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  • 1. Abourraja, Mohamed Nezar
    et al.
    Oudani, Mustapha
    Samiri, Mohamed Yassine
    Boudebous, Dalila
    El Fazziki, Abdelaziz
    Najib, Mehdi
    Bouain, Abdelhadi
    Rouky, Naoufal
    A multi-agent based simulation model for rail–rail transshipment: An engineering approach for gantry crane scheduling2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 13142-13156Article in journal (Refereed)
    Abstract [en]

    Le Havre Port Authority is putting into service a multimodal hub terminal with massified hinterland links (trains and barges) in order to restrict the intensive use of roads, to achieve a more attractive massification share of hinterland transportation and to provide a river connection to its maritime terminals that do not currently have one. This paper focuses on the rail-rail transshipment yard of this new terminal. In the current organizational policy, this yard is divided into two equal operating areas, and, in each one, a crane is placed, and it is equipped with reach stackers to enable container moves across both operating areas. However, this policy causes poor scheduling of crane moves, because it gives rise to many crane interference situations. For the sake of minimizing the occurrence of these undesirable situations, this paper proposes a multi-agent simulation model including an improved strategy for crane scheduling. This strategy is inspired by the ant colony approach and it is governed by a new configuration for the rail yard's working area that eliminates the use of reach stackers. The proposed simulation model is based on two planner agents, to each of which a time-horizon planning is assigned. The simulation results show that the model developed here is very successful in significantly reducing unproductive times and moves (undesirable situations), and it outperforms other existing simulation models based on the current organizational policy.

  • 2.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Ghafoor, Mubeen
    COMSATS University Islamabad, Pakistan.
    Tariq, Syed Ali
    COMSATS University Islamabad, Pakistan.
    Hassan, Ali
    COMSATS University Islamabad, Pakistan.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Computationally Efficient Light Field Image Compression Using a Multiview HEVC Framework2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 143002-143014Article in journal (Refereed)
    Abstract [en]

    The acquisition of the spatial and angular information of a scene using light eld (LF) technologies supplement a wide range of post-processing applications, such as scene reconstruction, refocusing, virtual view synthesis, and so forth. The additional angular information possessed by LF data increases the size of the overall data captured while offering the same spatial resolution. The main contributor to the size of captured data (i.e., angular information) contains a high correlation that is exploited by state-of-the-art video encoders by treating the LF as a pseudo video sequence (PVS). The interpretation of LF as a single PVS restricts the encoding scheme to only utilize a single-dimensional angular correlation present in the LF data. In this paper, we present an LF compression framework that efciently exploits the spatial and angular correlation using a multiview extension of high-efciency video coding (MV-HEVC). The input LF views are converted into multiple PVSs and are organized hierarchically. The rate-allocation scheme takes into account the assigned organization of frames and distributes quality/bits among them accordingly. Subsequently, the reference picture selection scheme prioritizes the reference frames based on the assigned quality. The proposed compression scheme is evaluated by following the common test conditions set by JPEG Pleno. The proposed scheme performs 0.75 dB better compared to state-of-the-art compression schemes and 2.5 dB better compared to the x265-based JPEG Pleno anchor scheme. Moreover, an optimized motionsearch scheme is proposed in the framework that reduces the computational complexity (in terms of the sum of absolute difference [SAD] computations) of motion estimation by up to 87% with a negligible loss in visual quality (approximately 0.05 dB).

  • 3.
    Ahmed, Bestoun S.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Bures, Miroslav
    Czech Technical University in Prague, Prague.
    Frajtak, Karel
    Czech Technical University in Prague, Prague.
    Cerny, Tomas
    Baylor University, Waco.
    Aspects of Quality in Internet of Things (IoT) Solutions: A Systematic Mapping Study2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 13758-13780Article in journal (Refereed)
    Abstract [en]

    Internet of Things (IoT) is an emerging technology that has the promising power to change our future. Due to the market pressure, IoT systems may be released without sufficient testing. However, it is no longer acceptable to release IoT systems to the market without assuring the quality. As in the case of new technologies, the quality assurance process is a challenging task. This paper shows the results of the first comprehensive and systematic mapping study to structure and categories the research evidence in the literature starting in 2009 when the early publication of IoT papers for IoT quality assurance appeared. The conducted research is based on the most recent guidelines on how to perform systematic mapping studies. A set of research questions is defined carefully regarding the quality aspects of the IoT. Based on these questions, a large number of evidence and research papers is considered in the study (478 papers). We have extracted and analyzed different levels of information from those considered papers. Also, we have classified the topics addressed in those papers into categories based on the quality aspects. The study results carry out different areas that require more work and investigation in the context of IoT quality assurance. The results of the study can help in a further understanding of the research gaps. Moreover, the results show a roadmap for future research directions.

  • 4.
    Ahmed, Bestoun
    et al.
    Czech Technical University, Czech Republic.
    Zamli, Kamal
    University Malaysia Pahang, Gambang, Malaysia..
    Afzal, Wasif
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Bures, Miroslav
    Czech Technical University, Czech Republic.
    Constrained Interaction Testing: A Systematic Literature Study2017In: IEEE Access, E-ISSN 2169-3536, IEEE Access, ISSN 2169-3536, Vol. PP, no 99Article, book review (Other academic)
    Abstract [en]

    Interaction testing can be used to effectively detect faults that are otherwise difficult to find by other testing techniques. However, in practice, the input configurations of software systems are subjected to constraints, especially in the case of highly configurable systems. Handling constraints effectively and efficiently in combinatorial interaction testing is a challenging problem. Nevertheless, researchers have attacked this challenge through different techniques, and much progress has been achieved in the past decade. Thus, it is useful to reflect on the current achievements and shortcomings and to identify potential areas of improvements. This paper presents the first comprehensive and systematic literature study to structure and categorize the research contributions for constrained interaction testing. Following the guidelines of conducting a literature study, the relevant data is extracted from a set of 103 research papers belonging to constrained interaction testing. The topics addressed in constrained interaction testing research are classified into four categories of constraint test generation, application, generation & application and model validation studies. The papers within each of these categories are extensively reviewed. Apart from answering several other research questions, this study also discusses the applications of constrained interaction testing in several domains such as software product lines, fault detection & characterization, test selection, security and GUI testing. The study ends with a discussion of limitations, challenges and future work in the area.

  • 5.
    Almas, Muhammad Shoaib
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. Statnett.
    A Hybrid Synchrophasor and GOOSE-Based Power System Synchronization Scheme2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 4659-4668Article in journal (Refereed)
    Abstract [en]

    The design and real-time hardware-in-the-loop implementation of a hybrid synchrophasors and GOOSE-based automatic synchronization algorithm are presented in this paper. Automatic synchronization is performed by utilizing the synchrophasor measurements from two commercial phasor measurement units (PMUs), while the coordinated control commands to automatic voltage regulator and/or turbine governor control and trip command to the circuit breaker are issued using IEC 61850-8-1 GOOSE messages. The algorithm is deployed inside the PMU using the protection logic equations, and direct communication between the PMUs is established to minimize the communication latencies. In addition, the algorithm is tested using a standard protection relay test-set, and automatic test sequences are executed to validate its performance. It is concluded that the hybrid synchrophasor and GOOSE-based automatic synchronization scheme ensures minimum communication latencies, reduces equipment cost, facilitates interoperability, and performs automatic reconnection adequately.

