Browsing GI-GTEC - Artigos by Author "Fresnedo, Óscar"

Now showing items 1-20 of 24

    • A Rank-Constrained Coordinate Ascent Approach to Hybrid Precoding for the Downlink of Wideband Massive (MIMO) Systems 

      González-Coma, José P.; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2023-12)
      [Abstract]: An innovative approach to hybrid analog-digital precoding for the downlink of wideband massive MIMO systems is developed. The proposed solution, termed Rank-Constrained Coordinate Ascent (RCCA), starts seeking ...

    • Alternating Minimization for Wideband Multiuser IRS-Aided MIMO Systems Under Imperfect CSI 

      Pérez-Adán, Darian; Joham, Michael; Fresnedo, Óscar; González-Coma, José P.; Castedo, Luis; Utschick, Wolfgang (Institute of Electrical and Electronics Engineers, 2023-11-28)
      [Abstract]: This work focuses on wideband intelligent reflecting surface (IRS)-aided multiuser MIMO systems. One of the major challenges of this scenario is the joint design of the frequency-dependent base station (BS) ...

    • Analog joint source-channel coding over MIMO channels 

      Vázquez-Araújo, Francisco J.; Fresnedo, Óscar; Castedo, Luis; Garcia-Frias, Javier (SpringerOpen & European Association for Signal Processing, 2014-02)
      [Abstract]: Analog joint source-channel coding (JSCC) is a communication strategy that does not follow the separation principle of conventional digital systems but has been shown to approach the optimal distortion-cost ...

    • Analog Transmission of Correlated Sources Over BC With Distortion Balancing 

      Suárez-Casal, Pedro; Fresnedo, Óscar; Castedo, Luis; Garcia-Frias, Javier (Institute of Electrical and Electronics Engineers, 2017-11)
      [Abstract]: Analog transmission of correlated information over Gaussian broadcast channels (BCs) using analog joint source- channel coding (JSCC) is addressed. This communication strategy has attractive advantages, such ...

    • Analog Transmission of Correlated Sources Over Fading SIMO Multiple Access Channels 

      Suárez-Casal, Pedro; Fresnedo, Óscar; Castedo, Luis; Garcia-Frias, Javier (Institute of Electrical and Electronics Engineers, 2017-07)
      [Abstract]: Joint source-channel coding for discrete-time analog sources is an appealing transmission approach because of its extremely low delay and complexity. When the users access the channel orthogonally, analog ...

    • Analog Transmission of Spatio-Temporal Correlated Sources Over MAC With Modulo Mappings 

      Suárez-Casal, Pedro; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2018-05)
      [Abstract]: Modulo mappings is an appealing scheme for the analog transmission of spatially correlated discrete-time analog source symbols over multiple access channels. In this letter, we show that the modulo mappings are ...

    • Analogue joint source-channel coding for multiple input multiple output–orthogonal frequency division multiplexing systems 

      Fresnedo, Óscar; Vázquez-Araújo, Francisco J.; Castedo, Luis; Garcia-Frias, Javier (Wiley, 2016)
      [Abstract]: Analogue joint source-channel coding (JSCC) has been shown to approach the optimal distortion-cost trade-off when transmitting over additive white Gaussian noise channels. In this work, we consider analogue ...

    • Coded Aperture Hyperspectral Image Reconstruction 

      García-Sánchez, Ignacio; Fresnedo, Óscar; González-Coma, José P.; Castedo, Luis (MDPI, 2021)
      [Abstract] In this work, we study and analyze the reconstruction of hyperspectral images that are sampled with a CASSI device. The sensing procedure was modeled with the help of the CS theory, which enabled efficient ...

    • Deep Contextual Bandit and Reinforcement Learning for IRS-Assisted MU-MIMO Systems 

      Pereira-Ruisánchez, Dariel; Fresnedo, Óscar; Pérez-Adán, Darian; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2023-07)
      [Abstract]: The combination of multiple-input multiple-output (MIMO) systems and intelligent reflecting surfaces (IRSs) is foreseen as a critical enabler of beyond 5G (B5G) and 6G. In this work, two different approaches ...

    • Design of Linear Precoders for Correlated Sources in MIMO Multiple Access Channels 

      Suárez-Casal, Pedro; González-Coma, José P.; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2018-12)
      [Abstract]: This paper focuses on distributed linear precoding when users transmit correlated information over a fading multiple-input and multiple-output multiple access channel. The precoders are optimized in order to ...

