New Rigorous Model for Rx ISI Effects in WDM Systems

Abstract

We present a model for Rx ISI effects using a new and completely general and rigorous dynamic Rx model formulation aiming at 10-40 Gbit/s WDM system design applications. The signal shaping part of an electrical filter is modelled in the optical domain using the filter impulse response to modify the signal vector and the covariance matrix. In this way inter-symbol-interference (ISI) effects from any type of electrical filter -specified by the filter impulse response -can be described. The formulation leads to a Hermitian form of the covariance matrix, thus allowing a straightforward analytical formulation of the moment generating function (MGF) which in turn specifies the bit-error-ratio (BER). Numerical examples for a 10 Gbit/s pre-amplified Rx shows that the ISI leads to (up to) several dBʼs degradation in sensitivity. Thus it is imperative to account for the Rx ISI effect in rigorous and accurate form in any general WDM transmission model.