  • 6.
    Alonso-Fernandez, Fernando
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Farrugia, Reuben A.
    University of Malta, Msida, Malta.
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Fierrez, Julian
    Universidad Autonoma de Madrid, Madrid, Spain.
    Gonzalez-Sosa, Ester
    Nokia Bell-Labs, Madrid, Spain.
    A Survey of Super-Resolution in Iris Biometrics with Evaluation of Dictionary-Learning2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 6519-6544Article in journal (Refereed)
    Abstract [en]

    The lack of resolution has a negative impact on the performance of image-based biometrics. While many generic super-resolution methods have been proposed to restore low-resolution images, they usually aim to enhance their visual appearance. However, an overall visual enhancement of biometric images does not necessarily correlate with a better recognition performance. Reconstruction approaches need thus to incorporate specific information from the target biometric modality to effectively improve recognition performance. This paper presents a comprehensive survey of iris super-resolution approaches proposed in the literature. We have also adapted an Eigen-patches reconstruction method based on PCA Eigentransformation of local image patches. The structure of the iris is exploited by building a patch-position dependent dictionary. In addition, image patches are restored separately, having their own reconstruction weights. This allows the solution to be locally optimized, helping to preserve local information. To evaluate the algorithm, we degraded high-resolution images from the CASIA Interval V3 database. Different restorations were considered, with 15 × 15 pixels being the smallest resolution evaluated. To the best of our knowledge, this is among the smallest resolutions employed in the literature. The experimental framework is complemented with six publicly available iris comparators, which were used to carry out biometric verification and identification experiments. Experimental results show that the proposed method significantly outperforms both bilinear and bicubic interpolation at very low-resolution. The performance of a number of comparators attain an impressive Equal Error Rate as low as 5%, and a Top-1 accuracy of 77-84% when considering iris images of only 15 × 15 pixels. These results clearly demonstrate the benefit of using trained super-resolution techniques to improve the quality of iris images prior to matching. © 2018, Emerald Publishing Limited.

  • 7.
    Ansari, Rafay Iqbal
    et al.
    Frederick University, Nicosia, Cyprus.
    Pervaiz, Haris
    Lancaster University, UK.
    Chrysostomou, Chrysostomos
    Frederick University, Nicosia, Cyprus.
    Hassan, Syed Ali
    National University of Sciences and Technology (NUST), Pakistan.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Control-Data Separation Architecture for Dual-Band mmWave Networks: A New Dimension to Spectrum Management2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 34925-34937, article id 8663278Article in journal (Refereed)
    Abstract [en]

    The exponential growth in global mobile data traffic, especially with regards to the massive deployment of devices envisioned for the fifth generation (5G) mobile networks, has given impetus to exploring new spectrum opportunities to support the new traffic demands. The millimeter wave (mmWave) frequency band is considered as a potential candidate for alleviating the spectrum scarcity. Moreover, the concept of multi-tier networks has gained popularity, especially for dense network environments. In this article, we deviate from the conventional multi-tier networks and employ the concept of control-data separation architecture (CDSA), which comprises of a control base station (CBS) overlaying the data base station (DBS). We assume that the CBS operates on the sub-6 GHz single band, while the DBS possesses a dual-band mmWave capability, i.e., 26 GHz unlicensed band and 60 GHz licensed band. We formulate a multi-objective optimization (MOO) problem, which jointly optimizes conflicting objectives: the spectral efficiency (SE) and the energy efficiency (EE). The unique aspect of this work includes the analysis of a joint radio resource allocation algorithm based on Lagrangian Dual Decomposition (LDD) and we compare the proposed algorithm with the maximal-rate (maxRx), dynamic sub-carrier allocation (DSA) and joint power and rate adaptation (JPRA) algorithms to show the performance gains achieved by the proposed algorithm.

  • 8.
    Arfaoui, Ghada
    et al.
    Orange, France.
    Bisson, Pascal
    Thales, France.
    Blom, Rolf
    RISE - Research Institutes of Sweden, ICT, SICS.
    Borgaonkar, Ravishankar
    University of Oxford, UK.
    Englund, Håkan
    Ericsson AB, Sweden.
    Felix, Edith
    Thales, France.
    Klaedtke, Felix
    NEC Labs Europe, Germany.
    Nakarmi, Prajwol K.
    Ericsson AB, Sweden.
    Naslund, Mats
    Ericsson AB, Sweden.
    O'Hanlon, Piers
    University of Oxford, UK.
    Papay, Juri
    IT Innovation Centre, UK.
    Suomalainen, Jani
    VTT Technical Research Centre of Finland, Finland.
    Surridge, Mike
    IT Innovation Centre, UK.
    Wary, Jean-Philippe
    Orange, France.
    Zahariev, Alexander
    Nixu Corporation, Finland.
    A Security Architecture for 5G Networks2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, no 17, p. 22466-22479Article in journal (Refereed)
    Abstract [en]

    5G networks will provide opportunities for the creation of new services, for new business models, and for new players to enter the mobile market. The networks will support efficient and cost-effective launch of a multitude of services, tailored for different vertical markets having varying service and security requirements, and involving a large number of actors. Key technology concepts are network slicing and network softwarisation, including network function virtualisation and software-defined networking. The presented security architecture builds upon concepts from the 3G and 4G security architectures but extends and enhances them to cover the new 5G environment. It comprises a toolbox for security relevant modelling of the systems, a set of security design principles, and a set of security functions and mechanisms to implement the security controls needed to achieve stated security objectives. In a smart city use case setting, we illustrate its utility; we examine the high-level security aspects stemming from the deployment of large numbers of IoT devices and network softwarisation.

  • 9.
    Arfaoul, Ghada
    et al.
    Orange Labs, F-75015 Paris, France..
    Bisson, Pascal
    Thales, F-45400 Fleury Les Aubrais, France..
    Blom, Rolf
    RISE SICS, Secur Lab, S-16480 Stockholm, Sweden..
    Borgaonkar, Ravishankar
    Univ Oxford, Dept Comp Sci, Oxford OX1 2JD, England..
    Englund, Hakan
    Ericsson AB, Ericsson Res, S-16480 Stockholm, Sweden..
    Felix, Edith
    Thales, F-45400 Fleury Les Aubrais, France..
    Klaedtke, Felix
    NEC Labs Europe, D-69115 Heidelberg, Germany..
    Nakarmi, Prajwol Kumar
    Ericsson AB, Ericsson Res, S-16480 Stockholm, Sweden..
    Näslund, Mats
    KTH.
    O'Hanlon, Piers
    Univ Oxford, Dept Comp Sci, Oxford OX1 2JD, England..
    Papay, Juri
    Univ Southampton, IT Innovat Ctr, Southampton SO16 7NS, Hants, England..
    Suomalainen, Jani
    VTT Tech Res Ctr Finland, Espoo 02044, Finland..
    Surridge, Mike
    Univ Southampton, IT Innovat Ctr, Southampton SO16 7NS, Hants, England..
    Wary, Jean-Philippe
    Orange Labs, F-75015 Paris, France..
    Zahariev, Alexander
    Nixu Corp, Espoo 02150, Finland..
    A Security Architecture for 5G Networks2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 22466-22479Article in journal (Refereed)
    Abstract [en]

    5G networks will provide opportunities for the creation of new services, for new business models, and for new players to enter the mobile market. The networks will support efficient and cost-effective launch of a multitude of services, tailored for different vertical markets having varying service and security requirements, and involving a large number of actors. Key technology concepts are network slicing and network softwarization, including network function virtualization and software-defined networking. The presented security architecture builds upon concepts from the 3G and 4G security architectures but extends and enhances them to cover the new 5G environment. It comprises a toolbox for security relevant modeling of the systems, a set of security design principles, and a set of security functions and mechanisms to implement the security controls needed to achieve stated security objectives. In a smart city use case setting, we illustrate its utility; we examine the high-level security aspects stemming from the deployment of a large number of IoT devices and network softwarization.

  • 10. Asan, Noor Badariah
    et al.
    Hassan, Emadeldeen
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Perez, Mauricio David
    Shah, Syaiful Redzwan Mohd
    Velander, Jacob
    Blokhuis, Taco J.
    Voigt, Thiemo
    Augustine, Robin
    Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 89886-89900Article in journal (Refereed)
    Abstract [en]

    The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.

