The accurate synthesis of realistic waveforms conforming to certain specica-

tions is a fundamental step in random vibration testing. Since real-time imple-

mentation of digital signal processing systems for random vibration and noise

synthesis necessarily operates frame by frame, the overlap-add (OLA) method,

by which frames are windowed and overlapped, is widely used in practice to

avoid artifacts at frame boundaries. When a wide-sense stationary random

signal is desired, however, the OLA method presents a shortcoming, because

the inherent periodicity of the frame-by-frame process unavoidably produces a

cyclostationary signal, i.e., its statistics present an undesired periodic behav-

ior. We analyze the impact of the window coecients in the cyclostationarity

properties of the synthetic process, and then present algorithms for window de-

sign with the goal of maximizing a measure of its stationarity, considering both

second- and fourth-order statistical properties. The proposed designs are shown

to signicantly improve the stationarity properties when compared to commonly

used windows.

VL - 122
ER -
TY - JOUR
T1 - MMSE filter design for Full-Duplex filter-and-forward MIMO relays under limited dynamic range
JF - Signal Processing
Y1 - 2019
A1 - Emilio Antonio-Rodríguez
A1 - Stefan Werner
A1 - R. López-Valcarce
A1 - Risto Wichman
KW - full-duplex
KW - winter
AB - We study the problem of optimizing the end-to-end performance of a full-duplex filter-and-forward MIMO relay link, consisting

of a source, a relay, and a destination node, by employing linear filtering at each node. The system model accounts for multipath

propagation and self-interference at the relay, as well as transmitter impairments and limited dynamic range at every node. The

design accommodates signals with arbitrary spectra and includes the direct link between the source and destination nodes. Under

the minimum mean square error criterion, the resulting non-convex problem is approximated by a sequence of convex problems

and solved by means of an alternating minimization method. Linear constraints allocate some of the degrees of freedom in the relay

to guarantee a sufficiently small residual self-interference. Simulations quantify the impact of degrees of freedom, the dynamic

range, and the balance between direct and relay paths on the link performance.

VL - 156
ER -
TY - CONF
T1 - Message-Splitting for Interference Cancellation in Multibeam Satellite Systems
T2 - 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC)
Y1 - 2018
A1 - Tomás Ramírez
A1 - Carlos Mosquera
A1 - Màrius Caus
A1 - Adriano Pastore
A1 - Mònica Navarro
A1 - Nele Noels
JF - 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC)
CY - Berlin, Germany
ER -
TY - JOUR
T1 - Multiantenna GLR detection of rank-one signals with known power spectral shape under spatially uncorrelated noise
JF - IEEE Transactions on Signal Processing
Y1 - 2016
A1 - Josep Sala
A1 - Gonzalo Vázquez-Vilar
A1 - R. López-Valcarce
A1 - Saeid Sedighi
A1 - Abbas Taherpour
KW - cognitive radio
KW - compass
AB - We establish the generalized likelihood ratio (GLR) test for a Gaussian signal of known power spectral shape and unknown rank-one spatial signature in additive white Gaussian noise with an unknown diagonal spatial correlation matrix. This is motivated by spectrum sensing problems in dynamic spectrum access (DSA), in which the temporal correlation of the primary signal can be assumed known up to a scaling, and where the noise is due to an uncalibrated receive array. For spatially independent identically distributed (i.i.d.) noise, the corresponding GLR test reduces to a scalar optimization problem, whereas the GLR detector in the general non-i.i.d. case yields a more involved expression, which can be computed via alternating optimization methods. Low signal-to-noise ratio (SNR) approximations to the detectors are given, together with an asymptotic analysis showing the influence on detection performance of the signal power spectrum and SNR distribution across antennas. Under spatial rank-P conditions, we show that the rank-one GLR detectors are consistent with a statistical criterion that maximizes the output energy of a beamformer operating on filtered data. Simulation results support our theoretical findings in that exploiting prior knowledge on the signal power spectrum can result in significant performance improvement.

