Optical path cross-connect systems for photonic transport networks

Optical path layer technologies will play a key role in the development of the platform on which future bandwidth abandoned B-ISDN should be created. The paper highlights the wavelength path (WP) and the virtual wavelength path (VWP) techniques, both of which can greatly enhance the path layer capability and the efficiency of network failure restoration. The WP and VWP schemes are compared focusing on network restoration performance. It is demonstrated that the VWP scheme can reduce the required number of wavelengths needed for network restoration, Optical cross-connect node architectures for both schemes are then examined. Cross-connect systems which utilise optical regeneration are shown to be effective, and system architectures are revealed to be basically identical. The authors propose two types of cross-connect switch architectures using space division switches and combinations of star-couplers and multi-wavelength selective filters (MWSFs). The hardware requirements are quantitatively evaluated. It is shown that when the port number is larger than 16, the amount of hardware required to support the VWPs ranges from two to three times that required for the WPs