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  • 1.
    Abeynanda, Hansi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Weeraddana, Chathuranga
    Univ Oulu, Ctr Wireless Commun, Oulu 90014, Finland..
    Lanel, G. H. J.
    Univ Sri Jayewardenepura, Dept Math, Nugegoda 10250, Sri Lanka..
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    On the Primal Feasibility in Dual Decomposition Methods Under Additive and Bounded Errors2023In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 71, p. 655-669Article in journal (Refereed)
    Abstract [en]

    With the unprecedented growth of signal processing and machine learning application domains, there has been a tremendous expansion of interest in distributed optimization methods to cope with the underlying large-scale problems. Nonetheless, inevitable system-specific challenges such as limited computational power, limited communication, latency requirements, measurement errors, and noises in wireless channels impose restrictions on the exactness of the underlying algorithms. Such restrictions have appealed to the exploration of algorithms' convergence behaviors under inexact settings. Despite the extensive research conducted in the area, it seems that the analysis of convergences of dual decomposition methods concerning primal optimality violations, together with dual optimality violations is less investigated. Here, we provide a systematic exposition of the convergence of feasible points in dual decomposition methods under inexact settings, for an important class of global consensus optimization problems. Convergences and the rate of convergences of the algorithms are mathematically substantiated, not only from a dual-domain standpoint but also from a primal-domain standpoint. Analytical results show that the algorithms converge to a neighborhood of optimality, the size of which depends on the level of underlying distortions.

  • 2.
    Afzal, Zeeshan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Karlstad University Karlstad Sweden.
    Brunstrom, A.
    Lindskog, S.
    Using Features of Encrypted Network Traffic to Detect Malware2021In: 25th Nordic Conference on Secure IT Systems, NordSec 2020, Springer Science and Business Media Deutschland GmbH , 2021, p. 37-53Conference paper (Refereed)
    Abstract [en]

    Encryption on the Internet is as pervasive as ever. This has protected communications and enhanced the privacy of users. Unfortunately, at the same time malware is also increasingly using encryption to hide its operation. The detection of such encrypted malware is crucial, but the traditional detection solutions assume access to payload data. To overcome this limitation, such solutions employ traffic decryption strategies that have severe drawbacks. This paper studies the usage of encryption for malicious and benign purposes using large datasets and proposes a machine learning based solution to detect malware using connection and TLS metadata without any decryption. The classification is shown to be highly accurate with high precision and recall rates by using a small number of features. Furthermore, we consider the deployment aspects of the solution and discuss different strategies to reduce the false positive rate.

  • 3.
    Ahmed, J.
    et al.
    Ericsson Research, Sweden.
    Josefsson, T.
    Uppsala University, Sweden.
    Johnsson, A.
    Ericsson Research, Sweden.
    Flinta, C.
    Ericsson Research, Sweden.
    Moradi, F.
    Ericsson Research, Sweden.
    Pasquini, R.
    Faculty of Computing (FACOM/UFU), Uberlândia, MG, Brazil.
    Stadler, Rolf
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre. RISE Swedish Institute of Computer Science (SICS), Sweden.
    Automated diagnostic of virtualized service performance degradation2018In: Proceedings 2018 IEEE/IFIP Network Operations and Management Symposium, NOMS 2018: Cognitive Management in a Cyber World, NOMS 2018, Institute of Electrical and Electronics Engineers (IEEE) , 2018, p. 1-9Conference paper (Refereed)
    Abstract [en]

    Service assurance for cloud applications is a challenging task and is an active area of research for academia and industry. One promising approach is to utilize machine learning for service quality prediction and fault detection so that suitable mitigation actions can be executed. In our previous work, we have shown how to predict service-level metrics in real-time just from operational data gathered at the server side. This gives the service provider early indications on whether the platform can support the current load demand. This paper provides the logical next step where we extend our work by proposing an automated detection and diagnostic capability for the performance faults manifesting themselves in cloud and datacenter environments. This is a crucial task to maintain the smooth operation of running services and minimizing downtime. We demonstrate the effectiveness of our approach which exploits the interpretative capabilities of Self- Organizing Maps (SOMs) to automatically detect and localize different performance faults for cloud services.

  • 4. Almgren, M.
    et al.
    Andersson, P.
    Björkman, Gunnar
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Ekstedt, Mathias
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Hallberg, J.
    Nadjm-Tehrani, S.
    Westring, E.
    RICS-el: Building a national testbed for research and training on SCADA security (short paper)2019In: Lect. Notes Comput. Sci., Springer Nature , 2019, p. 219-225Conference paper (Refereed)
    Abstract [en]

    Trends show that cyber attacks targeting critical infrastructures are increasing, but security research for protecting such systems are challenging. There is a gap between the somewhat simplified models researchers at universities can sustain contra the complex systems at infrastructure owners that seldom can be used for direct research. There is also a lack of common datasets for research benchmarking. This paper presents a national experimental testbed for security research within supervisory control and data acquisition systems (SCADA), accessible for both research training and experiments. The virtualized testbed has been designed and implemented with both vendor experts and security researchers to balance the goals of realism with specific research needs. It includes a real SCADA product for energy management, a number of network zones, substation nodes, and a simulated power system. This environment enables creation of scenarios similar to real world utility scenarios, attack generation, development of defence mechanisms, and perhaps just as important: generating open datasets for comparative research evaluation.

  • 5.
    Andrén, Samuel
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Lindström, Erik
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Hugosson, Alice
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Rönnqvist, Sofia
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Lagerström, Robert
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Hacks, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Assessing Alignment Between Business and IT Strategy: A Case Study2020In: Proceedings of the Forum at Practice of Enterprise Modeling 2020 co-located with the 13th IFIP WG 8.1 Working Conference on the Practice of Enterprise Modeling (PoEM 2020), CEUR-WS , 2020, Vol. 2793, p. 1-12Conference paper (Refereed)
    Abstract [en]

    Strategic alignment between business and IT is a topic of high importance to modern businesses, but it remainsproblematic to implement structured methods to improve and assess alignment in many organisations. Thisstudy investigates how organisations can better leverage published strategic alignment theory and methods,finding that previous research has not sufficiently considered the different dimensions of strategy and thatsuch considerations would help enterprises improve strategic alignment. The study proposes a framework forunderstanding strategic alignment in hierarchical business-led organisations, exemplified in a case study ofTrafikförvaltningen, the Stockholm public transport authority.