  • 11.
    Asan, Noor Badariah
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Univ Tekn Malaysia Melaka, Fac Elect & Comp Engn, Durian Tunggal 76100, Malaysia.
    Hassan, Emadeldeen
    Umea Univ, Dept Comp Sci, S-90187 Umea, Sweden;Menoufia Univ, Dept Elect & Elect Commun, Menoufia 32952, Egypt.
    Perez, Mauricio David
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Shah, Syaiful Redzwan Mohd
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Velander, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Blokhuis, Taco J.
    Maastricht Univ, Dept Surg, Med Ctr, NL-6229 HX Maastricht, Netherlands.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. ¨.
    Augustine, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 89886-89900Article in journal (Refereed)
    Abstract [en]

    The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.

  • 12.
    Asl, Reza Mohammadi
    et al.
    Laboratory of Intelligent Machines, Department of Mechanical Engineering, LUT University, Lappeenranta, Finland.
    Hagh, Yashar Shabbouei
    Laboratory of Intelligent Machines, Department of Mechanical Engineering, LUT University, Lappeenranta, Finland.
    Palm, Rainer
    Örebro University, School of Science and Technology.
    Handroos, Heikki
    Laboratory of Intelligent Machines, Department of Mechanical Engineering, LUT University, Lappeenranta, Finland.
    Integral Non-Singular Terminal Sliding Mode Controller for nth-Order Nonlinear Systems2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 102792-102802Article in journal (Refereed)
    Abstract [en]

    In this study, a new integral non-singular terminal sliding mode control method for nonlinear systems is introduced. The proposed controller is designed by defining a new sliding surface with an additional integral part. This new manifold is first introduced into the second-order system and then expanded to nth-order systems. The stability of the control system is demonstrated for both second-order and nth-order systems by using the Lyapunov stability theory. The proposed controller is applied to a robotic manipulator as a case study for second-order systems, and a servo-hydraulic system as a case study for third-order systems. The results are presented and discussed.

  • 13.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Attitudes and Perceptions of IoT Security in Critical Societal Services2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 2130-2138Article in journal (Refereed)
    Abstract [en]

    A quiet revolution that impacts several sectors, ranging over transport, home automation, energy, industrial control, and health services is undergoing with addition of new networked devices leading to enhanced services. In this paper, we aim to identify information security requirements that are common over several (vertical) sectors, and in particular, ones that impact critical societal services, namely, the energy, water, and health management systems. We present the results of an interview-based study where actors in these sectors were asked about their perceptions and attitudes on the security of Internet of Things (IoT). We set these perceptions and attitudes in context through a literature review of IoT security, and relate to current challenges in this area. This paper demonstrates that despite an overall optimistic view on IoT in critical societal services, there is a lack of consensus on risks related to IoT security.

  • 14.
    Aurangzeb, Khursheed
    et al.
    King Saud Univ, Riyadh, Saudi Arabia; COMSATS Inst Informat Technol, Attack, Pakistan.
    Alhussein, Musaed
    King Saud Univ, Riyadh, Saudi Arabia.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Analysis of Binary Image Coding Methods for Outdoor Applications of Wireless Vision sensor Networks2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 16932-16941Article in journal (Refereed)
    Abstract [en]

    The processing of images at the vision sensor nodes (VSN) requires a high computation power and their transmission requires a large communication bandwidth. The energy budget is limited in outdoor applications of wireless vision sensor networks (WVSN). This means that both the processing of images at the VSN and the communication to server must be energy efficient. The wireless communication of uncompressed data consumes huge amounts of energy. Data compression methods are efficient in reducing data in images and can be used for the reduction in transmission energy. We have evaluated seven binary image coding techniques. Our evaluation is based on the processing complexity and energy consumption of the compression methods on the embedded platforms. The focus is to come up with a binary image coding method, which has good compression efficiency and short processing time. An image coding method with such attributes will result in reduced total energy requirement of the node. We have used both statistically generated images and real captured images, in our experiments. Based on our results, we conclude that International Telegraph and Telephone Consultative Committee Group 4, gzip_pack and JPEG-LS are suitable coding methods for the outdoor applications of WVSNs.

  • 15.
    Aurangzeb, Khursheed
    et al.
    Computer Engineering Department, College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia.
    Alhussein, Musaed
    Computer Engineering Department, College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Data Reduction Using Change Coding for Remote Applications of wireless Visual Sensor Networks2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 37738-37747Article in journal (Refereed)
    Abstract [en]

    The data reduction capability of image compression schemes is limited by the underlying compression technique. For applications with minor changes between consecutive frames, change coding can be used to further reduce the data. We explored the efficiency of change coding for data reduction in a wireless visual sensor network (WVSN). This paper presents an analysis of the compression efficiency of change coding for a variety of changes, such as different shapes, sizes, and locations of white objects in adjacent sets of frames. Compressing change frame provides a better performance compared with compressing the original frames for up to 95% changes in the number of objects in adjacent frames. Due to illumination noise, the size of the objects increases at its boundaries, which negatively affects the performance of change coding. We experimentally proved that the negative impact of illumination noise could be reduced by applying morphology on the change frame. Communication energy consumption of the VSN is dependent on the data that are transmitted to the server. Our results show that the communication energy consumption of the VSN can be reduced by 27%, 29%, and 46% by applying change coding in combination with JBIG2, Group4, and Gzip_pack, respectively. The findings presented in this paper will aid researchers in enhancing the compression potential of image coding schemes in the energy-constrained applications of WVSNs.

  • 16.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 7394-7404Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyze the probabilistic cooperation of a full-duplex relay in a multiuser random-access network. The relay is equipped with on/off modes for the receiver and the transmitter independently. These modes are modeled as probabilities by which the receiver and the transmitter are activated. We provide analytical expressions for the performance of the relay queue, such as arrival and service rates, stability conditions, and the average queue size. We optimize the relays operation setup to maximize the network-wide throughput while, simultaneously, we keep the relays queue stable and lower the relays receptions and transmissions. Furthermore, we study the effect of the SINR threshold and the self-interference coefficient on the per-user and network-wide throughput. For low SINR threshold, we show under which circumstances it is beneficial to switch off the relay completely, or switch off the relays receiver only.

  • 17.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Life time Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 18927-18940, article id 8045999Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massive machine-type communications (MTC) over cellular networks. This paper is devoted to energy consumption modeling, battery lifetime analysis, lifetime-aware scheduling, and transmit power control for massive MTC over cellular networks. We consider a realistic energy consumption model for MTC and model network battery-lifetime. Analytic expressions are derived to demonstrate the impact of scheduling on both the individual and network battery lifetimes. The derived expressions are subsequently employed in the uplink scheduling and transmit power control for mixed-priority MTC traffic in order to maximize the network lifetime. Besides the main solutions, low complexity solutions with limited feedback requirement are investigated, and the results are extended to existing LIE networks. In addition, the energy efficiency, spectral efficiency, and network lifetime tradeoffs in resource provisioning and scheduling for MTC over cellular networks are investigated. The simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing scheduling schemes.

  • 18.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Lifetime Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massivemachine-type communications (MTC) over cellular networks.This work is devoted to energy consumption modeling,battery lifetime analysis, lifetime-aware scheduling and transmitpower control for massive MTC over cellular networks. Weconsider a realistic energy consumption model for MTC andmodel network battery-lifetime. Analytic expressions are derivedto demonstrate the impact of scheduling on both the individualand network battery lifetimes. The derived expressions aresubsequently employed in uplink scheduling and transmit powercontrol for mixed-priority MTC traffic in order to maximizethe network lifetime. Besides the main solutions, low-complexitysolutions with limited feedback requirement are investigated,and the results are extended to existing LTE networks. Also,the energy efficiency, spectral efficiency, and network lifetimetradeoffs in resource provisioning and scheduling for MTC overcellular networks are investigated. The simulation results showthat the proposed solutions can provide substantial networklifetime improvement and network maintenance cost reductionin comparison with the existing scheduling schemes.

