OSNR optimization in optical networks: Modeling and distributed algorithms via a central cost approach

This paper addresses the problem of optical signal-to-noise ratio (OSNR) optimization in optical networks. An analytical OSNR network model is developed for a general multi-link configuration, that includes the contribution of amplified spontaneous emission and crosstalk accumulation. The network OSNR optimization problem is formulated such that all channels maintain a desired individual OSNR level, while input optical power is minimized. Conditions for existence and uniqueness of the optimal solution are given. An iterative, distributed algorithm for channel power control is proposed, which is shown to converge geometrically to the optimal solution. The algorithm is valid for general network configurations, and uses only local measurements or decentralized feedback. Convergence is proved for both synchronous and asynchronous operation, which is particularly important for adaptation in a dynamic environment.