DSL: Teaching an Old Dog Faster Tricks

Carl Weinschenk

Analysts, bloggers and other journalists are quick to bury older technologies in favor of newer and shinier approaches.


The great promise of 4G wireless and the increasing affordability of fiber-to-the-premises platforms to some justifies that last rites be given to digital subscriber line (DSL), the telecommunications version of the station wagon. The desirability of ditching DSL in favor of WiMax is the subtext in this PCWorld piece, for example.


The reality is that there still are plenty of station wagons on the road. DSL, too, lives on. Indeed, AT&T, which committed itself to the technology by opting to make it a key element of the U-verse architecture, is said to be pushing the envelope.


Broadband Reports extrapolated from a Reuters report and provided insight into how AT&T is working to expand DSL capacity. The story notes that AT&T is planning a trial next month in which customers will be able to access throughput of 80 megabits per second (Mbps). The question posed by the article is how the DSL element of the infrastructure will be expanded to support such speeds. The answer, the writer was told by AT&T, is that pair bonding, vectoring and spectrum management all will be used. This can be done inexpensively and "on a per-user basis," AT&T told the site.

A cynic-not rare among the bloggers, reporters and analysts referred to above-may chuckle that news of AT&T's attempts to stretch copper comes at the same time the company is trying to settle a class action suit in Ohio in which it is accused of slowing DSL down. The suit, Ars Technica says, reaches back to 1994 and the company's ancient ancestors, such as Prodigy. Folks who think they have a claim can file online. (There is a link at the story.) A judge will rule on the proposed settlement-which features payments of $2.00 or $2.90 per month for each month of substandard service, depending on specific circumstances-on June 1.

Irony aside, Telecompetitor offers a good overview on why AT&T and others are looking to increase the DSL speed limit. Writes Bernie Arnason:


But there's no denying that DSL is still the workhorse of telco broadband and will be for many years, maybe even decades, to come. It's not just small rural telcos that depend on DSL as their main broadband option, its companies with global reach like AT&T and Qwest as well. Tier 2 providers like CenturyLink, TDS, FairPoint, and Frontier also have huge copper/DSL infrastructure to contend with.

Arnason points to the AT&T work covered by Broadband Reports and also links to releases describing work by Alcatel-Lucent and Ericsson. The companies aim to accelerate DSL into the 300 Mbps and 500 Mbps neighborhoods, respectively. Telecompetitor references this piece at Light Reading in which Graham Finnie walks through the advances.

The real-world "gating factors" of a transmission media -- coaxial cable, fiber or wireless-are the techniques used to transmit the data. The actual physical limits at which the laws of nature prevent another bit from being squeezed into the bus are orders of magnitude higher. The fact that smart players are paying such attention to DSL is evidence that it is possible to teach an old communications conduit tricks that, if not new, are perfomed a lot faster.

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