Now showing items 1-20 of 21

  • A family of asymptotically good binary fingerprinting codes 

    Cotrina Navau, Josep; Fernández Muñoz, Marcel (2010-10)
    Article
    Restricted access - publisher's policy
    A fingerprinting code is a set of codewords that are embedded in each copy of a digital object with the purpose of making each copy unique. If the fingerprinting code is c-secure with error, then the decoding of a pirate ...
  • Alternatives for indoor location estimation on uncoordinated environments 

    Gorricho Moreno, Juan Luis; Cotrina Navau, Josep (2011)
    Conference report
    Restricted access - publisher's policy
    Approaches based on signal-strength measurements are at present the most popular on indoor location due to their reasonable accuracy and cost effective deployment. In this paper, we present an outlook of our research on ...
  • A new class of codes for fingerprinting schemes 

    Fernández Muñoz, Marcel; Soriano Ibáñez, Miguel; Cotrina Navau, Josep (Springer, 2005)
    Conference report
    Restricted access - publisher's policy
    In this paper we discuss the problem of collusion secure fingerprinting. In the first part of our contribution we prove the existence of equidistant codes that can be used as fingerprinting codes. Then we show that by ...
  • A note about the traceability properties of linear codes 

    Fernández Muñoz, Marcel; Cotrina Navau, Josep; Soriano Ibáñez, Miguel; Domingo, Neus (Springer, 2007)
    Conference report
    Restricted access - publisher's policy
    We characterize the traceability properties of linear codes. It is well known that any code of length n and minimum distance d is a c-TA code if c 2¿<¿n/(n¿-¿d). In this paper, we show that a less restrictive condition can ...
  • Enhancement proposal for WLAN IEEE 802.11e: desynchronization of its working procedure 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep; Rojas Espinosa, Alfonso (Institute of Electrical and Electronics Engineers, 2005)
    Conference report
    Open Access
    Up to the present, several studies have been performed in order to provide prioritization of stations or classes of service for WLAN IEEE 802.11. The IEEE 802.11e draft specification aims to extend the original IEEE 802.11 ...
  • Evaluación de IEEE 802.11g en un entorno celular exterior 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep (2004-11)
    Conference report
    Open Access
    La mayoría de estudios que se encargan de analizar el comportamiento de IEEE 802.11 se encuentran limitados a entornos unicelulares. Sin embargo, la idea de diseñar una red celular basada en IEEE 802.11 resulta muy ...
  • Free form surfaces 

    Cotrina Navau, Josep; Pla García, Núria (2000-05)
    External research report
    Open Access
    A method to construct continuous order k surfaces of arbitrary topological type by tracing a mesh that represents a 2-manifold is presented. The presented approach constructs the surface from a collection of pieces which ...
  • IEEE 802.11g performance in presence of beacon control frames 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep (Institute of Electrical and Electronics Engineers, 2004-09)
    Conference report
    Open Access
    Most studies of the performance of IEEE 802.11 consider scenarios of ad-hoc topology networks and do not contemplate the network broadcast information contained in beacon frames. The paper presents a study of the performance ...
  • Modelling surfaces from planar irregular meshes 

    Cotrina Navau, Josep; Pla García, Núria (1998-06)
    External research report
    Open Access
    We present a method for constructing surfaces from irregular control meshes that can be embedded in the plane. This method results from a generalization of B-Splines using the known technology of manifolds. The resulting ...
  • Multisided patches 

    Pla García, Núria; Vigo Anglada, Marc; Cotrina Navau, Josep (2004-06)
    External research report
    Open Access
    We present a method to construct a patch of parametric surface of degree k + 1 that lls a n-sided hole, with n bigger than 2, and whose boundary coincides with a B-Spline, thus, the resulting patch can be easily connected ...
  • N-sided patches with B-spline boundaries 

