PERFORMANCE EVALUATION OF A MULTI-HOP WDM NETWORK WITH OXC ARCHITECTURE

Abstract

The combined effect of crosstalk and noise on Bit Error Rate (BER) of a multi-hop Wavelength Division Multiplexing (WDM) transmission system with Limited Wavelength Interchanging Cross Connects (L-WIXC) are investigated in this thesis. In an all-optical WDM network, the route to be followed and the wavelength to be used by the signal along the selected route is designated by an L-WIXC. But, propagation through the switching elements of an L-WIXC results in signal degradation and induces crosstalk both due to device intrinsic losses and their imperfect operation. Moreover, in a long-haul communication system, the cumulative loss of signal strength is restored using optical amplifiers which further degrade the signal due to spontaneous emission that adds noise to the signal during its amplification. In this thesis, the signal to crosstalk plus noise ratio at the receiver output of a multi-hop WDM network is derived for various L-WIXC architectures. An improved mathematical modelling is developed for the analysis of network performance in terms of BER and the mathematical formulations are then used to evaluate Bit Error Rate (BER) performance of the system in terms of parameters like number of hops, number of wavelength channels per fiber and number of fibers. Accordingly, the power penalty for different system parameters due to accumulated crosstalk and noise is determined at a given BER of 10-9. Results show that there is a significant power penalty due to accumulated crosstalk and noise depending on the number of hops. Subsequently, the maximum allowable number of hops that a signal can travel, sustaining a specific level of power penalty for any combination of wavelength channels and input fibers, is evaluated numerically. A Comparative study of the system performance is also depicted for all architectures of L-WIXC which will provide a guideline for system design in choosing the most effective one while designing a WDM network.