Discrete-time interference channel models are developed for information transmission over optical fiber using wavelength-division multiplexing. A set of coupled nonlinear Schroedinger equations forms the basis of the models. The first model is memoryless and captures the nonlinear phenomena of cross-phase modulation but ignores dispersion. For the case of two carriers, a new technique called interference focusing is proposed where each carrier achieves the capacity pre-log 1, thereby doubling the pre-log of 1/2 achieved by using conventional methods. For more than two carriers, interference focusing is also useful under certain conditions. The second model captures the nonlinear phenomena of cross-phase modulation in addition to dispersion due to group velocity mismatch. Moreover, the model captures the effect of filtering at the receivers. In a 3-user system, it is shown that all users can achieve the maximum pre-log factor 1 simultaneously by using interference focusing, a time-limited pulse and a bank of filters at the receivers.
['Hassan Ghozlan', 'Gerhard Kramer']
Models and Information Rates for Multiuser Optical Fiber Channels with Nonlinearity and Dispersion