    Cotrina Navau, Josep; Pla García, Núria; Vigo Anglada, Marc (2001-12)
    External research report
    Open Access
    We present a method to construct a patch of parametric surface of degree k+1 that fills a n-sided hole, with bigger than 2, and whose boundary coincides with a B-Spline, thus, the resulting patch can be easily connected ...
  • Outdoor IEEE 802.11g cellular network performance 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep (Institute of Electrical and Electronics Engineers, 2004)
    Conference report
    Open Access
    Most studies about the performance of IEEE 802.11 are limited to a single cell environment. Nevertheless, the idea of designing an outdoor cellular network based on WLAN IEEE 802.11 is very attractive, due to the several ...
  • Performance enhancement of outdoor IEEE 802.11 cellular networks 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Rojas Espinosa, Alfonso; Cotrina Navau, Josep (ACTA Press, 2005-07)
    Conference report
    Open Access
    Most studies about the performance of IEEE 802.11 are limited to a single cell environment. Nevertheless, the idea of designing an outdoor cellular network based on WLAN IEEE 802.11 results very attractive, due to the ...
  • Performance enhancement of WLAN IEEE 802.11 for asymmetric traffic 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep; Rojas Espinosa, Alfonso (Institute of Electrical and Electronics Engineers, 2005)
    Conference report
    Open Access
    Most studies about the performance of IEEE 802.11 consider scenarios of ad-hoc topology and networks where all stations have the same traffic load (symmetric traffic conditions). This paper presents a study of performance ...
  • Sobre la justicia en las redes IEEE 802.11e: desincronización de su mecanismo de acceso al medio 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep (Institute of Electrical and Electronics Engineers, 2007-10)
    Article
    Open Access
    Since the advent of the first IEEE 802.11 standard, several papers have proposed means of providing QoS to IEEE 802.11 networks and evaluate various traffic-prioritization mechanisms. Nevertheless, studies on the assignment ...
  • Study of asymmetric traffic influence on IEEE 802.11 WLAN family, enhancement proposals 

    López Aguilera, M. Elena; Casademont Serra, Jordi; Cotrina Navau, Josep (Institute of Electrical and Electronics Engineers, 2004-04)
    Conference report
    Open Access
    This paper is focused on the study of WLAN performance in IEEE 802.11 networks that are in a situation of asymmetric traffic, where the access point (AP) transmits much more than the user stations (US). This situation is ...
  • Surveillance with alert management system using conventional cell phones 

    Gorricho Moreno, Juan Luis; Brezmes, Tomas; Cotrina Navau, Josep; Rersa, Marc (IEEE Computer Society Publications, 2010)
    Conference report
    Open Access
    In the present paper we expose the development of a real-time monitoring prototype of human activities using a single cell phone equipped with some sensors. The monitoring system is reduced to the minimum expression; ...
  • Towards free form surfaces 

    Cotrina Navau, Josep; Pla García, Núria; Vigo Anglada, Marc (2001-03)
    External research report
    Open Access
    A theoretical approach to construct free form surfaces is presented. We develop the conceps that arise when a free form surface is generated by tracing a mesh, using differentiable manifold theory, and generalizing the ...
  • Tracing traitors by guessing secrets. The q-ary case 

    Fernández Muñoz, Marcel; Soriano Ibáñez, Miguel; Cotrina Navau, Josep (Springer, 2005)
    Conference report
    Restricted access - publisher's policy
    In this paper we present, by solving a variant of the guessing secrets problem defined by Chung, Graham and Leighton [3], a sequential traitor tracing scheme equipped with an efficient identification algorithm. Sequential ...
  • User activity monitoring using conventional cell phones 

    Brezmes, Tomas; Gorricho Moreno, Juan Luis; Cotrina Navau, Josep; Rersa, Marc (2010-04-09)
    Conference report
    Open Access
    User activity monitoring has a considerable potential for a whole range of new applications in different environments: user surveillance, military purposes, health-care, etc. More precisely, in health-care there is an ...