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Plouzane, France

Lagrange X.,Telecom Bretagne
Annales des Telecommunications/Annals of Telecommunications | Year: 2011

This work considers hybrid automatic repeat request (HARQ) protocols on a fading channel with Chase combining and deals with both Rayleigh and Nakagami-m fading. We derive the packet loss probability and the throughput for HARQ both for a slow-varying and a fast-varying channel. We then consider link adaptation with complete channel state information (CSI) for which the instantaneous signal-to-noise ratio (SNR) is known and with incomplete CSI for which only the average SNR is known. We derive analytical formulae of the long-term throughput. These formulae are simple enough to be used for higher level simulations. We show that the throughput is slightly higher on a slow-varying channel but at the expense of a higher loss probability. © 2011 Institut Télé com and Springer-Verlag.

In this paper, we develop two main results. The first one is a theorem proving that a second order Wiener model can be blindly identified, i.e. using only the mean, the third and fourth order cumulants of the output data. The second result is the application of this theorem to spectral inversion (i.e. the recovering of the power spectrum density) of the input signal of a second order Volterra model to which usual inversion schemes cannot be applied, in particular when the linear kernel has a strong attenuation in frequency range. Numerical results are discussed with respect to the nonlinear energy amount of the output, the time series length and the SNR values. © 2011 Elsevier B.V. All rights reserved.

Andriulli F.P.,Telecom Bretagne
IEEE Transactions on Antennas and Propagation | Year: 2012

A new analysis of the spectral properties of Loop-Star and Loop-Tree decompositions is presented in this work. The analysis will shed light on the behavior of these decompositions when used with regular operators such as the magnetic field and the Calderón preconditioned electric field integral operators. This work will explain the ill-conditioning problems reported in literature and will provide a family of efficient algorithms to solve the ill-conditioning and regularizing several Loop-Star/Tree decomposed equations of interest for applications. The theory will be corroborated by numerical results that will show the practical impact of the theoretical developments. © 2012 IEEE.

Karami A.,Shiraz University | Yazdi M.,Shiraz University | Mercier G.,Telecom Bretagne
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

The compression of hyperspectral images (HSIs) has recently become a very attractive issue for remote sensing applications because of their volumetric data. In this paper, an efficient method for hyperspectral image compression is presented. The proposed algorithm, based on Discrete Wavelet Transform and Tucker Decomposition (DWT-TD), exploits both the spectral and the spatial information in the images. The core idea behind our proposed technique is to apply TD on the DWT coefficients of spectral bands of HSIs. We use DWT to effectively separate HSIs into different sub-images and TD to efficiently compact the energy of sub-images. We evaluate the effect of the proposed method on real HSIs and also compare the results with the well-known compression methods. The obtained results show a better performance of the proposed method. Moreover, we show the impact of compression HSIs on the supervised classification and linear unmixing. © 2008-2012 IEEE.

Lagrange X.,Telecom Bretagne
IEEE Communications Letters | Year: 2010

This letter considers hybrid automatic repeat request (HARQ) protocols on a block Rayleigh fading channel. We derive the packet loss probability and the throughput for HARQ in closed-form. We propose a simple approximated but very accurate formula for the throughput. We deduce a crosslayer design of adaptive modulation and coding with HARQ. © 2010 IEEE.

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