DSL

The VDSL Experience

Very high speed DSL, like Jimi Hendrix's guitar work, arrived before its time. Hopefully, unlike Jimi Hendrix, the companies selling VDSL will survive to be appreciated. But beware the cold distance, the hour is getting late.

by Jim Wagner of internetnews.com [March 13, 2001]

Sometimes great things happen before they can be fully appreciated. For example, Ada Lovelace [ISP Glossary] came out with the first "real" computer program for the analytical machine in the mid-1800s, many years before Alan Turing was born..

And we also had Jimi Hendrix, who showed us the guitar was an instrument that did far more than just underscore the familiar plucky tunes of the time.

Add another unappreciated innovation to the list—very high data rate digital subscriber line (VDSL) technology [ISP Glossary].

DSL has been around for several years now and offers the promise of blistering download speeds up to 52 Mbps and uploads at 2.3 Mbps, with symmetrical speeds in the 24-26 Mbps range.

The cold distance
Finally, the promise of streaming video and teleconferencing over DSL was just around the corner, and an extensive fiber deployment wasn't necessary. Industry insiders started buzzing about what was many times mistakenly called Video DSL (the "v" is for "very," not "video").

DSL uses existing phone lines, but VDSL is far more expensive to deploy because deploying VDSL involves all the costs of deploying fiber.

After running fiber from the central office to an optical network unit (ONU) in a neighborhood, providers then use copper, either existing or new, for last-mile delivery of VDSL access to residential users.

The drawback to DSL, of course, is the distance from the central office. The industry-norm limits asymmetric DSL (ADSL) and symmetric DSL (SDSL) to a 17,000 feet radius from the nearest phone exchange (or "central office"). Even though some providers are attempting to break the distance barrier by using repeaters on the line—much like small transforms boost cable reception in coax throughout the average U.S. home, no "DSL extension" technology has gained acceptance.

VDSL is even more limited, only operating to specification a mere distance of 3,000 feet from a CO. It's hard to get a broadband provider to build a profitable broadband venture under these conditions.

There must be some kind of way out of here
Verizon Communications, burned by consumer groups and the media alike for its bungled DSL deployment, almost immediately balked at the costs involved with deploying VDSL.

Larry Plumb, Verizon Communications spokesperson, said both Bell Atlantic Corp. and GTE Corp. tested the technology, eventually deciding to drop it for the time being, because of the costs involved in digging up streets to put in fiber to the ONUs.

"It's something we opted not to employ because we're focused on deploying DSL as a way to get broadband as opposed to fiber," Plumb said. "VDSL is all part of the fiber scenario. We are in the planning stages in our overseas properties of testing some of our businesses, where you might be using VDSL for closed-circuit TV or something like that, but the economics for VDSL in the U.S. just aren't there right now."

So if you operate a data-centric competitive local exchange (DLEC), you can forget about VDSL opportunities, for now. Without universal adoption by incumbent carriers, plain old ADSL remains broadband users' only alternative to high-speed cable access.