http://hdl.handle.net/2117/3173 2013-06-19T23:08:53Z http://hdl.handle.net/2117/19378 Title: A summary of virtualization techniques Authors: Rodríguez Haro, Fernando; Freitag, Fèlix; Navarro Moldes, Leandro; Hernández Sánchez, Efraín; Farías Mendoza, Nicandro; Guerrero Ibáñez, Juan Antonio; González Potes, Apolinar Abstract: Nowadays, virtualization is a technology that is applied for sharing the capabilities of physical computers by splitting the resources among OSs. The concept of Virtual Machines (VMs) started back in 1964 with a IBM project called CP/CMS system. Currently, there are several virtualization techniques that can be used for supporting the execution of entire operating systems. We classify the virtualization techniques from the OS view. First, we discuss two techniques that executes modified guest OSs: operating system-level virtualization and para-virtualization. Second, we discuss two techniques that executes unmodified guest OSs: binary translation and hardware assisted. Finally, we present a summary of resource management facilities for capacity planning and consolidation of server applications. 2013-05-23T10:14:43Z http://hdl.handle.net/2117/18785 Title: Chains of trust in vehicular networks: a secure points of interest dissemination strategy Authors: Antolino Rivas, David; Guerrero Zapata, Manel Abstract: This article describes a scheme which to the best of our knowledge is the first one to use user signatures to share information about Points of Interest in Vehicular Ad hoc Networks. In this scheme, users rate restaurants, hotels, etc. and sign those rates with their private key. Then, they broadcast that information and other vehicles store it for future use. When another user needs a Point of Interest recommendation he queries the system for the other users stored reviews and after he visits that Points of Interest for himself, he evaluates it and his level of trust in the reviewers with rates similar to his own increases. In the end, a user will be able to request to his vehicle information on a certain Point of Interest category and itwill respond with the recommendations made by other users, prioritizing the ones in the user’s Web of Trust.poi-Sim is the tool designed to simulate this scheme. It processes a 24 h mobility trace produced by a Multi-Agent Traffic Simulator, which realistically simulates public and private traffic over regional maps of Switzerland. The result is a Chains of Trust simulation with over 260,000 nodes, which shows that the proposed scheme performs satisfactorily in a realistic scenario. 2013-04-15T09:56:22Z http://hdl.handle.net/2117/13392 Title: A QoS-based dynamic pricing approach for services provisioning in heterogeneous wireless access networks Authors: Guerrero Ibáñez, Juan Antonio; Contreras Castillo, Juan José; Barba Martí, Antonio; Reyes Muñoz, María Angélica Abstract: In this paper we propose a simple QoS-based dynamic pricing approach for services provisioning in a heterogeneous wireless access network environment which attempts to increase user’s satisfaction level by firstly, maximizing the provided QoS level, and secondly, by applying dynamic pricing strategies according to the QoS. These strategies will allow service providers to maximize their profits. Simulation results demonstrate that the proposed dynamic pricing approach benefits both users and wireless service providers (WSPs). Results also suggest that users have better overall satisfaction due to a better QoS level and fairer prices. The analysis shows that our proposed pricing approach contributes to an increase in WSPs profits compared to the application of the flat-rate pricing model in a competitive market-model. 2011-09-29T15:01:54Z http://hdl.handle.net/2117/13362 Title: Modeling and comparison of candidate selection algorithms in opportunistic routing Authors: Darehshoorzadeh, Amir; Cerdà Alabern, Llorenç Abstract: Opportunistic Routing (OR) has been investigated in recent years as a way to increase the performance of multihop wireless networks by exploiting its broadcast nature. In contrast to traditional routing, where traffic is sent along pre-determined paths, in OR an ordered set of candidates is selected for each next-hop. Upon each transmission, the candidates coordinate such that the most priority one receiving the packet actually forward it. Most of the research in OR has been ddressed to investigate candidate selection algorithms. In this paper we compare a selected group of algorithms that have been proposed in the literature. Our main conclusion is that optimality is obtained at a high computational cost, with a performance gain very similar to that of much simpler but non optimal algorithms. Therefore, we conclude that fast and simple OR candidate selection algorithms may be preferable in dynamic networks, where the candidate sets are likely to be updated frequently. 2011-09-27T12:50:03Z http://hdl.handle.net/2117/13304 Title: A communication infrastructure to ease the development of mobile collaborative applications Authors: Rodríguez-Covili, Juan Francisco; Ochoa, Sergio; Pino, José; Meseguer Pallarès, Roc; Medina Medina, Esunly; Royo Vallés, María Dolores Abstract: Mobile workers doing loosely coupled activities typically perform on demand collaboration in the physical workplace. Communication services available in such work scenarios are uncertain, therefore mobile collaborative applications supporting those activities must provide ad hoc communication mechanisms in order to use each cooperation opportunity. Typically, the complexity of implementing such mobile ad hoc communication mechanisms becomes a challenge that jeopardizes the development of mobile collaborative solutions. This article presents a communication infrastructure named HLMP API dealing with that challenge. HLMP API intends to ease the development of such applications through the reuse of communication services. The infrastructure is an application programming interface that implements the HLMP routing protocol and also some awareness mechanisms that are required for mobile loosely coupled work. Developers using this infrastructure do not have to perform low-level programming. 