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Segarra, Santiago (author), Chepuri, S.P. (author), Marques, Antonio G. (author), Leus, G.J.T. (author)Stationarity is a cornerstone property that facilitates the analysis and processing of random signals in the time domain. Although time-varying signals are abundant in nature, in many contemporary applications the information of interest resides in more irregular domains that can be conveniently represented using a graph. This chapter reviews...book chapter 2018
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- Rugini, L. (author), Leus, G. (author) conference paper 2007
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van der Meulen, P.Q. (author), Kruizinga, P. (author), Bosch, J.G. (author), Leus, G.J.T. (author)We study the optimal design of an aperture coding mask, and the optimal sensing positions of a single ultrasound sensor with a scanning configuration. In previous works, we have shown that 3D ultrasound imaging is possible using a randomly shaped coding mask with randomly chosen sensing positions. Here we propose an optimization algorithm for...conference paper 2018
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Liu, J. (author), Isufi, E. (author), Leus, G.J.T. (author)To accurately match a finite-impulse response (FIR) graph filter to a desired response, high filter orders are generally required leading to a high implementation cost. Autoregressive moving average (ARMA) graph filters can alleviate this problem but their design is more challenging. In this paper, we focus on ARMA graph filter design for a...conference paper 2016
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Zhang, Yu (author), Wang, Yue (author), Tian, Zhi (author), Leus, G.J.T. (author), Zhang, Gong (author)This paper proposes a super-resolution harmonic retrieval method for uncorrelated strictly non-circular signals, whose covariance and pseudo-covariance present Toeplitz and Hankel structures, respectively. Accordingly, the augmented covariance matrix constructed by the covariance and pseudo-covariance matrices is not only low rank but also...conference paper 2023
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Natali, A. (author), Leus, G.J.T. (author)Fitting a polynomial to observed data is an ubiquitous task in many signal processing and machine learning tasks, such as interpolation and prediction. In that context, input and output pairs are available and the goal is to find the coefficients of the polynomial. However, in many applications, the input may be partially known or not known at...conference paper 2023
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Nambur Ramamohan, K. (author), Chepuri, S.P. (author), Comesana, Daniel Fernandez (author), Leus, G.J.T. (author)In this paper, the focus is on the gain and phase calibration of sparse sensor arrays to localize more sources than the number of physical sensors. The proposed technique is a blind calibration method as it does not require any calibrator sources. Joint estimation of the gain errors, phase errors, and source directions is a complicated non...conference paper 2019
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Segarra, Santiago (author), Marques, Antonio G. (author), Leus, G.J.T. (author), Ribeiro, Alejandro (author)A novel scheme for sampling graph signals is proposed. Space-shift sampling can be understood as a hybrid scheme that combines selection sampling -- observing the signal values on a subset of nodes - and aggregation sampling - observing the signal values at a single node after successive aggregation of local data. Under the assumption of...conference paper 2016
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Hu, Y. (author), Leus, G.J.T. (author)The path-loss exponent (PLE) is a key parameter in wireless propagation channels. Therefore, obtaining the knowledge of the PLE is rather significant for assisting wireless communications and networking to achieve a better performance. Most existing methods for estimating the PLE not only require nodes with known locations but also assume an...conference paper 2016
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Coutino, Mario (author), Pribic, R (author), Leus, G.J.T. (author)In this paper, a new direction of arrival (DOA) estimation approach is devised using concepts from information geometry (IG). The proposed method uses geodesic distances in the statistical manifold of probability distributions parametrized by their covariance matrix to estimate the direction of arrival of several sources. In order to obtain a...conference paper 2016
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Coutino, Mario (author), Pribic, R (author), Leus, G.J.T. (author)A bound for sparse reconstruction involving both the signal-to-noise ratio (SNR) and the estimation grid size is presented. The bound is illustrated for the case of a uniform linear array (ULA). By reducing the number of possible sparse vectors present in the feasible set of a constrained ℓ1-norm minimization problem, ambiguities in the...conference paper 2016
