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http://hdl.handle.net/10662/265
2024-03-19T06:41:38ZEEG-based brain-computer interfaces using motor-imagery: Techniques and challenges
http://hdl.handle.net/10662/20662
Títulos: EEG-based brain-computer interfaces using motor-imagery: Techniques and challenges
Autores/as: Padfield, Natasha; Zabalza, Jaime; Zhao, Huimin; Masero Vargas, Valentín; Ren, Jinchang
Resumen: Electroencephalography (EEG)-based brain-computer interfaces (BCIs), particularly those using motor-imagery (MI) data, have the potential to become groundbreaking technologies in both clinical and entertainment settings. MI data is generated when a subject imagines the movement of a limb. This paper reviews state-of-the-art signal processing techniques for MI EEG-based BCIs, with a particular focus on the feature extraction, feature selection and classification techniques used. It also summarizes the main applications of EEG-based BCIs, particularly those based on MI data, and finally presents a detailed discussion of the most prevalent challenges impeding the development and commercialization of EEG-based BCIs.2019-01-01T00:00:00ZAn OAM Function to Improve the Packet Loss in MPLS-TP Domains for Prioritized QoS-Aware Services
http://hdl.handle.net/10662/20482
Títulos: An OAM Function to Improve the Packet Loss in MPLS-TP Domains for Prioritized QoS-Aware Services
Autores/as: Rodríguez Pérez, Francisco Javier; González Sánchez, José Luis, 1963-; Carmona Murillo, Javier Domingo; Cortés Polo, David Miguel
Resumen: La aparición de nuevos tipos de aplicaciones y tecnologías (por ejemplo, aplicaciones de uso intensivo de datos, virtualización de servidores y tecnología de big data) ha provocado una mayor utilización de los recursos de red. Estos servicios implican mayor consumo de ancho de banda y congestiones inesperadas, especialmente en las redes troncales.En este artículo se estudia una novedosa propuesta con el objetivo de mejorar el rendimiento de las clases de equivalencia de reenvío priorizadas endominios congestionados de Multiprotocol Label Switching Transport Profile (MPLS-TP). El impacto de la congestión sobre Se analiza el impacto de la congestión en los servicios de calidad de servicio que requieren alta fiabilidad y bajo retardo. Se ha implementado una nueva política implementada en MPLS-TP, que es una tecnología que proporciona QoS mediante la diferenciación de flujos en las redes troncales de Internet. La propuesta se conoce como política de recuperación local basada en Gossip y se ofrece como una operación administración y gestión para permitir la recuperación local del tráfico perdido para las clases de equivalencia de reenvío privilegiadas MPLS-TP. Para cumplir los requisitos de implementación en MPLS-TP, también se ha propuesto un conjunto mínimo de extensiones a la ingeniería de tráfico del protocolo de reserva de recursos para proporcionar rutas con capacidad de autogestión. Por último, hemos llevado a cabo una medición de la mejora del rendimiento mediante mediante un modelo analítico y simulaciones; The emergence of new kinds of applications and technologies (e.g., data-intensive applications, server virtualization, and big data technology) has led to a higher utilization of network resources. These services imply increased bandwidth consumption and unexpected congestions, especially in backbones. In this article, a novel proposal is studied with the aim of improving the performance of prioritized forwarding equivalence classes in congested Multiprotocol Label Switching Transport Profile (MPLS-TP) domains. The congestion impact on those QoS-aware services that require high reliability and low delay is analyzed. A new policy has been implemented on MPLS-TP, which is a technology that provides QoS by means of flow differentiation in the Internet backbones. The proposal is known as Gossip-based local recovery policy and is offered as an operation, administration, and management function to allow local recovery of lost traffic for MPLS-TP privileged forwarding equivalence classes. In order to fulfill the requirements for implementation on MPLS-TP, a minimum set of extensions to resource reservation protocol traffic engineering has also been proposed to provide self-management capable routes. Finally, we have carried out a performance improvement measurement by means of an analytical model and simulations2015-04-01T00:00:00ZNot in My Neighborhood: A User Equipment Perspective of Cellular Planning Under Restrictive EMF Limits
http://hdl.handle.net/10662/20414
Títulos: Not in My Neighborhood: A User Equipment Perspective of Cellular Planning Under Restrictive EMF Limits
Autores/as: Chiaraviglio, Luca; Galán Jiménez, Jaime; Fiore, Marco; Blefari Melazzi, Nicola
Resumen: The installation of base station (BS) sites is regulated by a variety of laws at international, national, and local levels. While international regulations are already severe, the national and local laws applied in many countries and regions follow precautionary principles and enforce electromagnetic field (EMF) constraints that are even more restrictive. This legal environment results in substantial constraints affecting the planning of cellular networks, as requests for new BS site installation are easily denied by national or local authorities. In this paper, we consider the problem of cellular planning under restrictive EMF limits from the user equipment (UE) viewpoint. We focus on outdoor urban areas and first evaluate the impact of the current, non-optimal network planning at the UE side through a quantitative measurement-driven analysis of the quality of service (QoS) observed by users in heterogeneous, large-scale urban scenarios. We then perform a qualitative assessment of the perceived QoS and generated EMF levels at one UE transferring data from/to a BS based on its position with respect to the serving BS. Finally, we run a what-if analysis by comparing the existing planning with the one where new BS sites can be installed, thanks to a relaxation of the restrictive EMF constraints. Our results clearly show that a cellular planning driven by restrictive EMF constraints forces UE to experience large distances from the serving BS, frequent non-line-of-sight conditions, and poor received signal. In turn, this entails a very negative combination of high electric field activity (EFA) levels generated by the UE and low QoS perceived by the user. We show that, by relaxing the restrictive EMF constraints, the problem could be sensibly mitigated with a positive impact on the UE channel conditions and consequently on the perceived QoS and the UE EFA.2018-12-20T00:00:00ZImproving dynamic service function chaining classification in NFV/SDN networks through the offloading concept
http://hdl.handle.net/10662/20413
Títulos: Improving dynamic service function chaining classification in NFV/SDN networks through the offloading concept
Autores/as: Polverini, Marco; Galán Jiménez, Jaime; Lavacca, Francesco G.; Cianfrani, Antonio; Eramo, Vincenzo
Resumen: Service Function Chaining (SFC) paradigm improves network capabilities thanks to the support of application-driven-networking, which is realized through the invocation of an ordered set of Service Functions (SFs). The programmability and flexibility provided by emerging technologies such as Software-Defined Networking (SDN) and Network Function Virtualization (NFV) are perfect features for efficiently managing the lifecycle of SFCs. However, the limitation of Ternary Content Address Memories (TCAMs) of the SDN nodes in SDN-based SFC scenarios can lead to network performance degradation when the SFC classifier is not able to install new classification rules. To tackle the Dynamic Chain Request Classification Offloading (D-CRCO) problem presented in this paper, a hybrid eviction and split-and-distribute approach is proposed, where i) the dynamic behavior of SFC requests is exploited by removing the corresponding idle rules from the flow tables if necessary; and ii) SFC classification is not forced to be carried out by the ingress node, but by any transit node in the domain. An Integer Linear Programming (ILP) formulation and an heuristic are provided to solve D-CRCO, with the goal of maximizing the number of SFC requests that can be served, respecting TCAM size, link capacity, and SF availability constraints. Simulation and emulation results over two real topologies show that the proposed solution is able to significantly increase the number of served SFC requests with a negligible impact on the network performance.2020-12-09T00:00:00Z