Designing fiber optic networks involves finding the most efficient way to
connect phones and computers that are in different places—a costly and
time-consuming process. Now, researchers from North Carolina State Univ. have
developed a model that can find optimal connections 10,000 times more quickly,
using less computing power to solve the problem.
“Problems that used to take days to solve can now be solved in just a few
seconds,” says Dr. George Rouskas, computer science professor at NC State and author
of a paper describing the new method. The model could solve problems more than
10,000 times faster when data is routed through larger “rings,” in the network,
Every time you make a phone call or visit a Website, you send and receive
data in the form of wavelengths of light through a network of fiber optic
cables. These data are often routed through rings that ensure the information
gets where it needs to go. These ring networks are faced with the constant
challenge of ensuring that their system design can meet user requirements
efficiently. As a result, ring network designers try to determine the best
fiber optic cable route for transmitting user data between two points, as well
as which wavelength of light to use. Most commercial fiber optics handle
approximately 100 different wavelengths of light.
Solving these design challenges is difficult and time-consuming. Using
existing techniques, finding the optimal solution for a ring can take days,
even for smaller rings. And a ring’s connections are modified on an ongoing
basis, to respond to changing use patterns and constantly increasing traffic
But the new model developed by Rouskas and his team should speed things up
considerably. Specifically, the researchers have designed a mathematical model
that identifies the exact optimal routes and wavelengths for ring network
designers. The model creates a large graph of all the paths in a ring, and
where those paths overlap. The model then breaks that graph into smaller units,
with each unit consisting of the paths in a ring that do not overlap. Because
these paths do not overlap, they can use the same wavelengths of light. Paths
that overlap cannot use the same wavelengths of light—because two things cannot
occupy the same space at the same time.
By breaking all of the potential paths down into these smaller groups, the
model is able to identify the optimal path and wavelength between two points
much more efficiently than previous techniques.
“This will significantly shorten the cycle of feedback and re-design for
existing rings,” Rouskas says. “It also means that the ring design work can be
done using fewer computer resources, which makes it less expensive. This should
allow network providers to be more responsive to user demands than ever
The paper, “Fast Exact ILP Decompositions for Ring RWA,” is published in the
Journal of Optical Communications and Networking.