VL - 64 IS - 23 ER - TY - CHAP T1 - Multibeam Joint Detection T2 - Cooperative and Cognitive Satellite Systems Y1 - 2015 A1 - J. Arnau A1 - R. de Lamare A1 - C. Mosquera KW - satcom JF - Cooperative and Cognitive Satellite Systems PB - Elsevier ER - TY - CONF T1 - Multipath cancellation in broadband acoustic local positioning systems T2 - IEEE 9th International Symposium on Intelligent Signal Processing (WISP) Y1 - 2015 A1 - Fernando J. Alvarez A1 - R. López-Valcarce KW - compass KW - wsn AB -This work proposes a novel method to estimate the Line-of-Sight Time-of-Flights (LOS-TOFs) in a broadband acoustic local positioning system (ALPS) with strong multipath interference. The proposed method is based on the Matching Pursuit channel estimation algorithm that provides a low complexity approximation to the Maximum Likelihood solution for sparse channels. A multichannel version of this algorithm has been implemented to estimate a minimum of three coefficients in the channel responses of a particular ALPS, composed of four beacons that perform the simultaneous emission of BPSK modulated 255-bit Kasami codes. A statistical analysis of performance has been carried out by using a set of test signals synthetically generated to simulate different positions and reflection coefficients of the environment. The results of this analysis show the enhanced capability of the proposed method to estimate the LOS-TOFs under strong multipath interference, with respect to that of a classical system based on correlation + thresholding.

JF - IEEE 9th International Symposium on Intelligent Signal Processing (WISP) PB - IEEE CY - Siena, Italy ER - TY - CONF T1 - Multivariate Lattices for Encrypted Image Processing T2 - IEEE International Conference on Acoustics, Speech and Signal Processing Y1 - 2015 A1 - Alberto Pedrouzo-Ulloa A1 - Juan Ramón Troncoso-Pastoriza A1 - Fernando Pérez-González KW - homomorphic encryption KW - lattice cryptography KW - SPED JF - IEEE International Conference on Acoustics, Speech and Signal Processing PB - IEEE CY - Brisbane, Australia ER - TY - JOUR T1 - MIMO precoding and combining solutions for millimeter wave systems JF - IEEE Communications Magazine Y1 - 2014 A1 - Ahmed Alkhateeb A1 - Jianhua Mo A1 - Nuria González-Prelcic A1 - Robert W. Heath Jr. KW - adaptive signal processing KW - compass KW - mmWave AB -Millimeter-wave communication is one way to alleviate the spectrum gridlock at lower frequencies while simultaneously providing high-bandwidth communication channels. MmWave makes use of MIMO through large antenna arrays at both the base station and the mobile station to provide sufficient received signal power. This article explains how beamforming and precoding are different in MIMO mmWave systems than in their lower-frequency counterparts, due to different hardware constraints and channel characteristics. Two potential architectures are reviewed: hybrid analog/digital precoding/combining and combining with low-resolution analog- to-digital converters. The potential gains and design challenges for these strategies are discussed, and future research directions are highlighted.

VL - 52 IS - 12 ER - TY - CONF T1 - Multiple JPEG compression detection by means of Benford-Fourier coefficients T2 - IEEE International Workshop on Information Forensics and Security (WIFS) Y1 - 2014 A1 - Cecilia Pasquini A1 - Giulia Boato A1 - Fernando Pérez-González JF - IEEE International Workshop on Information Forensics and Security (WIFS) CY - Atlanta, GA ER - TY - CONF T1 - Meet the Family of Statistical Disclosure Attacks T2 - GlobalSIP Y1 - 2013 A1 - Simon Oya A1 - Carmela Troncoso A1 - Fernando Pérez-González JF - GlobalSIP U1 -Submitted

ER - TY - JOUR T1 - MMSE Performance Analysis of Generalized Multibeam Satellite Channels JF - Communications Letters, IEEE Y1 - 2013 A1 - Christopoulos, D. A1 - J. Arnau A1 - Chatzinotas, S. A1 - C. Mosquera A1 - Ottersten, B. KW - dynacs KW - linear minimum mean square error receivers KW - multibeam satellites KW - Multiuser detection KW - return link KW - satcom ER - TY - CONF T1 - ML Estimation of the Resampling Factor T2 - IEEE International Workshop on Information Forensics and Security (WIFS) Y1 - 2012 A1 - David Vázquez-Padín A1 - Pedro Comesaña AB -In this work, the problem of resampling factor estimation for tampering detection is addressed following the maximum likelihood criterion. By relying on the rounding operation applied after resampling, an approximation of the likelihood function of the quantized resampled signal is obtained. From the underlying statistical model, the maximum likelihood estimate is derived for one-dimensional signals and a piecewise linear interpolation. The performance of the obtained estimator is evaluated, showing that it outperforms state-of-the-art methods.

