This paper presents an acoustic local positioning system (ALPS) suitable for indoor positioning

of portable devices such as smartphones or tablets, based on the transmission of high frequency

CDMA-coded signals from a fixed network of beacons. The main novelty of the proposed ALPS is

its capability to mitigate the effects of multipath propagation by performing an accurate estimation

of the Line-of-Sight Time-of-Flights (LOS-TOF) through the Matching Pursuit algorithm. Signal

detection, multipath cancellation and positioning estimation all take place within the portable device,

which provides a graphical representation of the updated position in less than a second. The

performance of the Matching Pursuit algorithm is analyzed in a real scenario and the results show

that the proposed method is capable to retrieve the multipath-free System Availability under strong

multipath conditions with SNR levels as low as 0 dB.

VL - 62
ER -
TY - JOUR
T1 - FER Estimation in a Memoryless BSC with Variable Frame Length and Unreliable ACK/NAK Feedback
JF - IEEE Transactions on Wireless Communications
Y1 - 2017
A1 - Alberto Rico-Alvariño
A1 - R. López-Valcarce
A1 - Carlos Mosquera
A1 - Robert W. Heath Jr.
KW - adaptive signal processing
KW - compass
KW - Cramér-Rao bound (CRB)
KW - frame error rate
KW - myrada
KW - winter
AB - We consider the problem of estimating the frame error rate (FER) of a given memoryless binary symmetric channel by observing the success or failure of transmitted packets. Whereas FER estimation is relatively straightforward if all observations correspond to packets with equal length, the problem becomes considerably more complex when this is not the case. We develop FER estimators when

transmissions of different lengths are observed, together with the Cramer-Rao Lower Bound (CRLB). Although the main focus is on Maximum Likelihood (ML) estimation, we also obtain low complexity schemes performing close to optimal in some scenarios. In a second stage, we consider the case in which FER estimation is performed at a node different from the receiver, and incorporate the impairment of unreliable observations by considering noisy ACK/NAK feedback links. The impact of unreliable feedback is analyzed by means of the corresponding CRLB. In this setting, the ML estimator is obtained by applying the Expectation-Maximization algorithm to jointly estimate the error probabilities of the data and feedback links. Simulation results illustrate the benefits of the proposed estimators.

VL - 16
IS - 6
ER -
TY - CONF
T1 - Filter design for delay-based anonymous communications
T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
Y1 - 2017
A1 - Simon Oya
A1 - Fernando Pérez-González
A1 - Carmela Troncoso
KW - adversarial signal processing
KW - compass
KW - Multimedia security
KW - winter
JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
ER -
TY - JOUR
T1 - Learning Power Spectrum Maps from Quantized Power Measurements
JF - IEEE Transactions on Signal Processing
Y1 - 2017
A1 - Daniel Romero
A1 - Seung-Jun Kim
A1 - Georgios Giannakis
A1 - R. López-Valcarce
KW - cognitive radio
KW - compass
KW - compressed sensing
KW - spectrum sensing
KW - winter
KW - wsn
AB - Using power measurements collected by a network of low-cost sensors, power spectral density (PSD) maps are con-

structed to capture the distribution of RF power across space and frequency. Linearly compressed and quantized power measure-

ments enable wideband sensing at affordable implementation complexity using a small number of bits. Strengths of data- and model-

driven approaches are combined to develop estimators capable of incorporating multiple forms of spectral and propagation prior

information while fitting the rapid variations of shadow fading across space. To this end, novel nonparametric and semiparametric

formulations are investigated. It is shown that the desired PSD maps can be obtained using support vector machine-type solvers.

In addition to batch approaches, an online algorithm attuned to real-time operation is developed. Numerical tests assess the performance of the novel algorithms.

VL - 65
IS - 10
ER -
TY - CONF
T1 - Secure Genomic Susceptibility Testing based on Lattice Encryption
T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)
Y1 - 2017
A1 - Juan Ramón Troncoso-Pastoriza
A1 - Alberto Pedrouzo-Ulloa
A1 - Fernando Pérez-González
KW - adversarial signal processing
KW - compass
KW - Genomic Privacy
KW - homomorphic encryption
KW - Lattice-Based Cryptography
KW - Privacy Protection
JF - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)
PB - IEEE
CY - New Orleans, USA
ER -
TY - CONF
T1 - Time-domain channel estimation for wideband millimeter wave systems with hybrid architecture
T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)
Y1 - 2017
A1 - Kiran Venugopal
A1 - Ahmed Alkhateeb
A1 - Robert W. Heath Jr.
A1 - Nuria González-Prelcic
KW - compass
KW - mmWave
KW - myrada
AB - Millimeter wave (mm Wave) systems will likely employ large antennas at both the transmitter and receiver for directional beamforming. Hybrid analog/digital MIMO architectures have been proposed previously for leveraging both array gain and multiplexing gain, while reducing the power consumption in analog-to-digital converters. Channel knowledge is needed to design the hybrid precoders/combiners, which is difficult to obtain due to the large antenna arrays and the frequency selective nature of the channel. In this paper, we propose a sparse recovery based time-domain channel estimation technique for hybrid architecture based frequency selective mmWave systems. The proposed compressed sensing channel estimation algorithm is shown to provide good estimation error performance, while requiring small training overhead. The simulation results show that using multiple RF chains at the receiver and the transmitter further reduces the training overhead.

