Helder A. Pereira

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We propose a model that considers several physical impairments in all-optical networks based on optical signal-to-noise degradation. Our model considers the gain saturation effect and amplified spontaneous emission depletion in optical amplifiers, coherent crosstalk in optical switches, and four-wave mixing in transmission fibers. We apply our model to(More)
In this paper, we propose two strategies for sparse regenerator placement (RP) in translucent optical networks, named most used regenerator placement (MU-RP), and most simultaneous used regenerator placement (MSU-RP). Our proposals are compared to well known RP algorithms presented in literature for two different network topologies for different network(More)
A fundamental issue in Elastic Optical Networks (EONs) relies on choosing a proper route and necessary number of contiguous frequency slots from end-to-end to accommodate the traffic demands. Spectrum assignment based on the traditional First-Fit assignment has been extensively employed in EON investigations due to its inherent simplicity and favorable(More)
In this paper, we propose two heuristics to perform regenerator assignment in translucent elastic optical networks. The first one tries to use the modulation format with the highest spectral efficiency, whereas the other one aims to transmit the optical signal as far as possible before it undergoes into a regeneration process. The former deploys several(More)
This paper presents a wavelength assignment algorithm suitable for optical networks mainly impaired by physical layer effects, named the Intelligent Wavelength Assignment algorithm (iWA). The main idea is to determine the wavelength activation order for a first-fit algorithm that balances the impact of the physical layer effects by using a training(More)
In this paper we propose the use a multiobjective evolutionary optimization algorithm to solve the regenerators placement problem (MORP). Network performance and capital costs are used as optimization objectives. We consider that optical signals are regenerated using a network element that performs 3R (re-amplifying, re-shaping and re-timing) in the(More)
In this paper we propose the use a multiobjective evolutionary optimization algorithm to solve the regenerators placement problem. The optical network performance and the capital costs are used as optimization objectives. The blocking probability is used as the network performance indicator, which is evaluated by network simulations with an impairment aware(More)
This paper presents a wavelength assignment algorithm for all optical networks. The main idea is to determine the wavelength assignment order for a first fit algorithm taking into account the physical layer effects, such as four wave mixing and residual dispersion, by using a training algorithm inspired in evolutionary computation concepts. The intelligent(More)
In this paper, we propose a novel algorithm to restore calls upon a single failure in transparent optical networks. After a failure, the proposed algorithm performs a path restoration searching for the route which presents the higher optical signal-to-noise ratio. We compared our proposal to three other well known approaches in the literature. We achieved(More)
In this paper we present a novel path restoration algorithm, named PSR-R. Our proposal is based on the power series routing (PSR) algorithm, which was proposed by Chaves et al. in 2011 for routing. The cost function for each link is given by a function expanded in a power series, considering as input variables the wavelength availability and the link(More)