  • 19.
    Baloch, Naveed Khan
    et al.
    Univ Engn & Technol Taxila, Comp Engn Dept, Taxila 47040, Pakistan..
    Baig, Muhammad Iram
    Univ Engn & Technol Taxila, Elect Engn Dept, Taxila 47040, Pakistan..
    Daneshtalab, Masoud
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Defender: A Low Overhead and Efficient Fault-Tolerant Mechanism for Reliable on-Chip Router2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 142843-142854Article in journal (Refereed)
    Abstract [en]

    The ever-shrinking size of a transistor has made Network on Chip (NoC) susceptible to faults. A single error in the NoC can disrupt the entire communication. In this paper, we introduce Defender, a fault-tolerant router architecture, that is capable of tolerating permanent faults in all the parts of the router. We intend to employ structural modifications in baseline router design to achieve fault tolerance. In Defender we provide the fault tolerance to the input ports and routing computation unit by grouping the neighboring ports together. Default winner strategy is used to provide fault resilience to the virtual channel arbiters and switch allocators. Multiple routes are provided to the crossbar to tolerate the faults. Defender provides improved fault tolerance to all stages of routers as compared to the currently prevailing fault tolerant router architectures. Reliability analysis using silicon protection factor (SPF) and Mean Time to Failure (MTTF) metrics confirms that our proposed design Defender is 10.78 times more reliable than baseline unprotected router and then the current state of the art architectures.

  • 20.
    Bo, Lin
    et al.
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Xu, Guanji
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Liu, Xiaofeng
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Bearing Fault Diagnosis Based on Subband Time-Frequency Texture Tensor2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 37611-37619Article in journal (Refereed)
    Abstract [en]

    The texture feature tensor established from a subband time–frequency image (TFI) was extracted and used to identify the fault states of a rolling bearing. The TFI of adaptive optimal-kernel distribution was optimally partitioned into TFI blocks based on the minimum frequency band entropy. The texture features were extracted from the co-occurrence matrix of each TFI block. Based on the order of the segmented frequency bands, the texture feature tensor was constructed using the multidimensional feature vectors from all the blocks; this preserved the inherent characteristic of the TFI structure and avoided the information loss caused by vectorizing multidimensional features. The linear support higher order tensor machine based on the feature tensor was applied to identify the fault states of the rolling bearing.

  • 21.
    Bogodorova, Tetiana
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Vanfretti, Luigi
    Model Structure Choice for a Static VAR Compensator Under Modeling Uncertainty and Incomplete Information2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, article id UNSP 22657Article in journal (Refereed)
    Abstract [en]

    To simulate the complex behavior of power systems, operators frequently rely on models. The task of model identification and validation becomes important in this context. The validity of the models has a direct influence on operator's decisions and actions. In other words, erroneous or imprecise models lead to erroneous predictions of the systems' behavior which may result in unwanted operator's actions. This paper addresses the challenge of model structure choice for modeling and parameter identification in power systems. Three types of model structures are analyzed: 1) physical principle-based modeling; 2) black-box modeling (NARX, transfer function, Hammerstein Wiener model); and 3) combination of physical and black-box modeling. This analysis has been performed using real grid measurements and available knowledge about a static VAR compensator (SVC) connected to the U.K.'s transmission network and operated by National Grid. The SVC's modeling is presented in the context of a generalized modeling and identification algorithm, that is offered as a guideline for engineers. The model validity issues of the identified SVC models that include modeling uncertainty are discussed.

  • 22.
    Bogodorova, Tetiana
    et al.
    KTH.
    Vanfretti, Luigi
    Peric, Vedran S.
    Turitsyn, Konstantin
    Identifying Uncertainty Distributions and Confidence Regions of Power Plant Parameters2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5Article in journal (Refereed)
    Abstract [en]

    Power system operators, when obtaining a model's parameter estimates; require additional information to guide their decision on a model's acceptance. This information has to establish a relationship between the estimates and the chosen model in the parameter space. For this purpose, this paper proposes to extend the usage of the particle filter (PF) as a method for the identification of power plant parameters; and the parameters' confidence intervals, using measurements. Taking into consideration that the PF is based on the Bayesian filtering concept, the results returned by the filter contain more information about the model and its parameters than usually considered by power system operators. In this paper the samples from the multi-modal posterior distribution of the estimate are used to identify the distribution shape and associated confidence intervals of estimated parameters. Three methods [rule of thumb, least-squares cross validation, plug-in method (HSJM)] for standard deviation (bandwidth) selection of the Gaussian mixture distribution are compared with the uni-modal Gaussian distribution of the parameter estimate. The applicability of the proposed method is demonstrated using field measurements and synthetic data from simulations of a Greek power plant model. The distributions are observed for different system operation conditions that consider different types of noise. The method's applicability for model validation is also discussed.

  • 23.
    Bokde, Neeraj Dhanraj
    et al.
    Department of Electronics and Communication Engineering, Visvesvaraya National Institute of Technology, Nagpur, India. Department of Engineering-Renewable Energy and Thermodynamics, Aarhus University, Denmark..
    Feijóo, Andrés
    Departamento de Enxeñería Eléctrica-Universidade de Vigo, Campus de Lagoas-Marcosende, Vigo, Spain..
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Yaseen, Zaher Mundher
    Sustainable Developments in Civil Engineering Research Group, Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam..
    A comparison between reconstruction methods for generation of synthetic time series applied to wind speed simulation2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 1353096-135398Article in journal (Refereed)
    Abstract [en]

    Wind energy is an attractive renewable sources and its prediction is highly essential for multiple applications. Over the literature, there are several studies have been focused on the related researches of synthetic wind speed data generation. In this research, two reconstruction methods are developed for synthetic wind speed time series generation. The modeling is constructed based on different processes including independent values generation from the known probability distribution function, rearrangement of random values and segmentation. They have been named as Rank-wise and Step-wise reconstruction methods. The proposed methods are explained with the help of a standard time series and the examination on wind speed time series collected from Galicia, the autonomous region in the northwest of Spain. Results evidenced the potential of the developed models over the state-of-the-art synthetic time series generation methods and demonstrated a successful validation using the means of mean and median wind speed values, autocorrelations, probability distribution parameters with their corresponding histograms and confusion matrix. Pros and cons of both methods are discussed comprehensively.

  • 24. Bonetto, Riccardo
    et al.
    Rossi, Michele
    Tomasin, Stefano
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Joint Optimal Pricing and Electrical Efficiency Enforcement for Rational Agents in Microgrids2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 19782-19798Article in journal (Refereed)
    Abstract [en]

    In electrical distribution grids, the constantly increasing number of power generation devices based on renewables demands a transition from a centralized to a distributed generation paradigm. In fact, power injection from distributed energy resources (DERs) can be selectively controlled to achieve other objectives beyond supporting loads, such as the minimization of the power losses along the distribution lines and the subsequent increase of the grid hosting capacity. However, these technical achievements are only possible if alongside electrical optimization schemes, a suitable market model is set up to promote cooperation from the end users. In contrast with the existing literature, where energy trading and electrical optimization of the grid are often treated separately, or the trading strategy is tailored to a specific electrical optimization objective, in this paper, we consider their joint optimization. We also allow for a modular approach, where the market model can support any smart grid optimization goal. Specifically, we present a multi-objective optimization problem accounting for energy trading, where: 1) DERs try to maximize their profit, resulting from selling their surplus energy; 2) the loads try to minimize their expense; and 3) the main power supplier aims at maximizing the electrical grid efficiency through a suitable discount policy. This optimization problem is proved to be non-convex, and an equivalent convex formulation is derived. Centralized solutions are discussed and a procedure to distribute the solution is proposed. Numerical results to demonstrate the effectiveness of the so obtained optimal policies are finally presented, showing the proposed model results in economic bene fits for all the users (generators and loads) and in an increased electrical efficiency for the grid.

