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.

%B Mechanical Systems and Signal Processing
%V 122
%P 642-657
%8 05/2019
%G eng
%R 10.1016/j.ymssp.2018.12.038
%0 Journal Article
%J Signal Processing
%D 2019
%T MMSE filter design for Full-Duplex filter-and-forward MIMO relays under limited dynamic range
%A Emilio Antonio-Rodríguez
%A Stefan Werner
%A R. López-Valcarce
%A Risto Wichman
%K full-duplex
%K winter
%X 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.

%B Signal Processing
%V 156
%P 208-219
%8 03/2019
%G eng
%R doi.org/10.1016/j.sigpro.2018.11.001
%0 Conference Paper
%B 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC)
%D 2018
%T Message-Splitting for Interference Cancellation in Multibeam Satellite Systems
%A Tomás Ramírez
%A Carlos Mosquera
%A Màrius Caus
%A Adriano Pastore
%A Mònica Navarro
%A Nele Noels
%B 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC)
%C Berlin, Germany
%G eng
%0 Journal Article
%J IEEE Transactions on Signal Processing
%D 2016
%T Multiantenna GLR detection of rank-one signals with known power spectral shape under spatially uncorrelated noise
%A Josep Sala
%A Gonzalo Vázquez-Vilar
%A R. López-Valcarce
%A Saeid Sedighi
%A Abbas Taherpour
%K cognitive radio
%K compass
%X 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.

%B IEEE Transactions on Signal Processing %V 64 %P 6269-6283 %8 12/2016 %G eng %N 23 %& 6269 %R 10.1109/TSP.2016.2601290 %0 Book Section %B Cooperative and Cognitive Satellite Systems %D 2015 %T Multibeam Joint Detection %A J. Arnau %A R. de Lamare %A C. Mosquera %K satcom %B Cooperative and Cognitive Satellite Systems %I Elsevier %G eng %0 Conference Paper %B IEEE 9th International Symposium on Intelligent Signal Processing (WISP) %D 2015 %T Multipath cancellation in broadband acoustic local positioning systems %A Fernando J. Alvarez %A R. López-Valcarce %K compass %K wsn %XThis 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.

%B IEEE 9th International Symposium on Intelligent Signal Processing (WISP) %I IEEE %C Siena, Italy %8 05/2015 %G eng %R 10.1109/WISP.2015.7139174 %0 Conference Paper %B IEEE International Conference on Acoustics, Speech and Signal Processing %D 2015 %T Multivariate Lattices for Encrypted Image Processing %A Alberto Pedrouzo-Ulloa %A Juan Ramón Troncoso-Pastoriza %A Fernando Pérez-González %K homomorphic encryption %K lattice cryptography %K SPED %B IEEE International Conference on Acoustics, Speech and Signal Processing %I IEEE %C Brisbane, Australia %8 04/2015 %G eng %0 Journal Article %J IEEE Communications Magazine %D 2014 %T MIMO precoding and combining solutions for millimeter wave systems %A Ahmed Alkhateeb %A Jianhua Mo %A Nuria González-Prelcic %A Robert W. Heath Jr. %K adaptive signal processing %K compass %K mmWave %XMillimeter-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.

%B IEEE Communications Magazine %V 52 %P 122-131 %8 12/2014 %G eng %N 12 %R 10.1109/MCOM.2014.6979963 %0 Conference Paper %B IEEE International Workshop on Information Forensics and Security (WIFS) %D 2014 %T Multiple JPEG compression detection by means of Benford-Fourier coefficients %A Cecilia Pasquini %A Giulia Boato %A Fernando Pérez-González %B IEEE International Workshop on Information Forensics and Security (WIFS) %C Atlanta, GA %8 12/2014 %G eng %0 Conference Paper %B GlobalSIP %D 2013 %T Meet the Family of Statistical Disclosure Attacks %A Simon Oya %A Carmela Troncoso %A Fernando Pérez-González %B GlobalSIP %8 12/2013 %G eng %1Submitted

%0 Journal Article %J Communications Letters, IEEE %D 2013 %T MMSE Performance Analysis of Generalized Multibeam Satellite Channels %A Christopoulos, D. %A J. Arnau %A Chatzinotas, S. %A C. Mosquera %A Ottersten, B. %K dynacs %K linear minimum mean square error receivers %K multibeam satellites %K Multiuser detection %K return link %K satcom %B Communications Letters, IEEE %P 1-4 %G eng %R 10.1109/LCOMM.2013.052013.122658 %0 Conference Paper %B IEEE International Workshop on Information Forensics and Security (WIFS) %D 2012 %T ML Estimation of the Resampling Factor %A David Vázquez-Padín %A Pedro Comesaña %XIn 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.