  • 6. Araldo, Andrea
    et al.
    Dán, György
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Rossi, Dario
    Caching Encrypted Content Via Stochastic Cache Partitioning2018In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 26, no 1, p. 548-561Article in journal (Refereed)
    Abstract [en]

    In-network caching is an appealing solution to cope with the increasing bandwidth demand of video, audio, and data transfer over the Internet. Nonetheless, in order to protect consumer privacy and their own business, content providers (CPs) increasingly deliver encrypted content, thereby preventing Internet service providers (ISPs) from employing traditional caching strategies, which require the knowledge of the objects being transmitted. To overcome this emerging tussle between security and efficiency, in this paper we propose an architecture in which the ISP partitions the cache space into slices, assigns each slice to a different CP, and lets the CPs remotely manage their slices. This architecture enables transparent caching of encrypted content and can be deployed in the very edge of the ISP's network (i.e., base stations and femtocells), while allowing CPs to maintain exclusive control over their content. We propose an algorithm, called SDCP, for partitioning the cache storage into slices so as to maximize the bandwidth savings provided by the cache. A distinctive feature of our algorithm is that ISPs only need to measure the aggregated miss rates of each CP, but they need not know the individual objects that are requested. We prove that the SDCP algorithm converges to a partitioning that is close to the optimal, and we bound its optimality gap. We use simulations to evaluate SDCP's convergence rate under stationary and nonstationary content popularity. Finally, we show that SDCP significantly outperforms traditional reactive caching techniques, considering both CPs with perfect and with imperfect knowledge of their content popularity.

  • 7.
    Aung, Pyae Sone
    et al.
    Kyung Hee University, Department of Computer Science and Engineering, Yongin-si, Republic of Korea.
    Nguyen, Loc X.
    Kyung Hee University, Department of Computer Science and Engineering, Yongin-si, Republic of Korea.
    Tun, Yan Kyaw
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Han, Zhu
    University of Houston, Department of Electrical and Computer Engineering, Houston, TX, USA.
    Hong, Choong Seon
    Kyung Hee University, Department of Computer Science and Engineering, Yongin-si, Republic of Korea.
    Deep Reinforcement Learning based Spectral Efficiency Maximization in STAR-RIS-Assisted Indoor Outdoor Communication2023In: Proceedings of IEEE/IFIP Network Operations and Management Symposium 2023, NOMS 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    The significant growth in data consumption among mobile users necessitates the development of new architecture to meet the increasing demand. On the other hand, reconfigurable intelligent surface (RIS) has grown in popularity in 6G due to its improved spectral efficiency, simplicity of deployment, and low cost. However, with the constrained limitation of the coverage by conventional RIS, the research direction has turned towards simultaneously transmitting and reflecting RIS (STAR-RIS) to provide 360° coverage alongside the benefits of RIS. In this paper, a STAR-RIS-assisted downlink communication system for both indoor and outdoor users is investigated. Then, the optimization problem to maximize the spectral efficiency while jointly controlling the beamforming power for each user and phase shift values of the STAR-RIS is formulated. Since the formulated problem is NP-hard and challenging to solve in polynomial time, a policy gradient method for reinforcement learning named proximal policy optimization (PPO) is implemented to solve the problem. To demonstrate the effectiveness of our proposed algorithm, extensive simulation results are executed. Numerical results prove that our proposed algorithm outperforms several benchmark schemes in the literature.

  • 8.
    Azimi Abarghouyi, Seyed Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Dhillon, Harpreet S.
    Virginia Tech, 24061, Blacksburg, VA, USA.
    Matérn cluster process with holes at the cluster centers2024In: Statistics and Probability Letters, ISSN 0167-7152, E-ISSN 1879-2103, Vol. 204, article id 109931Article in journal (Refereed)
    Abstract [en]

    Inspired by recent applications of point processes to biological nanonetworks, this paper presents a novel variant of a Matérn cluster process (MCP) in which the points located within a certain distance from the cluster centers are removed. We term this new process the MCP with holes at the cluster center (MCP-H, in short). Focusing on the three-dimensional (3D) space, we first characterize the conditional distribution of the distance between an arbitrary point of a given cluster to the origin, conditioned on the location of that cluster, for both MCP and MCP-H. These distributions are shown to admit remarkably simple closed forms in the 3D space, which is not even possible in the simpler two-dimensional (2D) case. Using these distributions, the contact distance distribution and the probability generating functional (PGFL) are characterized for both MCP and MCP-H.

  • 9.
    Azimi Abarghouyi, Seyed Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Dhillon, Harpreet S.
    Virginia Tech, Wireless@VT, Bradley Department of Electrical and Computer Engineering, Blacksburg, VA, USA.
    Tassiulas, Leandros
    Institute for Network Science, Yale University, Department of Electrical Engineering, New Haven, CT, USA.
    Fundamentals of Clustered Molecular Nanonetworks2023In: IEEE Transactions on Molecular, Biological, and Multi-Scale Communications, E-ISSN 2332-7804, Vol. 9, no 2, p. 135-145Article in journal (Refereed)
    Abstract [en]

    We present a comprehensive approach to the modeling, performance analysis, and design of clustered molecular nanonetworks in which nano-machines of different clusters release an appropriate number of molecules to transmit their sensed information to their respective fusion centers. The fusion centers decode this information by counting the number of molecules received in the given time slot. Owing to the propagation properties of the biological media, this setup suffers from both inter- and intra-cluster interference that needs to be carefully modeled. To facilitate rigorous analysis, we first develop a novel spatial model for this setup by modeling nano-machines as a Poisson cluster process with the fusion centers forming its parent point process. For this setup, we first derive a new set of distance distributions in the three-dimensional space, resulting in a remarkably simple result for the special case of the Thomas cluster process. Using this, total interference from previous symbols and different clusters is characterized and its expected value and Laplace transform are obtained. The error probability of a simple detector suitable for biological applications is analyzed, and approximate and upper-bound results are provided. The impact of different parameters on the performance is also investigated.

  • 10.
    B. da Silva Jr., Jose Mairton
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Optimization and Fundamental Insights in Full-Duplex Cellular Networks2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The next generations of cellular networks are expected to provide explosive data rate transmissions and very low latencies. To meet such demands, one of the promising wireless transmissions candidates is in-band full-duplex communications, which enable wireless devices to simultaneously transmit and receive on the same frequency channel. Full-duplex communications have the potential to double the spectral efficiency and reduce the transmission delays when compared to current half-duplex systems that either transmit or receive on the same frequency channel. Until recently, full-duplex communications have been hindered by the interference that leaks from the transmitter to its own receiver,the so-called self-interference. However, advances in digital and analog self-interference suppression techniques are making it possible to reduce the self-interference to manageable levels, and thereby make full-duplex a realistic candidate for advanced wireless systems.

    Although in-band full-duplex promises to double the data rates of existing wireless technologies, its deployment in cellular networks must be gradual due to the large number of legacy devices operating in half-duplex mode. When half-duplex devices are deployed in full-duplex cellular networks, the user-to-user interference may become the performance bottleneck. In such new interference situation, the techniques such as user pairing, frequency channel assignment, power control, beamforming, and antenna splitting become even more important than before, because they are essential to mitigate both the user-to-user interference and the residual self-interference. Moreover, introduction of full- duplex in cellular networks must comply with current multi-antenna systems and, possibly, transmissions in the millimeter-wave bands. In these new scenarios, no comprehensive analysis is available to understand the trade-offs in the performance of full-duplex cellular networks.

