G.T.F. de Abreu

Jacobs University, Bremen, Bremen, Germany

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Publications (96)44.97 Total impact

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    ABSTRACT: We perform an analysis of the secrecy outage of random networks under Nakagami-m fading with multiple transmit antennas. Specifically, using a network model that accounts for uncertainties both in node locations (distances) and channel coefficients (fading), we derive the distribution of the best path gain of eavesdroppers using Probability Generating Functional property of Poisson Point Process (PPP). Using this result, the secrecy outage probability and the conditional secrecy outage probability of random networks with multiple eavesdroppers are obtained, with basic factors such as the density of eavesdropping nodes, the number of transmit antennas and the fading figure all accounted for by explicit parameters. The impact of transmission factors, including number of transmit antennas, fading figure, legitimate node distance and node density are studied and analysed in numerical results.
    IEEE International Conference on Communications, London, UK, June 2015.; 06/2015
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    ABSTRACT: This position paper is an output of the Activity Chain 05 in the Internet of Things Cluster (IERC). The IERC has created a number of activity chains to support close cooperation between the projects addressing IoT topics and to form an arena for exchange of ideas and open dialog on important research challenges. The activity chains are defined as work streams that group together partners or specific participants from partners around well-defined technical activities that will result into at least one output or delivery that will be used in addressing the IERC objectives. IERC Activity Chain 05 is the crossproject activity, which has the objective to investigate how research can foster a trustworthy IoT at European level, identify solutions to protect the security and privacy of the citizens. These objectives can be quite challenging at the regulatory, ethical, market and technical levels. Next to Trusted IoT, privacy, data protection and security, which is at the core of policy issues already addressed today by the IERC, there are also other policy issues of concern that will need to be addressed if IoT is to be accepted by society, and wanted to make a difference where it can. These issues in particular include global governance (how are we going to make this all happen, in the full understanding that the way forward will need to involve multiple stakeholders around the globe), ethics (what would we expect those “global IoT solutions” to respect, and how will the way IoT is implemented potentially affect the understanding of ethical impact), and radio frequency spectrum. What can we do to make sure those issues are addressed, and how can we assure citizens and policy makers are well informed, thus to be able to take conscious decisions when moving forward. In this context, this position paper identifies relevant IoT challenges and describes solutions defined by the cluster projects, which can be used to address these challenges. FP7 projects have spent considerable effort in the definition of technical solutions and frameworks for the IoT domain. In some case, these solutions may overlap or they may leave gaps, which might become a basis for proposals for future IERC research activities and research programs like H2020. These research opportunities are identified and described in this position paper. Future activities of AC05 must address the integration of the identified solutions in this position paper with the results from the other Activity Chains in the IERC.
    Edited by European Communities, 01/2015; IERC - EUROPEAN RESEARCH CLUSTER ON THE INTERNET OF THINGS.
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    ABSTRACT: We examine the secrecy outage of unicast links in cognitive wireless sensor networks (CWSN) in the presence of interference from sensor users and model the interference power with suitable approximation techniques. Precisely, we perform a thorough analysis of the secrecy outage under the impact of Nakagami-m fading and Shadowing. The conclusions attained from our analysis can be specified as - the secrecy capacity can be maintained at lower equivocation rates, the impact of shadowing is severe as it increases the secrecy outage quickly and eavesdropper’s density impacts secrecy outage the most which is closely followed by the equivocation ratio.
    IEEE Fourty-Eigth Asilomar Conference Conference on Signals, Systems, and Computers (ASILOMAR 14), Pacific Grove, CA; 11/2014
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    Omotayo Oshiga, Stefano Severi, Giuseppe Abreu
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    ABSTRACT: We consider the problem of performing ranging measurements between a source and multiple receivers efficiently and accurately, as required by distance-based wireless localization systems. To this end, a new multipoint ranging algorithm is proposed, which is obtained by adapting superresolution techniques to the ranging problem, using for the sake of illustration the specific cases of ToA and PDoA, unified under the same mathematical framework. The algorithm handles multipoint ranging in an efficient manner by employing an orthogonalized non-uniform sampling scheme optimised via Golomb rulers. Since the approach requires the design of mutually orthogonal sets of Golomb rulers with equivalent properties -- a problem that founds no solution in current literature -- a new genetic algorithm to accomplish this task is presented, which is also found to outperform the best known alternative when used to generate a single ruler. Finally, a CRLB analysis of the overall optimised multipoint ranging solution is performed, which together with a comparison against simulation results validates the proposed techniques.
