Ara es mostren els items 1-10 de 10

  • Adaptive s-aloha cdma as an alternative way of integrating services in mobile environments 

    Sallent Roig, José Oriol; Agustí Comes, Ramon (2000-05)
    Article
    Accés obert
    Code-division multiple-access (CDMA) schemes appear to be very promising access techniques for coping with the requirements of third-generation mobile systems, mainly because of their flexibility. This paper proposes an ...
  • An efficient data transmission policy in an integrated voice-data ds-cdma network 

    Sallent Roig, José Oriol; Agustí Comes, Ramon (IEEE Vehicular Technology Society, 1998)
    Text en actes de congrés
    Accés obert
    CDMA schemes appear to be promising access techniques for coping with the requirements of third-generation mobile systems, mainly because of their flexibility. This paper proposes an adaptive S-ALOHA DS-CDMA access scheme ...
  • Analysis of diversity and equalization techniques applied to M-QAM digital mobile radio systems 

    Valdominos Bardají, Antonio; Casadevall Palacio, Fernando José (Institute of Electrical and Electronics Engineers (IEEE), 1994)
    Text en actes de congrés
    Accés obert
    Presents an investigation of diversity and/or equalization techniques applied to 4 and 16-QAM TDMA radio systems for rapid fading dispersive channels. In particular, typical urban (TU) environments have been considered. A ...
  • Blind channel estimation and data detection using hidden Markov models theory 

    Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1997-01-01)
    Article
    Accés obert
    In this correspondence, we propose applying the hidden Markov models (HMM) theory to the problem of blind channel estimation and data detection. The Baum–Welch (BW) algorithm, which is able to estimate all the parameters ...
  • Blind equalization of DS-CDMA and MC-CDMA modulations in time-variant frequency selective channels 

    Rey Micolau, Francesc; Vázquez Grau, Gregorio (Institute of Electrical and Electronics Engineers (IEEE), 1999)
    Text en actes de congrés
    Accés obert
    The paper addresses the blind equalization problem of spread spectrum modulations in the presence of fast time-variant frequency-selective channels. The basic assumption of the paper is that the channel response exhibits ...
  • Diversity in mobile communications for blind detection of block-coded modulations 

    Vázquez Grau, Gregorio; Rey Micolau, Francesc; Lamarca Orozco, M. Meritxell; Rodríguez Fonollosa, Javier (Institute of Electrical and Electronics Engineers (IEEE), 1999)
    Text en actes de congrés
    Accés obert
    Spatial, temporal, and frequency diversity structures are analyzed to address the blind equalization problem in the presence of time-variant frequency selective channels. The aim of the paper is to present equalization ...
  • New receivers for DS-SS in time variant multipath channels based on the PN alignment concept 

    Socoro, J; Pijoan, J L; Moran, J A; Tarrés Ruiz, Francisco (Institute of Electrical and Electronics Engineers (IEEE), 2000)
    Text en actes de congrés
    Accés obert
    We present new combined blind equalization and detection schemes for a DS-SS system. The new proposed algorithms improve the bit error rate compared to traditional RAKE receivers in time-variant channels with multipath. ...
  • On the inclusion of channel's time dependence in a hidden Markov model for blind channel estimation 

    Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (BOB WERNER IEEE COMPUTER SOCIETY PRESS, 1996)
    Text en actes de congrés
    Accés obert
    We introduce several modifications to the Baum&Welch (BW) formulas used to reestimate the parameters of a hidden Markov model (HMM). The estimated parameter is the channel impulse response (CIR) of a communication system ...
  • Optimum energy allocation for massive spread-spectrum multiple access in networks of uncoordinated energy-limited terminals 

    Villares Piera, Nemesio J.; Rey Micolau, Francesc; Sala Álvarez, José (Institute of Electrical and Electronics Engineers (IEEE), 2016)
    Text en actes de congrés
    Accés restringit per política de l'editorial
    This paper derives the energy allocation policy that maximizes the aggregate spectral efficiency of an uncoordinated spread-spectrum multiple access network operating in the large-user regime and subject to a longterm ...
  • Space-time coding for UMTS. Performance evaluation in combination with convolutional and turbo coding 

    Gaspa Maynou, Roger; Rodríguez Fonollosa, Javier (Institute of Electrical and Electronics Engineers (IEEE), 2000)
    Text en actes de congrés
    Accés obert
    Space-time codes provide both diversity and coding gain when using multiple transmit antennas to increase spectral efficiency over wireless communications systems. Space-time block codes have already been included in the ...