    This thesis investigates the optimization and fundamental insights in the design of spectral efficient and fair mechanisms in full-duplex cellular networks. The novel analysis proposed in this thesis suggests new solutions for maximizing full-duplex performance in the sub-6 GHz and millimeter-wave bands. The investigations are based on an optimization theory approach that includes distributed and nonconvex optimization with mixed integer-continuous variables, and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on fundamental questions such as which antenna architecture should be used and whether full-duplex in the millimeter-wave band is feasible. The results establish fundamental insights in the role of user pairing, frequency assignment, power control and beamforming; reveal the special behaviour between the self-interference and user- to-user interference; analyse the trade-offs between antenna sharing and splitting for uplink/downlink signal separation; and investigate the role of practical beamforming design in full-duplex millimeter-wave systems. This thesis may provide input to future standardization process of full-duplex communications.

    Download full text (pdf)
    MairtonBarros_Doctoral_Thesis
  • 11.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    How to Split UL/DL Antennas in Full-DuplexCellular Networks2018In: IEEE International Conference on Communication (ICC’18): ThirdWorkshop on Full-Duplex Communications for Future Wireless Networks, Kansas City, MO, USA: IEEE Communications Society, 2018Conference paper (Refereed)
    Abstract [en]

    To further improve the potential of full-duplex com-munications, networks may employ multiple antennas at thebase station or user equipment. To this end, networks thatemploy current radios usually deal with self-interference andmulti-user interference by beamforming techniques. Althoughprevious works investigated beamforming design to improvespectral efficiency, the fundamental question of how to split theantennas at a base station between uplink and downlink infull-duplex networks has not been investigated rigorously. Thispaper addresses this question by posing antenna splitting as abinary nonlinear optimization problem to minimize the sum meansquared error of the received data symbols. It is shown that thisis an NP-hard problem. This combinatorial problem is dealt withby equivalent formulations, iterative convex approximations, anda binary relaxation. The proposed algorithm is guaranteed toconverge to a stationary solution of the relaxed problem with muchsmaller complexity than exhaustive search. Numerical resultsindicate that the proposed solution is close to the optimal in bothhigh and low self-interference capable scenarios, while the usuallyassumed antenna splitting is far from optimal. For large numberof antennas, a simple antenna splitting is close to the proposedsolution. This reveals that the importance of antenna splittingdiminishes with the number of antennas.

  • 12. Babaheidarian, P.
    et al.
    Salimi, S.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS. KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Scalable Security in Interference Channels with Arbitrary Number of Users2020In: Proceedings of 2020 International Symposium on Information Theory and its Applications, ISITA 2020, Institute of Electrical and Electronics Engineers Inc. , 2020, p. 402-406Conference paper (Refereed)
    Abstract [en]

    In this paper, we present an achievable security scheme for an interference channel with arbitrary number of users. In this model, each receiver should be able to decode its intended message while it should remain ignorant regarding messages intended for other receivers. Our scheme relies ontransmitters to collectively ensure the confidentiality of the transmitted messages using a cooperative jamming technique and lattice alignment. The Asymmetric compute-and-forward framework is used to perform the decoding operation. The proposed scheme is the first asymptotically optimal achievable scheme for this security scenario which scales to arbitrary number of users and works for any finite-valued SNR. Also, our scheme achieves the upper bound sum secure degrees of freedom of 1 without using external helpers and thus the achievable rates lie within constant gap from sum secure capacity.

  • 13.
    Balliu, Musard
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Baudry, Benoit
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Bobadilla, Sofia
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Ekstedt, Mathias
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Monperrus, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Ron Arteaga, Javier
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Sharma, Aman
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Skoglund, Gabriel
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Soto Valero, César
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Wittlinger, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Challenges of Producing Software Bill of Materials for Java2023In: IEEE Security and Privacy, ISSN 1540-7993, E-ISSN 1558-4046, Vol. 21, no 6, p. 12-23Article in journal (Refereed)
    Abstract [en]

    Software bills of materials (SBOMs) promise to become the backbone of software supply chain hardening. We deep-dive into six tools and the SBOMs they produce for complex open source Java projects, revealing challenges regarding the accurate production and usage of SBOMs.

  • 14.
    Balliu, Musard
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Baudry, Benoit
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Bobadilla, Sofia
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Ekstedt, Mathias
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Monperrus, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Ron Arteaga, Javier
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Sharma, Aman
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Skoglund, Gabriel
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Soto Valero, César
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Wittlinger, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Software Bill of Materials in Java2023In: SCORED 2023 - Proceedings of the 2023 Workshop on Software Supply Chain Offensive Research and Ecosystem Defenses, Association for Computing Machinery (ACM) , 2023, p. 75-76Conference paper (Refereed)
    Abstract [en]

    Modern software applications are virtually never built entirely in-house. As a matter of fact, they reuse many third-party dependencies, which form the core of their software supply chain [1]. The large number of dependencies in an application has turned into a major challenge for both security and reliability. For example, to compromise a high-value application, malicious actors can choose to attack a less well-guarded dependency of the project [2]. Even when there is no malicious intent, bugs can propagate through the software supply chain and cause breakages in applications. Gathering accurate, upto- date information about all dependencies included in an application is, therefore, of vital importance.

  • 15.
    Barreto, Carlos
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Digital Futures.
    Reinert, Olof
    Wiesinger, Tobias
    Franke, Ulrik
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID. Digital Futures.
    Duopoly insurers’ incentives for data quality under a mandatory cyber data sharing regime2023In: Computers & security (Print), ISSN 0167-4048, E-ISSN 1872-6208, Vol. 131, p. 1-16, article id 103292Article in journal (Refereed)
    Abstract [en]

    We study the impact of data sharing policies on cyber insurance markets. These policies have been proposed to address the scarcity of data about cyber threats, which is essential to manage cyber risks. We propose a Cournot duopoly competition model in which two insurers choose the number of policies they offer (i.e., their production level) and also the resources they invest to ensure the quality of data regarding the cost of claims (i.e., the data quality of their production cost). We find that enacting mandatory data sharing sometimes creates situations in which at most one of the two insurers invests in data quality, whereas both insurers would invest when information sharing is not mandatory. This raises concerns about the merits of making data sharing mandatory.

    Download full text (pdf)
    fulltext
  • 16.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Royal Inst Technol, KTH, Stockholm, Sweden..
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    How to Split UL/DL Antennas in Full-Duplex Cellular Networks2018In: 2018 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    To further improve the potential of full-duplex communications, networks may employ multiple antennas at the base station or user equipment. To this end, networks that employ current radios usually deal with self-interference and multi-user interference by beamforming techniques. Although previous works investigated beamforming design to improve spectral efficiency, the fundamental question of how to split the antennas at a base station between uplink and downlink in full-duplex networks has not been investigated rigorously. This paper addresses this question by posing antenna splitting as a binary nonlinear optimization problem to minimize the sum mean squared error of the received data symbols. It is shown that this is an NP-hard problem. This combinatorial problem is dealt with by equivalent formulations, iterative convex approximations, and a binary relaxation. The proposed algorithm is guaranteed to converge to a stationary solution of the relaxed problem with much smaller complexity than exhaustive search. Numerical results indicate that the proposed solution is close to the optimal in both high and low self-interference capable scenarios, while the usually assumed antenna splitting is far from optimal. For large number of antennas, a simple antenna splitting is close to the proposed solution. This reveals that the importance of antenna splitting diminishes with the number of antennas.