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    ABSTRACT: This paper presents an experimentally-driven assessment of eigenvalue-based detection (EBD) for cognitive radio (CR), which puts such techniques to a realistic test beyond the assumptions of Gaussian target signals and the availability of large numbers of samples for detection purposes typically adopted in purely theoretical analysis. It is shown that these approximations lead to significantly optimistic results compared to those obtained in laboratory employing standard-compliant signals. Instead of relying on asymptotically large sample sizes, it is also found that better performance is obtained by splitting samples into smaller blocks (multiple covariance matrices), followed by an adequate combining of results based on corresponding test statistics. This approach, referred to as EBD with partial decision combining, is shown to outperform the standard (single-matrix) approach.
    2014 IEEE 8th Sensor Array and Multichannel Signal Processing Workshop (SAM); 06/2014
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    ABSTRACT: We survey the state-of-the-art on the Internet-of-Things (IoT) from a wireless communications point of view, as a result of the European FP7 project BUTLER which has its focus on pervasiveness, context-awareness and security for IoT. In particular, we describe the efforts to develop so-called (wireless) enabling technologies, aimed at circumventing the many challenges involved in extending the current set of domains (“verticals”) of IoT applications towards a “horizontal” (i.e. integrated) vision of the IoT. We start by illustrating current research effort in machine-to-machine (M2M), which is mainly focused on vertical domains, and we discuss some of them in details, depicting then the necessary horizontal vision for the future intelligent daily routine (“Smart Life”). We then describe the technical features of the most relevant heterogeneous communications technologies on which the IoT relies, under the light of the on-going M2M service layer standardization. Finally we identify and present the key aspects, within three major cross-vertical categories, under which M2M technologies can function as enablers for the horizontal vision of the IoT.
    2014 European Conference on Networks and Communications (EuCNC); 06/2014
  • Koji Ishibashi, Giuseppe Abreu
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    ABSTRACT: This paper reveals an impairment of well-known path-loss model generally assumed in conventional works with radio frequency (RF) energy harvesting. We will prove that, when RF energy harvesting is considered in a large-scale network, the summation of energy transferred to nodes in the network diverges while the radiated energy must be finite. Thus, we propose a new absorption function meeting this law and derive several expressions of average harvested energy based on the model. Furthermore, the effectiveness of RF energy harvesting with Poisson point process (PPP) network with a single transmitter is demonstrated.
    ICASSP 2014 - 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP); 05/2014
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    ABSTRACT: Motivated by the recent advances on internet of things (IoT) and the importance that location information has on many application scenarios, this article offers references to theoretical and localization-algorithmic tools that can be utilised in connection with IoT. We develop this discussion from basic to sophisticated localization techniques covering also some less-intuitive notions of localization, e.g. semantic positioning, for which we provide a novel solution which overcome the problem of privacy. We analyze the localization problem from a mathematical perspective; reviewing the most common and best-performing class of localization methods based on optimization and algebraic approaches and we discuss benefits of location information in a wireless system. In this regard we discuss few concrete applications scenario currently under investigation in the largest EU project on IoT, namely the FP-7 Butler project, how location information is one of the key enabling technology in the IoT. In addition to the theoretical aspect, this article provides references to the pervasive localization system architecture using the smart sensors developed within the Butler project.
    2014 IEEE World Forum on Internet of Things (WF-IoT); 03/2014
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    ABSTRACT: Although during the last decade considerable efforts have been invested in the integration of different wireless technologies, a new surge of interest is arising due to the upcoming internet of things (IoT) in which many relevant application scenarios rely on location information. However, due to the heterogeneity of the devices, ergo the heterogeneity of information available, novel indoor positioning algorithms capable to account for different types of information must be designed. Differently from the vast majority of localization solutions currently available which rely on one specific type of observation, e.g. range information only, in this article we consider the localization problem of multiple sources from range and angle measurements. To this end we first study the benefit of heterogeneous information via the rigidity theory and the Cramèr-Rao Lower Bound (CRLB) and then we show how to utilize an extension of the Euclidean-kernel, i.e. the Edge-kernel, to perform robust positioning under Non-Line-of-Sight (NLOS) conditions. In particular with reference to the latter contribution it is shown how to exploit the robust principal component analysis theory to improve the edge-kernel recovery and in turn the estimated target's locations.
    2014 IEEE World Forum on Internet of Things (WF-IoT); 03/2014
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    ABSTRACT: Information-theoretic security at the physical layer has been proposed to increase the privacy of wireless communications due to its achievable characteristics: unbreakability, provability, and quantifiability. An accurate and powerful analytical framework aimed at deriving the achievable security level provided by Gaussian channels is presented and validated. Its accuracy is assessed by mean of a narrowband fading scenario simulator with multi-antenna transceivers. The impact on the security level of a number of aspects, such as the Eavesdropper's distance as well as the number and distance of antennas in MIMO systems is finally discussed.
