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  • 1. Ali, Sadiq
    et al.
    Ramirez, David
    Jansson, Magnus
    Seco-Granados, Gonzalo
    Lopez-Salcedo, Jose A.
    Multi-antenna spectrum sensing by exploiting spatio-temporal correlation2014Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, s. 160-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we propose a novel mechanism for spectrum sensing that leads us to exploit the spatio-temporal correlation present in the received signal at a multi-antenna receiver. For the proposed mechanism, we formulate the spectrum sensing scheme by adopting the generalized likelihood ratio test (GLRT). However, the GLRT degenerates in the case of limited sample support. To circumvent this problem, several extensions are proposed that bring robustness to the GLRT in the case of high dimensionality and small sample size. In order to achieve these sample-efficient detection schemes, we modify the GLRT-based detector by exploiting the covariance structure and factoring the large spatio-temporal covariance matrix into spatial and temporal covariance matrices. The performance of the proposed detectors is evaluated by means of numerical simulations, showing important advantages over existing detectors.

  • 2.
    Ben Slimane, Slimane
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Zhou, Bo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Li, Xuesong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Delay Optimization in Cooperative Relaying with Cyclic Delay Diversity2008Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, s. 736818-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cooperative relaying has recently been recognized as an alternative to MIMO in a typical multicellularenvironment. Inserting random delays at the nonregenerative fixed relays further improve the system performance.However, random delays result in limited performance gain from multipath diversity. In this paper, two promisingdelay optimization schemes are introduced for a multicellular OFDM system with cooperative relaying withstationary multiple users and fixed relays. Both of the schemes basically aim to take the most advantages ofthe potential frequency selectivity by inserting predetermined delays at the relays, in order to further improve thesystem performance (coverage and throughput). Evaluation results for different multipath fading environments showthat the system performance with delay optimization increases tremendously compared with the case of randomdelay.

  • 3.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Signal Processing Lab., ACCESS Linnaeus Center, School of Electrical Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Achievable ADC Performance by Postcorrection Utilizing Dynamic Modeling of the Integral Nonlinearity2008Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, artikel-id 497187Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a need for a universal dynamic model of analog to digital converters (ADC) aimed for post-correction. However, it is complicated to fully describe the properties of an ADC by a single model. An alternative is to split up the ADC model in different components, where each component has unique properties. In this paper, a model based on three components is used, and a performance analysis for each component is presented. Each component can be post-corrected individually and by the method that best suits the application. The purpose with post-correction of an ADC is to improve the performance. Hence, for each component, expressions for the potential improvement have been developed. The measures of performance are total harmonic distortion (THD) and signal to noise and distortion (SINAD) and to some extent spurious free dynamic range (SFDR).

  • 4. Bollen, M.
    et al.
    Gu, I.
    Axelberg, P.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Styvaktakis, E.
    Classification of Underlying Causes of Power Quality Disturbances: Deterministic versus Statistical Methods.2007Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2007, nr 79747, s. 17-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the two main types of classification methods for power quality disturbances based on underlying causes: deterministic classification, giving an expert system as an example, and statistical classification, with support vector machines as an example. An expert system is suitable when one has limited amount of data and sufficient power system expert knowledge, however its application requires a set of threshold values. Statistical methods are suitable when large amount of data is available for training. Two important issues to guarantee the effectiveness of a classifier, data segmentation and feature extraction, are discussed. Segmentation of a sequence of data recording is pre-processing to partition the data into segments each representing a duration containing either an event or transition between two events. Extraction of features is applied to each segment individually. Some useful features and their effectiveness are then discussed. Some experimental results are included for demonstrating the effectiveness of both systems. Finally, conclusions are given together with the discussion of some future research directions.