  • 17.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fodor, Gabor
    Ericsson Research, Kista, Sweden..
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Smart Antenna Assignment is Essential in Full-Duplex Communications2021In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 69, no 5, p. 3450-3466Article in journal (Refereed)
    Abstract [en]

    Full-duplex communications have the potential to almost double the spectralefficiency. To realize such a potentiality, the signal separation at base station’s antennasplays an essential role. This paper addresses the fundamentals of such separationby proposing a new smart antenna architecture that allows every antenna to beeither shared or separated between uplink and downlink transmissions. The benefitsof such architecture are investigated by an assignment problem to optimally assignantennas, beamforming and power to maximize the weighted sum spectral efficiency.We propose a near-to-optimal solution using block coordinate descent that divides theproblem into assignment problems, which are NP-hard, a beamforming and powerallocation problems. The optimal solutions for the beamforming and power allocationare established while near-to-optimal solutions to the assignment problems are derivedby semidefinite relaxation. Numerical results indicate that the proposed solution isclose to the optimum, and it maintains a similar performance for high and low residualself-interference powers. With respect to the usually assumed antenna separationtechnique and half-duplex transmission, the sum spectral efficiency gains increase withthe number of antennas. We conclude that our proposed smart antenna assignment forsignal separation is essential to realize the benefits of multiple antenna full-duplexcommunications.

  • 18.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Ntougias, Konstantinos
    University of Cyprus.
    Krikidis, Ioannis
    University of Cyprus.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Simultaneous Wireless Information and PowerTransfer for Federated Learning2021In: IEEE 22nd International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Lucca, Italy, Sep. 2021, IEEE Communications Society, 2021, p. 296-300Conference paper (Refereed)
    Abstract [en]

    In the Internet of Things, learning is one of most prominent tasks. In this paper, we consider an Internet of Things scenario where federated learning is used with simultaneous transmission of model data and wireless power. We investigate the trade-off between the number of communication rounds and communication round time while harvesting energy to compensate the energy expenditure. We formulate and solve an optimization problem by considering the number of local iterations on devices, the time to transmit-receive the model updates, and to harvest sufficient energy. Numerical results indicate that maximum ratio transmission and zero-forcing beamforming for the optimization of the local iterations on devices substantially boost the test accuracy of the learning task. Moreover, maximum ratio transmission instead of zero-forcing provides the best test accuracy and communication round time trade-off for various energy harvesting percentages. Thus, it is possible to learn a model quickly with few communication rounds without depleting the battery.

  • 19.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Sabharwal, Ashutosh
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, S-16480 Stockholm, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    1-bit Phase Shifters for Large-Antenna Full-Duplex mmWave Communications2020In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 19, no 10, p. 6916-6931Article in journal (Refereed)
    Abstract [en]

    Millimeter-wave using large-antenna arrays is a key technological component forthe future cellular systems, where it is expected that hybrid beamforming along withquantized phase shifters will be used due to their implementation and cost efficiency.In this paper, we investigate the efficacy of full-duplex mmWave communicationwith hybrid beamforming using low-resolution phase shifters, without any analogself-interference cancellation. We formulate the problem of joint self-interferencesuppression and downlink beamforming as a mixed-integer nonconvex joint opti-mization problem. We propose LowRes, a near-to-optimal solution using penaltydual decomposition. Numerical results indicate that LowRes using low-resolutionphase shifters perform within 3% of the optimal solution that uses infinite phaseshifter resolution. Moreover, even a single quantization bit outperforms half-duplextransmissions, respectively by 29% and 10% for both low and high residual self-interference scenarios, and for a wide range of practical antenna to radio-chain ratios.Thus, we conclude that 1-bit phase shifters suffice for full-duplex millimeter-wavecommunications, without requiring any additional new analog hardware.

  • 20.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Sabharwal, Ashutosh
    Rice Univ, Houston, TX USA..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, Kista, Sweden..
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications2019In: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    Full-duplex base-stations with half-duplex nodes, allowing simultaneous uplink and downlink from different nodes, have the potential to double the spectrum efficiency without adding additional complexity at mobile nodes. Hybrid beam forming is commonly used in millimeter wave systems for its implementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask if low-resolution phase shifters suffice for beamforming-based full-duplex millimeter wave systems. We formulate the problem of joint design for both self-interference suppression and downlink beamforming as an optimization problem, which we solve using penalty dual decomposition to obtain a near-optimal solution. Numerical results indicate that low-resolution phase shifters can perform close to systems that use infinite phase shifter resolution, and that even a single quantization bit outperforms half-duplex transmissions in both low and high residual self-interference scenarios.

  • 21.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Skouroumounis, Christodoulos
    University of Cyprus.
    Krikidis, Ioannis
    University of Cyprus.
    Fodor, Gabor
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Energy Efficient Full-Duplex Networks2020In: Green Communications for Energy-Efficient Wireless Systems and Networks / [ed] H. Suraweera, J. Yang, A. Zappone, J. S. Thompson, The Institution of Engineering and Technology (IET) , 2020Chapter in book (Refereed)
    Abstract [en]

    As the specifications of the 5th generation of cellular networks mature, the deployment phase is starting up. Hence, peaks of data rates in the order of tens of Gbit/s as well as more energy efficient deployments are expected. Nevertheless, the quick development of new applications and services encourage the research community to look beyond 5G and explore new technological components. Indeed, to meet the increasing demand for mobile broadband as well as internet of things type of services, the research and standardization communities are currently investigating novel physical and medium access layer technologies, including further virtualization of networks, the use of the lower Terahertz bands, even higher cell densification, and full-duplex (FD) communications.

     

    FD has been proposed as one of the enabling technologies to increase the spectral efficiency of conventional wireless transmission modes, by overcoming our prior understanding that it is not possible for radios to transmit and receive simultaneously on the same time-frequency resource. Due to this, we can also refer to FD communications as in-band FD. In-band FD transceivers have the potential of improving the attainable spectral efficiency of traditional wireless networks operating with half-duplex (HD) transceivers by a factor close to two. In addition to the spectral efficiency gains, full-duplex can provide gains in the medium access control layer, in which problems such as the hidden/exposed nodes and collision detection can be mitigated and the energy consumption can be reduced.

