Broadband in Every House
Ioannis Kanellakopoulos: Forecasting the Future of IT

By Doug Peterson

In a television commercial running on the West Coast, a father announces to his family that from now on they're going to live on European time.  The reason?  In the evening, the cable modem is slow.  So the family will go to bed at 5 p.m., then wake up at 2 a.m. when the cable modem is not competing with so many other users.

This outlandish scenario is just one way that DSL companies are trying to drive home the message that digital subscriber lines are superior to cable modems in delivering broadband access to the Internet.  It's also an example of the turf battles taking place in the business world as the United States attempts to bring broadband into as many homes as possible, said CSL alumnus Ioannis Kanellakopoulos at the laboratory's 50th -anniversary symposium in the fall of 2001.

"The FCC chairman said that ubiquitous broadband connectivity is now the number one priority in the communications policy of the nation," Kanellakopoulos pointed out.

People want broadband, he said, but providers face many difficult problems, such as resource allocation.  That's why one of the hot topics is flexible resource allocation - having the ability to change the resources given to a broadband user depending on that user's needs at the moment.
For example, Kanellakopoulos noted, "one minute you're just typing e-mail and you don't care about how much bandwidth you have.  But the next minute you want to download a Web page with a lot of graphics and you want to have the bandwidth available."

Flexible resource allocation adapts to these changing needs.

Another major sticking point with broadband has been interference in DSL networks due to many factors, including crosstalk from the different wires in a shared cable.

The traditional solution, Kanellakopoulos said, is to consider each line running through the cable as an individual entity.  The goal would be to optimize transmission on that line only.  However, this typically means the system must be designed to operate on a worst-case scenario, cutting back on power and bandwidth even when it may not be necessary. 

"And that means you lose performance," Kanellakopoulos said.

The new push is for "dynamic spectrum management," in which you try to sense more about what the other lines are doing, and then you coordinate transmission across lines.  Your line would not cut back on power and bandwidth, unless it was necessary to prevent interference.

This is the approach being taken by Voyan Technology, where Kanellakopoulos serves as a chief scientist.  It's a systems approach, which he said he learned during his years as a student at CSL. 

"We're looking at systems as systems and not just as a collection of components," he said.  "That's where a lot of the challenges lie ahead of us."

Ioannis Kanellakopoulos
Chief scientist, Voyan Technology
PhD from U of I in electrical and computer engineering in 1991

Panel: Forecasting the Future of IT
Delivered: October 26, 2001