| 1. |
- Bollen, Math, et al.
(författare)
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Classification of Underlying Causes of Power Quality Disturbances: Deterministic versus Statistical Methods
- 2007
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Ingår i: Eurasip Journal on Applied Signal Processing. - : Springer Science and Business Media LLC. - 1110-8657 .- 1687-0433. ; 2007, s. 17 pages (Article ID 79747)-
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Tidskriftsartikel (refereegranskat)abstract
- 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 featureextraction, are discussed. Segmentation of a sequence of data recording is pre-processing to partition the datainto 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 theeffectiveness of both systems. Finally, conclusions are given together with the discussion of some future research directions.
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| 2. |
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| 3. |
- Christensen, Mads, et al.
(författare)
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Joint Fundamental Frequency and Order Estimation using Optimal Filtering
- 2011
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2011:june
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedIn this paper, the problem of jointly estimating the number of harmonics and the fundamental frequency of periodic signals is considered. We show how this problem can be solved using a number of methods that either are or can be interpreted as filtering methods in combination with a statistical model selection criterion. The methods in question are the classical comb filtering method, a maximum likelihood method, and some filtering methods based on optimal filtering that have recently been proposed, while the model selection criterion is derived herein from the maximum a posteriori principle. The asymptotic properties of the optimal filtering methods are analyzed and an order-recursive efficient implementation is derived. Finally, the estimators have been compared in computer simulations that show that the optimal filtering methods perform well under various conditions. It has previously been demonstrated that the optimal filtering methods perform extremely well with respect to fundamental frequency estimation under adverse conditions, and this fact, combined with the new results on model order estimation and efficient implementation, suggests that these methods form an appealing alternative to classical methods for analyzing multi-pitch signals
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| 4. |
- Sandsten, Maria
(författare)
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Mean square error optimal weighting for multitaper cepstrum estimation
- 2013
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; Oct 2013:2013:158, s. 1-158
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to find a multitaper-based spectrum estimator that is mean square error optimal for cepstrum coefficient estimation. The multitaper spectrum estimator consists of windowed periodograms which are weighted together, where the weights are optimized using the Taylor expansion of the log-spectrum variance and a novel approximation for the log-spectrum bias. A thorough discussion and evaluation are also made for different bias approximations for the log-spectrum of multitaper estimators. The optimized weights are applied together with the sinusoidal tapers as the multitaper estimator. Comparisons of the cepstrum mean square error are made of some known multitaper methods as well as with the parametric autoregressive estimator for simulated speech signals.
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| 5. |
- Wolkerstorfer, Martin, et al.
(författare)
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Modeling and Optimization of Line-Driver Power Consumption in xDSL Systems
- 2012
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Ingår i: EURASIP Journal on Advances in Signal Processing. - Heidelberg : Springer. - 1687-6172 .- 1687-6180. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Ali, Sadiq, et al.
(författare)
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Multi-antenna spectrum sensing by exploiting spatio-temporal correlation
- 2014
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; , s. 160-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Callmer, Jonas, 1981-, et al.
(författare)
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RADAR SLAM using Visual Features
- 2011
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2011:71
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
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| 9. |
- Lindgren, Erik, 1980
(författare)
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Detection, 3-D positioning, and sizing of small pore defects using digital radiography and tracking
- 2014
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6180 .- 1687-6172. ; 2014:1, s. 9-
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an algorithm that handles the detection, positioning, and sizing of submillimeter-sized pores in welds using radiographic inspection and tracking. The possibility to detect, position, and size pores which have a low contrast-to-noise ratio increases the value of the nondestructive evaluation of welds by facilitating fatigue life predictions with lower uncertainty. In this article, a multiple hypothesis tracker with an extended Kalman filter is used to track an unknown number of pore indications in a sequence of radiographs as an object is rotated. Each pore is not required to be detected in all radiographs. In addition, in the tracking step, three-dimensional (3-D) positions of pore defects are calculated. To optimize, set up, and pre-evaluate the algorithm, the article explores a design of experimental approach in combination with synthetic radiographs of titanium laser welds containing pore defects. The pre-evaluation on synthetic radiographs at industrially reasonable contrast-to-noise ratios indicate less than 1% false detection rates at high detection rates and less than 0.1 mm of positioning errors for more than 90% of the pores. A comparison between experimental results of the presented algorithm and a computerized tomography reference measurement shows qualitatively good agreement in the 3-D positions of approximately 0.1-mm diameter pores in 5-mm-thick Ti-6242.