JF - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) ER - TY - JOUR T1 - Wideband full-duplex MIMO relays with blind adaptive self-interference cancellation JF - Signal Processing Y1 - 2017 A1 - Emilio Antonio-Rodríguez A1 - Stefan Werner A1 - R. López-Valcarce A1 - Taneli Riihonen A1 - Risto Wichman KW - adaptive signal processing KW - compass KW - full duplex KW - winter AB -We develop adaptive self-interference cancellation algorithms for both filter-and-forward and decode-and-forward

multiple-input multiple-output relays. The algorithms are blind in the sense that they only exploit the spectral properties

of the transmitted signal to identify the self-interference channel, while dealing with frequency-selective channels and

arbitrary signal spectra. Our approach is non-intrusive in the sense that the algorithms can successfully identify, track,

and cancel the self-interference distortion while the relay is operating in its normal mode. We study the stationary

points of the algorithms and analyze under which conditions they achieve perfect cancellation of the self-interference.

Simulation results show that the algorithms provide residual self-interference levels below the noise floor by using

the time samples of only a few OFDM symbols.

VL - 130
ER -
TY - CONF
T1 - Advanced Signal Processing Techniques for Fixed and Mobile Satellite Communications
T2 - 8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop
Y1 - 2016
A1 - Pol Henarejos
A1 - Ana Pérez-Neira
A1 - Nicolò Mazzali
A1 - Carlos Mosquera
KW - compass
KW - full duplex
KW - satcom
JF - 8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop
ER -
TY - CONF
T1 - Array thinnig for antenna selection in millimeter wave MIMO systems
T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
Y1 - 2016
A1 - C. Rusu
A1 - Nuria González-Prelcic
A1 - R. W. Heath Jr
KW - compass
KW - mmWave
JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
ER -
TY - CONF
T1 - Bandwidth Allocation in Partial Duplex Relaying
T2 - The 17th IEEE International workshop on Signal Processing advances in Wireless Communications (SPAWC)
Y1 - 2016
A1 - Carlos Mosquera
A1 - R. López-Valcarce
KW - compass
KW - full duplex
KW - relay
JF - The 17th IEEE International workshop on Signal Processing advances in Wireless Communications (SPAWC)
CY - Edinburgh, UK
ER -
TY - JOUR
T1 - Compressive Covariance Sensing: Structure-Based Compressive Sensing Beyond Sparsity
JF - IEEE Signal Processing Magazine
Y1 - 2016
A1 - Daniel Romero
A1 - Dyonisius D Ariananda
A1 - Zhi Tian
A1 - Geert Leus
KW - compass
KW - compressed sensing
AB - Compressed sensing deals with the reconstruction of signals

from sub-Nyquist samples by exploiting the sparsity of their

projections onto known subspaces. In contrast, the present

article is concerned with the reconstruction of second-order

statistics, such as covariance and power spectrum, even in

the absence of sparsity priors. The framework described here

leverages the statistical structure of random processes to

enable signal compression and offers an alternative perspective

at sparsity-agnostic inference. Capitalizing on parsimonious

representations, we illustrate how compression and reconstruction

tasks can be addressed in popular applications such

as power spectrum estimation, incoherent imaging, direction

of arrival estimation, frequency estimation, and wideband

spectrum sensing.

VL - 33
IS - 1
ER -
TY - CONF
T1 - Design of data-injection adversarial attacks against spatial field detectors
T2 - IEEE Workshop on Statistical Signal Processing (SSP)
Y1 - 2016
A1 - R. López-Valcarce
A1 - Daniel Romero
KW - adversarial signal processing
KW - compass
KW - wsn
AB - Data-injection attacks on spatial field detection corrupt a subset of measurements to cause erroneous decisions. We consider a centralized decision scheme exploiting spatial field smoothness to overcome lack of knowledge on system parameters such as noise variance. We obtain closed-form expressions for system performance and investigate strategies for an intruder injecting false data in a fraction of the sensors in order to reduce the probability of detection. The problem of determining the most vulnerable subset of sensors is also analyzed.

JF - IEEE Workshop on Statistical Signal Processing (SSP) CY - Palma de Mallorca, Spain ER - TY - JOUR T1 - Design of pool mixes against profiling attacks in real conditions JF - IEEE/ACM Transactions on Networking Y1 - 2016 A1 - Simon Oya A1 - Fernando Pérez-González A1 - Carmela Troncoso KW - adversarial signal processing KW - compass VL - 24 IS - 6 ER - TY - JOUR T1 - Designing incoherent frames through convex techniques for optimized compressed sensing JF - IEEE Transactions on Signal Processing Y1 - 2016 A1 - Cristian Rusu A1 - Nuria González-Prelcic KW - compass KW - compressed sensing VL - 64 IS - 9 ER - TY - CONF T1 - Distributed multivariate regression with unknown noise covariance in the presence of outliers: a minimum description length approach T2 - IEEE Workshop on Statistical Signal Processing (SSP) Y1 - 2016 A1 - R. López-Valcarce A1 - Daniel Romero A1 - Josep Sala A1 - Alba Pagès-Zamora KW - compass KW - wsn AB -We consider the problem of estimating the coefficients in a multivariable linear model by means of a wireless sensor network

which may be affected by anomalous measurements. The noise covariance matrices at the different sensors are assumed

unknown. Treating outlying samples, and their support, as additional nuisance parameters, the Maximum Likelihood

estimate is investigated, with the number of outliers being estimated according to the Minimum Description Length

principle. A distributed implementation based on iterative consensus techniques is then proposed, and it is shown effective

for managing outliers in the data.

