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An important problem in WDM network design is to construct a logical topology and determine an optimal routing over that topology. Mixed Integer Linear Program (MILP) formulations to generate optimal solutions for this problem have been presented. Such formulations are computationally intractable, even for moderate sized networks. A standard approach is to decouple the problem of logical topology design and the problem of routing the traffic on this logical topology. Heuristics for finding the logical topology exist and a straight-forward linear program (LP), based on the node-arc formulation can be used to solve the routing problem over a given logical topology. We have found that such LP formulations become computationally infeasible for large networks. In this paper, we present a new formulation, based on the arc-chain representation, for optimally routing the specified traffic over a given logical topology to minimize the congestion of the network. We have used the revised simplex method incorporating an implicit column generation technique, and exploited the special Generalized Upper Bounding structure as well as the possibility of eta-factorization for efficiently updating the dual variables and finding the solution. Experimental results on a number of networks demonstrate the suitability of this approach. 相似文献
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Arunita Jaekel Ataul Bari Quazi Rahman Ying Chen Subir Bandyopadhyay Yash Aneja 《Optical Switching and Networking》2012,9(4):271-285
In WDM networks, path protection has emerged as a widely accepted technique for providing guaranteed survivability of network traffic. However, it requires allocating resources for backup lightpaths, which remain idle under normal fault-free conditions. In this paper, we introduce a new design strategy for survivable network design, which guarantees survivability of all ongoing connections that requires significantly fewer network resources than protection based techniques. In survivable routing, the goal is to find a Route and Wavelength Assignment (RWA) such that the logical topology remains connected for all single link failures. However, even if the logical topology remains connected after any single link fault, it may not have sufficient capacity to support all the requests for data communication, for all single fault scenarios. To address this deficiency, we have proposed two independent but related problem formulations. To handle our first formulation, we have presented an Integer Linear Program (ILP) that augments the concept of survivable routing by allowing rerouting of sub-wavelength traffic carried on each lightpath and finding an RWA that maximizes the amount of traffic that can be supported by the network in the presence of any single link failure. To handle our second formulation, we have proposed a new design approach that integrates the topology design and the RWA in such a way that the resulting logical topology is able to handle the entire set of traffic requests after any single link failure. For the second problem, we have first presented an ILP formulation for optimally designing a survivable logical topology, and then proposed a heuristic for larger networks. Experimental results demonstrate that this new approach is able to provide guaranteed bandwidth, and is much more efficient in terms of resource utilization, compared to both dedicated and shared path protection schemes. 相似文献
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Cauchy with whale optimizer based eagle strategy for multi-level color hematology image segmentation
Ray Swarnajit Das Arunita Dhal Krishna Gopal Gálvez Jorge Naskar Prabir Kumar 《Neural computing & applications》2021,33(11):5917-5949
Neural Computing and Applications - Pathological color image segmentation is an exigent procedure due to the existence of imperceptibly correlated, and indistinct multiple regions of concern.... 相似文献
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Das Arunita Dhal Krishna Gopal Ray Swarnajit Galvez Jorge Das Sanjoy 《Multimedia Tools and Applications》2022,81(20):28955-28986
Multimedia Tools and Applications - Flower Pollination Algorithm (FPA) is a well-known swarm intelligence optimization algorithm, which has shown an effective performance by solving many... 相似文献
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Higher power relay nodes can be used as cluster heads in two-tiered sensor networks to achieve improved network lifetime. The relay nodes may form a network among themselves to route data towards the base station. In this model, the lifetime of a network is determined mainly by the lifetimes of these relay nodes. An energy-aware communication strategy can greatly extend the lifetime of such networks. However, integer linear program (ILP) formulations for optimal, energy-aware routing quickly become computationally intractable and are not suitable for practical networks. In this paper, we have proposed an efficient solution, based on a genetic algorithm (GA), for scheduling the data gathering of relay nodes, which can significantly extend the lifetime of a relay node network. For smaller networks, where the global optimum can be determined, our GA based approach is always able to find the optimal solution. Furthermore, our algorithm can easily handle large networks, where it leads to significant improvements compared to traditional routing schemes. 相似文献
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Physical layer impairments in wavelength-routed networks limit the maximum distance, a signal can travel in the optical domain,
without significant distortion. Therefore, signal regeneration is required at some intermediate nodes for long-haul lightpaths.