%B IEEE International Workshop on Information Forensics and Security (WIFS) %I IEEE %C Tenerife, Spain %P 205-210 %8 12/2012 %G eng %0 Journal Article %J IEEE Trans. on Signal Processing %D 2012 %T Multiantenna GLR detection of rank-one signals with known power spectrum in white noise with unknown spatial correlation %A Josep Sala %A Gonzalo Vázquez-Vilar %A R. López-Valcarce %K cognitive radio %K dynacs %XMultiple-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.

%B IEEE Trans. on Signal Processing
%V 60
%P 3065 - 3078
%8 06/2012
%G eng
%N 6
%R 10.1109/TSP.2012.2189767
%0 Conference Paper
%B International Workshop on Digital-forensics and Watermarking
%D 2012
%T Multimedia operator chain topology and ordering estimation based on detection and information theoretic tools
%A Pedro Comesaña
%A Fernando Pérez-González
%B International Workshop on Digital-forensics and Watermarking
%C Shanghai, China
%G eng
%0 Conference Paper
%B ASILOMAR 2012
%D 2012
%T Multiuser Detection Performance in Multibeam Satellite Links under Imperfect CSI
%A Arnau, Jesus
%A C. Mosquera
%K dynacs
%K satcom
%B ASILOMAR 2012
%C Pacific Grove, CA
%G eng
%1 Accepted for publication

%R 10.1109/ACSSC.2012.6489048
%0 Conference Paper
%B IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
%D 2011
%T Multiantenna detection of constant-envelope signals in noise of unknown variance
%A Daniel Romero
%A R. López-Valcarce
%K cognitive radio
%K multiantenna detection
%K spectrum sensing
%X 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.