JF - IEEE Workshop on Statistical Signal Processing (SSP)
CY - Palma de Mallorca, Spain
ER -
TY - CONF
T1 - Estimating millimeter wave channels using out-of-band measurements
T2 - Information Theory and Applications Workshop (ITA
Y1 - 2016
A1 - Anum Ali
A1 - Nuria González-Prelcic
A1 - R.W. Heath Jr.
KW - compass
KW - mmWave
JF - Information Theory and Applications Workshop (ITA
ER -
TY - JOUR
T1 - Fast orthonormal sparsifying transforms based on Householder reflectors
JF - IEEE Transactions on Signal Processing
Y1 - 2016
A1 - C. Rusu
A1 - Nuria González-Prelcic
A1 - R.W. Heath Jr.
KW - compass
KW - compressed sensing
VL - 64
IS - 24
ER -
TY - CONF
T1 - Frequency selective multiuser hybrid precoding for mmWave systems with imperfect channel knowledge
T2 - Asilomar Conf. on Signals, Systems and Computers
Y1 - 2016
A1 - Jose P. Gonzalez-Coma
A1 - Nuria González-Prelcic
A1 - Luis Castedo
A1 - Robert W. Heath Jr.
KW - compass
KW - mmWave
JF - Asilomar Conf. on Signals, Systems and Computers
ER -
TY - CONF
T1 - Full-duplex operation in two-way broadcast service for maritime applications
T2 - 8th Advanced Satellite Multimedia Systems Conference and 14th Signal Processing for Space Communications Workshop
Y1 - 2016
A1 - Tomás Ramírez
A1 - Carlos Mosquera
KW - compass
KW - full duplex
KW - satcom
JF - 8th Advanced Satellite Multimedia Systems Conference and 14th Signal Processing for Space Communications Workshop
ER -
TY - CONF
T1 - Hybrid precoders and combiners for mmWave MIMO systems with per-antenna power constraints
T2 - IEEE Global Telecommunications Conf. (GLOBECOM)
Y1 - 2016
A1 - R. López-Valcarce
A1 - Nuria González-Prelcic
A1 - Cristian Rusu
A1 - R. W. Heath, Jr
KW - compass
KW - mmWave
AB - This paper considers the design of hybrid precoders

and combiners for mmWave MIMO systems with per-antenna

power constraints and the additional limitations introduced by

the phase-shifting network in the analog processing stage. Previous

hybrid designs were obtained using a total power constraint,

but in practical implementations per-antenna constraints are

more realistic, specially at mmWave, given the large number of

power amplifiers used in the transmit array. Assuming perfect

channel knowledge, we obtain first an approximation to the alldigital

solution for the precoder and the combiner given the

per-antenna constraints. Then, we develop a new method for the

design of the hybrid precoder and combiner which attempts to

match such all-digital approximation. Simulation results show

the effectiveness of the proposed approach, which performs close

to the all-digital solution.

JF - IEEE Global Telecommunications Conf. (GLOBECOM)
ER -
TY - CONF
T1 - Image denoising in the encrypted domain
T2 - IEEE International Workshop on Information Forensics and Security (WIFS)
Y1 - 2016
A1 - Alberto Pedrouzo-Ulloa
A1 - Juan Ramón Troncoso-Pastoriza
A1 - Fernando Pérez-González
KW - compass
KW - homomorphic processing
KW - Image Denoising
KW - Image Encryption
KW - lattice cryptography
JF - IEEE International Workshop on Information Forensics and Security (WIFS)
PB - IEEE
CY - Abu Dhabi, UAE
ER -
TY - CONF
T1 - The impact of feeder link interference in multiple gateway multibeam satellite systems
T2 - 8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop
Y1 - 2016
A1 - Vahid Joroughi
A1 - Carlos Mosquera
KW - compass
KW - satcom
JF - 8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop
ER -
TY - CONF
T1 - Link adaptation in mobile satellite links: field trials results
T2 - 8th Advanced Satellite Multimedia Systems Conference and 14th Signal Processing for Space Communications Workshop
Y1 - 2016
A1 - Anxo Tato
A1 - Carlos Mosquera
A1 - Iago Gómez
KW - compass
KW - satcom
JF - 8th Advanced Satellite Multimedia Systems Conference and 14th Signal Processing for Space Communications Workshop
ER -
TY - JOUR
T1 - Link adaptation in mobile satellite links: schemes for different degrees of CSI knowledge
JF - International Journal of Satellite Communications and Networking
Y1 - 2016
A1 - Alberto Rico-Alvariño
A1 - Jesus Arnau
A1 - Carlos Mosquera
KW - compass
KW - satcom
VL - 34
IS - 5
ER -
TY - JOUR
T1 - Low complexity hybrid precoding strategies for millimeter wave communication systems
JF - IEEE Trans. Wireless Communications
Y1 - 2016
A1 - Cristian Rusu
A1 - Roi Méndez-Rial
A1 - Nuria González-Prelcic
A1 - Robert W. Heath Jr.
KW - compass
KW - mmWave
AB - Millimeter communication systems use large antenna arrays to provide good average received power and to take advantage of multi-stream MIMO communication. Unfortunately, due to power consumption in the analog front-end, it is impractical to perform beamforming and fully digital precoding at baseband. Hybrid precoding/combining architectures have been proposed to overcome this limitation. The hybrid structure splits the MIMO processing between the digital and analog domains, while keeping the performance close to that of the fully digital solution. In this paper, we introduce and analyze several algorithms that efficiently design hybrid precoders and combiners starting from the known optimum digital precoder/combiner, which can be computed when perfect channel state information is available. We propose several low complexity solutions which provide different trade-offs between performance and complexity. We show that the proposed iterative solutions perform better in terms of spectral efficiency and/or are faster than previous methods in the literature. All of them provide designs which perform close to the known optimal digital solution. Finally, we study the effects of quantizing the analog component of the hybrid design and show that even with coarse quantization, the average rate performance is good.

