http://hdl.handle.net/2117/1936 2013-05-19T02:00:50Z http://hdl.handle.net/2117/19285 Title: Parallelization of the interpolation process in the Koetter-Vardy soft-decision list decoding algorithm Authors: Moreira Sánchez, José; Fernández Muñoz, Marcel; Soriano Ibáñez, Miguel Abstract: List decoding is a decoding strategy that provides a set of codewords at the output of the channel decoder. Since this technique corrects errors beyond the correcting bound of the code, upper layers in the application or in the communications protocol can choose the appropriate candidate codeword among the elements of the set. The Koetter-Vardy algorithm is a soft-decision decoding algorithm for Reed-Solomon codes. It is based on two sequential processes: interpolation and factorization. In most applications it is interesting to efficiently decode in real time. This paper discusses some parallelization results about the interpolation process, which is the highest time-consuming part of the Koetter-Vardy algorithm. 2013-05-16T10:33:32Z http://hdl.handle.net/2117/18557 Title: Adding QoS support for timeliness to the observe extension of CoAP Authors: Ludovici, Alessandro; García, Ernesto; Gimeno, Xavier; Calveras Augé, Anna M. Abstract: In this paper, we propose a modification of the observe extension of CoAP to include Quality of Service (QoS) support for timeliness. The proposed QoS support is based on delivery priority. Nodes are able to express the priority order with which they wish to be notified. Furthermore, they are also able to specify which notification they want to receive. We classify the notifications in two categories: Critical and Non-Critical. The provided QoS is the result of a negotiation between the client and server. The client demands a certain degree of QoS according to its role. The server could accept or negotiate it. This choice depends on the availability of server and network resources. We evaluate our proposal in a real Wireless Sensor Network. An e-health application has been chosen as target of our tests. The performance evaluation is done in terms of average delay, energy consumption and delivery ratio. 2013-04-03T10:08:30Z http://hdl.handle.net/2117/18556 Title: Presence-based architecture for wireless sensor networks using publish/subscribe paradigm Authors: Calveras Augé, Anna M.; Garcia Davis, Ernesto Abstract: Ubiquitous communication is a key component of Ambient Intelligence, enabling objects to communicate with each-other by means of a wireless ad-hoc network. A presence service allows knowing the availability or responsiveness status of elements in a communication (entities). Traditionally, only human use this service, however all smart devices or objects (with embedded wireless sensor nodes) could interact with each other thus a presence service could also enhance communication among them. To achieve this objective we look into existing protocols to propose the requirements needed to provide presence service on Wireless Sensor Networks (WSN). The main contribution of this paper is the discussion of requirements for presence services on WSN and the new proposed architecture to cope with presence services in WSN. 2013-04-03T09:50:03Z http://hdl.handle.net/2117/18528 Title: RAR: Un mecanismo "Risk-Aware" para redes vehiculares Authors: Hernández Gañán, Carlos; Muñoz Tapia, José Luis; Hinarejos Campos, M. Francisca; Isern Deyà, Andreu; Alins Delgado, Juan José Abstract: Las redes vehiculares requieren de alg ́ un meca- nismo para autenticar los mensajes, identificar a los veh ́ ıculos leg ́ ıtimos y sacar de la red aqu ́ ellos que no presenten un comportamiento adecuado. La infrastructura de clave p ́ ublica (PKI) puede proporcionar estos requisitos mediante el uso de certificados digitales. Sin embargo, la adopci ́ on de una PKI, conlleva la necesidad de gestionar no tan s ́ olo la emisi ́ on de certificados sino tambi ́ en su revocaci ́ on. El est ́ andar IEEE 1609.2 apunta que la revocaci ́ on de certificados en redes vehiculares debe depender del uso de Listas de Certificados Revocados (CRLs). En este art ́ ıculo, analizamos los problemas derivados del uso de CRLs en este tipo de redes. Asimismo, proponemos un mecanismo para gestionar el riesgo inherente del uso de estas listas el cual mejora el uso tradicional de las CRLs. Ayud ́ andose del canal de control de este tipo de redes, nuestro mecanismo es capaz de dar a conocer la frescura de los datos de revocaci ́ on en tiempo real. Adem ́ as, este mecanismo permite a los usuarios estimar el riesgo operacional que asumen al usar las CRLs. 2013-04-02T10:29:44Z http://hdl.handle.net/2117/18495 Title: Study of the results in a heterogenous group for a course on computer networks Authors: Barceló Arroyo, Francisco; Martín Escalona, Israel Abstract: This paper shows statistics of a group at the Faculty of Telecommunications Engineering in Barcelona (Spain). Due to the different origin and academic background of the students, planning the course is a challenging task. This work shows the features that characterize the group as heterogeneous. Statistics about the origin and the grades of a test before the course are shown along with the existing correlation between both. The paper also analyzes the grades obtained in the final exams and relates them to the origin and initial test. In the statistics some groups can be differentiated with students belonging to each group showing a similar degree of academic progress. The results allow drawing some conclusions on how a careful observation of the countries of origin, academic background and the results of a test before starting the course can help to plan a balanced course and evaluation. 