  • 5.
    Bollen, Math
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gu, I.Y.H
    Chalmers University of Technology, Department of Signals and Systems.
    Axelberg, P.G.V
    Chalmers University of Technology, Department of Signals and Systems.
    Styvaktakis, E
    Hellenic Transmission System Operator.
    Classification of underlying causes of power quality disturbances: deterministic versus statistical methods2007Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the two main types of classification methods for power quality disturbances based on underlying causes: deterministic classification, giving an expert system as an example, and statistical classification, with support vector machines (a novel method) as an example. An expert system is suitable when one has limited amount of data and sufficient power system expert knowledge; however, its application requires a set of threshold values. Statistical methods are suitable when large amount of data is available for training. Two important issues to guarantee the effectiveness of a classifier, data segmentation, and feature extraction are discussed. Segmentation of a sequence of data recording is preprocessing to partition the data into segments each representing a duration containing either an event or a transition between two events. Extraction of features is applied to each segment individually. Some useful features and their effectiveness are then discussed. Some experimental results are included for demonstrating the effectiveness of both systems. Finally, conclusions are given together with the discussion of some future research directions.

  • 6.
    Callmer, Jonas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Skoglund, Martin
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Silent Localization of Underwater Sensors Using Magnetometers2010Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2010, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sensor localization is a central problem for sensor networks. If the sensor positions are uncertain, the target tracking ability of the sensor network is reduced. Sensor localization in underwater environments is traditionally addressed using acoustic range measurements involving known anchor or surface nodes. We explore the usage of triaxial magnetometers and a friendly vessel with known magnetic dipole to silently localize the sensors. The ferromagnetic field created by the dipole is measured by the magnetometers and is used to localize the sensors. The trajectory of the vessel and the sensor positions are estimated simultaneously using an Extended Kalman Filter (EKF). Simulations show that the sensors can be accurately positioned using magnetometers.

  • 7.
    Callmer, Jonas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Törnqvist, David
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Svensson, Henrik
    Nira Dynamics, Sweden.
    Carlbom, Pelle
    Saab Dynamics AB, Sweden.
    RADAR SLAM using Visual Features2011Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2011, nr 71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A vessel navigating in a critical environment such as an archipelago, requires very accurate movement estimates. Intentional or unintentional jamming makes gps unreliable as the only source of information and an additional independent navigation system should be used. In this paper we suggest estimating the vessel movements using a sequence of radar images from the preexisting body-fixed radar. Island landmarks in the radar scans are tracked between multiple scans using visual features. This provides information not only about the position of the vessel but also of its course and velocity. We present here a complete navigation framework that requires no additional hardware than the already existing naval radar sensor. Experiments show that visual radar features can be used to accurately estimate the vessel trajectory over an extensive data set.

  • 8.
    Ehlers, Frank
    et al.
    NATO Research Centre, Italy.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Spaan, Matthijs
    Institute Super Technic, Portugal.
    Editorial: Signal Processing Advances in Robots and Autonomy2009Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2009Artikel i tidskrift (Refereegranskat)
  • 9.
    Eng, Frida
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Downsampling Non-Uniformly Sampled Data2008Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decimating a uniformly sampled signal a factor D involves low-pass antialias filtering with normalized cutoff frequency 1/D followed by picking out every Dth sample. Alternatively, decimation can be done in the frequency domain using the fast Fourier transform (FFT) algorithm, after zero-padding the signal and truncating the FFT. We outline three approaches to decimate non-uniformly sampled signals, which are all based on interpolation. The interpolation is done in different domains, and the inter-sample behavior does not need to be known. The first one interpolates the signal to a uniformly sampling, after which standard decimation can be applied. The second one interpolates a continuous-time convolution integral, that implements the antialias filter, after which every Dth sample can be picked out. The third frequency domain approach computes an approximate Fourier transform, after which truncation and IFFT give the desired result. Simulations indicate that the second approach is particularly useful. A thorough analysis is therefore performed for this case, using the assumption that the non-uniformly distributed sampling instants are generated by a stochastic process.

  • 10.
    Hendeby, Gustaf
    et al.
    German Research Centre Artificial Intelligence, Germany.
    Karlsson, Rickard
    NIRA Dynamics AB, Sweden.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Particle Filtering: The Need for Speed2010Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2010, nr 181403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The particle filter (PF) has during the last decade been proposed for a wide range of localization and tracking applications. There is a general need in such embedded system to have a platform for efficient and scalable implementation of the PF. One such platform is the graphics processing unit (GPU), originally aimed to be used for fast rendering of graphics. To achieve this, GPUs are equipped with a parallel architecture which can be exploited for general-purpose computing on GPU (GPGPU) as a complement to the central processing unit (CPU). In this paper, GPGPU techniques are used to make a parallel recursive Bayesian estimation implementation using particle filters. The modifications made to obtain a parallel particle filter, especially for the resampling step, are discussed and the performance of the resulting GPU implementation is compared to the one achieved with a traditional CPU implementation. The comparison is made using a minimal sensor network with bearings-only sensors. The resulting GPU filter, which is the first complete GPU implementation of a PF published to this date, is faster than the CPU filter when many particles are used, maintaining the same accuracy. The parallelization utilizes ideas that can be applicable for other applications.