VL - 15 IS - 12 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 - CONF T1 - Online EM-based distributed estimation in sensor networks with faulty nodes T2 - European Signal Processing Conference (EUSIPCO) Y1 - 2016 A1 - Pere Gimenez-Febrer A1 - Alba Pagès-Zamora A1 - R. López-Valcarce KW - compass KW - wsn AB -This paper focuses on the problem of the distributed estimation of a parameter vector based on noisy observations regularly acquired by the nodes of a wireless sensor network and assuming that some of the nodes have faulty sensors. We propose two online schemes, both centralized and distributed, based on the Expectation-Maximization (EM) algorithm. These algorithms are able to identify and disregard the faulty nodes, and provide a refined estimate of the parameters each time instant after a new set of observations is acquired. Simulation results demonstrate that the centralized versions of the proposed online algorithms attain the same estimation error as the centralized batch EM, whereas the distributed versions come very close to matching the batch EM.

JF - European Signal Processing Conference (EUSIPCO)
CY - Budapest, Hungary
ER -
TY - JOUR
T1 - An overview of signal processing techniques for millimeter wave MIMO systems
JF - IEEE J. Selected Topics in Signal Processing. Special issue on Signal Processing for Millimeter Wave Wireless Communications
Y1 - 2016
A1 - Robert W. Heath Jr.
A1 - Nuria González-Prelcic
A1 - Sundeep Rangan
A1 - Wonil Roh
A1 - Akbar M. Sayeed
KW - compass
KW - mmWave
AB - Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.

VL - 10 IS - 3 ER - TY - CONF T1 - Radar aided mmWave beam alignment in V2I communications supporting antenna diversity T2 - Information Theory and Applications Workshop (ITA Y1 - 2016 A1 - Nuria González-Prelcic A1 - R. Méndez-Rial A1 - R.W. Heath Jr. KW - compass KW - mmWave JF - Information Theory and Applications Workshop (ITA ER - TY - CONF T1 - Robust analog precoding designs for millimeter wave MIMO transceivers T2 - 20th International ITG Workshop on Smart Antennas (WSA) Y1 - 2016 A1 - Pengfei Xia A1 - Robert Heath A1 - Nuria González-Prelcic KW - compass KW - mmWave JF - 20th International ITG Workshop on Smart Antennas (WSA) ER - TY - JOUR T1 - Robust analog precoding designs for millimeter wave MIMO transceivers with frequency and time division duplexing JF - IEEE Trans. Communications Y1 - 2016 A1 - Pengfei Xia A1 - Robert W. Heath Jr. A1 - Nuria González-Prelcic KW - compass KW - mmWave AB -Millimeter wave (mmWave) communication provides high data rates thanks to large arrays at the transmitter and receiver, coupled with large bandwidth channels. Exploiting the arrays is challenging due to the need to configure precoding at the transmitter based on the large frequency selective channel. In this paper, we exploit the power iteration principle and propose a robust analog precoding training algorithm that can be applied in both frequency division duplex transmission systems and time division duplex transmission systems with or without RF calibration. We further analyze the convergence of the proposed algorithm and show how it converges to the singular value decomposition optimality exponentially. We propose null space projection on top of the power iteration to form multiple orthogonal beams at the transmitter and receiver. Strongest tap selection with proper energy pruning is used to collect as much precoding gain as possible from a frequency selective fading channel. The exponential effective SINR mapping performance is evaluated and demonstrates that the overall approach works smoothly. Numerical simulation results demonstrate algorithm robustness and the algorithm works not only for the simplified mmWave directional channels, but also for more general rich scattering channels.

VL - 64 IS - 11 ER - TY - JOUR T1 - Security in automotive radar and vehicular networks JF - Microwave Journal Y1 - 2016 A1 - E. R. Yeh A1 - J. Choi A1 - Nuria González-Prelcic A1 - C. Bhat A1 - R. W. Heath Jr. KW - compass KW - mmWave ER - TY - CONF T1 - The use of unit norm tight measurement matrices for one-bit compressed sensing T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) Y1 - 2016 A1 - C. Rusu A1 - Nuria González-Prelcic A1 - R. W. Heath Jr. KW - compass KW - compressed sensing AB -In this paper we analyze the mean squared error (MSE) for one-bit compressed sensing schemes based on measurement matrices that correspond to unit norm tight frames. We show that, as in the unquantized case, sensing with unit norm tight frames improves the MSE in the reconstruction of sparse vectors from one-bit measurements using l1 and thresholding algorithms. From our analytical and experimental results we conclude that when implementing one-bit compressed sensing schemes with fixed measurement matrices unit norm tight frames are the measurements of choice

JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) ER - TY - CONF T1 - Wideband self-interference cancellation for better spectrum use T2 - IEEE WoWMoM 2016 Workshop on Fifth Generation Wireless Y1 - 2016 A1 - Carlos Mosquera KW - adaptive signal processing KW - compass KW - full duplex JF - IEEE WoWMoM 2016 Workshop on Fifth Generation Wireless ER - TY - CONF T1 - Adaptive hybrid precoding and combining in mmWave multiuser MIMO systems based on compressed covariance estimation T2 - IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP) Y1 - 2015 A1 - R. Méndez-Rial A1 - Nuria González-Prelcic A1 - R. W. Heath Jr. KW - compass KW - mmWave JF - IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP) ER - TY - CONF T1 - Adaptive one-bit compressive sensing with application to low-precision receivers at mmWave T2 - IEEE Global Telecommunications Conf. (GLOBECOM), Y1 - 2015 A1 - C. Rusu A1 - R. Méndez-Rial A1 - Nuria González-Prelcic A1 - R. W. Heath, Jr KW - compass KW - mmWave JF - IEEE Global Telecommunications Conf. (GLOBECOM), ER - TY - CONF T1 - Attack detectors for data aggregation in clustered sensor networks T2 - European Signal Processing Conf. (EUSIPCO) Y1 - 2015 A1 - R. López-Valcarce A1 - Daniel Romero KW - adversarial signal processing KW - compass KW - wsn AB -Among many security threats to sensor networks, compromised sensing is particularly challenging due to the fact that it cannot be addressed by standard authentication approaches. We consider a clustered scenario for data aggregation in which an attacker injects a disturbance in sensor readings. Casting the problem in an estimation framework, we systematically apply the Generalized Likelihood Ratio approach to derive attack detectors. The analysis under different attacks reveals that detectors based on similarity of means across

clusters are suboptimal, with Bartlett’s test for homoscedasticity constituting a good candidate when lacking a priori knowledge of the variance of the underlying distribution.

JF - European Signal Processing Conf. (EUSIPCO)
PB - EURASIP
CY - Nice, France
ER -
TY - CONF
T1 - An attack on antenna subset modulation for millimeter-wave communication
T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
Y1 - 2015
A1 - Cristian Rusu
A1 - Nuria González-Prelcic
A1 - Robert W. Heath Jr.
KW - adversarial signal processing
KW - compass
KW - mmWave
AB - Antenna subset modulation (ASM) is a physical layer security technique that is well suited for millimeter wave communication systems. The key idea is to vary the radiation pattern at the symbol rate by selecting one from a subset of patterns with a similar main lobe and different side lobes. This paper shows that ASM is not robust to an eavesdropper that makes multiple simultaneous measurements at multiple angles. The measurements are combined and used to formulate an estimation problem to undo the effects of the side lobe randomization. Simulations show the performance of the estimation algorithms and how the eavesdropper can effectively recover the information if the signal-to-noise ratio exceeds a certain threshold. Using fewer active radio frequency chains makes it harder for the attacker to recover the transmit symbol, at the expense of more grating lobes.

JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) PB - IEEE CY - Brisbane, Australia ER - TY - CONF T1 - Blind Satellite Inter-Gateway Interference Mitigation T2 - IEEE International Conference on Communications (ICC) Y1 - 2015 A1 - J. Arnau A1 - C. Mosquera KW - compass KW - satcom JF - IEEE International Conference on Communications (ICC) ER - TY - JOUR T1 - Compression Limits for Random Vectors with Linearly Parameterized Second-Order Statistics JF - IEEE Trans. Information Theory Y1 - 2015 A1 - Daniel Romero A1 - R. López-Valcarce A1 - Geert Leus KW - compass KW - compressed sensing AB -The class of complex random vectors whose covariance

matrix is linearly parameterized by a basis of Hermitian

Toeplitz (HT) matrices is considered, and the maximum

compression ratios that preserve all second-order information

are derived — the statistics of the uncompressed vector must

be recoverable from a set of linearly compressed observations.

This kind of vectors arises naturally when sampling widesense

stationary random processes and features a number of

applications in signal and array processing.

Explicit guidelines to design optimal and nearly optimal

schemes operating both in a periodic and non-periodic fashion

are provided by considering two of the most common linear

compression schemes, which we classify as dense or sparse. It

is seen that the maximum compression ratios depend on the

structure of the HT subspace containing the covariance matrix of

the uncompressed observations. Compression patterns attaining

these maximum ratios are found for the case without structure as

well as for the cases with circulant or banded structure. Universal

samplers are also proposed to compress unknown HT subspaces.

VL - 61
IS - 3
ER -
TY - JOUR
T1 - Cramér-Rao Bounds for SNR Estimation of Oversampled Linearly Modulated Signals
JF - IEEE Trans. Signal Processing
Y1 - 2015
A1 - R. López-Valcarce
A1 - J. Villares
A1 - J. Riba
A1 - W. Gappmair
A1 - C. Mosquera
KW - adaptive signal processing
KW - compass
KW - Cramér-Rao bound (CRB)
KW - dynacs
KW - oversampling
KW - Signal-to-noise ratio (SNR)
AB - Most Signal-to-noise ratio (SNR) estimators use the

receiver matched filter output sampled at the symbol rate, an

approach which does not preserve all information in the analog

waveform due to aliasing. Thus, it is relevant to ask whether

avoiding aliasing could improve SNR estimation. To this end, we

compute the corresponding data-aided (DA) and non-data-aided

(NDA) Cramér-Rao bounds (CRBs). We adopt a novel dual filter

framework, which is shown to be information-preserving under

suitable conditions and considerably simplifies the analysis. It is

shown that the CRB can be substantially reduced by exploiting

any available excess bandwidth, depending on the modulation

scheme, the SNR range, and the estimator (DA or NDA) type.

