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 - CONF T1 - Generalized matched filter detector for fast fading channels T2 - IEEE Int. Conf. on Acoustics, Speech and Signal Processing (ICASSP 2012) Y1 - 2012 A1 - Daniel Romero A1 - R. López-Valcarce A1 - Geert Leus KW - cognitive radio KW - dynacs KW - spectrum sensing AB -We consider the problem of detecting a known signal with constant magnitude immersed in noise of unknown variance,

when the propagation channel is frequency-flat and randomly

time-varying within the observation window. A Basis Expansion

Model with random coefficients is used for the channel, and a Generalized Likelihood Ratio approach is adopted in order to cope with deterministic nuisance parameters. The resulting scheme can be seen as a generalization of the well-known

Matched Filter detector, to which it reduces for timeinvariant

channels. Closed-form analytical expressions are provided for the distribution of the test statistic under both hypotheses, which allow to assess the detection performance.

JF - IEEE Int. Conf. on Acoustics, Speech and Signal Processing (ICASSP 2012)
PB - IEEE
CY - Kyoto, Japan
ER -
TY - JOUR
T1 - Gain-Invariant Dirty Paper Coding for Hierarchical OFDM
JF - IEEE Transactions on Communications
Y1 - 2011
A1 - Scagliola, Michele
A1 - Fernando Pérez-González
A1 - Guccione, Pietro
KW - dirty paper
KW - dynacs
KW - Hierarchical OFDM
KW - watermarking
AB - A novel approach is here presented to superimpose a low-priority data stream on a high-priority data stream for OFDM systems. The main improvement with respect to conventional hierarchical modulation, which is included with the same purpose in various wireless technologies, is that the low-priority data stream can be decoded from the received subcarrier symbols without any previous equalization for multipath fading channels. As a consequence, the expected performance is nearly invariant of the channel estimation method used to equalize the channel. The low-priority stream is inserted adopting a gain-invariant dirty paper coding based on Rational Dither Modulation, which was proposed for data hiding applications. In this paper an analysis of the developed system is presented and several simulations have been carried out using DVB-T system parameters to verify the validity of the proposed approach. The experimental results show the better performance of the proposed method with respect to that of a conventional hierarchical modulation, particularly when the accuracy of the estimated channel response decreases.

VL - 59 ER - TY - CONF T1 - A Generalization of Benford's Law and Its Application to Images T2 - European Control Conference (ECC) Y1 - 2007 A1 - Fernando Pérez-González A1 - Gregory L. Heileman A1 - Chaouki T. Abdallah KW - benford KW - benford's-law JF - European Control Conference (ECC) CY - Kos, Greece ER -