     

    Until recently, in-band FD was not considered as a solution for wireless networks due to the inherent interference created from the transmitter to its own receiver, the so-called self-interference (SI). However, recent advancements in antenna and analog/digital interference cancellation techniques demonstrate FD transmissions as a viable alternative to traditional HD transmissions. Given the recent architectural progression of 5G towards smaller cells, higher densification, higher number of antennas and utilizing the millimeter wave (mmWave) band, the integration of FD communications into such scenarios is appealing. In-band FD communications are suited for short range communication, and although the SI remains a challenge, the use of multiple antennas and the transmission in the mmWave band are allies that help to mitigate the SI in the spatial domain and provide even more gains for spectral and energy efficiency. To achieve the spectral and energy efficiency gains, it is important to understand the challenges and solutions, which can be roughly divided into resource allocation, protocol design, hardware design and energy harvesting. Hence, FD communications appears as an important technology component to improve the spectral and energy efficiency of current communication systems and help to meet the goals of 5G and beyond.

     

    The chapter starts with an overview of FD communications, including its challenges and solutions. Next, a comprehensive literature review of energy efficiency in FD communications is presented along with the key solutions to improve energy efficiency. Finally, we evaluate the key aspects of energy efficiency in FD communications for two scenarios: single-cell with multiple users in a pico-cell scenario, and a system level evaluation with macro- and small-cells with multiple users.

  • 22.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Wikström, Gustav
    Mungara, Ratheesh K.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Full-Duplex and Dynamic-TDD: Pushing the Limits of Spectrum Reuse in Multi-Cell Communications2021In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, ISSN 1536-1284, Vol. 28, no 1, p. 44-50Article in journal (Refereed)
    Abstract [en]

    Although in cellular networks full duplex and dynamic time-division duplexing promise increased spectrum efficiency, their potential is so far challenged by increased interference. While previous studies have shown that self-interference can be suppressed to a sufficient level, we show that the cross-link interference for both duplexing modes, especially from base station to base station, is the remaining challenge in multi-cell networks, restricting the uplink performance. Using beamforming techniques of low complexity, we show that this interference can be mitigated, and that full duplex and dynamic time-division duplexing can substantially increase the capacity of multi-cell networks. Our results suggest that if we can control the cross-link interference in full duplex, we can almost double the multi-cell network capacity as well as user throughput. Therefore, the techniques in this article have the potential to enable a smooth introduction of full duplex into cellular systems.

  • 23. Bjuhr, O.
    et al.
    Segeljakt, K.
    Addibpour, M.
    Heiser, F.
    Lagerström, Robert
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Software architecture decoupling at ericsson2017In: Proceedings - 2017 IEEE International Conference on Software Architecture Workshops, ICSAW 2017: Side Track Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 259-262, article id 7958500Conference paper (Refereed)
    Abstract [en]

    In order to evaluate and increase modularity this paper combines a method for visualizing and measuring software architectures and two algorithms for decoupling. The combination is tested on a software system at Ericsson. Our analysis show that the system has one large cluster of components (18% of the system, a Core), all interacting with each other. By employing cluster and dominator analysis we suggest 19 dependencies to be removed in order to decouple the Core. Validating the analysis output with experts at Ericsson six of the suggested dependencies where deemed impossible to remove. By removing the remaining 13 dependencies Ericsson would improve the architecture of their system considerably, e.g. core size would go down to 5%.

  • 24.
    Björn, Camilla
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Edström, Kristina
    KTH, School of Industrial Engineering and Management (ITM), Learning, Learning in Stem.
    Gingnell, Liv
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Lilliesköld, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Magnell, Marie
    KTH, School of Industrial Engineering and Management (ITM), Learning, Learning in Stem.
    The Nature of Progression Between Yearly Project Courses2023In: Proceedings of the 19th International CDIO Conference, Norway: NTNU SEED , 2023, p. 692-704Conference paper (Refereed)
    Abstract [en]

    This study focuses on the progression between courses in a programme, meaning that thelearning experiences build upon and reinforce the previous ones. The idea of mutuallysupporting courses is a cornerstone of the integrated curriculum, and hence of the CDIOapproach. However, despite much use of the term, there is a lack of work to conceptualiseprogression. The aim of this paper is, accordingly, to provide a richer theoreticalconceptualisation of progression and to apply this in analysing the implementation in aprogramme. In this case, we focus specifically on the progression through a series of coursesbased on authentic engineering projects. Such courses, called Design-implementExperiences, are a prominent feature of the CDIO framework; Standard 5 recommends at leasttwo project courses with progression through the curriculum. The context for the study is the5-year Electrical Engineering programme at KTH Royal Institute of Technology. It contains aseries of yearly project courses starting in the first year and ending with the master thesisproject. The purpose is to support students to synthesise and consolidate their learning inprevious and parallel subject courses, and to develop professional engineering skills. Here,the progression between the three first project courses is described with detailed elaborationof three themes: communication, project planning and management, and ethics. The questionsguiding our investigation are: What is the nature of progression across these project courses?In particular, along what dimensions is progression planned, and how is that implemented inthe course design?

  • 25. Blom, Rikard
    et al.
    Korman, Matus
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Robert, Lagerström
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Mathias, Ekstedt
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Analyzing attack resilience of an advanced meter infrastructure reference model2016In: Joint Workshop on Cyber-Physical Security and Resilience in Smart Grids (CPSR-SG), IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    Advanced metering infrastructure (AMI) is a key component of the concept of smart power grids. Although several functional/logical reference models of AMI exist, they are not suited for automated analysis of properties such as cyber security. This paper briefly presents a reference model of AMI that follows a tested and even commercially adopted formalism allowing automated analysis of cyber security. Finally, this paper presents an example cyber security analysis, and discusses its results.

  • 26.
    Bokaei, Mohammad
    et al.
    Electrical Engineering Department, Sharif University of Technology, Iran; Department of Electronic Systems, Aalborg university, Denmark.
    Razavikia, Saeed
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Electrical Engineering Department, Sharif University of Technology, Iran.
    Rini, Stefano
    Electrical and Computer Engineering Department, National Yang-Ming Chao-Tung University (NYCU), Taiwan.
    Amini, Arash
    Electrical Engineering Department, Sharif University of Technology, Iran.
    Behrouzi, Hamid
    Electrical Engineering Department, Sharif University of Technology, Iran.
    Harmonic retrieval using weighted lifted-structure low-rank matrix completion2024In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 216, article id 109253Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the problem of recovering the frequency components of a mixture of K complex sinusoids from a random subset of N equally-spaced time-domain samples. Because of the random subset, the samples are effectively non-uniform. Besides, the frequency values of each of the K complex sinusoids are assumed to vary continuously within a given range. For this problem, we propose a two-step strategy: (i) we first lift the incomplete set of uniform samples (unavailable samples are treated as missing data) into a structured matrix with missing entries, which is potentially low-rank; then (ii) we complete the matrix using a weighted nuclear minimization problem. We call the method a weighted lifted-structured (WLi) low-rank matrix recovery. Our approach can be applied to a range of matrix structures such as Hankel and double-Hankel, among others, and provides improvement over the unweighted existing schemes such as EMaC and DEMaC. We provide theoretical guarantees for the proposed method, as well as numerical simulations in both noiseless and noisy settings. Both the theoretical and the numerical results confirm the superiority of the proposed approach.

