Abstract
We develop a framework that supports impairment-aware
lightpath routing and wavelength assignments in optical transport networks.
Different from most existing studies, we consider a more generic optical
transport network with physical-layer heterogeneity, including different
fiber types, variable amplification span distances and attenuation
coefficients. In addition, rather than a single amplifier type as in most of
the existing studies, we consider multiple amplifier types for different
amplification situations. Owing to the high cost of OEO regeneration, the
total number of required regenerators is considered as the major objective
for optimization. A signal-quality-aware routing algorithm is developed to
find routes that are expected to require the fewest regenerators. The
first-fit wavelength assignment algorithm is extended to assign
wavelength(s) for lightpaths after placement of some regenerators which can
freely function as wavelength converters. Simulation studies indicate that
the proposed algorithm can significantly reduce the required number of
regenerators compared to the simple shortest-path routing algorithm.
Moreover, it is found that the signal-quality-aware algorithm shows stronger
benefits when a network demonstrates higher physical-layer heterogeneity
such as different fiber types and non-uniform span losses. The
signal-quality-aware algorithm also demonstrates better performance when a
network has a higher average nodal degree. Finally, the results indicate
that multiple amplifier options are important for cost-effective optical
transport network design. For a network with high physical-layer
heterogeneity, multiple amplifier options can significantly reduce the
required number of regenerators (up to 50%) over a single amplifier
option.
© 2011 IEEE
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