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 - 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 - 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 - 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 - 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 - 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 - 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 - JOUR T1 - Learning-Based Adaptive Transmission for Limited Feedback Multiuser MIMO-OFDM JF - IEEE Transactions on Wireless Communications Y1 - 2014 A1 - Alberto Rico-Alvariño A1 - Robert W. Heath Jr. KW - adaptive signal processing KW - dynacs 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 - 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 - TY - CONF T1 - Adaptive Self-interference Cancellation in Wideband Full-Duplex Decode-and-Forward MIMO Relays T2 - IEEE 14th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC) Y1 - 2013 A1 - Emilio Antonio-Rodríguez A1 - R. López-Valcarce A1 - Taneli Riihonen A1 - Stefan Werner A1 - Risto Wichman KW - adaptive signal processing KW - dynacs KW - full duplex JF - IEEE 14th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC) CY - Darmstadt, Germany ER - TY - CONF T1 - Autocorrelation-based adaptation rule for feedback equalization in Wideband Full-Duplex Amplify-and-Forward MIMO relays T2 - Int. Conf. Acoust., Speech, Signal Process. (ICASSP) Y1 - 2013 A1 - Emilio Antonio-Rodríguez A1 - R. López-Valcarce A1 - Taneli Riihonen A1 - Stefan Werner A1 - Risto Wichman KW - adaptive signal processing KW - dynacs KW - full duplex AB -Simultaneous reception and transmission in the same frequency, so-called full-duplex operation, causes an infinite feedback loop in an amplify-and-forward relay. The unwanted echoes may result in oscillation at the relay, making it unstable, and distorting the spectrum. This paper presents an adaptive MIMO filtering method for full-duplex amplify-and-forward relays that aims at solving the joint problem of self-interference mitigation and equalization of the source-relay channel. The scheme exploits knowledge of the autocorrelation of the transmitted signal as the only side information while allowing the relay, in the best case, to implement precoding as if there was not any self-interference or frequency selectivity in the source-relay channel. Finally, the proposed adaptation algorithm is investigated by determining its stationary points and by performing simulations in a MIMO-OFDM framework.

JF - Int. Conf. Acoust., Speech, Signal Process. (ICASSP)
ER -
TY - CONF
T1 - Cancelling self-interference in full-duplex relays without Angle-of-Arrival information
T2 - Int. Conf. Acoust., Speech, Signal Process. (ICASSP)
Y1 - 2013
A1 - Emilio Antonio-Rodríguez
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - dynacs
KW - full duplex
AB - With full-duplex relays, simultaneous reception and transmission in

the same frequency produce self-interference distortion and relay oscillation,

hampering reception at the receiver end unless properly

mitigated. Previous adaptive methods for self-interference cancellation

using multiple receive antennas require knowledge of the direction

of arrival of the source signal. We present a novel architecture

and adaptive scheme for Amplify-and-Forward relays allowing cancellation

without such knowledge. The temporal filter is updated

under the property restoral paradigm in order to match the power

spectrum of the retransmitted signal to that of the source signal.

JF - Int. Conf. Acoust., Speech, Signal Process. (ICASSP)
ER -
TY - JOUR
T1 - An Adaptive Feedback Canceller for Full-Duplex Relays Based on Spectrum Shaping
JF - IEEE J. Selected Areas in Communications
Y1 - 2012
A1 - R. López-Valcarce
A1 - Emilio Antonio-Rodríguez
A1 - C. Mosquera
A1 - Fernando Pérez-González
KW - adaptive signal processing
KW - dynacs
KW - full duplex
AB - Although full-duplex relaying schemes are appealing in order to improve spectral efficiency, simultaneous reception and transmission in the same frequency results in selfinterference,

distorting the retransmitted signal and making the relay prone to oscillation. Current feedback cancellation techniques by means of adaptive filters are hampered by the fact that the useful and interference signals are highly correlated. We present a new adaptive algorithm which effectively and blindly

restores the spectral shape of the desired signal. In contrast

with previous schemes, the novel adaptive feedback canceller has low complexity, does not introduce additional delay in the relay station, and partly compensates for multipath propagation.

VL - 30
IS - 8
ER -
TY - CONF
T1 - Adaptive self-interference suppression for full-duplex relays with multiple receive antennas
T2 - IEEE 13th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC 2012)
Y1 - 2012
A1 - Emilio Antonio-Rodríguez
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - dynacs
KW - full duplex
AB - In full-duplex relays, simultaneous reception and transmission

in the same frequency results in self-interference which distorts the retransmitted signal and makes the relay prone to oscillation. We present an adaptive feedback canceller for multiple-input single-output (MISO) relays, efficiently combining spatial and temporal processing. The receive array is adaptively steered towards the minimum variance distortionless response (MVDR), whereas the temporal filter update is based on a novel low-complexity spectrum shaping scheme which avoids introducing additional delay in the relay station.

JF - IEEE 13th Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC 2012)
PB - IEEE
CY - Çesme, Turkey
ER -
TY - CONF
T1 - Optimum Training for CSI Acquisition in Cognitive Radio Channels
T2 - Asilomar Conference on Signals, Systems, and Computers
Y1 - 2012
A1 - Alberto Rico-Alvariño
A1 - C. Mosquera
KW - adaptive signal processing
KW - cognitive radio
KW - dynacs
JF - Asilomar Conference on Signals, Systems, and Computers
CY - Pacific Grove, CA
ER -
TY - JOUR
T1 - Secure Adaptive Filtering
JF - IEEE Transactions on Information Forensics and Security
Y1 - 2011
A1 - Juan Ramón Troncoso-Pastoriza
A1 - Fernando Pérez-González
KW - adaptive signal processing
KW - computational complexity
KW - cryptography
KW - digital data protection
KW - encrypted domain
KW - homomorphic encryption systems
KW - least mean squares algorithm
KW - least mean squares methods
KW - privacy
KW - secure adaptive filtering
KW - security
KW - signal privacy preservation
KW - SPED techniques
KW - watermarking
VL - 6
ER -
TY - THES
T1 - Design of Nonlinear Precoding and Estimation Schemes for Advanced Communication Systems
Y1 - 2010
A1 - Marcos Álvarez-Díaz
KW - adaptive signal processing
KW - satcom
VL - Ph.D.
ER -
TY - CONF
T1 - Analysis of a first-order adaptive recursive predictor
T2 - IEEE Conference on Decision and Control / European Control Conference (CDC/ECC)
Y1 - 2005
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - equalization
KW - second-order statistics
JF - IEEE Conference on Decision and Control / European Control Conference (CDC/ECC)
CY - Seville, Spain
ER -
TY - CONF
T1 - Diamond contour-based phase recovery for (cross-)QAM constellations
T2 - IEEE Workshop on Statistical Signal Processing (SSP)
Y1 - 2005
A1 - Marcos Álvarez-Díaz
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - synchronization
JF - IEEE Workshop on Statistical Signal Processing (SSP)
CY - Bordeaux, France
ER -
TY - JOUR
T1 - Realizable minimum mean-squared error channel shorteners
JF - IEEE Transactions on Signal Processing
Y1 - 2005
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - Channel shortening
VL - 53
ER -
TY - JOUR
T1 - Realizable linear and decision feedback equalizers: properties and connections
JF - IEEE Transactions on Signal Processing
Y1 - 2004
A1 - R. López-Valcarce
KW - adaptive signal processing
KW - channel equalization
VL - 52
N1 - Recipient of a 2005 Best Paper Award of the IEEE Signal Processing Society
U1 - **Best Paper Award** of the IEEE Signal Processing Society (Signal Processing for Communications), 2005