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| 10. |
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| 11. |
- Löfgren, Johan, 1983, et al.
(författare)
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Sea level measurements using multi-frequency GPS and GLONASS observations
- 2014
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2014:1
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Tidskriftsartikel (refereegranskat)abstract
- Global Positioning System (GPS) tide gauges have been realized in different configurations, e.g., with one zenith-looking antenna, using the multipath interference pattern for signal-to-noise ratio (SNR) analysis, or with one zenith- and one nadir-looking antenna, analyzing the difference in phase delay, to estimate the sea level height. In this study, for the first time, we use a true Global Navigation Satellite System (GNSS) tide gauge, installed at the Onsala Space Observatory. This GNSS tide gauge is recording both GPS and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) signals and makes it possible to use both the one- and two-antenna analysis approach. Both the SNR analysis and the phase delay analysis were evaluated using dual-frequency GPS and GLONASS signals, i.e., frequencies in the L-band, during a 1-month-long campaign. The GNSS-derived sea level results were compared to independent sea level observations from a co-located pressure tide gauge and show a high correlation for both systems and frequency bands, with correlation coefficients of 0.86 to 0.97. The phase delay results show a better agreement with the tide gauge sea level than the SNR results with root-mean-square differences of 3.5 cm (GPS L1 and L2) and 3.3/3.2 cm (GLONASS L1/L2 bands) compared to 4.0/9.0 cm (GPS L1/L2 ) and 4.7/8.9 cm (GLONASS L1/L2 bands). GPS and GLONASS show similar performance in the comparison, and the results show that for the phase delay analysis, it is possible to use both frequencies, whereas for the SNR analysis, the L2 band should be avoided if other signals are available. Note that standard geodetic receivers using code-based tracking, i.e., tracking the un-encrypted C/A-code on L1 and using the manufacturers’ proprietary tracking method for L2 , were used. Signals with the new C/A-code on L2 , the so-called L2C, were not tracked.Using wind speed as an indicator for sea surface roughness, we find that the SNR analysis performs better in rough sea surface conditions than the phase delay analysis. The SNR analysis is possible even during the highest wind speed observed during this campaign (17.5 m/s), while the phase delay analysis becomes difficult for wind speeds above 6 m/s.
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| 12. |
- Nilsson, John-Olof, et al.
(författare)
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Cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging
- 2013
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 164
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 13. |
- Savic, Vladimir, et al.
(författare)
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Nonparametric generalized belief propagation based on pseudo-junction tree for cooperative localization in wireless networks
- 2013
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 14. |
- Skoglar, Per, et al.
(författare)
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Pedestrian Tracking with an Infrared Sensor using Road Network Information
- 2012
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 1:26, s. 2012a-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 15. |
- Werghi, Naoufel, et al.
(författare)
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An ordered topological representation of 3D triangular mesh facial surface : concept and applications
- 2012
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; :144
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 16. |
- Zachariah, Dave, et al.
(författare)
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Schedule-based sequential localization in asynchronous wireless networks
- 2014
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2014:1, s. 16-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 17. |
- Ahmadi, Shervin Parvini, et al.
(författare)
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Distributed localization using Levenberg-Marquardt algorithm
- 2021
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : SPRINGER. - 1687-6172 .- 1687-6180. ; 2021:1
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a distributed algorithm for sensor network localization based on a maximum likelihood formulation. It relies on the Levenberg-Marquardt algorithm where the computations are distributed among different computational agents using message passing, or equivalently dynamic programming. The resulting algorithm provides a good localization accuracy, and it converges to the same solution as its centralized counterpart. Moreover, it requires fewer iterations and communications between computational agents as compared to first-order methods. The performance of the algorithm is demonstrated with extensive simulations in Julia in which it is shown that our method outperforms distributed methods that are based on approximate maximum likelihood formulations.