2011-09-22T13:21:28Z http://hdl.handle.net/2117/12863 Title: A method for clustering and cooperation in wireless multimedia sensor networks Authors: Alaei, Mohammad; Barceló Ordinas, José María Abstract: Wireless multimedia sensor nodes sense areas that are uncorrelated to the areas covered by radio neighbouring sensors. Thus, node clustering for coordinating multimedia sensing and processing cannot be based on classical sensor clustering algorithms. This paper presents a clustering mechanism for Wireless Multimedia Sensor Networks (WMSNs) based on overlapped Field of View (FoV) areas. Overlapping FoVs in dense networks cause the wasting of power due to redundant area sensing. The main aim of the proposed clustering method is energy conservation and network lifetime prolongation. This objective is achieved through coordination of nodes belonging to the same cluster to perform assigned tasks in a cooperative manner avoiding redundant sensing or processing. A paradigm in this concept, a cooperative scheduling scheme for object detection, is presented based on the proposed clustering method. 2011-07-04T10:26:23Z http://hdl.handle.net/2117/11647 Title: Follow-up and feedback processes in the EHEA Authors: Valero García, Miguel; Santamaria Barnadas, Eduard; Salamí San Juan, Esther; Canto Rodrigo, Pablo del; Gallego Fernández, María Isabel; López Canalda, José Manuel; Medina, Esunly; Mochón Duro, Francisco; Mora Serrano, Javier; Reyes Muñoz, María Angélica; Rodríguez Luna, Eva Abstract: In the present paper, we describe the work being carried out by a group of professors so as to implement the follow-up and feedback processes of the activities students do throughout the first academic years in their Engineering studies. Not to mention, this project is within the EHEA (European Higher Education Area) framework. Our results show that these processes are key to enhance students learning, they can also have an impact in their academic performance and can be optimized in such a way that professors can assume the time it requires. 2011-03-03T15:50:58Z http://hdl.handle.net/2117/11208 Title: Exact decoding probability under random linear network coding Authors: Trullols Cruces, Óscar; Barceló Ordinas, José María; Fiore, Marco Abstract: In this letter, we compute the exact probability that a receiver obtains N linearly independent packets among K ≥ N received packets, when the sender/s use/s random linear network coding over a Galois Field of size q. Such condition maps to the receiver's capability to decode the original information, and its mathematical characterization helps to design the coding so to guarantee the correctness of the transmission. Our formulation represents an improvement over the current upper bound for the decoding probability, and provides theoretical grounding to simulative results in the literature. 2011-01-26T08:54:43Z http://hdl.handle.net/2117/10788 Title: Context awareness for collaborative learning with uncertainty management Authors: Meseguer Pallarès, Roc; Damián-Reyes, Pedro; Favela Vara, Jesús; Navarro Moldes, Leandro 2010-12-28T15:31:29Z http://hdl.handle.net/2117/9117 Title: La evaluación en el contexto del Espacio Europeo de Educación Superior. Authors: Valero García, Miguel; Santamaria Barnadas, Eduard; Canto Rodrigo, Pablo del; Gallego Fernández, María Isabel; López Canalda, José Manuel; Mochón Duro, Francisco; Mora Serrano, Javier; Reyes Muñoz, María Angélica; Rodríguez Luna, Eva; Sanjeevan, Kanapathipillai Abstract: La evaluación es un elemento que preocupa siempre a todos los implicados en el proceso educativo (profesores, alumnos, responsables académicos, etc.). Sin embargo, la evaluación es un concepto muy amplio y no todas sus facetas preocupan de igual manera ni reciben la misma atención. Evaluar, desde luego, es asignar una calificación que refleje el nivel de aprendizaje. Pero evaluar es también identificar lo que debe mejorarse de cara al curso siguiente. En nuestro artículo, partiendo del modelo de Donald Kirkpatrick sobre los diferentes enfoques de la evaluación, describimos las estrategias y técnicas que utilizamos en la actualidad para desplegar un sistema de evaluación de amplio alcance, en el contexto del proceso de adaptación de nuestras asignaturas de primeros cursos de ingeniería a los requerimientos del Espacio Europeo de Educación Superior (EEES). Precisamente en el contexto del EEES algunos enfoques de la evaluación a los que normalmente se presta poca atención, como es el caso de la evaluación del seguimiento de la actividad del alumno, adquieren una relevancia muy importante. 2010-09-27T17:31:19Z http://hdl.handle.net/2117/8916 Title: Cómo usamos Moodle en nuestras asignaturas adaptadas al EEES Authors: Valero García, Miguel; Canto Rodrigo, Pablo del; Gallego Fernández, María Isabel; López Canalda, José Manuel; Mora Serrano, Javier; Reyes Muñoz, María Angélica; Rodríguez Luna, Eva; Sanjeevan, Kanapathipillai; Santamaria Barnadas, Eduard Abstract: This paper describes how do we use our digital campus based on Moodle as a key tool in our subjects. These subjects belong to a first course in an engineering degree and have been adapted to the requirements of the European Higher Education Area in accordance with an educational model whose essential elements are the detailed planning of student work, both in class and out of class, and the evaluation of student work with frequent feedback. Our experience indicates that the digital campus has become an essential tool that allows us to be very productive in implementing the educational model, in a scenario with several groups of class and several teachers teaching the same program. This paper describes our educational model and how few resources our Moodle based digital campus are used to support key elements of this model. 2010-09-16T13:38:36Z