  • 11.
    Hendeby, Gustaf
    et al.
    German Research Centre for Artificial Intelligence, Germany.
    Karlsson, Rickard
    Swedish Defence Research Agency, Sweden.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    The Rao-Blackwellized Particle Filter: A Filter Bank Implementation2010Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2010, nr 724087Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For computational efficiency, it is important to utilize model structure in particle filtering. One of the most important cases occurs when there exists a linear Gaussian substructure, which can be efficiently handled by Kalman filters. This is the standard formulation of the Rao-Blackwellized particle filter (RBPF). This contribution suggests an alternative formulation of this well-known result that facilitates reuse of standard filtering components and which is also suitable for object-oriented programming. Our RBPF formulation can be seen as a Kalman filter bank with stochastic branching and pruning.

  • 12.
    Händel, Peter
    Signal Processing Lab, School of Electrical Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Power Spectral Density Error Analysis of Spectral Subtraction Type of Speech Enhancement Methods2007Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, nr 96384Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A theoretical framework for analysis of speech enhancement algorithms is introduced for performance assessment of spectral subtraction type of methods. The quality of the enhanced speech is related to physical quantities of the speech and noise (such as stationarity time and spectral flatness), as well as to design variables of the noise suppressor. The derived theoretical results are compared with the outcome of subjective listening tests as well as successful design strategies, performed by independent research groups.

  • 13.
    Jorswieck, Eduard A.
    et al.
    Technical University of Dresden, Germany .
    Boche, Holger
    University of Berlin, Berlin, Germany.
    Han, Zhu
    University of Houston, USA.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Game Theory in Signal Processing and Communications2009Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, artikel-id 128184Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Game theory is a branch of mathematics aimed at the modeling and understanding of resource conflict problems. Essentially, the theory splits into two branches: noncooperative and cooperative game theory. The distinction between the two is whether or not the players in the game can make joint decisions regarding the choice of strategy. Noncooperative game theory is closely connected to minimax optimization and typically results in the study of various equilibria, most notably the Nash equilibrium. Cooperative game theory examines how strictly rational (selfish) actors can benefit from voluntary cooperation by reaching bargaining agreements. Another distinction is between static and dynamic game theory, where the latter can be viewed as a combination of game theory and optimal control. In general, the theory provides a structured approach to many important problems arising in signal processing and communications, notably resource allocation and robust transceiver optimization. Recent applications also occur in other emerging fields, such as cognitive radio, spectrum sharing, and in multihop-sensor and adhoc networks.

  • 14.
    Jorswieck, Eduard A.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Sezgin, Aydin
    Information Systems Laboratory, Stanford University, USA.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Stanford University, USA.
    Feedback reduction in uplink MIMO OFDM systems by chunk optimization2008Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of multiuser MIMO systems can be significantly increased by channel-aware scheduling and signal processing at the transmitters based on channel state information. In the multiple antenna uplink multicarrier scenario, the base station decides centrally on the optimal signal processing and spectral power allocation as well as scheduling. An interesting challenge is the reduction of the overhead in order to inform the mobiles about their transmit strategies. In this work, we propose to reduce the feedback by chunk processing and quantization. We maximize the weighted sum rate of a MIMO OFDM MAC under individual power constraints and chunk size constraints. An efficient iterative algorithm is developed and convergence is proved. The feedback overhead as a function of the chunk size is considered in the rate computation and the optimal chunk size is determined by numerical simulations for various channel models. Finally, the issues of finite modulation and coding schemes as well as quantization of the precoding matrices are addressed.