VL - 63
IS - 7
ER -
TY - CONF
T1 - Dictionary-free Hybrid Precoders and Combiners for mmWave MIMO Systems
T2 - IEEE Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
Y1 - 2015
A1 - Roi Méndez-Rial
A1 - Cristian Rusu
A1 - Nuria González-Prelcic
A1 - Robert W. Heath Jr.
KW - compass
KW - mmWave
JF - IEEE Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
PB - IEEE
CY - Stockholm, Sweden
ER -
TY - CONF
T1 - Distributed AoA-based Source Positioning in NLOS with Sensor Networks
T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
Y1 - 2015
A1 - Pere Gimenez-Febrer
A1 - Alba Pagès-Zamora
A1 - Silvana Silva Pereira
A1 - R. López-Valcarce
KW - compass
KW - wsn
AB - This paper focuses on the problem of positioning a source using angle-of-arrival measurements taken by a wireless sensor network in which some of the nodes experience non-line-of-sight (NLOS) propagation conditions. In order to mitigate the errors induced by the nodes in NLOS, we derive an algorithm that combines the expectation-maximization algorithm with a weighted least-squares estimation of the source position so that the nodes in NLOS are eventually identified and discarded. Moreover, a distributed version of this algorithm based on a diffusion strategy that iteratively refines the position estimate while driving the network to a consensus is presented.

JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
PB - IEEE
CY - Brisbane, Australia
ER -
TY - CONF
T1 - Distributed TLS Estimation under Random Data Faults
T2 - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
Y1 - 2015
A1 - Silvana Silva Pereira
A1 - Alba Pagès-Zamora
A1 - R. López-Valcarce
KW - compass
KW - wsn
AB - This paper addresses the problem of distributed estimation of a parameter vector in the presence of noisy input and output data as well as data faults, performed by a wireless sensor network in which only local interactions among the nodes are allowed. In the presence of unreliable observations, standard estimators become biased and perform poorly in low signal-to-noise ratios. We propose two different distributed approaches based on the Expectation-Maximization algorithm: in the first one the regressors are estimated at each iteration,

whereas the second one does not require explicit regressor estimation. Numerical results show that the proposed methods approach the performance of a clairvoyant scheme with knowledge of the random data faults.

JF - IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
PB - IEEE
CY - Brisbane, Australia
ER -
TY - THES
T1 - Estimation, Detection, and Learning for Dynamic Spectrum Access
Y1 - 2015
A1 - Daniel Romero
KW - cognitive radio
KW - compass
KW - dynacs
KW - wsn
PB - University of Vigo
CY - Vigo, Spain
VL - Ph.D.
ER -
TY - JOUR
T1 - Forensic detection of processing operator chains: recovering the history of filtered JPEG images
JF - IEEE Transactions on Information Forensics and Security
Y1 - 2015
A1 - Valentina Conotter
A1 - Pedro Comesaña
A1 - Fernando Pérez-González
KW - compass
KW - forensics
U1 - Accepted for publication.

ER - TY - CONF T1 - Frequency Reuse in Dual Satellite Settings: an Initial Evaluation of Full Duplex Operation T2 - IEEE International Conference on Communications (ICC) Y1 - 2015 A1 - D. Martiñán-Otero A1 - C. Mosquera KW - compass KW - full duplex KW - satcom JF - IEEE International Conference on Communications (ICC) ER - TY - JOUR T1 - A Greedy Topology Design to Accelerate Consensus in Broadcast Wireless Sensor Networks JF - Information Processing Letters Y1 - 2015 A1 - Massimo Vecchio A1 - R. López-Valcarce KW - compass KW - wsn AB -We present techniques to improve convergence speed of distributed average consensus algorithms in wireless sensor networks by means of topology design. A broadcast network is assumed, so that only the transmit power of each node can be independently controlled, rather than each individual link. Starting with a maximally connected configuration in which all nodes transmit at full power, the proposed methods successively reduce the transmit power of a chosen node in order to remove one and only one link; nodes are greedily selected either in order to yield fastest convergence at each step, or if they have the largest degree in the network. These greedy schemes provide a good complexity-performance tradeoff with respect to full-blown global search methods. As a side benefit, improving the convergence speed also results in savings in energy consumption with respect to the maximally connected setting.

VL - 115 IS - 3 ER - TY - JOUR T1 - Improving Area Coverage of Wireless Sensor Networks Via Controllable Mobile Nodes: a Greedy Approach JF - Journal of Network and Computer Applications Y1 - 2015 A1 - Massimo Vecchio A1 - R. López-Valcarce KW - compass KW - wsn AB -Reliable wide-area monitoring with Wireless Sensor Networks (WSNs) remains a problem of

interest: simply deploying more nodes to cover wider areas is generally not a viable solution, due to

deployment and maintenance costs and the increase in radio interference. One possible solution

gaining popularity is based on the use of a reduced number of mobile nodes with controllable

trajectories in the monitored field. In this framework, we present a distributed technique for iteratively

computing the trajectories of the mobile nodes in a greedy fashion. The static sensor nodes actively

assist the mobile nodes in this task by means of a bidding protocol, thus participating towards the goal

of maximizing the area coverage of the monitored field. The performance of the proposed technique is

evaluated on various simulation scenarios with different number of mobile and static nodes in terms of

achieved coverage and mean time to achieve X% coverage. Comparison with previous state-of-the-art

techniques reveals the effectiveness and stability of the proposed method.