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| 18. |
- Ben Slimane, Slimane, et al.
(författare)
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Delay Optimization in Cooperative Relaying with Cyclic Delay Diversity
- 2008
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; , s. 736818-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 19. |
- Björsell, Niclas, et al.
(författare)
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Achievable ADC Performance by Post-Correction Utilizing Dynamic Modeling of the Integral Nonlinearity
- 2008
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1110-8657 .- 1687-6180 .- 1687-6172. ; , s. 497187-1-497187-10
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for a universal dynamic model of analog-to-digital converters (ADC’s) aimed for postcorrection. 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 postcorrected individually and by the method that best suits the application. The purpose of postcorrection 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).
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| 20. |
- Blad, Anton, et al.
(författare)
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Multirate formulation for mismatch sensitivity analysis of analog-to-digital converters that utilize parallel S?-modulators
- 2008
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2008
-
Tidskriftsartikel (refereegranskat)abstract
- A general formulation based on multirate filterbanktheory for analog-to-digital converters using parallel sigmadeltamodulators in conjunction with modulation sequences ispresented. The time-interleaved modulators (TIMs), Hadamard modulators(HMs), and frequency-band decomposition modulators(FBDMs) can be viewed as special cases of the proposeddescription. The usefulness of the formulation stems from itsability to analyze a system's sensitivity to aliasing due to channel mismatch and modulation sequence level errors. BothNyquist-rate and oversampled systems are considered, and it isshown how the matching requirements between channels canbe reduced for oversampled systems. The new formulation isuseful also for the derivation of new modulation schemes, andan example is given of how it can be used in this context.
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| 21. |
- Boche, Holger, et al.
(författare)
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Game Theory in Signal Processing and Communications
- 2009
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 22. |
- Callmer, Jonas, 1981-, et al.
(författare)
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Silent Localization of Underwater Sensors Using Magnetometers
- 2010
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; 2010:1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 23. |
- Christensen, Mads, et al.
(författare)
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Sinusoidal Order Estimation using Angles between Subspaces
- 2009
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedWe consider the problem of determining the order of a parametric model from a noisy signal based on the geometry of the space. More specifically, we do this using the nontrivial angles between the candidate signal subspace model and the noise subspace. The proposed principle is closely related to the subspace orthogonality property known from the MUSIC algorithm, and we study its properties and compare it to other related measures. For the problem of estimating the number of complex sinusoids in white noise, a computationally efficient implementation exists, and this problem is therefore considered in detail. In computer simulations, we compare the proposed method to various well-known methods for order estimation. These show that the proposed method outperforms the other previously published subspace methods and that it is more robust to the noise being colored than the previously published methods. Copyright (C) 2009 Mads Graesboll Christensen et al.
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| 24. |
- Conte, Gianpaolo, et al.
(författare)
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Vision-Based Unmanned Aerial Vehicle Navigation Using Geo-Referenced Information
- 2009
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; 2009:387308, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the possibility of augmenting an Unmanned Aerial Vehicle (UAV) navigation system with a passive video camera in order to cope with long-term GPS outages. The paper proposes a vision-based navigation architecture which combines inertial sensors, visual odometry, and registration of the on-board video to a geo-referenced aerial image. The vision-aided navigation system developed is capable of providing high-rate and drift-free state estimation for UAV autonomous navigation without the GPS system. Due to the use of image-to-map registration for absolute position calculation, drift-free position performance depends on the structural characteristics of the terrain. Experimental evaluation of the approach based on offline flight data is provided. In addition the architecture proposed has been implemented on-board an experimental UAV helicopter platform and tested during vision-based autonomous flights.
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| 25. |
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| 26. |
- Eng, Frida, et al.
(författare)
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Downsampling Non-Uniformly Sampled Data
- 2008
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180.
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 27. |
- Hendeby, Gustaf, et al.
(författare)
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Particle Filtering : The Need for Speed
- 2010
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; 2010:181403
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 28. |
- Hendeby, Gustaf, et al.