2013-03-22T12:57:41Z http://hdl.handle.net/2117/18486 Title: Design and analysis of a framework to enhance optical network utilization resources by means of virtualization Authors: Hesselbach Serra, Xavier; Naumenko, Nikolay Abstract: The time for an all-optical network is already here. The huge capacity of the optical resources, in backbones, distribution and access networks cannot be completely used by current services. The remainders can be used under the deployment of new models for service provisio ning. Network virtualizati on is considered as a serious candidate to enable the flexibl e provision of services in the future Internet. This paper introduces a framework to enhance network virtualization allocati on in optical networks. To increase resources utilization efficiency, a new layer above virtualized elements is introduced to map the demands over the resour ces and infrastructures. For that layer, a strategy based on a resource squa tting model is presented, modeled and analyzed. 2013-03-22T12:01:26Z http://hdl.handle.net/2117/18484 Title: RAR: Risk aware revocation mechanism for vehicular networks Authors: Hernández Gañán, Carlos; Muñoz Tapia, José Luis; Esparza Martín, Óscar; Mata Diaz, Jorge; Alins Delgado, Juan José; Silva Cárdenas, Carlos; Bartra Gardini, Gumercindo Abstract: Vehicular Ad Hoc Networks (VANETs) require some mechanism to authenticate messages, identify valid vehicles, and remove misbehaving ones. A Public Key Infrastructure (PKI) can provide this functionality using digital certificates. In PKI, key management and corresponding issuance and revocation of digital certificates is one of the key issues that have to be solved. The IEEE 1609.2 standard states that VANETs will rely on the use of certificate revocation lists (CRLs) to achieve revocation. In this paper, we analyze the problems of using CRLs in these type of networks. Moreover, we describe the Risk Aware Revocation (RAR) mechanism that improves the traditional use of CRLs. RAR takes advantage of the two distinct channel types in VANETs to increase the freshness of the revocation information. Moreover, RAR allows users to gauge the risk of operating in a VANET when using CRLs. 2013-03-22T11:52:09Z http://hdl.handle.net/2117/18332 Title: Implementation of context-aware network architecture for smart objects based on functional composition Authors: Ferrer Riera, José Luis; Sánchez Loro, Xavier; Calveras Augé, Anna M.; Paradells Aspas, Josep Abstract: Lack of flexibility of current Internet architecture led researchers to come up with new paradigms for a novel Internet architecture, which would be able to reduce complexity and increase flexibility compared to current Internet architecture. Functional co mposition is a promising approach to flexible and evolvable architecture design. The idea is composing complex protocol suites by dynamically bind and arrange different functions to obtain certain behavior. Herein, we present the implementation of a contex t - aware network architecture based on functional composition for smart objects. A sub - set of those basic functional blocks has been implemented and validated on an experimental testbed using different network topologies . 2013-03-15T09:39:46Z http://hdl.handle.net/2117/18100 Title: Enabling SCI-FI: service-oriented context-aware and intelligent future Internet Authors: González Cela, Alberto José; Germán Duarte, Martín; Alcober Segura, Jesús Ángel; Martin de Pozuelo, Ramon; Pinyol, Francesc; Ghafoor, Kayhan Zrar Abstract: Internet is becoming a huge heterogeneous and dynamic network that is growing beyond its architectural limits. The scaling up of the number of communicating nodes and services is leading the Internet to an architectural crisis which in turn makes it difficult to provide services efficiently considering the requirements and context conditions of users. The Information-Centric Networking (ICN) approach proposes a network where the main paradigm is not an end-to-end communication between hosts, as in the current Internet. Instead, an increasing demand for efficient distribution of content has motivated the development of architectures that focus on information objects. ICN supports the proliferation of services and contents allowing seamless access to them. This work proposes a context-aware service negotiation protocol which will enable to find and compose services whilst meeting requesters’ requirements and, consequently, maximizing the QoE of users. We also provide the main details of a first implementation of the proposed service-oriented solution (SCI-FI) and discuss the gathered results. 