Publications (13)1.98 Total impact
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Chapter: Genetic Algorithms for Semi-Static Wavelength-Routed Optical Networks
03/2012; , ISBN: 978-953-51-0146-8 -
Conference Proceeding: Advantages of using cognition when solving impairment-aware virtual topology design problems
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ABSTRACT: In this paper, the advantages of using cognition when solving the impairment-aware virtual topology design problem are demonstrated. To this end, an algorithm to design the virtual topology, GAPDELT, previously proposed by the University of Valladolid, has been extended to ensure that all the lightpaths of the virtual topology comply with quality of transmission constraints. The new version, called IA-GAPDELT, is a multiobjective genetic algorithm which uses Pareto optimality to reduce both the network congestion and the number of transmitters in operation, and so the energy consumption. By means of simulation, we show that when the algorithm is enhanced with a simple cognitive technique, it obtains a higher number of feasible solutions (virtual topologies) and, moreover, they are generally better in terms of the optimization parameters, than those obtained without cognition.Transparent Optical Networks (ICTON), 2011 13th International Conference on; 07/2011 -
Article: A bandwidth assignment polling algorithm to enhance the efficiency in QoS long‐reach EPONs
European Transactions on Telecommunications 11/2010; 22(1):35 - 44. · 0.45 Impact Factor -
Conference Proceeding: Interleaved polling algorithm with inserted cycles to support service level agreement in Long-Reach EPONs
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ABSTRACT: A new dynamic bandwidth allocation algorithm for long-reach Ethernet passive optical networks is proposed in order to provide client differentiation. The new algorithm differs clients as it takes into consideration the service level agreement (SLA) contracted by each subscriber, achieving better performance for the highest service level agreements in terms of the mean packet delay. Moreover, the algorithm is able to work with the same efficiency even when the long-reach EPON distance is highly increased up to 225 km. Therefore, it keeps the same good values of throughput, mean packet delay and mean cycle time independently of the end to end distance.Transparent Optical Networks, 2009. ICTON '09. 11th International Conference on; 08/2009 -
Conference Proceeding: Efficient reconfiguration of logical topologies: Multiobjective design algorithm and adaptation policy
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ABSTRACT: Communication networks are facing continuous variations of traffic patterns as well as occasional failures of network equipment. Wavelength-routed optical networks (WRONs) offer the possibility of dynamically adapting to traffic conditions by means of reconfiguring the logical topology, that is, the set of lightpaths embedded in it. However, reconfiguration has a cost, the number of packets lost during the reconfiguration process. Hence, it is necessary to use efficient reconfiguration policies and algorithms to design the logical topologies. In this paper, a new algorithm is proposed to design logical topologies that jointly minimizes the number of lightpaths changed (reconfiguration cost) and the network congestion (reconfiguration reward). This method is based on the combination of genetic algorithms with Pareto optimality techniques. Thus, the algorithm provides a set of optimal (or near-optimal) solutions in terms of both parameters, the Pareto optimal set. Moreover, a novel policy to minimize the packet loss ratio considering all the solutions provided by the algorithm is also proposed. A simulation study is presented to show how the combination of the new algorithm and policy can reduce in more than one order of magnitude the packet loss ratio in stationary state and respond to abrupt changes in less time when compared with previous work on logical topology reconfiguration.Broadband Communications, Networks and Systems, 2008. BROADNETS 2008. 5th International Conference on; 10/2008 -
Conference Proceeding: Multiobjective Genetic Algorithm to Design Cost-Efficient Wavelength-Routed Optical Networks
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ABSTRACT: A new algorithm, GAPDELT, is presented to jointly design the resource provisioning and the logical topology of wavelength-routed optical networks. GAPDELT is based on genetic algorithms and uses Pareto optimality to reduce both the network congestion and the number of resources employed. By means of a simulation study, we show that GAPDELT designs a set of good alternatives that achieve up to 50% of reduction in terms of congestion or 75% of reduction in the number of transmitters and receivers required when compared with another well-knownTransparent Optical Networks, 2007. ICTON '07. 9th International Conference on; 08/2007 -
Conference Proceeding: Interleaved Polling Algorithm with Service Level Agreement (SLA) to Improve QoS in Ethernet PONs
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ABSTRACT: We propose a dynamic bandwidth allocation algorithm for ethernet passive optical networks (EPON) called IP-SLA (interleaved polling with SLA) to offer quality of service (QoS) in the upstream direction. IP-SLA differs clients inside the network as it takes into consideration the service level agreement (SLA) contracted by each subscriber, achieving better performance for the highest service levels agreement in terms of both mean packet delay and packet loss rate. On the other hand, IP-SLA also provides service differentiation based on the strict priority queueing method, which provides the minimum mean packet delay for the most priority services without considering the penalization caused to the lowest priority traffic. However, our algorithm keeps the mean packet delay for the most priority classes of services inside the specified bounds and uses the remaining resources to improve the performance of the lowest priority services in terms of mean packet delay and packet loss rate.Transparent Optical Networks, 2007. ICTON '07. 9th International Conference on; 08/2007 -