  • 27.
    Borsub, Jatesada
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Hardened registration process for participatory sensing2018In: WiSec 2018 - Proceedings of the 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks, Association for Computing Machinery, Inc , 2018, p. 281-282Conference paper (Refereed)
    Abstract [en]

    Participatory sensing systems need to gather information from a large number of participants. However, the openness of the system is a double-edged sword: by allowing practically any user to join, the system can be abused by an attacker who introduces a large number of virtual devices. This poster proposes a hardened registration process for Participatory Sensing to raise the bar: registrations are screened through a number of defensive measures, towards rejecting spurious registrations that do not correspond to actual devices. This deprives an adversary from a relatively easy take-over and, at the same time, allows a flexible and open registration process.

  • 28.
    Bourgerie, Rémi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Zanouda, Tahar
    Global AI Accelerator, Ericsson AB, Global AI Accelerator, Ericsson AB.
    Fault Detection in Telecom Networks Using Bi-Level Federated Graph Neural Networks2023In: 2023 IEEE International Conference on Data Mining Workshops (ICDMW), Institute of Electrical and Electronics Engineers (IEEE) , 2023, p. 1608-1617Conference paper (Refereed)
    Abstract [en]

    5G and Beyond Networks become increasingly complex and heterogeneous, with diversified and high requirements from a wide variety of emerging applications. The complexity and diversity of Telecom networks place an increasing strain on maintenance and operation efforts. Moreover, the strict security and privacy requirements present a challenge for mobile operators to leverage network data. To detect network faults, and mitigate future failures, prior work focused on leveraging traditional ML/DL methods to locate anomalies in networks. The current approaches, although powerful, do not consider the intertwined nature of embedded and software-intensive Radio Access Network systems. In this paper, we propose a Bi-level Federated Graph Neural Network anomaly detection and diagnosis model that is able to detect anomalies in Telecom networks in a privacy-preserving manner, while minimizing communication costs. Our method revolves around conceptualizing Telecom data as a bi-level temporal Graph Neural Networks. The first graph captures the interactions between different RAN nodes that are exposed to different deployment scenarios in the network, while each individual Radio Access Network node is further elaborated into its software (SW) execution graph. Additionally, we use Federated Learning to address privacy and security limitations. Furthermore, we study the performance of anomaly detection model under three settings: (1) Centralized (2) Federated Learning and (3) Personalized Federated Learning using real-world data from an operational network. Our comprehensive experiments showed that Personalized Federated Temporal Graph Neural Networks method outperforms the most commonly used techniques for Anomaly Detection.

  • 29.
    Butun, Ismail
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Decision Support Systems and Industrial IoT in Smart Grid, Factories, and Cities2021Book (Other academic)
    Abstract [en]

    Internet of things (IoT) is an emerging research field that is rapidly becoming an important part of our everyday lives including home automation, smart buildings, smart things, and more. This is due to cheap, efficient, and wirelessly-enabled circuit boards that are enabling the functions of remote sensing/actuating, decentralization, autonomy, and other essential functions. Moreover, with the advancements in embedded artificial intelligence, these devices are becoming more self-aware and autonomous, hence making decisions themselves. Current research is devoted to the understanding of how decision support systems are integrated into industrial IoT. Decision Support Systems and Industrial IoT in Smart Grid, Factories, and Cities presents the internet of things and its place during the technological revolution, which is taking place now to bring us a better, sustainable, automated, and safer world. This book also covers the challenges being faced such as relations and implications of IoT with existing communication and networking technologies; applications like practical use-case scenarios from the real world including smart cities, buildings, and grids; and topics such as cyber security, user privacy, data ownership, and information handling related to IoT networks. Additionally, this book focuses on the future applications, trends, and potential benefits of this new discipline. This book is essential for electrical engineers, computer engineers, researchers in IoT, security, and smart cities, along with practitioners, researchers, academicians, and students interested in all aspects of industrial IoT and its applications. 

  • 30.
    Butun, Ismail
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Chalmers University of Technology, Sweden; Konya Food and Agriculture University, Turkey.
    Preface2021In: Decision Support Systems and Industrial IoT in Smart Grid, Factories, and Cities, IGI Global , 2021, p. xvii-xxiChapter in book (Refereed)
  • 31.
    Butun, Ismail
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Department of Computer Engineering, Konya Food and Agriculture University, Konya 42080, Turkey.
    Tuncel, Yusuf Kursat
    Oztoprak, Kasim
    Application Layer Packet Processing Using PISA Switches2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 23, article id 8010Article in journal (Refereed)
    Abstract [en]

    This paper investigates and proposes a solution for Protocol Independent Switch Architecture (PISA) to process application layer data, enabling the inspection of application content. PISA is a novel approach in networking where the switch does not run any embedded binary code but rather an interpreted code written in a domain-specific language. The main motivation behind this approach is that telecommunication operators do not want to be locked in by a vendor for any type of networking equipment, develop their own networking code in a hardware environment that is not governed by a single equipment manufacturer. This approach also eases the modeling of equipment in a simulation environment as all of the components of a hardware switch run the same compatible code in a software modeled switch. The novel techniques in this paper exploit the main functions of a programmable switch and combine the streaming data processor to create the desired effect from a telecommunication operator perspective to lower the costs and govern the network in a comprehensive manner. The results indicate that the proposed solution using PISA switches enables application visibility in an outstanding performance. This ability helps the operators to remove a fundamental gap between flexibility and scalability by making the best use of limited compute resources in application identification and the response to them. The experimental study indicates that, without any optimization, the proposed solution increases the performance of application identification systems 5.5 to 47.0 times. This study promises that DPI, NGFW (Next-Generation Firewall), and such application layer systems which have quite high costs per unit traffic volume and could not scale to a Tbps level, can be combined with PISA to overcome the cost and scalability issues.

  • 32. Camenisch, J.
    et al.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Preface2018In: 17th International Conference on Cryptology and Network Security, CANS 2018, Springer Verlag , 2018Conference paper (Refereed)
  • 33.
    Canat, Mert
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Català, Nuria
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Jourkovski, Alexander
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Petrov, Svetlomir
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Wellme, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Lagerström, Robert
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Enterprise Architecture and Agile Development: Friends or Foes?2018Conference paper (Refereed)
    Abstract [en]

    Nowadays, both agile development and enterprise architecture are often employed in large organizations. However there is still some confusion if these can and should be used together, and there is not much research about the possible interplay. The aim of this study is to bring new knowledge to the field of enterprise architecture and its relation to agile development. Twelve qualitative interviews with professionals in different roles, such as developers and architects, have been carried out. The participants belong to five different companies and the information obtained from them has been used to compare opinions and stated challenges regarding agile and EA. We found that some common opinions among the interviewees are; 1) agile development and enterprise architecture can be combined, 2) there are clear communication problems among architects, different teams, and project owners, and 3) there is a lack of system and application reusability. 