  • 25.
    Bucaioni, Alessio
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Arcticus Systems AB, Järfälla, Sweden.
    Addazi, Lorenzo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Cicchetti, Antonio
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ciccozzi, Federico
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Eramo, Romina
    University of L’Aquila, L’Aquila, Italy..
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Arcticus Systems AB, Järfälla, Sweden.
    Nolin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    MoVES: a Model-driven methodology for Vehicular Embedded Systems2018In: IEEE Access, E-ISSN 2169-3536, p. 6424-6445Article in journal (Refereed)
    Abstract [en]

    This paper introduces a novel model-driven methodology for the software development of real-time distributed vehicular embedded systems on single- and multi-core platforms. The proposed methodology discloses the opportunity of improving the cost-efficiency of the development process by providing automated support to identify viable design solutions with respect to selected non-functional requirements. To this end, it leverages the interplay of modelling languages for the vehicular domain whose integration is achieved by a suite of model transformations. An instantiation of the methodology is discussed for timing requirements, which are among the most critical ones for vehicular systems. To support the design of temporally correct systems, a cooperation between EAST-ADL and the Rubus Component Model is opportunely built-up by means of model transformations, enabling timing-aware design and model-based timing analysis of the system. The applicability of the methodology is demonstrated as proof of concepts on industrial use cases performed in cooperation with our industrial partners.

  • 26.
    Bucaioni, Alessio
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Arcticus Systems AB.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ciccozzi, Federico
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Cicchetti, Antonio
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sjödin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Metamodel for the Rubus Component Model: Extensions for Timing and Model Transformation from EAST-ADL2017In: IEEE Access, E-ISSN 2169-3536, ISSN 2169-3536, p. 9005-9020Article in journal (Refereed)
    Abstract [en]

    According to the Model-Driven Engineering paradigm, one of the entry requirements when realising a seamless tool chain for the development of software is the definition of metamodels, to regulate the specification of models, and model transformations, for automating manipulations of models. In this context, we present a metamodel definition for the Rubus Component Model, an industrial solution used for the development of vehicular embedded systems. The metamodel includes the definition of structural elements as well as elements for describing timing information. In order to show how, using Model-Driven Engineering, the integration between different modelling levels can be automated, we present a model-to-model transformation between models conforming to EAST-ADL and models described by means of the Rubus Component Model. To validate our solution, we exploit a set of industrial automotive applications to show the applicability of both the Rubus Component Model metamodel and the model transformation.

  • 27.
    Chandhar, Prabhu
    et al.
    Chandhar Res Labs, India.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Massive MIMO for Connectivity With Drones: Case Studies and Future Directions2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 94676-94691Article in journal (Refereed)
    Abstract [en]

    Unmanned aerial vehicles (UAVs), also known as drones, are proliferating. Applications, such as surveillance, disaster management, and drone racing, place high requirements on the communication with the drones in terms of throughput, reliability, and latency. The existing wireless technologies, notably Wi-Fi, that are currently used for drone connectivity are limited to short ranges and low-mobility situations. New, scalable technology is needed to meet future demands on long connectivity ranges, support for fast-moving drones, and the possibility to simultaneously communicate with entire swarms of drones. Massive multiple-input and multiple-output (MIMO), the main technology component of emerging 5G standards, has the potential to meet these requirements.

  • 28.
    Chandhar, Prabhu
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Sekhar Das, Suvra
    Indian Institute Technology, India.
    Multi-Objective Framework for Dynamic Optimization of OFDMA Cellular Systems2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 1889-1914Article in journal (Refereed)
    Abstract [en]

    Green cellular networking has become an important research area in recent years due to environmental and economical concerns. Switching OFF underutilized base stations (BSs) during oFF-peak traffic load conditions is a promising approach to reduce energy consumption in cellular networks. In practice, during initial cell planning, the BS locations and radio access network (RAN) parameters (BS transmit power, antenna height, and antenna tilt) are optimized to meet the basic system design requirements, such as coverage, capacity, overlap, quality of service (QoS), and so on. As these metrics are tightly coupled with each other due to co-channel interference, switching OFF certain BSs may affect the system requirements. Therefore, identifying a subset of large number of BSs, which are to be put into the sleep mode, is a challenging dynamic optimization problem. In this paper, we develop a multi-objective framework for dynamic optimization framework for orthogonal frequency division multiple access-based cellular systems. The objective is to identify the appropriate set of active sectors and RAN parameters that maximize coverage and area spectral efficiency, while minimizing overlap and area power consumption without violating the QoS requirements for a given traffic demand density. The objective functions and constraints are obtained using appropriate analytical models, which capture the traffic characteristics, propagation characteristics (path-loss, shadowing, and small-scale fading), as well as load condition in neighboring cells. A low-complexity evolutionary algorithm is used for identifying the global Pareto optimal solutions at a faster convergence rate. The inter-relationships between the system objectives are studied, and the guidelines are provided to find an appropriate network configuration that provides the best achievable tradeoffs. The results show that using the proposed framework, significant amount of energy saving can be achieved and with a low computational complexity while maintaining good tradeoffs among the other objectives.

  • 29.
    Chen, Bolin
    et al.
    Univ Sheffield, England.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Chen, Zheng
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Jie
    Univ Sheffield, England.
    Throughput and Delay Analysis of LWA With Bursty Traffic and Randomized Flow Splitting2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 24667-24678Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of bursty traffic in a long term evolution (LTE) and Wi-Fi aggregation (LWA)-enabled network. The LTE base station routes packets of the same IP flow through the LIE and Wi-Fi links independently. We motivate the use of superposition coding at the LWA-mode Wi-Fi access point (AP) so that it can serve LWA users and Wi-Fi users simultaneously. A random access protocol is applied in such system, which allows the native-mode AP to access the channel with probabilities that depend on the queue size of the LWA-mode AP to avoid impeding the performance of the LWA-enabled network. We analyze the throughput of the native Wi-Fi network and the delay experienced by the LWA users, accounting for the native-mode AP access probability, the traffic flow splitting between LTE and Wi-Fi, and the operating mode of the LWA user with both LIE and Wi-Fi interfaces. Our results show some fundamental tradeoffs in the throughput and delay behavior of LWA-enabled networks, which provide meaningful insight into the operation of such aggregated systems.

  • 30.
    Chen, Jiayu
    et al.
    Beihang University, Beijing, China.
    Zhou, Dong
    Beihang University, Beijing, China.
    Guo, Ziyue
    Beihang University, Beijing, China.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    LYU, Chuan
    Beihang University, Beijing, China.
    LU, Chen
    Beihang University, Beijing, China.
    An Active Learning Method Based on Uncertainty and Complexity for Gearbox Fault Diagnosis2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 9022-9031Article in journal (Refereed)
    Abstract [en]

    It is crucial to implement an effective and accurate fault diagnosis of a gearbox for mechanical systems. However, being composed of many mechanical parts, a gearbox has a variety of failure modes resulting in the difficulty of accurate fault diagnosis. Moreover, it is easy to obtain raw vibration signals from real gearbox applications, but it requires significant costs to label them, especially for multi-fault modes. These issues challenge the traditional supervised learning methods of fault diagnosis. To solve these problems, we develop an active learning strategy based on uncertainty and complexity. Therefore, a new diagnostic method for a gearbox is proposed based on the present active learning, empirical mode decomposition-singular value decomposition (EMD-SVD) and random forests (RF). First, the EMD-SVD is used to obtain feature vectors from raw signals. Second, the proposed active learning scheme selects the most valuable unlabeled samples, which are then labeled and added to the training data set. Finally, the RF, trained by the new training data, is employed to recognize the fault modes of a gearbox. Two cases are studied based on experimental gearbox fault diagnostic data, and a supervised learning method, as well as other active learning methods, are compared. The results show that the proposed method outperforms the two common types of methods, thus validating its effectiveness and superiority.

