Karcius D. R. Assis

Optimization in spectrum-sliced optical networks

Current communication in optical networks presents a wide range of granularities, making it hard to use the optical spectrum efficiently under the WDM framework. In Spectrum Sliced Optical Networks, the WDM rigid frequency grid is replaced by a more flexible structure, in which the spectrum is organized in frequency slots, and each traffic flow is assigned to an appropriate set of contiguous slots. The classical Routing and Wavelength Assignment (RWA) problem is then replaced by a Routing and Spectrum assignment (RSA) problem. This paper addresses an iterativa approach to balance the network load during the routing decision in Spectrum-Elastic Optical Path Networks. We have built numerical examples to illustrate the performance of our routing approach. Comparisons to other routing techniques show that our approach mitigates the lightpath requests blocking probability.

Iterative Optimization in VTD to Maximize the Open Capacity of WDM Networks

We propose an iterative algorithm for the Virtual Topology Design (VTD) in optical networks. The algorithm eliminates lighter traffic lightpaths and re-arrange the traffic through the remaining lightpaths. This tries to preserve the open capacity for the accommodation of future unknown demands. The results suggest that it is feasible to preserve enough open capacity to avoid blocking of future requests in networks with scarce resources; this is, maximize the traffic scaling.

Loose virtual topology design for WDM networks

Traditional approaches to wavelength routing network design divide it into two separate problems: virtual topology design (VTD), in which best connections among nodes are derived from traffic demand, generating requests for connections; and routing-and-wavelength assignment (RWA), in which physical paths are accommodated in the physical topology to support the requested connections. This separation is necessitated by complexity, but it is suboptimal and will only yield the best static solution. For the case of dynamic traffic, one needs to set up a connection for each request as it arrives, and the lightpath is released after some finite amount of time. The routing and wavelength assignments must then preserve enough open capacity to avoid blocking of future requests. Several algorithms have been proposed for this purpose. We consider a loose topology, in which static and dynamic traffic demands share the physical resources of the network. For this purpose, the static assignment problems (VTD and RWA) are solved so that blocking probability is minimized for the dynamic traffic while minimum performance objectives are met for the static demand. The proposed strategy entails the use of the dynamic RWA heuristics to guide the solution of the static VTD/RWA problem.

VIRTUAL TOPOLOGY DESIGN FOR A HYPOTHETICAL OPTICAL NETWORK

In this paper a study of the design of wide area optical networks is presented, more specifically the problem of design of the virtual topology in optical networks. A network with a small number of nodes was analyzed through a Mixed-Integer Linear Programming formulation for the problem of the virtual topology design. Heuristic methods were then applied for a hypothetical optical network with a larger number of nodes plausibly located on the Brazilian territory. The work resulted in some suggested guidelines for the design of virtual topologies.

Efficient Traffic Routing of Optical Networks for Future Demands

We propose a linear formulation for the flow routing of packets in Virtual Topology Design (VTD) of optical networks. The formulation maximizes the established the future ability to accept additional traffic through optimization of the remaining idle capacity. The results suggest that t is feasible to preserve enough open capacity to avoid blocking of future traffic in networks with scarce resources.

On Planning Optical Networks with the Uncertainty of Traffic Demand

This work aims to show the possibility of WDM optical network planning using the virtual topology. For this analysis, heuristics methods were applied to take current and future traffic into account to plan a network under limited link capacity. The results suggest that it is feasible to preserve enough open capacity to avoid blocking of future traffic, without network disruption, allocating appropriate link capacities for a given planning period.