%B IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC) %P 446 -450 %8 june %G eng %R 10.1109/SPAWC.2011.5990449 %0 Conference Paper %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %D 2011 %T Multiantenna detection under noise uncertainty and primary user's spatial structure %A David Ramírez %A Gonzalo Vázquez-Vilar %A R. López-Valcarce %A Javier Vía %A Ignacio Santamaría %K cognitive radio %K generalized likelihood ratio test (GLRT) %K spectrum sensing %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %I IEEE %C Prage, Czech Republic %P 2948-2951 %8 May %G eng %0 Journal Article %J IEEE Trans. on Wireless Communications %D 2011 %T Multiantenna Spectrum Sensing Exploiting Spectral a priori Information %A Gonzalo Vázquez-Vilar %A R. López-Valcarce %A Josep Sala %K cognitive radio %K dynacs %K spectrum sensing %B IEEE Trans. on Wireless Communications %V 10 %P 4345 - 4355 %8 12/2011 %G eng %N 12 %R 10.1109/TWC.2011.101211.110665 %0 Conference Paper %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %D 2010 %T Multiantenna spectrum sensing: detection of spatial correlation among time-series with unknown spectra %A David Ramírez %A Javier Vía %A Ignacio Santamaría %A R. López-Valcarce %A L. L. Scharf %K cognitive radio %K coherence spectrum %K generalized likelihood ratio test %K Hadamard ratio %K multiple-channel signal detection %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %C Dallas, TX %G eng %0 Conference Paper %B International Workshop on Cognitive Information Processing (CIP) %D 2010 %T Multiantenna spectrum sensing for Cognitive Radio: overcoming noise uncertainty %A R. López-Valcarce %A Gonzalo Vázquez-Vilar %A Josep Sala %B International Workshop on Cognitive Information Processing (CIP) %C Elba Island, Italy %G eng %0 Conference Paper %B Media Forensics and Security %D 2009 %T Model-based steganalysis using invariant features %A Tu-Thach Quach %A Fernando Pérez-González %A Gregory L. Heileman %K Invariant features %K Model-based %K Steganalysis %B Media Forensics and Security %C San Jose, CA, U.S.A. %8 January %G eng %0 Conference Paper %B IEEE International Conference on Image Processing (ICIP) %D 2009 %T Modeling Magnitudes of Gabor Coefficients: The β-Rayleigh Distribution %A Daniel González-Jiménez %A Enrique Argones-Rúa %A Fernando Pérez-González %A José Luis Alba-Castro %K Gabor %K generalized Gaussian %K Rayleigh %K watermarking %B IEEE International Conference on Image Processing (ICIP) %I IEEE %C Cairo, Egypt %8 November %G eng %0 Conference Paper %B International Conference on Cognitive Radio Oriented Wireless Networks and Communications (Crowncom) %D 2009 %T Multiantenna detection of multicarrier primary signals exploiting spectral a priori information %A R. López-Valcarce %A Gonzalo Vázquez-Vilar %A Marcos Álvarez-Díaz %B International Conference on Cognitive Radio Oriented Wireless Networks and Communications (Crowncom) %C Hannover, Germany %8 June 22-24 %G eng %0 Conference Paper %B IEEE International Workshop on Signal Processing Advances in Wireless Communications %D 2008 %T Maximum Likelihood SNR Estimation for Asynchronously Oversampled OFDM Signals %A R. López-Valcarce %A C. Mosquera %K estimation %K ML %K OFDM %K SNR %B IEEE International Workshop on Signal Processing Advances in Wireless Communications %C Recife, Brazil %G eng %0 Conference Paper %B International Symposium on Communication Systems, Networks and Signal Processing (CNSDSP) %D 2008 %T ML and EM Algorithm for non-data-aided SNR Estimation of Linearly Modulated Signals %A Wilfried Gappmair %A R. López-Valcarce %A C. Mosquera %K EM %K ML %K SNR estimation %B International Symposium on Communication Systems, Networks and Signal Processing (CNSDSP) %P 530-534 %G eng %0 Conference Paper %B IEEE International Conference on Image Processing (ICIP) %D 2007 %T Modeling Gabor coefficients via Generalized Gaussian Distributions for face recognition %A Daniel González-Jiménez %A Fernando Pérez-González %A Pedro Comesaña %A Luis Pérez-Freire %A José Luis Alba-Castro %K biometrics %K face-recognition %B IEEE International Conference on Image Processing (ICIP) %C San Antonio, TX, USA %P 1261-1264 %8 September %G eng %0 Journal Article %J IEEE Signal Processing Letters %D 2004 %T Minimum delay spread TEQ design in multicarrier systems %A R. López-Valcarce %K channel shortener %K cyclic prefix %K delay spread %K Digital Communications %K multicarrier communications %K time domain equalizer %B IEEE Signal Processing Letters %V 11 %P 682–685 %8 August %G eng %R 10.1109/LSP.2004.831676 %0 Conference Paper %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %D 2000 %T Misconvergence and stabilization of adaptive IIR lattice filters %A Fernando Pérez-González %A R. López-Valcarce %K adaptive IIR filters %K lattice filters %K system identification %B IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) %C Istanbul, Turkey %V 1 %P 65–68 %G eng %0 Conference Paper %B IFAC World Congress %D 1996 %T The Master-Slave family of system identification algorithms: theoretical results and new structures %A R. López-Valcarce %A Fernando Pérez-González %K adaptive IIR filters %K lattice filters %K system identification %B IFAC World Congress %I IFAC %C San Francisco, CA, USA %V J %P 185–190 %8 June %G eng %0 Journal Article %J Applied Signal Processing %D 1996 %T A multipulse-like wavelet-based speech coder %A Nuria González-Prelcic %A D. Docampo %B Applied Signal Processing %V 3 %P 78-87 %G eng %0 Conference Paper %B UK Symposium on Applications of Time-Frequency and Time-Scale Methods (TFTS) %D 1995 %T A Multipulse-like Wavelet-based Speech Coder %A Nuria González-Prelcic %A D. Docampo %B UK Symposium on Applications of Time-Frequency and Time-Scale Methods (TFTS) %C Warwick, UK %8 August %G eng