Chapter 11 - Transport Solutions for Optically Amplified Networks

Abstract

In recent years, the distinction between the system reach of metro and long-haul systems has diminished. Today's metro systems can be easily extended to cover distances longer than 500 km. This development has profound impact on the architecture of the European national networks, where the size of networks is closer to that of current metro/regional networks. Moreover, since signal wavelengths can be extended to distances nearing 100 km without re-amplification, the requirement of a large number of central offices in the legacy national networks in countries like Germany has also diminished. It is therefore more cost effective to consider network architectures with fewer central offices, potentially eliminating up to 90% of the existing ones. Cost benefits will also be derived from the implementation of new technologies such as new modulation formats and coherent detection, particularly for high-data-rate channels. In this chapter, network architecture issues and physical impairments due to chromatic dispersion, polarization mode dispersion (PMD), and related mitigation techniques for these networks are described from the point of view of a European network operator. Simulation results are also presented to show a comparison of the system reach over different types of fiber for signals with return to zero (RZ) and carrier suppressed RZ (CSRZ) modulation formats and the use of Raman and EDFA hybrid amplifiers to optimize the network design.