Capacity expansion of fiber optic infrastructure networks using wavelength division multiplexing systems

For the last decade, carriers have been aggressively installing optical fiber in their backbone and metro networks, replacing aging copper plant to improve capacity and network services. Nevertheless, explosive growth in Internet diffusion and advances in Internet based voice and data applications has resulted in unprecedented demand for additional bandwidth. To satisfy this demand in a cost effective manner, carriers are deploying Wavelength Division Multiplexing (WDM) systems to leverage existing optical infrastructure. A WDM system allows transmission of multiple wavelengths (lambdas) over a single fiber strand, substantially increasing bandwidth while incurring much less cost compared to the huge investment of adding new fiber cables to the fiber plant. This paper develops a cost minimization model for capacity expansion of optical networks using WDM systems. The model assumes that an existing optical network is in place and therefore takes into consideration the technological constraints on placing and operating new WDM components for capacity expansion. An LP-based heuristic solution procedure is proposed and tested on sample problems. Proposed improvements to the solution procedure are also discussed in conclusion.