  • 34.
    Champati, Jaya Prakash
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    On the Distribution of AoI for the GI/GI/1/1 and GI/GI/1/2*Systems: Exact Expressions and Bounds2019In: IEEE CONFERENCE ON COMPUTER COMMUNICATIONS (IEEE INFOCOM 2019), IEEE , 2019, p. 37-45Conference paper (Refereed)
    Abstract [en]

    Since Age of Information (AoI) has been proposed as a metric that quantifies the freshness of information updates in a communication system, there has been a constant effort in understanding and optimizing different statistics of the AoI process for classical queueing systems. In addition to classical queuing systems, more recently, systems with no queue or a unit capacity queue storing the latest packet have been gaining importance as storing and transmitting older packets do not reduce AoI at the receiver. Following this line of research, we study the distribution of AoI for the GI/GI/1/1 and GI/GI/1/2* systems, under non-preemptive scheduling. For any single-source-single-server queueing system, we derive, using sample path analysis, a fundamental result that characterizes the AoI violation probability, and use it to obtain closed-form expressions for D/GI/1/1, M/GI/1/1 as well as systems that use zero-wait policy. Further, when exact results are not tractable, we present a simple methodology for obtaining upper bounds for the violation probability for both GI/GI/1/1 and GI/GI/1/2* systems. An interesting feature of the proposed upper bounds is that, if the departure rate is given, they overestimate the violation probability by at most a value that decreases with the arrival rate. Thus, given the departure rate and for a fixed average service, the bounds are tighter at higher utilization.

  • 35.
    Chari, Shreya K.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS). Stockholm Research Centre, Huawei Technologies Sweden.
    Koudouridis, George
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Huawei Technologies Sweden, Stockholm Research Centre, Sweden.
    Link Blockage Modelling for Channel State Prediction in Higher Frequencies Using Deep Learning2021In: 2021 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021, Institute of Electrical and Electronics Engineers Inc. , 2021, article id 9493379Conference paper (Refereed)
    Abstract [en]

    Wireless communications using higher frequencies is now possible due to the advancements in the field of high gain antennas. Using such technologies has enabled accessing wireless media within a short range supplying frequency bands with capacity worth multi-gigabits. Higher frequencies are however exposed to blockage events that can hinder the wireless system performance by reducing the throughput and losing user connectivity. The blockage effect becomes more severe with the addition of mobile blockers like vehicles. In order to understand the blockage events induced by a mobile vehicle, an efficient blockage model is required that can assist in the maintenance of the user connection. This paper proposes using a four state channel model based on the user's signal strength for describing the occurrence of blockage events at high frequencies. Signal strength prediction and the channel state classification are then conducted and evaluated using two deep learning neural network disciplines. The high accuracy of the simulation results observed suggest the possibility and implementation of the model in real systems. 

  • 36.
    Chemouil, Prosper
    et al.
    Orange Labs, Convergent Network Control Lab, F-92320 Chatillon, France..
    Hui, Pan
    Univ Helsinki, Dept Comp Sci, Helsinki 00014, Finland.;Hong Kong Univ Sci & Technol, Dept Comp Sci & Engn, Hong Kong, Peoples R China..
    Kellerer, Wolfgang
    Tech Univ Munich, Dept Elect & Comp Engn, D-80333 Munich, Germany..
    Li, Yong
    Tsinghua Univ, Dept Elect Engn, Beijing Natl Res Ctr Informat Sci & Technol, Beijing 100084, Peoples R China..
    Stadler, Rolf
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Tao, Dacheng
    Univ Sydney, Fac Engn & IT, Sch Comp Sci, UBTECH Sydney AI Ctr, Sydney, NSW 2008, Australia..
    Wen, Yonggang
    Nanyang Technol Univ, Sch Comp Sci & Engn, Singapore 639798, Singapore..
    Zhang, Ying
    Facebook, Network Infrastruct, Menlo Pk, CA 94025 USA..
    Special Issue on Artificial Intelligence and Machine Learning for Networking and Communications2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 6, p. 1185-1191Article in journal (Refereed)
  • 37. Chemouil, Prosper
    et al.
    Hui, Pan
    Kellerer, Wolfgang
    Limam, Noura
    Stadler, Rolf
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Wen, Yonggang
    Special Issue on Advances in Artificial Intelligence and Machine Learning for Networking2020In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 38, no 10, p. 2229-2233Article in journal (Other academic)
    Abstract [en]

    Artificial Intelligence (AI) and Machine Learning (ML) approaches have emerged in the networking domain with great expectation. They can be broadly divided into AI/ML techniques for network engineering and management, network designs for AI/ML applications, and system concepts. AI/ML techniques for networking and management improve the way we address networking. They support efficient, rapid, and trustworthy engineering, operations, and management. As such, they meet the current interest in softwarization and network programmability that fuels the need for improved network automation in agile infrastructures, including edge and fog environments. Network design and optimization for AI/ML applications addresses the complementary topic of supporting AI/ML-based systems through novel networking techniques, including new architectures and algorithms. The third topic area is system implementation and open-source software development.

  • 38.
    Chen, Zheng
    et al.
    Linköping Univ, Dept Elect Engn, S-58183 Linköping, Sweden..
    Larsson, Erik G.
    Linköping Univ, Dept Elect Engn, S-58183 Linköping, Sweden..
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Digital futures KTH.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Malitsky, Yura
    Univ Vienna, Dept Math, A-1090 Vienna, Austria..
    Over-the-Air Computation for Distributed Systems: Something Old and Something New2023In: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 37, no 5, p. 240-246Article in journal (Refereed)
    Abstract [en]

    Facing the upcoming era of Internet-of-Things and connected intelligence, efficient information processing, computation, and communication design becomes a key challenge in large-scale intelligent systems. Recently, Over-the-Air (OtA) computation has been proposed for data aggregation and distributed computation of functions over a large set of network nodes. Theoretical foundations for this concept exist for a long time, but it was mainly investigated within the context of wireless sensor networks. There are still many open questions when applying OtA computation in different types of distributed systems where modern wireless communication technology is applied. In this article, we provide a comprehensive overview of the OtA computation principle and its applications in distributed learning, control, and inference systems, for both server-coordinated and fully decentralized architectures. Particularly, we highlight the importance of the statistical heterogeneity of data and wireless channels, the temporal evolution of model updates, and the choice of performance metrics, for the communication design in OtA federated learning (FL) systems. Several key challenges in privacy, security, and robustness aspects of OtA FL are also identified for further investigation.

