| Wavelength Division Multiplexing (WDM) is now being widely used in optical networks. WDM significantly increases the capacity of a single fiber by allowing it to simultaneously transmit multiple wavelengths. While such enormous capacity is very exciting, it has also led to the advent of drastically more complex WDM networks. In this work, we consider two architecture design problems for optical networks: (1) the optimal amplifier placement problem, and (2) the traffic grooming, routing, and protection problem for optical networks.; In an optical network, optical signals from transmitters attenuate gradually as they propagate through optical fibers, therefore their strength needs to be restored by optical amplifiers before they become too weak to be detected by receivers. Optical amplifiers, however, also introduce the spontaneous emission noise, which is a major problem associated with them. In general, a long optical channel needs enough amplifiers in order to limit the cumulative spontaneous emission noise and attain adequate amplification gain. In our amplifier placement problem, the goal is to minimize the cost associated with optical amplifiers in an optical network subject to constraints on the cumulative spontaneous emission noise. The optical network can be a linear or a mesh network, and the locations of amplifiers can be arbitrary or pre-specified, which are referred as continuous and discrete case, respectively. We propose several different methods based on various optimization techniques and heuristics to solve the problem.; In the second part of this work, we consider the traffic grooming, routing, and protection problem in optical networks. There are two basic architectures used in optical networks: ring and mesh. The ring architecture is relatively simple and easy to implement, and it also provides a straightforward way for traffic protection. On the other hand, the mesh architecture is more resilient to various network failures, but is much more complex. Recently, a hybrid architecture that is based on and takes advantage of both ring and mesh architectures has been proposed. We study the traffic grooming, routing, and protection problem for ring, mesh, and hybrid architectures, and use a two-step approach in conjunction with the linear programming technique to solve the problem. Numerical results are provided for a comprehensive comparison between these different architectures. |