    2013 Asilomar Conference on Signals, Systems and Computers; 11/2013
  • 2013 Asilomar Conference on Signals, Systems and Computers; 11/2013
  • Satyanarayana Vuppala, Giuseppe Abreu
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    ABSTRACT: We investigate the secrecy transmission capacity of random networks with Nakagami-m fading. Using a model that accounts for uncertainties both in node locations (distances) and channel coefficients (fading), we derive the path-gain distribution of the collusion of nodes, as well as the corresponding secrecy outage probability and secrecy rate distribution. These results are then used to obtain the secrecy transmission capacity of the network. The results are useful in quantifying the impact of fading and density of legitimate/eavesdropping nodes on the performance of random networks.
    IEEE Fourty-Seventh Asilomar Conference Conference on Signals, Systems, and Computers, Pacific Grove, CA; 11/2013
  • Jani Saloranta, Davide Macagnano, Giuseppe Abreu
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    ABSTRACT: In this paper we extend the previous work on positioning problems using the Circular Interval-based scaling (CIS) algorithm previously proposed by the authors. In particular it is shown how the radius that the CIS algorithm associates to the targets is related to the average statistic of the set of measurements related to them. Together with a factor computed on the basis of the geometric dilution of precision (GDOP), this parameter is utilized to compute a confidence measure for the targets's locations which can be utilized to account for a priori information over the position estimates when recomputing the network configuration. The results show that the proposed extended CIS cost function, called CIS;, dramatically improve the estimates over the targets' locations. Non-line-of-sight (NLOS) range observations are also accounted for by modifying the least-square term in the extended CIS cost function with a term favoring sparsity, resulting in the R-CIS; solution. Under these conditions the R-CIS; solution is shown to compensate eventual NLOS range measurements without need for any bias identification algorithm.
    2013 Asilomar Conference on Signals, Systems and Computers; 11/2013
  • Davide Macagnano, G.T.F. de Abreu
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    ABSTRACT: We offer a redesigned form of the classical multidimensional scaling (C-MDS) algorithm suitable to handle the localization of multiple sources under line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. To do so we propose to modify the kernel matrix used in the MDS algorithm to allow for both distance and angle information to be processed algebraically (without iteration) and simultaneously. In so doing we also show that the new formulation overcomes two well known limitations of the C-MDS approach, namely the propagation error problem and the possibility to weight the dissimilarities used as measurement information, including, for the case of binary weights, the data erasure problem. Due to the increased size of the proposed edge kernel matrix KE used in the algorithm, the Nystrom approximation is applied to reduce the overall computational complexity to few matrix multiplications. Range only scenarios are also dealt with by approximating the matrix KE. Simulations in range-angle as well as range-only scenarios demonstrate the superiority of our solution under both LOS and NLOS conditions versus semidefinite programming (SDP) formulations of the problem specifically designed to exploit the heterogeneity of the information available.
    IEEE Transactions on Wireless Communications 10/2013; 12(10):5334-5345. DOI:10.1109/TWC.2013.090313.130301 · 2.76 Impact Factor
  • Satyanaranaya Vuppala, G.T.F. de Abreu
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    ABSTRACT: We consider the secrecy capacity of unicast channels of ad hoc networks exposed to randomly located eavesdroppers, as modeled by S-Graphs. Expressions that quantify the impact of fading and of the density of legitimate nodes relative to that of eavesdroppers are obtained, in terms of the probability that secrecy capacities of unicast channels are nonzero. The results indicate that depending on the relative density of eavesdroppers and the fading intensity, the secrecy capacity of unicast channels subject to fading may be higher than under additive white Gaussian noise (AWGN).
    IEEE Transactions on Information Forensics and Security 09/2013; 8(9):1469-1481. DOI:10.1109/TIFS.2013.2274954 · 2.07 Impact Factor
  • Satyanaranaya Vuppala, Giuseppe Abreu
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    ABSTRACT: We investigated the secrecy outage of unicast channels in random networks exposed to unknown numbers of randomly located eavesdroppers, obtaining original expressions which include uncertainty in terms of the location of legitimate nodes relative to eavesdroppers, the number of eavesdroppers, and fading. Under such conditions, we derive the path gain distributions of legitimate and eavesdropper nodes, as well as the corresponding secrecy non-outage. Two interesting conclusions can be drawn from our analysis. The first is that the uncertainty on the number of eavesdropper does not play a significant role in quantifying secrecy outage; and the second is that secret communication at a given rate is possible (albeit subjected to outage), with very low power. Specifically, it is found that the for a given fading figure and network density (which fundamentally determines the secrecy outage) similar secrecy outage is experience by the k-th furthest legitimate node, independent on the source's transmit power.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2013 IEEE 24th International Symposium on; 01/2013
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    ABSTRACT: We propose a new Nakagami phase-envelope fading channel simulator that (i) allows for arbitrary real values of fading parameter, (ii) exactly matches the Nakagami first-order statistics, (iii) and closely matches the second-order statistics classically assigned to Nakagami fading. The proposed simulator is based on a cascade of two existing simulators-the random-mixture simulator and the rank-matching simulator. It combines the strengths of these two simulators, outperforming them both.