  • 15.
    Lindgren, David
    et al.
    Swedish Defence Research Agency, Sweden.
    Wilsson, Olof
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Habberstad, Hans
    Swedish Defence Research Agency, Sweden.
    Shooter Localization in Wireless Microphone Networks2010Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Shooter localization in a wireless network of microphones is studied. Both the acoustic muzzle blast (MB) from the gunfire and the ballistic shock wave (SW) from the bullet can be detected by the microphones and considered as measurements. The MB measurements give rise to a standard sensor network problem, similar to time difference of arrivals in cellular phone networks, and the localization accuracy is good, provided that the sensors are well synchronized compared to the MB detection accuracy. The detection times of the SW depend on both shooter position and aiming angle and may provide additional information beside the shooter location, but again this requires good synchronization. We analyze the approach to base the estimation on the time difference of MB and SW at each sensor, which becomes insensitive to synchronization inaccuracies. Cramer-Rao lower bound analysis indicates how a lower bound of the root mean square error depends on the synchronization error for the MB and the MB-SW difference, respectively. The estimation problem is formulated in a separable nonlinear least squares framework. Results from field trials with different types of ammunition show excellent accuracy using the MB-SW difference for both the position and the aiming angle of the shooter.

  • 16.
    Liu, Jianhua
    et al.
    Department of Electrical and Computer Engineering, University of Florida, USA.
    Li, Jian
    Department of Electrical and Computer Engineering, University of Florida, USA.
    Larsson, Erik G.
    Department of Electrical and Computer Engineering, University of Florida, USA.
    Differential space-time block code modulation for DS-CDMA systems2002Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, nr 3, s. 289-296Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A differential space-time block code (DSTBC) modulation scheme is used to improve the performance of DS-CDMA systems in fast time-dispersive fading channels. The resulting scheme is referred to as the differential space-time block code modulation for DS-CDMA (DSTBC-CDMA) systems. The new modulation and demodulation schemes are especially studied for the down-link transmission of DS-CDMA systems. We present three demodulation schemes, referred to as the differential space-time block code Rake (D-Rake) receiver, differential space-time block code deterministic (D-Det) receiver, and differential space-time block code deterministic de-prefix (D-Det-DP) receiver, respectively. The D-Det receiver exploits the known information of the spreading sequences and their delayed paths deterministically besides the Rake type combination; consequently, it can outperform the D-Rake receiver, which employs the Rake type combination only. The D-Det-DP receiver avoids the effect of intersymbol interference and hence can offer better performance than the D-Det receiver.

  • 17. Nilsson, John-Olof
    et al.
    Zachariah, Dave
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Skog, Isaac
    Händel, Peter
    Cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging2013Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2013, s. 164:1-17Artikel i tidskrift (Refereegranskat)
  • 18.
    Nilsson, John-Olof
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Zachariah, Dave
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoog, Isaac
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging2013Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The implementation challenges of cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging are discussed and work on the subject is reviewed. System architecture and sensor fusion are identified as key challenges. A partially decentralized system architecture based on step-wise inertial navigation and step-wise dead reckoning is presented. This architecture is argued to reduce the computational cost and required communication bandwidth by around two orders of magnitude while only giving negligible information loss in comparison with a naive centralized implementation. This makes a joint global state estimation feasible for up to a platoon-sized group of agents. Furthermore, robust and low-cost sensor fusion for the considered setup, based on state space transformation and marginalization, is presented. The transformation and marginalization are used to give the necessary flexibility for presented sampling based updates for the inter-agent ranging and ranging free fusion of the two feet of an individual agent. Finally, characteristics of the suggested implementation are demonstrated with simulations and a real-time system implementation.

  • 19.
    Roth, Michael
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Hendeby, Gustaf
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Fritsche, Carsten
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    The Ensemble Kalman filter: a signal processing perspective2017Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, artikel-id 56Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The ensemble Kalman filter (EnKF) is a Monte Carlo-based implementation of the Kalman filter (KF) for extremely high-dimensional, possibly nonlinear, and non-Gaussian state estimation problems. Its ability to handle state dimensions in the order of millions has made the EnKF a popular algorithm in different geoscientific disciplines. Despite a similarly vital need for scalable algorithms in signal processing, e.g., to make sense of the ever increasing amount of sensor data, the EnKF is hardly discussed in our field. This self-contained review is aimed at signal processing researchers and provides all the knowledge to get started with the EnKF. The algorithm is derived in a KF framework, without the often encountered geoscientific terminology. Algorithmic challenges and required extensions of the EnKF are provided, as well as relations to sigma point KF and particle filters. The relevant EnKF literature is summarized in an extensive survey and unique simulation examples, including popular benchmark problems, complement the theory with practical insights. The signal processing perspective highlights new directions of research and facilitates the exchange of potentially beneficial ideas, both for the EnKF and high-dimensional nonlinear and non-Gaussian filtering in general.

