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Designing Survivable and Quantum Key Distribution Secured Elastic Optical Networks

Ehsani Moghaddam, Elham | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54858 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Salehi, Jawad; Beyranvand, Hamzeh
  7. Abstract:
  8. Elastic optical networks, due to their key features including flexible spectrum allocation, ability to convey high bitrates, and distance adaptive modulation assignment are considered as a promising solution for providing higher capacity, more efficiency, and scalability in core optical networks.Furthermore, Multi-Core Fibers (MCFs) and Space Division Multiplexing (SDM) technique can be utilized to overcome the capacity limitation of the conventional Single Mode Fibers (SMFs). However, the inter-core crosstalk issue in MCFs should be addressed in the design of these networks.With the use of these technologies and, as a result, increasing the transmission rate in optical networks, the issue of security, which has always been a concern of network designers, becomes much more important.Quantum security methods have received a lot of attention from researchers because of providing unconditional security, which means that in contrast to classical (non-quantum) methods, they do not depend on computational power, and their security is based on physical laws.In this research, we have investigated the quantum security issue based on the quantum key distribution in elastic optical networks with single or multi core fibers and optimum routing and spectrum and core assignment providing survivability and supporting multi-class traffic in terms of required security level.Due to the coexistence of quantum and classical channels in the network, intense classical signals could destructively impact the pale quantum signals. Thus, we first calculated the background noise consisting of impactive noise sources and the combination of the resulting noise signals. Then, we calculated the secret key rate in quantum channels accordingly while considering different values for effective fiber and network parameters.Then, we extracted mathematical formulations as an integer linear programming (ILP) to model the resource allocation to the quantum and classical channels of QKD and the conventional classical data channels. We proposed novel strategies for core and spectrum assignment and applied the mathematical equations accordingly. These strategies have been designed to allocate network resources to each of the classical and quantum channels of the secret key sharing process and the classical data channels, considering the impact of intra-core noise signals (e.g. Raman scattering) and inter-core noise signals (e.g. the crosstalk resulted from Raman scattering).In order to solve the introduced problems in a faster way, we proposed a heuristic algorithm that shows a near-optimal performance but in a very shorter time. This algorithm includes the core and spectrum assignment strategies and can solve the problem for real large networks and requests set in a logical amount of time. We also applied the difference of requests in terms of security level and survivability in both ILP and heuristic algorithm.Finally, by extensive simulations and extracting the results, we evaluated the proposed methods, including the ILP formulation and the heuristic algorithm in terms of secret key rate and the utilization of network resources. In order to have a comprehensive evaluation, we considered different topologies, fixed and distance adaptive input power for classical signals, different fiber specifications, and different assumptions regarding the relative locations of quantum and classical channels in a multi-core fiber.
  9. Keywords:
  10. Elastic Optical Networks (EON) ; Quantum Key Distribution ; Space Division Multiplexing ; Multicore Fibers ; Survivability ; Secret Key Rate

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