Design of Advanced optical networks based on the filterless concept

Abstract

Global Internet traffic will continue to grow at high speed in the forthcoming years. To meet this requirement and challenge, the capacity of optical core and regional networks has increased significantly over the past few years by leveraging the wavelength division multiplexing (WDM) technology. Telecommunications network providers have been steadily focusing on reducing their operational costs and increasing the transmission efficiency so as to deploy more costeffective and spectrally efficient agile optical networks. Failure survivability is one of network operators’ major concerns considering that enormous losses could be caused by one small node or link failure in actual ultra high capacity optical networks. The filterless network concept has been proposed as a simpler and more cost-effective method to deliver network agility compared to conventional wavelength selective switch (WSS) -based active photonic switching networks. This concept is based on the premise that the need for network agility and reconfigurability can be provided by using tunable transmitters and coherent receivers at the network edge terminals, as in radio networks. A filterless network is devised by solving the fiber link interconnection problem, and then the resulting solutions are characterized by an intrinsic protection ratio. In this thesis, we propose a 1+1 dedicated optical-layer protection strategy for filterless networks in an effort to provide 100% protection for any connection within the topology. The wavelength consumption of protected filterless solutions is evaluated by solving the routing and wavelength assignment (RWA) problem. The simulation results show that the survivable filterless network solutions can be more cost-effective than its active counterpart while keeping the number of used wavelengths at a comparable level. Elastic (flex-grid) optical networking is a promising solution to improve spectral efficiency and flexibility since channel bandwidth can be assigned to a traffic demand dynamically, according to its capacity and distance requirements. In this thesis, we present the concept of elastic filterless optical networks, which combines the advantages of filterless network architectures and flex-grid networking. Besides, we propose not only an mathematical optimization method based on an integer linear programming (ILP) formulation but also more computationally efficient heuristic methods to solve the routing and spectrum assignment (RSA) problem in the elastic filterless optical networks. The performance in terms of spectrum utilization and cost for fixed- and flex-grid filterless solutions are compared and the benefits of periodical spectrum defragmentation are quantified through simulations as well