  • 20.
    Savic, Vladimir
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Zazo, Santiago
    Technical University of Madrid, Spain.
    Nonparametric generalized belief propagation based on pseudo-junction tree for cooperative localization in wireless networks2013Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-parametric belief propagation (NBP) is a well-known message passing method for cooperative localization in wireless networks. However, due to the over-counting problem in the networks with loops, NBP’s convergence is not guaranteed, and its estimates are typically less accurate. One solution for this problem is non-parametric generalized belief propagation based on junction tree. However, this method is intractable in large-scale networks due to the high-complexity of the junction tree formation, and the high-dimensionality of the particles. Therefore, in this article, we propose the non-parametric generalized belief propagation based on pseudo-junction tree (NGBP-PJT). The main difference comparing with the standard method is the formation of pseudo-junction tree, which represents the approximated junction tree based on thin graph. In addition, in order to decrease the number of high-dimensional particles, we use more informative importance density function, and reduce the dimensionality of the messages. As by-product, we also propose NBP based on thin graph (NBP-TG), a cheaper variant of NBP, which runs on the same graph as NGBP-PJT. According to our simulation and experimental results, NGBP-PJT method outperforms NBP and NBP-TG in terms of accuracy, computational, and communication cost in reasonably sized networks.

  • 21.
    Skoglar, Per
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Orguner, Umut
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Törnqvist, David
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Pedestrian Tracking with an Infrared Sensor using Road Network Information2012Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 1, nr 26, s. 2012a-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a pedestrian tracking methodology using an infrared sensor for surveillance applications. A distinctive feature of this study compared to the existing pedestrian tracking approaches is that the road network information is utilized for performance enhancement. A multiple model particle filter, which uses two different motion models, is designed for enabling the tracking of both road-constrained (on-road) and unconstrained (off-road) targets. The lateral position of the pedestrians on the walkways are taken into account by a specific on-road target model. The overall framework seamlessly integrates the negative information of occlusion events into the algorithm for which the required modifications are discussed. The resulting algorithm is illustrated on real data from a field trial for different scenarios.

  • 22.
    Testa, I
    et al.
    Dipartimento di Scienze Fisiche,, Università di Napoli, Italy.
    Evangelista, Gianpaolo
    Dipartimento di Scienze Fisiche, Università di Napoli, Italy.
    Cavaliere, S
    Dipartimento di Scienze Fisiche, Università di Napoli, Italy.
    Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides2004Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2004, nr 7, s. 964-977Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We review the derivation and design of digital waveguides from physical models of stiff systems, useful for the synthesis of sounds from strings, rods, and similar objects. A transform method approach is proposed to solve the classic fourth-order equations of stiff systems in order to reduce it to two second-order equations. By introducing scattering boundary matrices, the eigenfrequencies are determined and their n2 dependency is discussed for the clamped, hinged, and intermediate cases. On the basis of the frequency-domain physical model, the numerical discretization is carried out, showing how the insertion of an all-pass delay line generalizes the Karplus-Strong algorithm for the synthesis of ideally flexible vibrating strings. Knowing the physical parameters, the synthesis can proceed using the generalized structure. Another point of view is offered by Laguerre expansions and frequency warping, which are introduced in order to show that a stiff system can be treated as a nonstiff one, provided that the solutions are warped. A method to compute the all-pass chain coefficients and the optimum warping curves from sound samples is discussed. Once the optimum warping characteristic is found, the length of the dispersive delay line to be employed in the simulation is simply determined from the requirement of matching the desired fundamental frequency. The regularization of the dispersion curves by means of optimum unwarping is experimentally evaluated.