(författare)
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The Rao-Blackwellized Particle Filter : A Filter Bank Implementation
- 2010
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; 2010:724087
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 29. |
- Javid, Alireza Mahdavi, et al.
(författare)
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High-dimensional neural feature design for layer-wise reduction of training cost
- 2020
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Nature. - 1687-6172 .- 1687-6180. ; 2020:1
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Tidskriftsartikel (refereegranskat)abstract
- We design a rectified linear unit-based multilayer neural network by mapping the feature vectors to a higher dimensional space in every layer. We design the weight matrices in every layer to ensure a reduction of the training cost as the number of layers increases. Linear projection to the target in the higher dimensional space leads to a lower training cost if a convex cost is minimized. Anl(2)-norm convex constraint is used in the minimization to reduce the generalization error and avoid overfitting. The regularization hyperparameters of the network are derived analytically to guarantee a monotonic decrement of the training cost, and therefore, it eliminates the need for cross-validation to find the regularization hyperparameter in each layer. We show that the proposed architecture is norm-preserving and provides an invertible feature vector and, therefore, can be used to reduce the training cost of any other learning method which employs linear projection to estimate the target.
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| 30. |
- Jorswieck, Eduard A., 1975-, et al.
(författare)
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Feedback reduction in uplink MIMO OFDM systems by chunk optimization
- 2008
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 31. |
- Kalantari, Ashkan, et al.
(författare)
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Statistical test for GNSS spoofing attack detection by using multiple receivers on a rigid body
- 2020
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : SPRINGEROPEN. - 1687-6172 .- 1687-6180. ; 2020:1
-
Tidskriftsartikel (refereegranskat)abstract
- Global navigation satellite systems (GNSS) are being the target of various jamming, spoofing, and meaconing attacks. This paper proposes a new statistical test for the presence of multiple spoofers based on range measurements observed by a plurality of receivers located on a rigid body platform. The relative positions of the receivers are known, but the location and orientation of the platform are unknown. The test is based on the generalized likelihood ratio test (GLRT) paradigm and essentially performs a consistency check between the set of observed range measurements and known information about the satellite topology and the geometry of the receiver constellation. Optimal spoofing locations and optimal artificial time delays (as induced by the spoofers) are also determined.Exact evaluation of the GLRT requires the maximum-likelihood estimates of all parameters, which proves difficult. Instead, approximations based on iterative algorithms and the squared-range least squares algorithm are derived. The accuracy of these approximations is benchmarked against Cramer-Rao lower bounds.Numerical examples demonstrate the effectiveness of the proposed algorithm and show that increasing the number of GNSS receivers makes the attack easier to detect. We also show that using multiple GNSS receivers limits the availability of optimal attack positions.
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| 32. |
- Lindgren, David, et al.
(författare)
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Shooter Localization in Wireless Microphone Networks
- 2010
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Hindawi Publishing Corporation. - 1687-6172 .- 1687-6180. ; 2010
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 33. |
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| 34. |
- Lindqvist, Neiva, et al.
(författare)
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Impact of crosstalk channel estimation on the DSM performance for DSL networks
- 2010
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- The development and assessment of spectrum management methods for the copper access network are usually conducted under the assumption of accurate channel information. Acquiring such information implies, in practice, estimation of the crosstalk coupling functions between the twisted-pair lines in the access network. This type of estimation is not supported or required by current digital subscriber line (DSL) standards. In this work, we investigate the impact of the inaccuracies in crosstalk estimation on the performance of dynamic spectrum management (DSM) algorithms. A recently proposed crosstalk channel estimator is considered and a statistical sensitivity analysis is conducted to investigate the effects of the crosstalk estimation error on the bitloading and on the achievable data rate for a transmission line. The DSM performance is then evaluated based on the achievable data rates obtained through experiments with DSL setups and computer simulations. Since these experiments assume network scenarios consisting of real twisted-pair cables, both crosstalk channel estimates and measurements (for a reference comparison) are considered. The results indicate that the error introduced by the adopted estimation procedure does not compromise the performance of the DSM techniques, that is, the considered crosstalk channel estimator provides enough means for a practical implementation of DSM.
