Semi-filterless Optical Network : A Cost-efficient Passive Wide Area Network with Effective Resource Utilization

Abstract: Two novel passive wide area network (WAN) approaches, filterless and semi-filterless optical networks, utilizing advanced optical coherent transmission and electrical compensation technologies are introduced. These approaches are able to eliminate or reduce the use of expensive active photonic reconfigurable components by interconnecting nodes with passive components. The resulting networks are more cost- and energy-efficient, as well as more reliable, compared to the networks based on active optical switching. Beside the advantages which filterless optical networks offer, they suffer from broadcasting characteristics. A single wavelength goes further than the intended destination node and consequently any assigned wavelength can only be used once in a given fiber tree. Addressing the drawback of the filterless approach, semi-filterless optical networks introduce passive wavelength filters at some selected nodes. Such an approach can improve resource utilization, because placing filters at some predefined nodes prevents signals from going further than their intended destination and the broadcast nature of the purely filterless approach can be limited. This thesis project proposes an efficient algorithm to design a semi-filterless optical network. Moreover, a simulation tool for filter placement and wavelength assignment has been developed in order to validate the devised algorithm. Performance evaluation, done by using this tool, confirms that a properly designed semi-filterless optical network can provide a significant reduction in resource usage, while keeping the deployment cost as low as the filterless network.