game in delivering innovative IPTV products.
Competition, it's a good thing...
Alcatel-Lucent isn't the only one able to achieve multiple 100's of Mb/s over the existing copper plant...
Check out www.bondeddslrings.com. This one can do rural areas at > 100 Mb/s as well.
If it were anybody but MIT, I might not comment, but should this not be:
Achieving Fiber-Optic data rates over Copper Lines?
Thanks for the great source of info.
If AT&T wants to get my business, they need do nothing more than bill me the correct amount for services they already offer!
In the past year, they've managed to overbill me nearly $3,000, while enrolled in service planes that should have resulted in costs of around $150. I spent hours of time over months trying to sort it out. It was only when I threatened to QUIT that they did anything at all.
And then they overbilled me almost $20 the following month!
And it's not just any "one time" thing, it's repeatedly. They even charged me $170 for not signing a contract for an iPhone that I decided not to purchase!
Sure, broadband, blah blah. How about just billing me the right amount? I won't own an iPhone as long as AT&T has its name attached!
This is interesting, but without a feel for what the return rate is, I can't tell if this is going to be great for consumers or for both consumer and business if it's actually implemented.
Sure, most of us are more than a kilometer from our local CO, but if this is a symmetric technology then getting even 20 mbps would be fantastic for a lot of branch offices.
When copper gets wet, it shorts out. Did you ever hear "popcorn" on the line? Water on the copper messes with those pesky electrons.
When glass gets wet, so what? Glass doesn't care if it's wet or dry. It just conducts photons... at high speed!
Actually I have seen copper lines that are corroded completely through that still transmit DSL signals at almost full line rate. The higher frequencies used in DSL allow it to "jump" a corroded or wet pair, even when the pair could not transmit traditional POTS voice.
Your comment regarding fiber being immune to wet conditions is not entirely correct. Wet fiber can and is affected by wet conditions as it changes the index of refraction in the cladding if the moisture ingress is severe and swells the cladding. As such, you will experience a degree of chromatic dispersion (CD) and polarization mode distortion (PMD) in wet fiber.
That said, the effect is usually small and not service affecting for shorter/slower fiber runs. Higher rate and longer metro transport circuits can and are affected by wet fiber.
Hi,
* First I doubt that phantom lines will ever bring any improvement to the ADSL bandwidth as correctly stated at the end of the article.
* Second ADSL is a good technology with provision for further improvements.
* So I would bet there is no reason why ADSL couldn't offer real rates up to 200 Mbits/sec over 5 km lines. In my past job experience I sent digital streams at such rates on ordinary phone lines of such length here in France in the 80'. In fact the main roadblock isn't theoretical but economical: One has to design very low cost, low consumption but robust modems and DSP. Such circuits where only available in the last 10 years.
* To reach 200 Mbits/sec on copper line with low cost IC, Telco engineers could use another old timer trick which makes all this possible on the economical side while being not as technically challenging as the signal to noise ratio of phantom lines. It only seems Alcatel/Lucent isn't aware of it.
Jean-Pierre
The fact that one can do this does not mean it is commercially viable. In a report done by Telcordia in 2004 (Bernstein: Fiber: Revolutionizing the Bells' Telecom Networks) the point was made that converting to fiber would reduce the operating expense for subscriber connections to pay back the cost of going to fiber in only a few years - and that ignores the additional revenue from new services that FTTH can offer. Remember Verizon justified it's investment in FiOS by noting that it would save almost $5 BILLION in 4 years.
Articles like these cause me to wonder why we allowed Bell Labs to go away .. (while others are "too big to fail") .. or Lucent with its vast inherited knowledge base, R&D experience, and array of patents to be "sold" in spite of the stock market (which always "values" things correctly ...). This has always seemed a real "national security" and R&D infrastructure blunder of the first order.
I live in an area where cable is not available and this sounds like an excellent solution. I can't wait until its implemented and i can finally have a broad band connection. Who would have thought 10 years ago that broadband would NOT be availalbe to the entire country.
The spot price of copper is continually increasing. Very, very soon it's going to be completely uneconomical to lay down copper wiring—fiber optics will be the only viable option.
I don't have the background in digital communications (and the article is short on detail), but it's not clear whether this will actually work on existing, real-world wiring, especially when you take into account restrictions, i.e. diameter of bends, minimum amount of shielding, etc. In my experience telephone lines can be wired pretty horrifically.
You are correct that the price of Cu is going to keep increasing. This is why most telcos are adopting a greenfield (new) and brownfield (old) deployment strategy.
New greenfield developments being built today are deployed using fiber to the home (FTTH) technology and will be 100% fiber fed.
Telcos have already invested billions of dollars in laying Cu cables in established brownfield communities however. In this case it is actually more economical to utilize a fiber to the node (FTTN) strategy to deliver faster broadband via fiber to a remote carrier unit and then utilize the existing Cu plant if it is in good shape. If it is not, the telcos will consider an "overlay" of fiber into that area.
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devassocx
110 Comments
dsl speed
I and I'll bet many other dsl users would be
impressed if they could even get the advertised
speed from their connections. Mine run about
70% of the advertised rate.
Can you say 'truth in advertising'?
Reply
network-gal
1 Comment
Re: dsl speed
your speed is directly proportional to the distance from the last CO. ( or last DSLAM)
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