Next Generation Optical Networks and New Services: an Operator's Point of View

The optical network must be suitable for new services with high quality of service and high availability offered by network operators. Private and business customers demand more and more triple play services. In the access domain the optical fibre will directly reach the buildings to satisfy the customers' demand on data rates and quality of the service with high flexibility and short provisioning time. Customer data rates directly influence on the transmission capacity of the links and require flexibility of the transport network. Classical optical networks in the backbone are based on fixed WDM transmission links with point-to-point configuration. Dense WDM systems (DWDM) for high capacity links coexist with Coarse WDM systems (CWDM) for cost effective links. The link data rate of the WDM channels is either 2.5 Gbit/s or 10 Gbit/s. But the next step of the network migration is the introduction of 40 Gbit/s channels. The 10 Gbit/s links must be suitable for implementation of 40 Gbit/s without any changes of the link design to minimise capex and opex. For more flexibility of the network reconfigurable OADM will be inserted in the links and network nodes. Thus the maximum transparency length can be increased but network operators have to take into account limiting physical effects like PMD, chromatic dispersion and spectral characteristics of the cascaded OADM while extending transmission speed of the channels up to 40 Gbit/s. The transport hierarchy of the network migrates from classical SDH-infrastructure to OTH-infrastructure with completely new features satisfying future network requirements. An automatically switched network supports flexibility and the necessary bandwidth can be provided to the customers on demand.