2013-03-06T13:15:09Z http://hdl.handle.net/2117/18096 Title: ATENEA UPC and the new "Activity Stream" or "Wall" feature Authors: Alcober Segura, Jesús Ángel; Sanchez, Oriol; Otero, Javier; Marti, Ramon Abstract: The Universitat Politècnica de Catalunya–Barcelona Tech (UPC), has added a new feature to its ATENEA UPC e-Learning platform based on Moodle. ATENEA UPC Service is UPC’s e-Learning platform which supports the Bachelor and Master studies, both face-to-face and blended. This new feature, called "Activity Stream" or "wall", allows progress in the implementation of methodologies based on social learning and mobile learning within the field of university studies. The Institut de Ciències de la Educació (Education Sciences Institute - ICE) leads the educational aims of the platform, and UPCnet -UPC’s ICT services company- offers the service and carries out the technical evolution projects of the platform (change of versions, development of new features, ...) The ICE, teachers at UPC and UPCnet, through working groups and projects in ATENEA Teaching Innovation LABs, evolve and test the new features of the platform that will later incorporate to UPC’s ATENEA Service. The aim of this presentation is to explain the pedagogical motivation of the initiative, the feature’s design process, the technological development done and the result of the actual experience carried out between February and June 2012 within the framework of the official engineering studies taught at the Escola d'Enginyeria de Telecomunicació i Aeronàutica in Castelldefels (EETAC). 2013-03-06T12:08:18Z http://hdl.handle.net/2117/17907 Title: Performance evaluation of the passive TDOA algorithm in dark areas Authors: Martín Escalona, Israel; Malpartida, Marta; Barceló Arroyo, Francisco Abstract: Positioning in wireless networks has recently concentrated the interest of the research community. Outdoor positioning has been addressed successfully, but location indoors poses some open issues. Time-based ranging techniques, such as 2-way time-of-arrival (TOA), are promising for indoor positioning but present issues such as scalability and landmark dependency. Handling these problems separately makes it difficult to find solutions that can be implemented over communication networks on which positioning solutions rely. The passive TDOA algorithm was proposed for overcoming both issues together. Preliminary results indicate that scalability can be improved. This work assesses the performance of the passive TDOA in scenarios where there are not enough landmarks to run a regular 2-way TOA algorithm. Results show that the accuracy provided is worse than in scenarios with enough landmarks but, depending on the power of the ranging noise, good enough for most of the location-based services indoors. 2013-02-21T11:37:17Z http://hdl.handle.net/2117/17808 Title: Cross-layer energy optimization under image quality constraints for wireless image transmissions Authors: Yang, N.; Seyfettin Demirkol, Ilker; Heinzelman, W. Abstract: Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances. 2013-02-18T09:49:36Z http://hdl.handle.net/2117/17792 Title: Should we use the default protocol settings for networks of constrained devices? Authors: Betzler, August; Gómez Montenegro, Carlos; Seyfettin Demirkol, Ilker; Paradells Aspas, Josep Abstract: Constrained devices will play a crucial role in the Internet of Things. These devices use communication technologies which often support the formation of wireless multihop topologies. Therefore, end-to-end data transfer involves the collaboration of multiple protocol layers. However, the settings and mechanisms used in a specific layer affect performance of the others. In this paper, we assess a set of crucial network design criteria for potential MAC layer, network layer and transport layer protocols for networks of constrained devices. We evaluate the default and alternative settings and mechanisms for these protocols on a 60-node testbed. The experiments show how performance can be improved significantly by using different settings and mechanisms from the default ones. 2013-02-15T12:57:19Z http://hdl.handle.net/2117/17787 Title: Enhanced vehicle navigation unit with wifi 802.11 ranging and communication capabilities Authors: Tappero, Fabrizio; Ciurana Adell, Marc; Batlle, Jordi; Uijt de Haag, M.; Martín Escalona, Israel; Fernández Fernández, Daniel Abstract: This paper discusses the implementation of a modified IEEE 802.11 transceiver that is employed to enhance the positioning capabilities of a traditional vehicle on-board navigation unit (OBU). In this paper, we propose to use the current wireless local access network (WLAN) as enhancing infrastructure for ubiquitous localisation and positioning. We describe the architecture of a localisation receiver built around a FPGA that is capable of measuring the signal round trip time and thus distance between itself and visible WiFi access points. The proposed system has great potentials to enhance the performance of traditional hardware solutions often based on GNSS plus INS traditionally used as fundamental component in an intelligent transportation system. The proposed system offers vehicle-to-vehicle communication and ranging capabilities using the current IEEE 802.11 standard. This paper describes the details of the WLAN ranging estimation method, possible integration approaches with a GPS plus INS system and an analysis of the proposed system’s positioning performance in a crowded urban environment. 2013-02-15T12:13:55Z http://hdl.handle.net/2117/17785 Title: Almost separating and almost secure frameproof codes Authors: Fernández Muñoz, Marcel; Kabatiansky, Grigory; Moreira Sánchez, José Abstract: The theory of separating codes has been applied in several areas of science ranging from automata synthesis to the protection of distribution rights. In this paper, we introduce a relaxed version of separating and secure frameproof codes and show that for the relaxed definitions these two notions are different, as opposed to the original definitions when these notions coincide. Moreover, we also discuss how this new relaxed versions of the codes can be used to construct a family of fingerprinting codes. 2013-02-15T11:26:01Z