On the offline physical layer impairment aware RWA algorithms in transparent optical networks: state-of-the-art and beyond

In transparent optical networks with no regeneration, the problem of capacity allocation to traffic demands is called "Roting and Wavelength Assignment". Much work on this topic recently has focused on the dynamic case, whereby demands arrive and must be served in real-time. In addition, due to lack of regeneration, physical impairments accumulate as light propagates and QoT may become inappropiate (e.g., too high Bit Error Rate). Considering the physical layer impairments in the network planning phase gives rise to a class of RWA algorithms: offline Physical Layer Impairment Aware- (PLIA-)RWA. This paper makes a survey of such algorithms, proposes a taxonomy, and a comparison between these algorithms for common metrics. We also propose a novel offline PLIA-RWA algorithm, called POLIO-RWA, and show through simulations that it decreases blocking rate compared with other PLIA-RWA algorithms.Postprint (published version

Experimental comparison of impairment-aware RWA algorithms in a GMPLS-controlled dynamic optical network

The European research project DICONET proposed and implemented a multi-plane impairment-aware solution for flexible, robust and cost-effective core optical networks. The vision of DICONET was realized via a set of cross-layer optimization algorithms designed to serve the network during planning and operation. The cross-layer modules were incorporated in a common software platform forming a planning and operation tool that takes into account physical-layer impairments in the decision making. The overall solution relies on a GMPLS-based control plane that was extended to disseminate the physical layer information required by the cross-layer modules. One of the key activities in DICONET concerns the routing and wavelength assignment of traffic demands that arrive dynamically during the network operation. Identifying the important role of dynamic lightpath provisioning, in this work we focused on the performance of routing algorithms in dynamic optical networks. We tested the suitability and performance of two different online IA-RWA algorithms in a 14-node experimental test-bed that employed centralized control-plane architecture under the same network and traffic conditions. The parameters used to evaluate the two routing engines included the lightpath setup time and the blocking ratio in a traffic scenario where connections arrive and depart from the network dynamically. Results for different traffic loads showed that optimum impairment-aware decisions are made at the expense of higher lightpath setup times.Postprint (published version

Semantic web technologies for ubiquitous computing resource management in smart spaces

Abstract: Context-aware ubiquitous computing environments tend to be highly distributed and heterogeneous, while also featuring increased dynamism as elements, devices and middleware components join, leave and change their status. In such environments, information is derived and fused with numerous sensors and context-aware middleware components. As a result, directory and naming services, along with reasoning mechanisms, are at the heart of any non-trivial ubiquitous computing application. In this paper, we argue that semantic web technologies can deal with directory service requirements of ubiquitous computing environments, much more efficiently than the wide range of legacy mechanisms. To justify this claim, we introduce a model that could greatly facilitate the development, deployment and management of ubiquitous computing applications. This model relies on semantic web technologies (i.e., ontology management) and facilitates the integration of hardware and middleware elements in the scope of a ubiquitous computing application. Using this model and its underlying ontology management schemes, we implemented proof-of-concept applications in the scope of a smart space comprising numerous sensors, actuators and middleware components. Based on the implementation experience, we outline the merits of using semantic web technologies in ubiquitous context-aware computing and smart spaces