    • Estimation of Laplacian Symbols for Analog Transmission Over MIMO Channels 

      Suárez-Casal, Pedro; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2015-12)
      [Abstract]: The MAP and MMSE estimation of Laplace-distributed symbols transmitted over multiple-input multiple-output channels is studied. This is an important problem in analog joint source channel coding with spiral ...

    • Evaluation of Analog Joint Source-Channel Coding Systems for Multiple Access Channels 

      Fresnedo, Óscar; González-Coma, José P.; Hassanin, Mohamed; Castedo, Luis; Garcia-Frias, Javier (Institute of Electrical and Electronics Engineers, 2015-06)
      [Abstract]: We address the evaluation of low-complexity analog Joint Source Channel Coding (JSCC) methods for the transmission of discrete-time analog symbols over Multiple-Input Multiple-Output (MIMO) Multiple Access ...

    • Eye State Identification Based on Discrete Wavelet Transforms 

      Laport López, Francisco; Castro-Castro, Paula-María; Dapena, Adriana; Vázquez Araújo, Francisco Javier; Fresnedo, Óscar (MDPI, 2021)
      [Abstract]: We present a prototype to identify eye states from electroencephalography signals captured from one or two channels. The hardware is based on the integration of low-cost components, while the signal processing ...

    • Intelligent Reflective Surfaces for Wireless Networks: An Overview of Applications, Approached Issues, and Open Problems 

      Pérez-Adán, Darian; Fresnedo, Óscar; González-Coma, José P.; Castedo, Luis (MDPI, 2021)
      [Abstract] An intelligent reflective surface (IRS) is a novel and revolutionizing communication technology destined to enable the control of the radio environment. An IRS is a real-time controllable reflectarray with a ...

    • JSCC-Cast: A Joint Source Channel Coding Video Encoding and Transmission System with Limited Digital Metadata 

      Balsa, José; Fresnedo, Óscar; García-Naya, José A.; Domínguez-Bolaño, Tomás; Castedo, Luis (MDPI, 2021)
      [Abstract] This work considers the design and practical implementation of JSCC-Cast, a comprehensive analog video encoding and transmission system requiring a reduced amount of digital metadata. Suitable applications for ...

    • Lattice-Based Analog Mappings for Low-Latency Wireless Sensor Networks 

      Suárez-Casal, Pedro; Fresnedo, Óscar; Pérez-Adán, Darian; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2023-10-01)
      [Abstract]: We consider the transmission of spatially correlated analog information in a wireless sensor network (WSN) through fading single-input and multiple-output (SIMO) multiple access channels (MACs) with low-latency ...

    • Low-Complexity Near-Optimal Decoding for Analog Joint Source Channel Coding Using Space-Filling Curves 

      Fresnedo, Óscar; Vázquez-Araújo, Francisco J.; Castedo, Luis; Garcia-Frias, Javier (Institute of Electrical and Electronics Engineers, 2013-04)
      [Abstract]: Analog Joint Source-Channel Coding (JSCC) is a communication strategy that does not follow the separation principle of conventional digital systems but approaches the optimal distortion-cost tradeoff over AWGN ...

    • Rank Constrained Precoding for the Downlink of mmWave Massive MIMO Hybrid Systems 

      González-Coma, José P.; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2021-02-11)
      [Abstract] The hybrid design of precoding schemes for millimeter-wave communications allows exploiting the gains by using large antenna array with an affordable hardware cost and power consumption. In this work, we present ...

    • Service-Learning methodology to develop Bachelor’s Thesis in Information and Computer Science Degrees 

      Castro-Castro, Paula-María; Fresnedo, Óscar; Dapena, Adriana; Pereira-Loureiro, Javier; Vázquez Araújo, Francisco Javier (PKP Publishing Services Network, 2024)
      [Abstract]: Service-Learning (SL) is a powerful methodology to acquire competences and values in Higher Education. However, there is still no widespread use in Information and Computer Science (ICS) degrees where most of ...

    • Transmission of Analog Information Over the Multiple Access Relay Channel Using Zero-Delay Non-Linear Mappings 

      Fresnedo, Óscar; Suárez-Casal, Pedro; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2019-04-04)
      [Abstract]: We consider the zero-delay encoding of discrete-time analog information over the Multiple Access Relay Channel (MARC) using non-linear mapping functions. On the one hand, zero-delay non-linear mappings are ...