Network Information Theory for NonLinear optical channels

Optical fiber systems carry nearly all of the global Internet traffic and are critical infrastructure for modern

society. Long-haul optical networks are often based on the notion of wavelength division multiplexing (WDM). At

high signal intensities, WDM systems are impaired by the inherent nonlinear effects involved in fiber

propagation. In the literature, the fundamental limits of WDM transmission are investigated using information

theory. The prevalent viewpoint only focuses on achievable rates for individual users under different behavioral

assumptions for the interfering users. NIT-NL deviates significantly from this single-user viewpoint and proposes

a multi-user information theoretic approach for the WDM channel that investigates the region of simultaneously

achievable rates for all the different users. NIT-NL aims to exploit this holistic perspective and realize a more

efficient utilization of the optical network resources. This will be achieved via a) characterization of closed form

inner and outer bounds to the capacity region based on realistic channel models, b) asymptotic analyses in the

limit of high transmit power to infer the nature of optimal strategies in the highly nonlinear regime, and c)

derivation of optimality conditions for simple and practical schemes such as treating interference as noise to

achieve the sum-capacity of the given model. NIT-NL will have a direct impact on the scientific community

engaged in the long-standing quest of dealing with nonlinear impairments in optical channels, and the multi-user

information theory community that will welcome its enrichment on nonlinear channel models. It will also benefit

the European telecommunications industry and standardization initiatives.