    IEEE Transactions on Wireless Communications 01/2013; 12(5):2323-2333. DOI:10.1109/TWC.2013.032113.120978 · 2.76 Impact Factor
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    ABSTRACT: This tutorial offers a comprehensive view of technological solutions and theoretical fundamentals of localization and tracking (LT) systems for wireless networks. We start with a brief classification of the most common types of LT systems, e.g. active versus passive technologies, centralized versus distributed solutions and so forth. To continue, we categorize the LT techniques based on the elementary types of position-related information, namely, connectivity, angle, distance and power-profile. The attention is then turned to the difference between active and passive LT systems, highlighting the evolution of the localization techniques. Motivated by the interests of industry and academia on distance-based active localization system, a deep review of the most common algorithms used in these systems is provided. Non-Bayesian and Bayesian techniques will be tackled and compared with numerical simulations. To list some of the proposed approaches, we mention the multidimensional scaling (MDS), the semidefinite programming (SDP) and the Kalman filter (KF) methods. To conclude the tutorial, we address the fundamental limits of the accuracy of range-based positioning. Based on the unifying framework proposed by Abel, we derive the closed-form expressions for the Cramér–Rao lower bound (CRLB), the Battacharyya Bound (BB), the Hammersley–Chapmann–Robbins Bound (HCRB) and the Abel Hybrid Bound (AHB) in a source localization scenario. We show a comparison of the aforementioned bounds with respect to a Maximum-Likelihood estimator and explore the difference between random and regular (equi-spaced anchors) network topologies. Finally, extensions to cooperative scenarios are also discussed in connection with the concept of information-coupling existing in multitarget networks.
    International Journal of Wireless Information Networks 12/2012; 19(4). DOI:10.1007/s10776-012-0190-4
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    ABSTRACT: In this paper we introduce the concept of algebraic confidence, defined as the measure of belief provided by an algebraic algorithm without a priori information of ranging statistics. This is obtained by employing the Circular-based Interval SMACOF (CIS) algorithm which outputs an algebraic confidence level on targets' estimates, without relying on the propagation of location distributions. We illustrate the validity of our confidence by comparing it to the Fisher error ellipses derived from the Cramér-Rao lower bound (CRLB), corroborating the concept. To exploit the proposed confidence measures during the optimization process, we modify the cost function used in the Circular-based Interval SMACOF (CIS) algorithm and describe how to solve the corresponding optimization problem by means of majorization techniques. The resulting CIS+ algorithm is shown to outperform the CIS algorithm both in terms of accuracy as well as in terms of computational complexity.
    Signals, Systems and Computers (ASILOMAR), 2012 Conference Record of the Forty Sixth Asilomar Conference on; 11/2012
  • Giuseppe Abreu
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    ABSTRACT: We present new lower and upper bounds on the Gaussian Q-function, unified in a single and simple algebraic expression which contains only two exponential terms with a constant and a rational coefficient, respectively. Lower- and upper-bounding properties are obtained from such unified expression by selecting the coefficients accordingly. Despite the remarkable simplicity, the bounds are found to be as tight as multi-term alternatives obtained e.g. from the Exponential [2] and Jensen-Cotes [3] families of bounds. A corollary result is that the n-th integer power of Q(x) can also be tightly bounded both below and above with only n+1 algebraic terms. In addition to offering remarkable accuracy and mathematical tractability combined, the new bounds are very consistent, in which both lower and upper counterparts are similarly tight over the entire domain.
    IEEE Transactions on Communications 09/2012; 60(9):2415-2420. DOI:10.1109/TCOMM.2012.080612.110075 · 1.98 Impact Factor

Publication Stats

385 Citations
44.97 Total Impact Points


  • 2011–2014
    • Jacobs University
      • SES - School of Engineering & Science
      Bremen, Bremen, Germany
  • 2006–2012
    • University of Oulu
      • • Department of Electrical and Information Engineering
      • • Centre for Wireless Communications (CWC)
      Uleoborg, Northern Ostrobothnia, Finland
  • 2000–2008
    • Yokohama National University
      • • Department of Physics, Electrical and Computer Engineering
      • • Graduate School of Engineering
      Yokohama-shi, Kanagawa-ken, Japan