Routing Modulation Level and Spectrum Allocation

This paper describes the physical implementation of an all-optical implementation security architecture for optical code division multiple access networks based on lattice cryptography. Our design is mainly based on the use of loop-based optical delay lines and fiber brag grating. The encryption process is achieved by delaying a pulse in the optical delay line according to the structure of the codewords. The number of loops is defined by the position of the pulse in codeword. We demonstrate that our implementation is less complex and more flexible than classical approachs such as fixed length optical delay lines. In addition, a performance evaluation using eye diagrams shows that our architecture is more robust against eavesdropping security attacks.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5970837&tag=1

Orthogonal Frequency Division Multiplexing (OFDM)
has recently been proposed as a modulation technique for optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments. We consider the planning problem of an OFDM optical network, where we are given a traffic matrix that includes the requested transmission rates of the connections to be served. Connections are provisioned for their requested rate by elastically allocating spectrum using a variable number of OFDM subcarriers and choosing an appropriate modulation level, taking into account the transmission distance. We introduce the Routing,
Modulation Level and Spectrum Allocation (RMLSA) problem, as opposed to the typical Routing and Wavelength Assignment (RWA) problem of traditional WDM networks, prove that is also NP-complete and present various algorithms to solve it. We start by presenting an optimal ILP RMLSA algorithm that minimizes the spectrum used to serve the traffic matrix, and also present a decomposition method that breaks RMLSA into its two substituent subproblems, namely, (i) routing and modulation level, and (ii) spectrum allocation (RML+SA), and solves them sequentially. We also propose a heuristic algorithm that serves connections one-by-one and use it to solve the planning problem by sequentially serving all the connections in the traffic matrix. In the sequential algorithm, we investigate two policies for defining the order in which connections are considered. We also use a simulated annealing meta-heuristic to obtain even better orderings. We examine the performance of the proposed algorithms through simulation experiments and evaluate the spectrum utilization benefits that can be obtained by utilizing OFDM elastic bandwidth allocation, when compared to a traditional WDM network.