  • 23. Vu, Thang X.
    et al.
    Duhamel, Pierre
    Chatzinotas, Symeon
    Ottersten, Björn
    University of Luxembourg, Luxembourg, Luxembourg.
    Finite-SNR analysis for partial relaying cooperation with channel coding and opportunistic relay selection2017Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2017, nr 1, artikel-id 30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work studies the performance of a cooperative network which consists of two channel-coded sources, multiple relays, and one destination. To achieve high spectral efficiency, we assume that a single time slot is dedicated to relaying. Conventional network-coded-based cooperation (NCC) selects the best relay which uses network coding to serve the two sources simultaneously. The bit error rate (BER) performance of NCC with channel coding, however, is still unknown. In this paper, we firstly study the BER of NCC via a closed-form expression and analytically show that NCC only achieves diversity of order two regardless of the number of available relays and the channel code. Secondly, we propose a novel partial relaying-based cooperation (PARC) scheme to improve the system diversity in the finite signal-to-noise ratio (SNR) regime. In particular, closed-form expressions for the system BER and diversity order of PARC are derived as a function of the operating SNR value and the minimum distance of the channel code. We analytically show that the proposed PARC achieves full (instantaneous) diversity order in the finite SNR regime, given that an appropriate channel code is used. Finally, numerical results verify our analysis and demonstrate a large SNR gain of PARC over NCC in the SNR region of interest.

  • 24.
    Werghi, Naoufel
    et al.
    Khalifa University, Sharjah, UAE.
    Rahayem, Mohamed
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Kjellander, Johan
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    An ordered topological representation of 3D triangular mesh facial surface: concept and applications2012Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, nr 144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, we present an original unified framework for analyzing, describing, and encoding 3D facial surfaces. This framework allows the derivation of topologically ordered structures from triangular mesh surfaces, addressing thus the lack of ordered structure in such a modality. After describing the foundations of the framework and highlighting its advantages with respect to close representations, we show its adaptability to a variety of facial mesh surface processing tasks which includes mesh regularity assessment, facial surface cropping, facial surface compression, and facial surface alignment. In addition, it can be used for the extraction of a rich variety of local and global face descriptors. We validate this framework by testing it with raw 3D facial mesh surfaces.

  • 25.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Trautmann, Steffen
    Lantiq A GmbH, Villach, Austria.
    Nordström, Tomas
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Putra, Bakti
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Modeling and Optimization of Line-Driver Power Consumption in xDSL Systems2012Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2012, artikel-id 226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optimization of the power spectrum alleviates the crosstalk noise in Digital Subscriber Lines (DSL) and thereby reduces their power consumption at present. In order to truly assess the DSL system power consumption, thispaper presents realistic line driver (LD) power consumption models. These are applicable to any DSL system andextend previous models by parameterizing various circuit-level non-idealities. Based on the model of a class-ABLD we analyze the multi-user power spectrum optimization problem and propose novel algorithms for its global or approximate solution. The thereby obtained simulation results support our claim that this problem can besimplified with negligible performance loss by neglecting the LD model. This motivates the usage of established spectral optimization algorithms, which are shown to significantly reduce the LD power consumption comparedto static spectrum management.

  • 26.
    Zachariah, Dave
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    De Angelis, Alessio
    Dwivedi, Satyam
    Händel, Peter
    Schedule-based sequential localization in asynchronous wireless networks2014Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2014, s. 16:1-12Artikel i tidskrift (Refereegranskat)
  • 27.
    Zachariah, Dave
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    De Angelis, Alessio
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Schedule-based sequential localization in asynchronous wireless networks2014Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2014, nr 1, s. 16-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we consider the schedule-based network localization concept, which does not requiresynchronization among nodes and does not involve communication overhead. The concept makesuse of a common transmission sequence, which enables each node to perform self-localization andto localize the entire network, based on noisy propagation-time measurements. We formulate theschedule-based localization problem as an estimation problem in a Bayesian framework. This pro-vides robustness with respect to uncertainty in such system parameters as anchor locations and timing devices. Moreover, we derive a sequential approximate maximum a posteriori (AMAP) estimator.The estimator is fully decentralized and copes with varying noise levels. By studying the fundamentalconstraints given by the considered measurement model, we provide a system design methodology which enables a scalable solution. Finally, we evaluate the performance of the proposed AMAPestimator by numerical simulations emulating an impulse-radio ultra-wideband (IR-UWB) wireless network.