Conference Proceeding: A Genetic Algorithm to Design Logical Topologies with Low Congestion in Reconfigurable WDM Networks
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ABSTRACT: We present a novel genetic algorithm to design logical topologies for reconfigurable wavelength-routed optical networks. Not only does the algorithm determine which nodes should be connected by means of lightpaths with the aim of minimizing congestion, but it also solves the routing and wavelength assignment problem and routes the traffic in the logical topology. The algorithm is effective in terms of congestion achieving reductions of up to 80% when compared with previous works.Photonics in Switching, 2006. PS '06. International Conference on; 11/2006 -
Conference Proceeding: Multipurpose Genetic Algorithm Based in Pareto Optimality to Design Logical Topologies in Reconfigurable WDM Networks
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ABSTRACT: We propose a novel multipurpose genetic algorithm based in Pareto optimality to design logical topologies for wavelength-routed optical networks with the aim of minimizing both the global average end-to-end delay and the average end-to-end delay of the most delayed traffic flow. The algorithm determines which nodes should be connected by means of lightpaths, solves the routing and wavelength assignment problem, and routes the traffic in the logical topology. When compared with another multipurpose genetic algorithm based in random selections of two fitness functions (one for each parameter to be optimized), the novel algorithm leads to reductions of up to 5% in both parametersTransparent Optical Networks, 2006 International Conference on; 07/2006 -
Article: Analysis and optimisation of the apodisation sharpness for linearly chirped dispersion compensating gratings
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ABSTRACT: The impact of the apodisation sharpness on the spectral response of linearly chirped dispersion compensating gratings is evaluated. It will be demonstrated that the behaviour of the mean dispersion, group delay ripple, reflection bandwidth and insertion losses shows stronger dependence on the apodisation sharpness than on the type of apodisation profile. A detailed analysis is carried out with the view to compare the spectral characteristics of linearly chirped gratings applying different apodisation profiles with increasing sharpness to compensate the dispersion of 100 km of standard single-mode fibre. It will be shown that an apodisation factor of ∼0.8 results in minimum group delay ripple impact, minimum deviation from the required dispersion value and maximum reflection bandwidth ensuring, at the same time, minor increase of grating length and insertion losses compared with the non-apodised case. This value can be considered as the optimum apodisation sharpness for the profiles under study, allowing faster modelling and more effective fabrication steps for reflective dispersion compensating gratings.IEE Proceedings - Optoelectronics 05/2004; · 0.71 Impact Factor -
Article: Optimization of the apodization strength of linearly chirped Bragg gratings for span dispersion compensation
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ABSTRACT: We present an optimization process for the apodization strength factor of fiber Bragg grating dispersion compensators. It will be demonstrated that a proper choice of the apodization strength factor results in minimum deviation of the dispersion from the required level, maximum reflection bandwidth and minimum group delay ripple impact, thus leading to a reduction of the Q-factor penalty of the dispersion compensating system. We also discuss the influence of the fiber link length in the determination of the optimum apodization strength factor, taking into account that shorter links minimize the group delay ripple amplitude, whereas the longer ones maximize the bandwidth of interest. It is determined that a fiber link length of 80 km can balance the requirements of group delay ripple impact and bandwidth. The results obtained through this analysis allow a faster modeling of the Bragg grating parameters in order to achieve an improved spectral performance, as well as a cost-effective fabrication process.Optical and Quantum Electronics 12/2003; 36(1):57-66. · 0.82 Impact Factor -
Conference Proceeding: Simulation and design tool for spectral characterization of fiber Bragg gratings
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ABSTRACT: The apodized linearly chirped Bragg grating filters (ALCFBG) are of increasing interest for compensating chromatic dispersion in fiber-optic WDM communication networks. In this paper we present a Matlab graphic application that allows the analysis of ALCFG's, taking into account the effect of the fabrication process on the averaged refractive index of the designed grating. A design process to determine the fiber grating parameters needed to achieve the dispersion compensation of a certain link of standard single-mode fiber is also included in this tool as well as the deviation range from the ideal theoretical compensator.Transparent Optical Networks, 2002. Proceedings of the 2002 4th International Conference on; 02/2002 -
Conference Proceeding: Advantages of using cognition when solving impairment-aware virtual topology design problems
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ABSTRACT: Export Date: 10 February 2012, Source: Scopus, Art. No.: 5970810
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Institutions
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2004–2011
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Universidad de Valladolid
- Departamento de Teoría de la Señal y Comunicaciones e Ingeniería Telemática
Valladolid, Castile and Leon, Spain
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