In an OFDM-based optical network, how will spectrum overlapping between connections (which are served at their requested transmission rate) affect the Routing, Modulation Level, and Spectrum Allocation (RMLSA) problem?
In orthogonal frequency division multiplexing overlapping of spectrum would not affect but the synchronization of frequency should be maintained.
In that case, how can the synchronization be maintained, lets say, if the connection requests to be provisioned are dynamic in nature.
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.
By presenting an optimal ILP RMLSA algorithm that minimizes
the spectrum used to serve the traffic matrix, and also 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.
Take a look at this publication: https://www.ceid.upatras.gr/webpages/faculty/manos/files/papers/ofdm_jlt_revision_2.pdf
Not sure you still need to simulate Coherent Optical OFDM Systems in Matlab. There are commercial matlab modules for simulation of linear fiber optic coherent OFDM systems that are available with CodeSScientific. The link is:
http://codesscientific.com/fiber-optic-communication-systems-simulations/10/
Also there are commercial matlab modules for compensating laser phase noise in a QPSK system and compensating fiber chromatic dispersion in a x- span QPSK system. The Link is:
http://codesscientific.com/fiber-optic-communication-systems-simulations/12/
You can go through them. May be they will be helpful for you.
Best Regards,
Kalpana Tewari, PhD
Research Scientist
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