  • 28.
    Zenteno, Efrain
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. University of Gavle, Sweden .
    Piazza, Roberto
    University of Luxembourg, Luxembourg.
    Shankar, Bhavani
    University of Luxembourg, Luxembourg.
    Rönnow, Daniel
    University of Gävle, Sweden.
    Ottersten, Björn
    Univesity of Luxembourg, Luxembourg.
    Low Complexity Predistortion and Equalization in Nonlinear Multicarrier Satellite Communications2015Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 1, nr 1, s. 1-15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aiming to reduce the power/mass requirements in satellite transponders and to reduce mission costs, joint amplification of multiple-carriers using a single High-Power Amplifier (HPA) is being considered. In this scenario, a carefulinvestigation of the resulting power efficiency is essential as amplification isnonlinear, and multicarrier signals exhibit enlarged peak-to-average power ratio. Thus, operating the amplifier close to saturation vastly increases signal distortion resulting in a severe degradation of performance, especially for higher order modulations. This paper proposes a reduced-complexity digital pre-distortion (DPD) scheme at the transmitter and a corresponding equalizer (EQ) at thereceiver to mitigate these nonlinear effects. Scenarios include both the forward as well as the return links. In particular, the paper exploits the MIMO Volterra representation and builds on a basis pursuit approach using a LASSO (least absolute shrinkage and selection operator) algorithm to achieve an effienct basis representation, avoiding large computational complexity, to describe the selection of pre-distorter/ equalizer model. The work further compares and contrasts the two mitigation techniques taking various system aspects into consideration. The gains, in performance and amplification efficiency, demonstrated by the use of DPD/ EQ motivate their inclusion in next generation satellite systems.

  • 29.
    Zenteno, Efrain
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Piazza, Roberto
    University of Luxembourg.
    Shankar, Bhavani
    University of Luxembourg.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Ottersten, Björn
    University of Luxembourg.
    Low complexity predistortion and equalization in nonlinear multicarrier satellite communications2015Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2015, artikel-id 30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aiming to reduce the power/mass requirements in satellite transponders and toreduce mission costs, joint amplification of multiple-carriers using a singleHigh-Power Amplifier (HPA) is being considered. In this scenario, a carefulinvestigation of the resulting power efficiency is essential as amplification isnonlinear, and multicarrier signals exhibit enlarged peak-to-average power ratio.Thus, operating the amplifier close to saturation vastly increases signal distortionresulting in a severe degradation of performance, especially for higher ordermodulations. This paper proposes a reduced-complexity digital pre-distortion(DPD) scheme at the transmitter and a corresponding equalizer (EQ) at thereceiver to mitigate these nonlinear effects. Scenarios include both the forward aswell as the return links. In particular, the paper exploits the MIMO Volterrarepresentation and builds on a basis pursuit approach using a LASSO (leastabsolute shrinkage and selection operator) algorithm to achieve an effienct basisrepresentation, avoiding large computational complexity, to describe the selectionof pre-distorter/ equalizer model. The work further compares and contrasts thetwo mitigation techniques taking various system aspects into consideration. Thegains, in performance and amplification efficiency, demonstrated by the use ofDPD/ EQ motivate their inclusion in next generation satellite systems.

  • 30.
    Zhang, Xi
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Jorswieck, Eduard A.
    Communications Laboratory, Faculty of Electrical Engineering and Information Technology,Dresden University of Technology (TUD), Germany.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Stanford University, US.
    On the Asymptotic Optimality of Opportunistic Norm-Based User Selection with Hard SINR Constraint2009Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, ISSN 1687-6172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, user selection algorithms in combination with linear precoding have been proposed that achieve the same scaling as the sum capacity of the MIMO broadcast channel. Robust opportunistic beamforming, which only requires partial channel state information for user selection, further reduces feedback requirements. In this work, we study the optimality of the opportunistic norm-based user selection system in conjunction with hard SINR requirements under max-min fair beamforming transmit power minimization. It is shown that opportunistic norm-based user selection is asymptotically optimal, as the number of transmit antennas goes to infinity when only two users are selected in high SNR regime. The asymptotic performance of opportunistic norm-based user selection is also studied when the number of users goes to infinity. When a limited number of transmit antennas and/or median range of users are available, only insignificant performance degradation is observed in simulations with an ideal channel model or based on measurement data.

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