In translucent WDM networks, sparsely located regenerators at certain nodes can be used to offset the impact of physical layer
impairments. The routing and wavelength assignment (RWA) techniques in such translucent networks need to take into consideration
the availability of regenerators and the maximum optical reach of the transparent lightpaths (without any regeneration). Although
there has been significant research interest in RWA algorithms for translucent networks, much of the research has focused
on dynamic RWA techniques. Only a handful of recent papers have considered the static (offline) case, and they typically propose heuristic algorithms to solve this complex design problem for practical networks.
In this paper, we propose a generalized integer linear program (ILP) based formulation for static regenerator assignment and RWA in translucent WDM optical networks, with sparse regenerator placement. To the best of our
knowledge, such a formulation that optimally allocates resources for a set of lightpaths for translucent networks, given the
physical network, the locations of the regenerators, and the maximum optical reach has not been considered before. The proposed
formulation is important for two reasons. First, it can serve as a benchmark for evaluating different heuristic approaches
that may be developedin the future. Second, we show that using a novel node representation technique, it is possible to drastically
reduce the number of integer variables. This means that unlike existing ILP formulations, our approach can actually be used
to generate optimal solutions for practical networks, with hundreds of lightpath demands. 相似文献
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Two possible approaches can be considered for solving the virtual topology design problem for periodic (multi-hour) traffic demands. The first approach attempts to design a static topology that can accommodate all the traffic variations over time. The second option is to determine an appropriate series of virtual topologies to accommodate the different traffic loads at different times. This can lead to some savings in terms of the number of transceivers needed, but it requires the use of costly reconfigurable switching equipment. So, strategies for stable virtual topology design have received considerable attention in recent years. However, all the works reported in the literature so far, focus on the fixed window scheduled traffic model, where the start and end times of the demands are known in advance. In this paper, we propose a new integrated approach using the more general sliding window model, for jointly scheduling the demands in time and designing a logical topology that can accommodate all the scheduled demands. The goal is to a find a suitable static topology that can handle fluctuations in the offered sub-wavelength traffic load, without requiring the use of reconfigurable optical switching equipment. We first present a comprehensive integer linear program (ILP) formulation for designing a cost-efficient, stable logical topology for time-varying demands, and then propose an integrated heuristic algorithm capable of handling larger networks. Simulation results demonstrate the advantages of the proposed approaches, not only compared to holding time unaware models, but also over the traditional fixed window model. 相似文献
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Ataul Bari Arunita Jaekel Subir Bandyopadhyay 《Wireless Communications and Mobile Computing》2009,9(7):920-937
In hierarchical sensor networks using relay nodes, sensor nodes are arranged in clusters and higher powered relay nodes can be used as cluster heads. The lifetime of such a network is determined primarily by the lifetime of the relay nodes. In this paper, we propose two new integer linear programs (ILPs) formulations for optimal data gathering, which maximize the lifetime of the upper tier relay node network. Unlike most previous approaches considered in the literature, our formulations can generate optimal solutions under the non‐flow‐splitting model. Experimental results demonstrate that our approach can significantly extend network lifetime, compared to traditional routing schemes, for the non‐flow‐splitting model. The lifetime can be further enhanced by periodic updates of the routing strategy based on the residual energy at each relay node. The proposed rescheduling scheme can be used to handle single or multiple relay node failures. We have also presented a very simple and straightforward algorithm for the placement of relay nodes. The placement algorithm guarantees that all the sensor nodes can communicate with at least one relay node and that the relay node network is at least 2‐connected. This means that failure of a single relay node will not disconnect the network, and data may be routed around the failed node. The worst case performance of the placement algorithm is bounded by a constant with respect to any optimum placement algorithm. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Arunita Jaekel Ataul Bari Ying Chen Subir Bandyopadhyay 《Photonic Network Communications》2010,19(2):223-232
Traffic grooming techniques are used to combine low-speed data streams onto high-speed lightpaths with the objective of minimizing
the network cost, or maximizing the network throughput. In this article, we present a complete suite of efficient Integer
Linear Program (ILP) formulations for logical topology design and traffic grooming on mesh WDM networks. Our formulations
can be easily modified to implement different objective functions and, contrary to previous formulations, our ILP formulation
can be used to generate optimal solutions for practical sized networks with hundreds of requests. Our first set of formulations
addresses the complete logical topology design traffic grooming problem, including RWA and traffic routing. The second set
uses the simplifying assumption that RWA is not an issue. The last two sets address optimal traffic grooming alone, where
the logical topology is already specified. We have studied these formulations, using simulation with networks having up to
30 nodes, and with hundreds and, in some cases, over a thousand low-speed data streams and have shown that the formulations
are able to generate optimal solutions within a reasonable amount of time. 相似文献