JF - IEEE International Workshop on Information Forensics and Security (WIFS) PB - IEEE CY - Tenerife, Spain ER - TY - JOUR T1 - Multiantenna GLR detection of rank-one signals with known power spectrum in white noise with unknown spatial correlation JF - IEEE Trans. on Signal Processing Y1 - 2012 A1 - Josep Sala A1 - Gonzalo Vázquez-Vilar A1 - R. López-Valcarce KW - cognitive radio KW - dynacs AB -Multiple-antenna detection of a Gaussian signal with spatial rank one in temporally white Gaussian noise with arbitrary and unknown spatial covariance is considered. This is motivated by spectrum sensing problems in the context of Dynamic Spectrum Access in which several secondary networks coexist but do not cooperate, creating a background of spatially correlated broadband interference. When the temporal correlation of the signal of interest is assumed known up to a scale factor, the corresponding Generalized Likelihood Ratio Test is shown to yield a scalar optimization problem. Closed-form expressions of the test are obtained for the general signal spectrum case in the low signal-to-noise ratio (SNR) regime, as well as for signals with binary-valued power spectrum in arbitrary SNR. The two resulting detectors turn out to be equivalent. An asymptotic approximation to the test distribution for the low-SNR regime is derived, closely matching empirical results from spectrum sensing simulation experiments.

VL - 60
IS - 6
ER -
TY - CONF
T1 - Multimedia operator chain topology and ordering estimation based on detection and information theoretic tools
T2 - International Workshop on Digital-forensics and Watermarking
Y1 - 2012
A1 - Pedro Comesaña
A1 - Fernando Pérez-González
JF - International Workshop on Digital-forensics and Watermarking
CY - Shanghai, China
ER -
TY - CONF
T1 - Multiuser Detection Performance in Multibeam Satellite Links under Imperfect CSI
T2 - ASILOMAR 2012
Y1 - 2012
A1 - Arnau, Jesus
A1 - C. Mosquera
KW - dynacs
KW - satcom
JF - ASILOMAR 2012
CY - Pacific Grove, CA
U1 - Accepted for publication

ER -
TY - CONF
T1 - Multiantenna detection of constant-envelope signals in noise of unknown variance
T2 - IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
Y1 - 2011
A1 - Daniel Romero
A1 - R. López-Valcarce
KW - cognitive radio
KW - multiantenna detection
KW - spectrum sensing
AB - Detection of unknown signals with constant modulus (CM) using multiple antennas in additive white Gaussian noise of unknown variance is considered. The channels from the source to each antenna are assumed frequency-flat and unknown. This problem is of interest for spectrum sensing in cognitive radio systems in which primary signals are known to have the CM property. Examples include analog frequency modulated signals such as those transmitted by wireless microphones in the TV bands and Gaussian Minimum Shift Keying modulated signals as in the GSM cellular standard. The proposed detector, derived from a Generalized Likelihood Ratio (GLR) approach, exploits both the CM property and the spatial independence of noise, outperforming the GLR test for Gaussian signals as shown by simulation.