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| 35. |
- Liu, Jianhua, et al.
(författare)
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Differential space-time block code modulation for DS-CDMA systems
- 2002
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Ingår i: EURASIP Journal on Advances in Signal Processing. - 1687-6172 .- 1687-6180. ; :3, s. 289-296
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 36. |
- Magesacher, Thomas, et al.
(författare)
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Analysis of Adaptive Interference Cancellation Using Common-Mode Information in Wireline Communications
- 2007
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- Joint processing of common-mode (CM) and differential-mode (DM) signals in wireline transmission can yield significant improvements in terms of throughput compared to using only the DM signal. Recent work proposed the employment of an adaptive CM-reference-based interference canceller and reported performance improvements based on simulation results. This paper presents a thorough investigation of the cancellation approach. A subchannel model of the CM-aided wireline channel is presented and the Wiener solutions for different adaptation strategies are derived. It is shown that a canceller, whose coefficients are adapted while the far-end transmitter is silent, yields a signal-to-noise power ratio (SNR) that is higher than the SNR at the DM channel output for a large class of practically relevant cases. Adaptation while the useful far-end signal is present yields a front-end whose output SNR is considerably lower compared to the SNR of the DM channel output. The results are illustrated by simulations based on channel measurement data.
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| 37. |
- Malki, Suleyman, et al.
(författare)
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A CNN-Specific Integrated Processor
- 2009
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- Integrated Processors (IP) are meant to supply algorithm-specific cores to a micro-electronic system. They are usually developed separately, and upon success turned into a part, that either by programming or by configuration can be re-used within many systems. This paper looks at architectures for Cellular Neural Networks (CNN) to become realized as IP. First current digital implementations are reviewed, and the memory-processor bandwidth issues are analyzed. Then a generic view is taken on the structure of the network, and a new intra-communication protocol based on rotating wheels is proposed. It is shown that this provides for guaranteed high-performance with a minimal network interfaces. The resulting node is small and supports multi-level CNN designs, giving the system a 30-fold increase in capacity compared to classical designs. As it facilitates multiple operations on a single image, and single operations on multiple images, with minimal access to the external image memory, balancing the internal and external data transfer requirements can optimize the system operation. Special consideration is given to the treatment of the boundary nodes. In conventional digital CNN designs, such requires additional logic to handle the CNN value propagation scheme. In the new architecture, only a slight modification of the existing cells is necessary to model the boundary effect. A typical prototype for visual pattern recognition will house 4096 CNN cells with a 2% overhead for making it an IP.
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| 38. |
- Osama, Muhammad, et al.
(författare)
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Robust localization in wireless networks from corrupted signals
- 2021
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2021:1
-
Tidskriftsartikel (refereegranskat)abstract
- We address the problem of timing-based localization in wireless networks, when an unknown fraction of data is corrupted by non-ideal propagation conditions. While timing-based techniques can enable accurate localization, they are sensitive to corrupted data. We develop a robust method that is applicable to a range of localization techniques, including time-of-arrival, time-difference-of-arrival and time-difference in schedule-based transmissions. The method is distribution-free, is computationally efficient and requires only an upper bound on the fraction of corrupted data, thus obviating distributional assumptions on the corrupting noise. The robustness of the method is demonstrated in numerical experiments.
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| 39. |
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| 40. |
- Roth, Michael, et al.
(författare)
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The Ensemble Kalman filter: a signal processing perspective
- 2017
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : SPRINGER INTERNATIONAL PUBLISHING AG. - 1687-6172 .- 1687-6180.
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Forskningsöversikt (refereegranskat)abstract
- 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.
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| 41. |
- Sandberg, Johan, et al.