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van der Hoeven, Jelmer (author), Natali, A. (author), Leus, G.J.T. (author)Forecasting time series on graphs is a fundamental problem in graph signal processing. When each entity of the network carries a vector of values for each time stamp instead of a scalar one, existing approaches resort to the use of product graphs to combine this multidimensional information, at the expense of creating a larger graph. In this...conference paper 2023
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Ebihara, Tadashi (author), Leus, G.J.T. (author), Ogasawara, Hanako (author)In this paper, we propose a novel underwater acoustic communication scheme that achieves energy and spectrum efficiency simultaneously by combining Doppler-resilient orthogonal signal division multiplexing (D-OSDM) and multiple-input multiple-output (MIMO) signaling. We present both the transmitter and receiver processing for MIMO D-OSDM. We...conference paper 2018
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Leus, G.J.T. (author), Yang, Maosheng (author), Coutino, Mario (author), Isufi, E. (author)To deal with high-dimensional data, graph filters have shown their power in both graph signal processing and data science. However, graph filters process signals exploiting only pairwise interactions between the nodes, and they are not able to exploit more complicated topological structures. Graph Volterra models, on the other hand, are also...conference paper 2021
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Natali, A. (author), Coutino, Mario (author), Isufi, E. (author), Leus, G.J.T. (author)Signal processing and machine learning algorithms for data sup-ported over graphs, require the knowledge of the graph topology. Unless this information is given by the physics of the problem (e.g., water supply networks, power grids), the topology has to be learned from data. Topology identification is a challenging task, as the problem is often...conference paper 2021
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Hu, Yuyang (author), Doğan, D. (author), Brown, Michael (author), Bulot, Mahé (author), Ferin, Guillaume (author), Leus, G.J.T. (author), Kruizinga, P. (author), Steen, Antonius F.W. (author), Bosch, Johannes G. (author)It has been previously demonstrated that applying an aberrating mask for 2D compressive imaging using a low number of sensors (elements) can significantly improve image resolution, as evaluated via the point spread function. Here we investigate the potential to apply a similar approach for 3D flow monitoring. We conducted a 3D k-Wave simulation...conference paper 2023
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Doğan, D. (author), Kruizinga, P. (author), Bosch, Johannes G. (author), Leus, G.J.T. (author)Ultrasound imaging of the vasculature has major significance for the detection of cardiovascular diseases and cancer. However, limited spatial resolution or long acquisition times of existing techniques limit the visualization of the microvascular structures. Enforcing sparsity in the underlying vasculature as well as exploiting statistical...conference paper 2021
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Generowicz, B.S. (author), Verhoef, Luuk (author), Mastik, Frits (author), Dijkhuizen, Stefanie (author), van Dorp, Nikki (author), Voorneveld, Jason (author), Bosch, Johannes (author), Kumar, Karishma (author), Leus, G.J.T. (author)Power Doppler (PD) imaging has become a staple in high frame rate ultrasound imaging due to its ability to image small vessels and slow-moving flows, such as in the case of imaging blood flow in the brain. Alternatively, color Doppler (CD) can be used to determine the one-dimensional directional information of the blood scatterers. This can help...conference paper 2020
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Pizzo, A. (author), Chepuri, S.P. (author), Leus, G.J.T. (author)In this paper we focus on the relative position and orientation estimation between rigid bodies in an anchorless scenario. Several sensor units are installed on the rigid platforms, and the sensor placement on the rigid bodies is known beforehand (i.e., relative locations of the sensors on the rigid body are known). However, the absolute...conference paper 2016
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Rugini, L (author), Banelli, Paolo (author), Leus, G.J.T. (author)We focus on the performance of the energy detector for cognitive radio applications. Our aim is to incorporate, into the energy detector, low-complexity algorithms that compute the performance of the detector itself. The main parameters of interest are the probability of detection and the required number of samples. Since the exact performance...conference paper 2016