  • 31. Chen, Weili
    et al.
    Zheng, Zibin
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zheng, Peilin
    Zhou, Yuren
    Exploiting blockchain data to detect smart Ponzi schemes on Ethereum2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 37575-37586Article in journal (Refereed)
  • 32.
    Chu, Thi My Chinh
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Zepernick, Hans-Juergen
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Optimal Power Allocation for Hybrid Cognitive Cooperative Radio Networks with Imperfect Spectrum Sensing2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 10365-10380Article in journal (Refereed)
    Abstract [en]

    In this paper, two optimal power allocation strategies for hybrid interweave-underlay cognitive cooperative radio networks (CCRNs) are proposed to maximize channel capacity and minimize outage probability. The proposed power allocation strategies are derived for the case of Rayleigh fading taking into account the impact of imperfect spectrum sensing on the performance of the hybrid CCRN. Based on the optimal power allocation strategies, the transmit powers of the secondary transmitter and secondary relay are adapted according to the fading conditions, the interference power constraint imposed by the primary network (PN), the interference from the PN to the hybrid CCRN, and the total transmit power limit of the hybrid CCRN. Numerical results are provided to illustrate the effect of the interference power constraint of the PN, arrival rate of the PN, imperfect spectrum sensing, and the transmit power constraint of the hybrid CCRN on channel capacity and outage probability. Finally, comparisons of the channel capacity and outage probability of underlay, overlay, and hybrid interweaveunderlay CCRNs are presented to show the advantages of the hybrid spectrum access. OAPA

  • 33.
    Chu, Thi My Chinh
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Zepernick, Hans-Juergen
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Performance Optimization for Hybrid Two-Way Cognitive Cooperative Radio Networks with Imperfect Spectrum Sensing2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 70582-70596Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider a two-way cognitive cooperative radio network (TW-CCRN) with hybrid interweaveunderlay spectrum access in the presence of imperfect spectrum sensing. Power allocation strategies are proposed that maximize the sum-rate and minimize the outage probability of the hybrid TW-CCRN. Specifically, based on the state of the primary network (PN), fading conditions, and system parameters, suitable power allocation strategies subject to the interference power constraint of the PN are derived for each transmission scenario of the hybrid TW-CCRN. Given the proposed power allocation strategies, we analyze the sum-rate and outage probability of the hybrid TW-CCRN over Rayleigh fading taking imperfect spectrum sensing into account. Numerical results are presented to illustrate the effect of the arrival rate, interference power threshold, transmit power of the PN, imperfect spectrum sensing, and maximum total transmit power on the sum-rate and outage probability of the hybrid TW-CCRN. OAPA

  • 34.
    Ciccozzi, Federico
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Di Ruscio, Davide
    University of L’Aquila, L’Aquila, Italy.
    Malavolta, Ivano
    Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
    Pelliccione, Patrizio
    Department of Computer Science and Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Adopting MDE for Specifying and Executing Civilian Missions of Mobile Multi-Robot Systems2016In: IEEE Access, E-ISSN 2169-3536, ISSN 21693536, Vol. 4, p. 6451-6466Article in journal (Refereed)
    Abstract [en]

    Robots are meant to replace humans for a broad variety of everyday tasks such as environmental monitoring or patrolling large public areas for security assurance. The main focus of researchers and practitioners thus far has been on providing tailored software and hardware solutions for very specific and often complex tasks. On one hand, these solutions display, in some cases, great potential and provide advanced capabilities for solving the specific task. On the other hand, the polarized attention to task-specific solutions makes them hard to reuse and combined. In this paper we propose a family of domain-specific modeling languages for the specification of civilian missions of mobile multi-robot systems. These missions are meant to be described in terms of models that are (i) closer to the general problem domain, (ii) independent from the underlying technologies, (ii)i ready to be analyzed, simulated, and executed, and (iv) extensible to new application domains, thus opening up the use of robots to even non-technical operators. Moreover, we show the applicability of the proposed family of languages in two real-world application domains: unmanned multicopters and autonomous underwater vehicles.

  • 35.
    Ciccozzi, Federico
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Seceleanu, Tiberiu
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Corcoran, Diarmuid
    Ericsson Software Research.
    Scholle, Detlef
    Alten Sverige AB.
    UML-based Development of Embedded Real-Time Software on Multi-core in Practice: Lessons Learned and Future Perspectives2016In: IEEE Access, E-ISSN 2169-3536, E-ISSN 2169-3536, Vol. 4Article in journal (Refereed)
    Abstract [en]

    Model-Driven Engineering has got a foothold in industry as an effective way to tame the complexity of modern software which is meant to run on embedded systems with real-time constraints by promoting abstraction, in terms of prescriptive models, and automation, in terms of model manipulations. In the plethora of modelling languages, the Unified Modeling Language (UML) has emerged and established itself as a de facto standard in industry, the most widely used architectural description language and an ISO/IEC standard. In the SMARTCore project we have provided solutions for UML-based development of software to run on multicore embedded real-time systems with the specific focus of automating the generation of executable code and the optimization of task allocation based on a unique combination of model-based and execution-based mechanisms. In this paper we describe the lessons learned in the research work carried out within SMARTCore and provide a set of perspectives that we consider to be highly relevant for the forthcoming future of this research area to enable a wider adoption of UML-based development in industry in general, and in the multicore embedded real-time domain in particular.

  • 36.
    Dai, Wenbai
    et al.
    Department of Automation, Shanghai Jiao Tong University, Shanghai, China.
    Wang, Peng
    Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang, China.
    Sun, Weiqi
    Department of Automation, Shanghai Jiao Tong University, Shanghai, China.
    Wu, Xian
    Department of Automation, Shanghai Jiao Tong University, Shanghai, China.
    Zhang, Hualiang
    Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang, China.
    Vyatkin, Valeriy
    Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland.
    Yang, Genke
    Department of Automation, Shanghai Jiao Tong University, Shanghai, China.
    Semantic Integration of Plug-and-Play Software Components for Industrial Edges Based on Microservices2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 125882-125892Article in journal (Refereed)
    Abstract [en]

    The industrial cyber-physical system enables collaboration between distributed nodes across industrial clouds and edge devices. Flexibility and interoperability could be enhanced significantly by introducing the service-oriented architecture to industrial edge devices. From the industrial edge computing perspective, software components shall be dynamically composed across heterogeneous edge devices to perform various functionalities. In this paper, a knowledge-driven Microservice-based architecture to enable plug-and-play software components is proposed for industrial edges. These software components can be dynamically configured based on the orchestration of microservices with the support of the knowledge base and the reasoning process. These semantically enhanced plug-and-play microservices could provide rapid online reconfiguration without any programming efforts. The use of the plug-and-play software components is demonstrated by an assembly line example.

  • 37. De Alcantara Dias, Bruno Martin
    et al.
    Maria Lagana, Armando Antonio
    Justo, Joao Francisco
    Yoshioka, Leopoldo Rideki
    Dias Santos, Max Mauro
    Gu, Zonghua
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Model-based development of an engine control module for a spark ignition engine2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 53638-53649Article in journal (Refereed)
    Abstract [en]

    A Spark ignition (SI) engine is a complex, multi-domain component of the vehicle powertrain system. The engine control module (ECM) for an SI engine must achieve both high performance and good fuel efficiency. In this paper, we present a model-based development methodology for an open architecture ECM, addressing the entire development lifecycle including a control algorithm design, parameter calibration, hardware/software implementation, and verification/validation of the final system, both with bench tests on a dynamometer and in a real vehicle on the road. The ECM is able to achieve similar performance as the original proprietary ECM provided by the original equipment manufacturer. Its flexible and modular design enables easy extensibility with new control algorithms, and development of new engine types.

