Now showing items 1-20 of 85

    • A framework for joint design of pilot sequence and linear precoder 

      Pastore, Adriano; Joham, Michael; Rodríguez Fonollosa, Javier (2016-09-01)
      Article
      Open Access
      Most performance measures of pilot-assisted multiple-input multiple-output systems are functions of the linear precoder and the pilot sequence. A framework for the optimization of these two parameters is proposed, based ...
    • A new positive time-frequency distribution 

      Rodríguez Fonollosa, Javier; Nikias, C L (1994)
      Conference report
      Open Access
      This article studies the formulation of new members of the Cohen-Posch (1985) class of positive time-frequency energy distributions. Members of this class are always positive functionals and satisfy the marginal constraints. ...
    • A probabilistic method for blind multiuser detection using array observations 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (IEEE, 1997)
      Conference report
      Open Access
      In this paper, a blind algorithm for detecting active users in a DS-CDMA system is presented. This probabilistic algorithm relies on the theory of hidden Markov models (HMM) and is completely blind in the sense that no ...
    • A rate-splitting approach to fading channels with imperfect channel-state information 

      Pastore, Adriano; Koch, Tobias; Rodríguez Fonollosa, Javier (2014-07)
      Article
      Restricted access - publisher's policy
      As shown by Médard, the capacity of fading channels with imperfect channel-state information can be lower-bounded by assuming a Gaussian channel input X with power P and by upper-bounding the conditional entropy h(X|Y,H) ...
    • A rate-splitting approach to fading multiple-access channels with imperfect channel-state information 

      Pastore, Adriano; Koch, Tobias; Rodríguez Fonollosa, Javier (2014)
      Conference report
      Restricted access - publisher's policy
      As shown by Medard, the capacity of fading channels with imperfect channel-state information (CSI) can be lowerbounded by assuming a Gaussian channel input and by treating the unknown portion of the channel multiplied ...
    • Adaptive Beamforming for High Bit Rate Services in the FDD Mode of UTRA 

      Mestre Pons, Francesc X.; Nájar Martón, Montserrat; Antón Haro, Carles; Rodríguez Fonollosa, Javier (Institute of Electrical and Electronics Engineers (IEEE), 1999)
      Conference report
      Open Access
      Most time-reference beamforming algorithms suffer from severe beampattern distortion effects when applied to high bit rate services in WCDMA, causing serious performance degradation in terms of output BER, especially at ...
    • Algorithms for flexible multi-standard array processing: FDD mode of UTRA 

      Antón Haro, Carles; Rodríguez Fonollosa, Javier (1999)
      Conference report
      Open Access
    • Application of hidden markov models to blind channel estimation and data detection in a gsm environment 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (1996)
      Conference report
      Open Access
      In this paper, we present an algorithm based on the Hidden Markov Models (HMM) theory to solve the problem of blind channel estimation and sequence detection in mobile digital communications. The environment in which the ...
    • Apuntes tema 2: Transmisión digital a través de canales AWGN 

      Cabrera-Bean, Margarita; Rodríguez Fonollosa, Javier (Universitat Politècnica de Catalunya, 2009)
      Lecture notes / Problem statement, exercise
      Open Access
    • Array gain in the DMT framework for MIMO channels 

      García Ordoñez, Luis; Palomar, D.P.; Rodríguez Fonollosa, Javier (2012)
      Article
      Restricted access - publisher's policy
      Following the seminal work by Zheng and Tse on the diversity and multiplexing tradeoff (DMT) of multiple-input multiple-output (MIMO) channels, in this paper, we introduce the array gain to investigate the fundamental ...
    • Array joint detection for C/TDMA systems in UMTS environments 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (Institute of Electrical and Electronics Engineers (IEEE), 1998)
      Conference report
      Open Access
      Two array-based schemes for intracell and intercell interference suppression are proposed. In both cases, the spatial and temporal characteristics of the propagation are jointly exploited by placing a narrowband beamformer ...
    • Balancing egoistic and altruistic transmit beamforming in femtocell networks 

      Husso, Mika; Dowhuszko, Alexis; Hamalainen, K.; Pastore, Adriano; Rodríguez Fonollosa, Javier (Institute of Electrical and Electronics Engineers (IEEE), 2011)
      Conference report
      Restricted access - publisher's policy
      In this paper, we study the balancing of egoistic (maximum-ratio, MR) and altruistic (zero-forcing, ZF) beamforming (BF) in femtocells through simulations. To investigate the achievable gains from operating between the ...
    • 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
      Open Access
      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 multiuser deconvolution in fading and dispersive channels 

      Rodríguez Fonollosa, Javier; Rodríguez Fonollosa, José Adrián; Zvonar, Z; Vidal Manzano, José (. S.N., 1995)
      Conference report
      Open Access
      An adaptive near-far resistant technique for the blind joint multiuser identification and detection in asynchronous CDMA systems is analyzed in fading and dispersive GSM channels.
    • Blind multiuser detection using hidden markov models theory 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (BOB WERNER IEEE, 1996)
      Conference report
      Open Access
      We present an adaptive algorithm based on the theory of hidden Markov models (HMM) which is capable of jointly detecting the users in a DS-CDMA system. The proposed technique is near-far resistant and completely blind in ...
    • Blind multiuser detection with array observations 

      Rodríguez Fonollosa, Javier; Zvonar, Z; Rodríguez Fonollosa, José Adrián; Catala, J (1998-01)
      Article
      Open Access
      Cochannel interference is usually a major limitation to the performance of mobile wireless systems. Examples of different forms of cochannel interference include multi-access interference in CDMA systems and cochannel ...
    • Blind multiuser detection with probabilistic algorithms - application to underwater communications 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Zvonar, Zaran; Rodríguez Fonollosa, Javier (IEEE IEEE, 1997)
      Conference report
      Open Access
      In this paper, two probabilistic adaptive algorithms for jointly detecting active users in a DS-CDMA system are compared. The first one, which is based on the theory of hidden Markov models (HMM) is proposed within the ...
    • Blind multiuser identification and detection in cdma systems 

      Rodríguez Fonollosa, Javier; Rodríguez Fonollosa, José Adrián; Zvonar, Z; Vidal Manzano, José (Institute of Electrical and Electronics Engineers (IEEE), 1995)
      Conference report
      Open Access
      Multiuser detection in code division multiple access systems usually requires either knowledge of the transmitted signature sequences and channel state information or use of a known training sequence for adaptation. We ...
    • Capacity of MIMO Channels: asymptotic evaluation under correlated fading 

      Mestre Pons, Francesc X.; Rodríguez Fonollosa, Javier; Pagès Zamora, Alba Maria (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2003-06-30)
      Article
      Open Access
      This paper investigates the asymptotic uniform power allocation capacity of frequency nonselective multiple-input multiple-output channels with fading correlation at either the transmitter or the receiver. We consider ...
    • Capacity results on frequency-selective Rayleigh MIMO channels 

      Pérez Palomar, Daniel; Lagunas Hernandez, Miguel A.; Rodríguez Fonollosa, Javier (European Commission, 2000)
      Conference report
      Open Access