VL - 48
ER -
TY - CONF
T1 - Low Complexity Hybrid Sparse Precoding and Combining in Millimeter Wave MIMO Systems
T2 - IEEE Int. Conference on Communications (ICC)
Y1 - 2015
A1 - Cristian Rusu
A1 - Roi Méndez-Rial
A1 - Nuria González-Prelcic
A1 - Robert W. Heath Jr.
KW - compass
KW - mmWave
JF - IEEE Int. Conference on Communications (ICC)
PB - IEEE
CY - London, UK
ER -
TY - CONF
T1 - Low Resolution Adaptive Compressed Sensing for mmWave MIMO receivers
T2 - Asilomar Conf. on Signals, Systems, and Computers
Y1 - 2015
A1 - C. Rusu
A1 - Nuria González-Prelcic
A1 - R.W. Heath Jr.
KW - compass
KW - mmWave
JF - Asilomar Conf. on Signals, Systems, and Computers
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 - Robust Adaptive Coding and Modulation Scheme for the Mobile Satellite Forward Link T2 - IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC Y1 - 2015 A1 - Alberto Rico-Alvariño A1 - Anxo Tato A1 - Carlos Mosquera KW - compass KW - satcom JF - IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC ER - TY - CONF T1 - Spectrum Cartography using quantized observations T2 - IEEE Int. Conference on Acoustics, Speech and Signal Processing (ICASSP) Y1 - 2015 A1 - Daniel Romero A1 - Seung-Jun Kim A1 - R. López-Valcarce A1 - Georgios Giannakis KW - cognitive radio KW - compass KW - compressed sensing KW - spectrum sensing AB -This work proposes a spectrum cartography algorithm used for learning the power spectrum distribution over a wide frequency band across a given geographic area. Motivated by low-complexity sensing hardware and stringent communication constraints, compressed and quantized measurements are considered. Setting out from a nonparametric regression framework, it is shown that a sensible approach leads to a support vector machine formulation. The simulated tests verify that accurate spectrum maps can be constructed using a simple sensing architecture with significant savings in the feedback.

JF - IEEE Int. Conference on Acoustics, Speech and Signal Processing (ICASSP)
PB - IEEE
CY - Brisbane, Australia
ER -
TY - CONF
T1 - Subspace-constrained SINR optimization in MIMO full-duplex relays under limited dynamic range
T2 - IEEE 16th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
Y1 - 2015
A1 - Emilio Antonio-Rodríguez
A1 - R. López-Valcarce
A1 - Taneli Riihonen
A1 - Stefan Werner
A1 - Risto Wichman
KW - adaptive signal processing
KW - compass
KW - full duplex
AB - We propose a method for maximizing the signal-to-interference-plus-noise ratio (SINR) in a wideband full-duplex MIMO regenerative relay that accounts limited dynamic range of the receiver and transmitter impairments. Transmit and receive filters are designed at the relay, by means of an alternating minimization algorithm, to minimize the interference at the decoder input in the destination node. We impose channel shortening and subspace constraints to ensure that the received signal at the destination is not compromised. Simulation results show that the presented method significantly outperforms other constrained approaches.

JF - IEEE 16th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
PB - IEEE
CY - Stockholm, Sweden
ER -
TY - CONF
T1 - An SVD Approach to Forensic Image Resampling Detection
T2 - EUSIPCO
Y1 - 2015
A1 - David Vázquez-Padín
A1 - Pedro Comesaña
A1 - Fernando Pérez-González
KW - compass
KW - digital image forensics
KW - resampling detection
KW - SVD
KW - tampering detection
AB - This paper describes a new strategy for image resampling detection whenever the applied resampling factor is larger than one. Delving into the linear dependencies induced in an image after the application of an upsampling operation, we show that interpolated images belong to a subspace defined by the interpolation kernel. Within this framework, by computing the SVD of a given image block and a measure of its degree of saturated pixels per row/column, we derive a simple detector capable of discriminating between upsampled images and genuine images. Furthermore, the proposed detector shows remarkable results with blocks of small size and outperforms state-of-the-art methods.

JF - EUSIPCO
ER -
TY - JOUR
T1 - Active Interference Cancellation for OFDM Spectrum Sculpting: Linear Processing is Optimal
JF - IEEE Communications Letters
Y1 - 2014
A1 - Schmidt, J.F.
A1 - Daniel Romero
A1 - R. López-Valcarce
KW - cognitive radio
KW - compass
KW - dynacs
KW - spectrum shaping
AB - Active interference cancellation (AIC) is a multicarrier spectrum sculpting technique which reduces the power of undesired out-of-band emissions by adequately modulating a subset of reserved cancellation subcarriers. In most schemes online complexity is a concern, and thus cancellation subcarriers have traditionally been constrained to linear combinations of the data subcarriers. Recent AIC designs truly minimizing out-of-band emission shift complexity to the offline design stage, motivating the consideration of more general mappings to improve performance. We show that there is no loss in optimality incurred by constraining these mappings to the set of linear functions.