  • 38.
    De Donno, Michele
    et al.
    DTU Compute, Technical University of Denmark, Kongens Lyngby, Denmark.
    Tange, Koen
    DTU Compute, Technical University of Denmark, Kongens Lyngby, Denmark.
    Dragoni, Nicola
    Örebro University, School of Science and Technology. DTU Compute, Technical University of Denmark, Kongens Lyngby, Denmark.
    Foundations and Evolution of Modern Computing Paradigms: Cloud, IoT, Edge, and Fog2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 150936-150948Article in journal (Refereed)
    Abstract [en]

    In the last few years, Internet of Things, Cloud computing, Edge computing, and Fog computing have gained a lot of attention in both industry and academia. However, a clear and neat definition of these computing paradigms and their correlation is hard to find in the literature. This makes it difficult for researchers new to this area to get a concrete picture of these paradigms. This work tackles this deficiency, representing a helpful resource for those who will start next. First, we show the evolution of modern computing paradigms and related research interest. Then, we address each paradigm, neatly delineating its key points and its relation with the others. Thereafter, we extensively address Fog computing, remarking its outstanding role as the glue between IoT, Cloud, and Edge computing. In the end, we briefly present open challenges and future research directions for IoT, Cloud, Edge, and Fog computing.

  • 39.
    Della Penda, Demia
    et al.
    Ericsson AB, S-16480 Kista, Sweden..
    Abrardo, Andrea
    Univ Siena, Dept Informat Engn, I-53100 Siena, Italy.;Consorzio Nazl Interuniv Telecomunicaz, I-43124 Parma, Italy..
    Moretti, Marco
    Consorzio Nazl Interuniv Telecomunicaz, I-43124 Parma, Italy.;Univ Pisa, Dept Informat Engn, I-56122 Pisa, Italy..
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Distributed Channel Allocation for D2D-Enabled 5G Networks Using Potential Games2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 11195-11208Article in journal (Refereed)
    Abstract [en]

    Frequency channel allocation is a key technique for improving the performance of cellular networks. In this paper, we address the channel allocation problem for a 5G multi-cell system. We consider a heterogeneous network in which cellular users, micro-cell users, and device-to-device (D2D) communications coexist within the radio footprint of the macro cell. We maximize the aggregate transmission rate, exploiting channel diversity and managing both the inter-cell interference, typical of cellular networks and the intra-cell interference generated by the nonorthogonal transmissions of the small-cell and D2D users. By modeling the allocation problem as a potential game, whose Nash equilibria correspond to the local optima of the objective function, we propose a new decentralized solution. The convergence of our scheme is enforced by using a better response dynamic based on a message passing approach. The simulation results assess the validity of the proposed scheme in terms of convergence time and achievable rate under different settings.

  • 40.
    Deng, Shuiguang
    et al.
    Zhejiang University, China..
    Xiang, Zhengzhe
    Zhejiang University, China..
    Yin, Jianwei
    Zhejiang University, China..
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zomaya, Albert Y.
    University of Sydney, Australia..
    Composition-Driven IoT Service Provisioning in Distributed Edges2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 54258-54269Article in journal (Refereed)
    Abstract [en]

    The increasing number of Internet of Thing (IoT) devices and services makes it convenient for people to sense the real world and makes optimal decisions or complete complex tasks with them. However, the latency brought by unstable wireless networks and computation failures caused by constrained resources limit the development of IoT. A popular approach to solve this problem is to establish an IoT service provision system based on a mobile edge computing (MEC) model. In the MEC model, plenty of edge servers are placed with access points via wireless networks. With the help of cached services on edge servers, the latency can be reduced, and the computation can be offloaded. The cache services must be carefully selected so that many requests can by satisfied without overloading resources in edge servers. This paper proposes an optimized service cache policy by taking advantage of the composability of services to improve the performance of service provision systems. We conduct a series of experiments to evaluate the performance of our approach. The result shows that our approach can improve the average response time of these IoT services.

  • 41.
    Dong, Pingping
    et al.
    Hunnan Provincial Key Laboratory of Intelligent Computing and Language Information Processing, Hunan Normal University, Changsha, China.
    Xie, Jingyun
    Hunnan Provincial Key Laboratory of Intelligent Computing and Language Information Processing, Hunan Normal University, Changsha, China.
    Tang, Wensheng
    Hunnan Provincial Key Laboratory of Intelligent Computing and Language Information Processing, Hunan Normal University, Changsha, China.
    Xiong, Naixue
    College of Intelligence and Computing, Tianjin University, Tianjin, 300350, China.
    Zhong, Hua
    Hunnan Provincial Key Laboratory of Intelligent Computing and Language Information Processing, Hunan Normal University, Changsha, China.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Performance Evaluation of Multipath TCP Scheduling Algorithms2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 29818-29825Article in journal (Refereed)
    Abstract [en]

    One of the goals of 5G is to provide enhanced mobile broadband and enable low latency in some use cases. To achieve this aim, the Internet Engineering Task Force (IETF) has proposed the Multipath TCP (MPTCP) by utilizing the feature of dual connectivity in 5G, where a 5G device can be served by two different base stations. However, the path heterogeneity between the 5G device to the server may cause packet out-of-order problem. The researchers proposed a number of scheduling algorithms to tackle this issue. This paper introduces the existing algorithms, and with the aim to make a thorough comparison between the existing scheduling algorithms and provide guidelines for designing new scheduling algorithms in 5G, we have conducted an extensive set of emulation studies based on the real Linux experimental platform. The evaluation covers a wide range of network scenarios to investigate the impact of different network metrics, namely, RTT, buffer size and file size on the performance of existing widely-deployed scheduling algorithms.

  • 42.
    Fan, Ye
    et al.
    Department of Information and Communication Engineering, Xi’an Jiaotong University, Xi’an, China.
    Liao, Xuewen
    Department of Information and Communication Engineering, Xi’an Jiaotong University, Xi’an, China.
    Vasilakos, Athanasios V.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Physical Layer Security Based on Interference Alignment in K-User MIMO Y Wiretap Channels2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 5747-5759Article in journal (Refereed)
    Abstract [en]

    This paper studies the secure degree of freedom (SDOF) of the multiway relay wiretap system K -user MIMO Y wiretap channel, where each legitimate user equipped with M antennas intends to convey independent signals via an intermediate relay with N antennas. There exists an eavesdropper which is equipped with Neantennas close to the legitimate users. In order to eliminate the multiuser interference and keep the system security, interference alignment is mainly utilized in the proposed broadcast wiretap channel (BWC) and multi-access BWC (MBWC), and cooperative jamming is adopted as a supplementary approach in the MBWC model. The general feasibility conditions of the interference alignment are deduced asM≥K−1,2M>N and N≥((K(K−1))/2) . In the BWC model, we have deduced the secure degrees of freedom (SDOF) asKmin{M,N}−min{Ne,K(K−1)/2} , which is always a positive value. While in the MBWC model, the SDOF is given by Kmin{M,N} . Finally, since the relay transmits the synthesized signals of the legal signal and the jamming signal in the MBWC model, we propose a power allocation scheme to maximize the secrecy rate. Simulation results demonstrate that our proposed power allocation scheme can improve secrecy rate under various antenna configurations.

  • 43.
    Fathi, Masood
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Nourmohammadi, Amir
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    An optimization model for balancing assembly lines with stochastic task times and zoning constraints2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 32537-32550, article id 8663269Article in journal (Refereed)
    Abstract [en]

    This study aims to bridge the gap between theory and practice by addressing a real-world assembly line balancing problem (ALBP) where task times are stochastic and there are zoning constraints in addition to the commonly known ALBP constraints. A mixed integer programming (MIP) model is proposed for each of the straight and U-shaped assembly line configurations. The primary objective in both cases is to minimize the number of stations; minimizing the maximum of stations’ mean time and the stations’ time variance are considered secondary objectives. Four different scenarios are discussed for each model, with differences in the objective function. The models are validated by solving a real case taken from an automobile manufacturing company and some standard test problems available in the literature. The results indicate that both models are able to provide optimum solutions for problems of different sizes. The technique for order preference by similarity to ideal solution (TOPSIS) is used to create reliable comparisons of the different scenarios and valid analysis of the results. Finally, some insights regarding the selection of straight and U-shaped layouts are provided.

