Photonic transport networks based on optical paths

This paper explores the technologies that will enable a further leap forward in transport network evolution. First, requirements of the future transport network are elucidated. Existing network cost is evaluated and the viable means to reduce transport network cost are identified. It is demonstrated that optical path technologies such as WP (wavelength path) and VWP (virtual wavelength path) will play a key role in this. They enhance not only transmission capacity but also cross-connect node throughput cost-effectively by capitalizing on the wavelength routeing scheme. Optical path realization technologies focusing on optical path cross-connect systems are examined. Requirements for the optical path cross-connect system are then elucidated, and a new cross-connect system architecture is evaluated. The architecture exploits PLC (planar lightwave circuit) and other commercially available technologies suitable for large-scale production. The evaluations include cross-connect node upgradability, modular growth capability, total node cost, optical loss and switching power consumption. It is proved that the architecture has significant advantages over existing switch architectures. The optical path technologies provided in this paper will pave the way for a new transport network paradigm, a ubiquitous, bandwidth-abundant and affordable broadband ISDN.