JF - IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC) ER - TY - CONF T1 - Multiantenna detection under noise uncertainty and primary user's spatial structure T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) Y1 - 2011 A1 - David Ramírez A1 - Gonzalo Vázquez-Vilar A1 - R. López-Valcarce A1 - Javier Vía A1 - Ignacio Santamaría KW - cognitive radio KW - generalized likelihood ratio test (GLRT) KW - spectrum sensing JF - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) PB - IEEE CY - Prage, Czech Republic ER - TY - JOUR T1 - Multiantenna Spectrum Sensing Exploiting Spectral a priori Information JF - IEEE Trans. on Wireless Communications Y1 - 2011 A1 - Gonzalo Vázquez-Vilar A1 - R. López-Valcarce A1 - Josep Sala KW - cognitive radio KW - dynacs KW - spectrum sensing VL - 10 IS - 12 ER - TY - CONF T1 - Multiantenna spectrum sensing: detection of spatial correlation among time-series with unknown spectra T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) Y1 - 2010 A1 - David Ramírez A1 - Javier Vía A1 - Ignacio Santamaría A1 - R. López-Valcarce A1 - L. L. Scharf KW - cognitive radio KW - coherence spectrum KW - generalized likelihood ratio test KW - Hadamard ratio KW - multiple-channel signal detection JF - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) CY - Dallas, TX ER - TY - CONF T1 - Multiantenna spectrum sensing for Cognitive Radio: overcoming noise uncertainty T2 - International Workshop on Cognitive Information Processing (CIP) Y1 - 2010 A1 - R. López-Valcarce A1 - Gonzalo Vázquez-Vilar A1 - Josep Sala JF - International Workshop on Cognitive Information Processing (CIP) CY - Elba Island, Italy ER - TY - CONF T1 - Model-based steganalysis using invariant features T2 - Media Forensics and Security Y1 - 2009 A1 - Tu-Thach Quach A1 - Fernando Pérez-González A1 - Gregory L. Heileman KW - Invariant features KW - Model-based KW - Steganalysis JF - Media Forensics and Security CY - San Jose, CA, U.S.A. ER - TY - CONF T1 - Modeling Magnitudes of Gabor Coefficients: The β-Rayleigh Distribution T2 - IEEE International Conference on Image Processing (ICIP) Y1 - 2009 A1 - Daniel González-Jiménez A1 - Enrique Argones-Rúa A1 - Fernando Pérez-González A1 - José Luis Alba-Castro KW - Gabor KW - generalized Gaussian KW - Rayleigh KW - watermarking JF - IEEE International Conference on Image Processing (ICIP) PB - IEEE CY - Cairo, Egypt ER - TY - CONF T1 - Multiantenna detection of multicarrier primary signals exploiting spectral a priori information T2 - International Conference on Cognitive Radio Oriented Wireless Networks and Communications (Crowncom) Y1 - 2009 A1 - R. López-Valcarce A1 - Gonzalo Vázquez-Vilar A1 - Marcos Álvarez-Díaz JF - International Conference on Cognitive Radio Oriented Wireless Networks and Communications (Crowncom) CY - Hannover, Germany ER - TY - CONF T1 - Maximum Likelihood SNR Estimation for Asynchronously Oversampled OFDM Signals T2 - IEEE International Workshop on Signal Processing Advances in Wireless Communications Y1 - 2008 A1 - R. López-Valcarce A1 - C. Mosquera KW - estimation KW - ML KW - OFDM KW - SNR JF - IEEE International Workshop on Signal Processing Advances in Wireless Communications CY - Recife, Brazil ER - TY - CONF T1 - ML and EM Algorithm for non-data-aided SNR Estimation of Linearly Modulated Signals T2 - International Symposium on Communication Systems, Networks and Signal Processing (CNSDSP) Y1 - 2008 A1 - Wilfried Gappmair A1 - R. López-Valcarce A1 - C. Mosquera KW - EM KW - ML KW - SNR estimation JF - International Symposium on Communication Systems, Networks and Signal Processing (CNSDSP) ER - TY - CONF T1 - Modeling Gabor coefficients via Generalized Gaussian Distributions for face recognition T2 - IEEE International Conference on Image Processing (ICIP) Y1 - 2007 A1 - Daniel González-Jiménez A1 - Fernando Pérez-González A1 - Pedro Comesaña A1 - Luis Pérez-Freire A1 - José Luis Alba-Castro KW - biometrics KW - face-recognition JF - IEEE International Conference on Image Processing (ICIP) CY - San Antonio, TX, USA ER - TY - JOUR T1 - Minimum delay spread TEQ design in multicarrier systems JF - IEEE Signal Processing Letters Y1 - 2004 A1 - R. López-Valcarce KW - channel shortener KW - cyclic prefix KW - delay spread KW - Digital Communications KW - multicarrier communications KW - time domain equalizer VL - 11 ER - TY - CONF T1 - Misconvergence and stabilization of adaptive IIR lattice filters T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) Y1 - 2000 A1 - Fernando Pérez-González A1 - R. López-Valcarce KW - adaptive IIR filters KW - lattice filters KW - system identification JF - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) CY - Istanbul, Turkey VL - 1 ER - TY - CONF T1 - The Master-Slave family of system identification algorithms: theoretical results and new structures T2 - IFAC World Congress Y1 - 1996 A1 - R. López-Valcarce A1 - Fernando Pérez-González KW - adaptive IIR filters KW - lattice filters KW - system identification JF - IFAC World Congress PB - IFAC CY - San Francisco, CA, USA VL - J ER - TY - JOUR T1 - A multipulse-like wavelet-based speech coder JF - Applied Signal Processing Y1 - 1996 A1 - Nuria González-Prelcic A1 - D. Docampo VL - 3 ER - TY - CONF T1 - A Multipulse-like Wavelet-based Speech Coder T2 - UK Symposium on Applications of Time-Frequency and Time-Scale Methods (TFTS) Y1 - 1995 A1 - Nuria González-Prelcic A1 - D. Docampo JF - UK Symposium on Applications of Time-Frequency and Time-Scale Methods (TFTS) CY - Warwick, UK ER -