  • 44.
    Fodor, Gábor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Sweden.
    Parkvall, S.
    Sorrentino, S.
    Wallentin, P.
    Lu, Q.
    Brahmi, N.
    Device-to-device communications for national security and public safety2014In: IEEE Access, E-ISSN 2169-3536, Vol. 2, p. 1510-1520, article id 6985517Article in journal (Refereed)
    Abstract [en]

    Device-to-device (D2D) communications have been proposed as an underlay to long-term evolution (LTE) networks as a means of harvesting the proximity, reuse, and hop gains. However, D2D communications can also serve as a technology component for providing public protection and disaster relief (PPDR) and national security and public safety (NSPS) services. In the United States, for example, spectrum has been reserved in the 700-MHz band for an LTE-based public safety network. The key requirement for the evolving broadband PPDR and NSPS services capable systems is to provide access to cellular services when the infrastructure is available and to efficiently support local services even if a subset or all of the network nodes become dysfunctional due to public disaster or emergency situations. This paper reviews some of the key requirements, technology challenges, and solution approaches that must be in place in order to enable LTE networks and, in particular, D2D communications, to meet PPDR and NSPS-related requirements. In particular, we propose a clustering-procedure-based approach to the design of a system that integrates cellular and ad hoc operation modes depending on the availability of infrastructure nodes. System simulations demonstrate the viability of the proposed design. The proposed scheme is currently considered as a technology component of the evolving 5G concept developed by the European 5G research project METIS.

  • 45.
    Fodor, Gábor
    et al.
    Ericsson Research, Sweden.
    Roger, Sandra
    Rajatheva, Nandana
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Svensson, Tommy
    Popovski, Petar
    B. da Silva Jr., Jose Mairton
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Ali, Samad
    An Overview of Device-to-Device Communications Technology Components in METIS2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 3288-3299Article in journal (Refereed)
    Abstract [en]

    As the standardization of network-assisted deviceto-device (D2D) communications by the 3 rd Generation Partnership Project progresses, the research community has started to explore the technology potential of new advanced features that will largely impact the performance of 5G networks. For 5G, D2D is becoming an integrative term of emerging technologies that take advantage of the proximity of communicating entities in licensed and unlicensed spectra. The European 5G research project Mobile and Wireless Communication Enablers for the 2020 Information Society (METIS) has identified advanced D2D as a key enabler for a variety of 5G services, including cellular coverage extension, social proximity and communicating vehicles. In this paper, we review the METIS D2D technology components in three key areas of proximal communications – network-assisted multi-hop, full-duplex, and multi-antenna D2D communications – and argue that the advantages of properly combining cellular and ad hoc technologies help to meet the challenges of the information society beyond 2020.

  • 46.
    Geraci, Giovanni
    et al.
    Univ Pompeu Fabra, Spain.
    Garcia-Rodriguez, Adrian
    Nokia Bell Labs, Ireland.
    Giordano, Lorenzo Galati
    Nokia Bell Labs, Ireland.
    Lopez-Perez, David
    Nokia Bell Labs, Ireland.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Understanding UAV Cellular Communications: From Existing Networks to Massive MIMO2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 67853-67865Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to bestow the reader with a timely study of UAV cellular communications, bridging the gap between the 3GPP standardization status quo and the more forward-looking research. Special emphasis is placed on the downlink command and control (Camp;C) channel to aerial users, whose reliability is deemed of paramount technological importance for the commercial success of UAV cellular communications. Through a realistic side-by-side comparison of two network deployments - a present-day cellular infrastructure versus a next-generation massive MIMO system - a plurality of key facts are cast light upon, with the three main ones summarized as follows: 1) UAV cell selection is essentially driven by the secondary lobes of a base stations radiation pattern, causing UAVs to associate to far-flung cells; 2) over a 10 MHz bandwidth, and for UAV heights of up to 300 m, massive MIMO networks can support 100 kbps Camp;C channels in 74% of the cases when the uplink pilots for channel estimation are reused among base station sites, and in 96% of the cases without pilot reuse across the network; and 3) supporting UAV Camp;C channels can considerably affect the performance of ground users on account of severe pilot contamination, unless suitable power control policies are in place.

  • 47.
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Analyzing Glide-Symmetric Holey Metasurfaces Using a Generalized Floquet Theorem2018In: IEEE Access, E-ISSN 2169-3536Article in journal (Refereed)
  • 48.
    Ghazi, Ahmad Nauman
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Petersen, Kai
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Bjarnason, Elizabeth
    Lund University, SWE.
    Runeson, Per
    Lund University, SWE.
    Levels of Exploration in Exploratory Testing: From Freestyle to Fully Scripted2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 26416-26423Article in journal (Refereed)
    Abstract [en]

    Exploratory testing (ET) is a powerful and efficient way of testing software by integrating design, execution, and analysis of tests during a testing session. ET is often contrasted with scripted testing, and seen as a choice of either exploratory testing or not. In contrast, we pose that exploratory testing can be of varying degrees of exploration from fully exploratory to fully scripted. In line with this, we propose a scale for the degree of exploration and define five levels. In our classification, these levels of exploration correspond to the way test charters are defined. We have evaluated this classification through focus groups at four companies and identified factors that influence the choice of exploration level. The results show that the proposed levels of exploration are influenced by different factors such as ease to reproduce defects, better learning, verification of requirements, etc., and that the levels can be used as a guide to structure test charters. Our study also indicates that applying a combination of exploration levels can be beneficial in achieving effective testing.

  • 49.
    Ghazi, Ahmad Nauman
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Petersen, Kai
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Reddy, Sri Sai Vijay Raj
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Nekkanti, Harini
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Survey Research in Software Engineering: Problems and Mitigation Strategies2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 24703-24718Article in journal (Refereed)
    Abstract [en]

    Background: The need for empirical investigations in software engineering is growing. Many researchers nowadays, conduct and validate their solutions using empirical research. The Survey is an empirical method which enables researchers to collect data from a large population. The main aim of the survey is to generalize the findings.

    Aims: In this study, we aim to identify the problems researchers face during survey design and mitigation strategies.

    Method: A literature review, as well as semi-structured interviews with nine software engineering researchers, were conducted to elicit their views on problems and mitigation strategies. The researchers are all focused on empirical software engineering.

    Results: We identified 24 problems and 65 strategies, structured according to the survey research process. The most commonly discussed problem was sampling, in particular, the ability to obtain a sufficiently large sample. To improve survey instrument design, evaluation and execution recommendations for question formulation and survey pre-testing were given. The importance of involving multiple researchers in the analysis of survey results was stressed.

    Conclusions: The elicited problems and strategies may serve researchers during the design of their studies. However, it was observed that some strategies were conflicting. This shows that it is important to conduct a trade-off analysis between strategies.

  • 50.
    Gong, Shaofang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Karlsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Pushing the wireless data rate to the Internet speed2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 8787-8792Article in journal (Refereed)
    Abstract [en]

    This article intends to answer the question how to achieve wireless data rates that can catch up with current Internet speed, from a basic physics point of view. It is shown that the traditional electric circuit theory and design methodology that have been used for generations are unfortunately not adequate for wireless communications in the future. Instead, disruptive approaches such as six-port modulators for processing of electromagnetic waves and optical pulses should be employed to push up the wireless data rate above 100 gigabits per second. The key variables to consider for high speed digital communications are bandwidth, modulation order and signal-to-noise ratio. In principle, it should be possible to achieve a wireless data rate at 100 Gbps within the frequency spectrum below 20 GHz.

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