VL - 18 IS - 9 ER - TY - CONF T1 - A Benford-Fourier JPEG compression detector T2 - IEEE International Conference on Image Processing (ICIP) Y1 - 2014 A1 - Cecilia Pasquini A1 - Fernando Pérez-González A1 - Giulia Boato KW - compass KW - forensics JF - IEEE International Conference on Image Processing (ICIP) CY - Paris, France ER - TY - CONF T1 - Channel estimation in millimeter wave MIMO systems with one-bit quantization T2 - Asilomar Conf. on Signals, Systems and Computers Y1 - 2014 A1 - Jianhua Mo A1 - Phil Schniter A1 - Nuria González-Prelcic A1 - Robert W. Heath Jr. KW - adaptive signal processing KW - compass KW - mmWave JF - Asilomar Conf. on Signals, Systems and Computers ER - TY - CONF T1 - Circular Sparse Rulers Based On Co-prime Sampling For Compressive Power Spectrum Estimation T2 - IEEE Global Communications Conference Y1 - 2014 A1 - Nuria González-Prelcic A1 - M. E. Domíngez-Jiménez KW - cognitive radio KW - compass KW - compressed sensing JF - IEEE Global Communications Conference PB - IEEE CY - Austin, TX ER - TY - CONF T1 - Detecting Misreporting Attacks to the Proportional Fair Scheduler T2 - IEEE Workshop on Information Forensics and Security (WIFS) Y1 - 2014 A1 - Schmidt, J.F. A1 - R. López-Valcarce KW - adversarial signal processing KW - compass AB -

The Proportional Fair Scheduler (PFS) has become

a popular channel-aware resource allocation method in wireless

networks, as it effectively exploits multiuser diversity while

providing fairness to users. PFS decisions on which mobile station

(MS) to schedule next are based on Channel Quality Indicator

(CQI) values. Since CQI values are reported by the MSs to the

scheduler, network performance can be severely degraded if some

malicious MSs report forged information. Previous approaches to

this security issue are based either on modifying PFS, which may

be undesirable in some contexts, or authenticating CQI reports

by periodic transmission of challenges, which increases overhead.

Instead, we propose to detect misreporting attackers, based on the

time correlation features of the wireless channel. Our approach

does not require scheduler modification, and it does not increase

overhead. Simulation results under realistic settings are provided

to show the effectiveness of the proposed test.

JF - IEEE Workshop on Information Forensics and Security (WIFS)
CY - Atlanta, USA
ER -
TY - CONF
T1 - Do dummies pay off? Limits of dummy traffic protection in anonymous communications
T2 - Privacy Enhancing Technologies Symposium
Y1 - 2014
A1 - Simon Oya
A1 - Carmela Troncoso
A1 - Fernando Pérez-González
KW - anonymous communications
KW - compass
KW - disclosure attacks
KW - dummies
JF - Privacy Enhancing Technologies Symposium
ER -
TY - CONF
T1 - FER prediction with variable codeword length
T2 - ICASSP2014 - Signal Processing for Communications and Networking (ICASSP2014 - SPCOM)
Y1 - 2014
A1 - Alberto Rico-Alvariño
A1 - Robert W. Heath Jr.
A1 - Carlos Mosquera
KW - adaptive signal processing
KW - compass
KW - dynacs
KW - Effective SNR
KW - FER prediction
KW - PHY abstraction
AB - Frame error rate (FER) prediction in wireless communication systems is an important tool with applications to system level simulations and link adaptation, among others. Although in realistic communication scenarios it is expected to have codewords of different lengths, previous work on FER prediction marginally treated the dependency of the FER on the codeword length. In this paper, we present a method to estimate the FER using codewords of different length. We derive a low complexity FER estimator for frames of different length transmitted over a binary symmetric channel of unknown error probability. We extend this technique to coded systems by the use of effective SNR FER predictors. The proposed estimation scheme is shown to outperform other simpler estimation methods.

JF - ICASSP2014 - Signal Processing for Communications and Networking (ICASSP2014 - SPCOM) CY - Florence, Italy ER - TY - CONF T1 - How to Implement Doubly-Stochastic Matrices for Consensus-Based Distributed Algorithms T2 - IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM) Y1 - 2014 A1 - S. Valcárcel-Macua A1 - C. Moreno-León A1 - J. S. Romero A1 - Silvana Silva Pereira A1 - Javier Zazo A1 - Alba Pagès-Zamora A1 - R. López-Valcarce A1 - S. Zazo KW - compass KW - dynacs KW - wsn AB -Doubly-stochastic matrices are usually required by

consensus-based distributed algorithms. We propose a simple

and efficient protocol and present some guidelines for implementing

doubly-stochastic combination matrices even in noisy,

asynchronous and changing topology scenarios. The proposed

ideas are validated with the deployment of a wireless sensor

network, in which nodes run a distributed algorithm for robust

estimation in the presence of nodes with faulty sensors.

JF - IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM)
CY - A Coruña, Spain
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 - The optimal attack to histogram-based forensic detectors is simple(x) T2 - IEEE International Workshop on Information Forensics and Security (WIFS) Y1 - 2014 A1 - Pedro Comesaña A1 - Fernando Pérez-González KW - compass KW - Multimedia security JF - IEEE International Workshop on Information Forensics and Security (WIFS) CY - Atlanta, GA U1 -IEEE WIFS 2015 Best Paper Award

ER - TY - CONF T1 - SINR Optimization in Wideband Full-Duplex MIMO Relays under Limited Dynamic Range T2 - IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM) Y1 - 2014 A1 - Emilio Antonio-Rodríguez A1 - R. López-Valcarce A1 - Taneli Riihonen A1 - Stefan Werner A1 - Risto Wichman KW - adaptive signal processing KW - compass KW - full duplex JF - IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM) CY - A Coruña, Spain ER -