Browsing by Author "Rak, Jacek"
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- Fundamental schemes to determine disjoint paths for multiple failure scenariosPublication . Gomes, Teresa; Jorge, Luisa; Girão-Silva, Rita; Yallouz, Jose; Babarczi, Péter; Rak, JacekDisjoint path routing approaches can be used to cope with multiple failure cenarios. This can be achieved using a set of k (k>2) link- (or node-) disjoint path pairs (in single-cost and multi-cost networks). Alternatively, if Shared Risk Link Groups (SRLGs) information is available, the calculation of an SRLG-disjoint path pair (or of a set of such paths) can protect a connection against the joint failure of the set of links in any single SRLG. Paths traversing disaster-prone regions should be disjoint, but in safe regions it may be acceptable for the paths to share links or even nodes for a quicker recovery. Auxiliary algorithms for obtaining the shortest path from a source to a destination are also presented in detail, followed by the illustrated description of Bhandari’s and Suurballe’s algorithms for obtaining a pair of paths of minimal total additive cost. These algorithms are instrumental for some of the presented schemes to determine disjoint paths for multiple failure scenarios.
- Interdependence between power grids and communication networks: a resilience perspectivePublication . Martins, Lúcia; Girão-Silva, Rita; Jorge, Luisa; Gomes, Álvaro; Musumeci, Francesco; Rak, JacekPower network resilience is increasingly dependent on communication networks. Besides traditional generation, power networks need to accommodate increasingly high penetration levels of dispersed micro generation, mostly based on renewable sources, and increasing and challenging demand, such as electric vehicles. At the same time the deployment of enabling technologies throughout the power grid makes available new demand resources and storage capacity. These resources have to be jointly managed for efficient and resilient operation. Therefore a resilient communication network is mandatory for the smart control of these different resources. Communication networks in turn also rely on the power networks in spite of some power backup that they may have. This interdependence is especially critical in bad weather conditions where both networks can be severely affected, even more when they strongly depend on each other. This work describes ongoing research related with the interdependence between both networks regarding resilience, cascading failure effects, applicable models and simulation techniques.
- A survey of strategies for communication networks to protect against large-scale natural disastersPublication . Gomes, Teresa; Tapolcai, Janos; Esposito, Christian; Hutchison, David; Kuipers, Fernando; Rak, Jacek; Sousa, Amaro de; Iossifides, Athanasios; Travanca, Rui; André, João; Jorge, Luísa; Martins, Lúcia; Ugalde, Patricia Ortiz; Pasic, Alija; Pezaros, Dimitrios; Jouet, Simon; Secci, Stefano; Tornatore, MassimoAbstract—Recent natural disasters have revealed that emer- gency networks presently cannot disseminate the necessary dis- aster information, making it difficult to deploy and coordinate relief operations. These disasters have reinforced the knowledge that telecommunication networks constitute a critical infrastruc- ture of our society, and the urgency in establishing protection mechanisms against disaster-based disruptions. Hence, it is important to have emergency networks able to maintain sustainable communication in disaster areas. Moreover, the network architecture should be designed so that network connectivity is maintained among nodes outside of the impacted area, while ensuring that services for costumers not in the affected area suffer minimal impact. As a first step towards achieving disaster resilience, the RE- CODIS project was formed, and its Working Group 1 members conducted a comprehensive literature survey on “strategies for communication networks to protect against large-scale natural disasters,” which is summarized in this article.
- A survey on network resiliency methodologies against weather-based disruptionsPublication . Tornatore, Massimo; André, João; Babarczi, Péter; Braun, Torsten; Folstad, Eirik; Heegaard, Poul; Hmaity, Ali; Furdek, Marija; Jorge, Luísa; Kmiecik, Wojciech; Mas Machuca, Carmen; Martins, Lúcia; Medeiros, Carmo; Musumeci, Francesco; Pasic, Alija; Rak, Jacek; Simpson, Steven; Travanca, Rui; Voyiatzis, ArtemiosDue to the increasing dependence on network ser- vices of our society, research has recently been concentrating on enhancing traditional protection strategies to withstand large- scale failures, as in case of disaster events. The recently-formed EU-funded RECODIS project aims at coordinating and fostering research collaboration in Europe on disaster resiliency in com- munication networks. In particular, the Working Group (WG) 2 of the RECODIS project focuses on developing new network- resiliency strategies to survive weather-based disruptions. As a first step, WG2 members have conducted a comprehensive literature survey on existing studies on this topic. This paper classifies and summarizes the most relevant studies collected by WG2 members in this first phase of the project. While the majority of studies regarding weather-based disruptions deals with wireless network (as wireless channel is directly affected by weather conditions), in this survey we cover also disaster- resiliency approaches designed for wired network if they leverage network reconfiguration based on disaster “alerts”, considering that many weather-based disruptions grant an “alert” thanks to weather forecast.