(författare)
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Optimal Nonparametric Covariance Function Estimation for Any Family of Nonstationary Random Processes
- 2011
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- A covariance function estimate of a zero-mean nonstationary random process in discrete time is accomplished from one observed realization by weighting observations with a kernel function. Several kernel functions have been proposed in the literature. In this paper, we prove that the mean square error (MSE) optimal kernel function for any parameterized family of random processes can be computed as the solution to a system of linear equations. Even though the resulting kernel is optimized for members of the chosen family, it seems to be robust in the sense that it is often close to optimal for many other random processes as well. We also investigate a few examples of families, including a family of locally stationary processes, nonstationary AR-processes, and chirp processes, and their respective MSE optimal kernel functions.
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| 42. |
- Sandsten, Maria
(författare)
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Optimal Multitaper Wigner Spectrum Estimation of a Class of Locally Stationary Processes Using Hermite Functions
- 2011
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the time-discrete multitapers that give a mean square error optimal Wigner spectrum estimate for a class of locally stationary processes (LSPs). The accuracy in the estimation of the time-variable Wigner spectrum of the LSP is evaluated and compared with other frequently used methods. The optimal multitapers are also approximated by Hermite functions, which is computationally more efficient, and the errors introduced by this approximation are studied. Additionally, the number of windows included in a multitaper spectrum estimate is often crucial and an investigation of the error caused by limiting this number is made. Finally, the same optimal set of weights can be stored and utilized for different window lengths. As a result, the optimal multitapers are shown to be well approximated by Hermite functions, and a limited number of windows can be used for a mean square error optimal spectrogram estimate.
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| 43. |
- Sandsten, Maria, et al.
(författare)
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Optimization of Weighting Factors for Multiple Window Spectrogram of Event-Related Potentials
- 2010
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the mean square error optimal weighting factors for multiple window spectrogram of different stationary and nonstationary processes. It is well known that the choice of multiple windows is important, but here we show that the weighting of the different multiple window spectrograms in the final average is as important to consider and that the equally averaged spectrogram is not mean square error optimal for non-stationary processes. The cost function for optimization is the normalized mean square error where the normalization factor is the multiple window spectrogram. This means that the unknown weighting factors will be present in the numerator as well as in the denominator. A quasi-Newton algorithm is used for the optimization. The optimization is compared for a number of well-known sets of multiple windows and common weighting factors and the results show that the number and the shape of the windows are important for a small mean square error. Multiple window spectrograms using these optimal weighting factors, from ElectroEncephaloGram data including steady-state visual evoked potentials, are shown as examples.
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| 44. |
- Sandsten, Maria, et al.
(författare)
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Robust feature representation for classification of bird song syllables
- 2016
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2016:1
-
Tidskriftsartikel (refereegranskat)abstract
- A novel feature set for low-dimensional signal representation, designed for classification or clustering of non-stationary signals with complex variation in time and frequency, is presented. The feature representation of a signal is given by the first left and right singular vectors of its ambiguity spectrum matrix. If the ambiguity matrix is of low rank, most signal information in time direction is captured by the first right singular vector while the signal’s key frequency information is encoded by the first left singular vector. The resemblance of two signals is investigated by means of a suitable similarity assessment of the signals’ respective singular vector pair. Application of multitapers for the calculation of the ambiguity spectrum gives an increased robustness to jitter and background noise and a consequent improvement in performance, as compared to estimation based on the ordinary single Hanning window spectrogram. The suggested feature-based signal compression is applied to a syllable-based analysis of a song from the bird species Great Reed Warbler and evaluated by comparison to manual auditive and/or visual signal classification. The results show that the proposed approach outperforms well-known approaches based on mel-frequency cepstral coefficients and spectrogram cross-correlation.
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| 45. |
- Seifi, Nima, 1981, et al.
(författare)
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Multimode Transmission in Network MIMO Downlink with Incomplete CSI
- 2011
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2011, s. Art. no. 743916-
-
Tidskriftsartikel (refereegranskat)abstract
- We consider a cooperative multi-cell MIMO (a.k.a network MIMO) downlink system with multiantennabase stations (BSs), which are connected to a central unit and communicate with multi-antennausers. In such a network, obtaining perfect channel state information (CSI) of all users at the central unitto exploit opportunistic scheduling requires a substantial amount of feedback and backhaul signaling.In this paper, we propose a scheduling algorithm based only on the knowledge of the average receivedSNR at each user from all the cooperating BSs, denoted as incomplete CSI. Multi-mode transmission isapplied that is able to adaptively adjust the number of data streams transmitted to each user. Utilizingthe results of random matrix theory, an analytical framework is proposed to approximate the ergodicrate of each user with different number of data streams. Using these approximate ergodic rates, a jointuser and mode selection algorithm is proposed, where only the scheduled users need to feed backinstantaneous CSI. Simulation results demonstrate that the developed analytical framework providesa good approximation for a practical number of antennas. While substantially reducing the feedbackoverhead, it is shown that the proposed scheduling algorithm performs closely to the opportunisticscheduling algorithm that requires instantaneous CSI feedback from all users.
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| 46. |
- Stadler, Svante, et al.
(författare)
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Prediction of Speech Recognition in Cochlear Implant Users by Adapting Auditory Models to Psychophysical Data
- 2009
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2009, s. 175243-
-
Tidskriftsartikel (refereegranskat)abstract
- Users of cochlear implants (CIs) vary widely in their ability to recognize speech in noisy conditions. There are many factors that may influence their performance. We have investigated to what degree it can be explained by the users' ability to discriminate spectral shapes. A speech recognition task has been simulated using both a simple and a complex models of CI hearing. The models were individualized by adapting their parameters to fit the results of a spectral discrimination test. The predicted speech recognition performance was compared to experimental results, and they were significantly correlated. The presented framework may be used to simulate the effects of changing the CI encoding strategy.
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| 47. |
- Testa, I, et al.
(författare)
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Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides
- 2004
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2004:7, s. 964-977
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 48. |
- von Wrycza, Peter, 1981-, et al.
(författare)
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Spectrum Allocation for Decentralized Transmission Strategies : Properties of Nash Equilibria
- 2009
-
Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of two transmit-receive pairs coexisting in the same area and communicating using the same portion of the spectrum is analyzed from a game theoretic perspective. Each pair utilizes a decentralized iterative water-filling scheme to greedily maximize the individual rate. We study the dynamics of such a game and find properties of the resulting Nash equilibria. The region of achievable operating points is characterized for both low-and high-interference systems, and the dependence on the various system parameters is explicitly shown. We derive the region of possible signal space partitioning for the iterative water-filling scheme and show how the individual utility functions can be modified to alter its range. Utilizing global system knowledge, we design a modified game encouraging better operating points in terms of sum rate compared to those obtained using the iterative water-filling algorithm and show how such a game can be imitated in a decentralized noncooperative setting. Although we restrict the analysis to a two player game, analogous concepts can be used to design decentralized algorithms for scenarios with more players. The performance of the modified decentralized game is evaluated and compared to the iterative water-filling algorithm by numerical simulations.
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| 49. |
- Vu, Thang X., et al.
(författare)
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Finite-SNR analysis for partial relaying cooperation with channel coding and opportunistic relay selection
- 2017
-
Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2017:1
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 50. |
- Wang, Jianfeng, 1984-, et al.
(författare)
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Error bounds of block sparse signal recovery based on q-ratio block constrained minimal singular values
- 2019
-
Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2019
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we introduce the q-ratio block constrained minimal singular values (BCMSV) as a new measure of measurement matrix in compressive sensing of block sparse/compressive signals and present an algorithm for computing this new measure. Both the mixed ℓ2/ℓq and the mixed ℓ2/ℓ1 norms of the reconstruction errors for stable and robust recovery using block basis pursuit (BBP), the block Dantzig selector (BDS), and the group lasso in terms of the q-ratio BCMSV are investigated. We establish a sufficient condition based on the q-ratio block sparsity for the exact recovery from the noise-free BBP and developed a convex-concave procedure to solve the corresponding non-convex problem in the condition. Furthermore, we prove that for sub-Gaussian random matrices, the q-ratio BCMSV is bounded away from zero with high probability when the number of measurements is reasonably large. Numerical experiments are implemented to illustrate the theoretical results. In addition, we demonstrate that the q-ratio BCMSV-based error bounds are tighter than the block-restricted isotropic constant-based bounds.
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