  • 39.
    Cucuzzella, M.
    et al.
    University of Groningen, Groningen.
    Bouman, T.
    University of Groningen, Groningen.
    Kosaraju, K. C.
    Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, USA.
    Schuitema, G.
    College of Business, University College Dublin, Dublin, Ireland.
    Lemmen, N. H.
    University of Groningen, Groningen.
    Johnson-Zawadzki, S.
    University of Groningen, Groningen.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Steg, L.
    University of Groningen, Groningen.
    Scherpen, J. M. A.
    University of Groningen, Groningen.
    Distributed Control of DC Grids: Integrating Prosumers' Motives2022In: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 37, no 4, p. 3299-3310Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel distributed control strategy addressing a (feasible) psycho-social-physical welfare problem in islanded Direct Current (DC) smart grids is proposed. Firstly, we formulate a (convex) optimization problem that allows prosumers to share current with each other, taking into account the technical and physical aspects and constraints of the grid (e.g., stability, safety), as well as psycho-social factors (i.e., prosumers' personal values). Secondly, we design a controller whose (unforced) dynamics represent the continuous time primal-dual dynamics of the considered optimization problem. Thirdly, a passive interconnection between the physical grid and the controller is presented. Global asymptotic convergence of the closed-loop system to the desired steady-state is proved and simulations based on collected data on psycho-social aspects illustrate and confirm the theoretical results.

  • 40.
    da Silva, Joakim M. B.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Skouroumounis, C.
    Krikidis, I.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Research, Stockholm, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Energy-efficient full-duplex networks2020In: Green Communications for Energy-Efficient Wireless Systems and Networks, Institution of Engineering and Technology , 2020, p. 331-362Chapter in book (Other academic)
  • 41.
    Daei, Sajad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Razavikia, Saeed
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Kountouris, Marios
    Communication Systems Department, EURECOM, 06410 Sophia Antipolis, France.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Research, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Blind Asynchronous Goal-Oriented Detection for Massive Connectivity2023In: 2023 21st International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2023, Institute of Electrical and Electronics Engineers Inc. , 2023, p. 167-174Conference paper (Refereed)
    Abstract [en]

    Resource allocation and multiple access schemes are instrumental for the success of communication networks, which facilitate seamless wireless connectivity among a growing population of uncoordinated and non-synchronized users. In this paper, we present a novel random access scheme that addresses one of the most severe barriers of current strategies to achieve massive connectivity and ultra reliable and low latency communications for 6G. The proposed scheme utilizes wireless channels’ angular continuous group-sparsity feature to provide low latency, high reliability, and massive access features in the face of limited time-bandwidth resources, asynchronous transmissions, and preamble errors. Specifically, a reconstruction-free goal oriented optimization problem is proposed which preserves the angular information of active devices and is then complemented by a clustering algorithm to assign active users to specific groups. This allows to identify active stationary devices according to their line of sight angles. Additionally, for mobile devices, an alternating minimization algorithm is proposed to recover their preamble, data, and channel gains simultaneously, enabling the identification of active mobile users. Simulation results show that the proposed algorithm provides excellent performance and supports a massive number of devices. Moreover, the performance of the proposed scheme is independent of the total number of devices, distinguishing it from other random access schemes. The proposed method provides a unified solution to meet the requirements of machine-type communications and ultra reliable and low latency communications, making it an important contribution to the emerging 6G networks.

  • 42.
    Delcourt, Marguerite
    et al.
    Ecole Polytech Fed Lausanne, Dept Comp Sci, CH-1015 Lausanne, Switzerland..
    Shereen, Ezzeldin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Dán, György
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Le Boudec, Jean-Yves
    Ecole Polytech Fed Lausanne, Sch Comp & Commun Sci I&C, CH-1015 Lausanne, Switzerland..
    Paolone, Mario
    Ecole Polytech Fed Lausanne, Inst Elect Engn, CH-1015 Lausanne, Switzerland..
    Time-Synchronization Attack Detection in Unbalanced Three-Phase Systems2021In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 12, no 5, p. 4460-4470Article in journal (Refereed)
    Abstract [en]

    Phasor measurement units (PMU) rely on an accurate time-synchronization to phase-align the phasors and timestamp the voltage and current phasor measurements. Among the symmetrical components computed from the phasors in three-phase systems, the standard practice only uses the direct-sequence component for state estimation and bad data detection (BDD). Time-synchronization attacks (TSAs) can compromise the measured phasors and can, thus, significantly alter the state estimate in a manner that is undetectable by widely used power-system BDD algorithms. In this paper we investigate the potential of utilizing the three-phase model instead of the direct-sequence model for mitigating the vulnerability of state estimation to undetectable TSAs. We show analytically that if the power system is unbalanced then the use of the three-phase model as input to BDD algorithms enables to detect attacks that would be undetectable if only the direct-sequence model was used. Simulations performed on the IEEE 39-bus benchmark using real load profiles recorded on the grid of the city of Lausanne confirm our analytical results. Our results provide a new argument for the adoption of three-phase models for BDD, as their use is a simple, yet effective measure for reducing the vulnerability of PMU measurements to TSAs.

  • 43. Di Fatta, G.
    et al.
    Liotta, A.
    Agoulmine, N.
    Agrawal, G.
    Berthold, M. R.
    Bordini, R. H.
    Borgelt, C.
    Boutaba, R.
    Calzarossa, M. C.
    Cannataro, M.
    Choudhary, A.
    Cortes, U.
    Dagiuklas, T.
    De Turck, F.
    De Vleeschauwer, B.
    Demestichas, P.
    Dhoedt, B.
    Festor, O.
    Fortino, G.
    Friderikos, V.
    Giunchiglia, F.
    Gravier, C.
    Guo, Y.
    Hunter, D.
    Karypis, G.
    Krishnaswamy, S.
    Limam, N.
    Medhi, D.
    Merani, M. L.
    Nürnberger, A.
    Pardede, E.
    Parthasarathy, S.
    Gaspary, L. P.
    Ranc, D.
    Sivakumar, K.
    Stadler, Rolf
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Stiller, B.
    Strassner, J.
    Syed, A.
    Talia, D.
    Urso, M. A.
    Van Der Meer, S.
    Wolff, R.
    Granville, L. Z.
    Preface2011In: IEEE International Conference on Data Mining. Proceedings, ISSN 1550-4786, p. xlviii-xlvix, article id 6137551Article in journal (Refereed)
  • 44.
    Du, Rong
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Optimal Networking in Wirelessly Powered Sensor Networks2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless sensor networks (WSNs) are nowadays widely used for the long-term monitoring of small or large regions, such as lakes, forests, cities, and industrial areas. The performance of a WSN typically consists of two aspects: i) the monitoring performance, e.g., the accuracy and the timeliness of the measurements or estimations produced by the sensor nodes of the WSN; and ii) the lifetime, i.e., how long the WSN can sustain such a performance. Naturally, we would like to have the monitoring performance as good as possible, and the lifetime as long as possible. However, in traditional WSNs, the sensor nodes generally have limited resources, especially in terms of battery capacity. If the nodes make measurements and report them frequently for a good monitoring performance, they drain their batteries and  this leads to a severely shortened network lifetime. Conversely, the sensors can have a longer lifetime by sacrificing the monitoring performance. It shows the inherent trade-off between the monitoring performance and the lifetime in WSNs.

    We can overcome the limitations of the trade-off described above by wireless energy transfer (WET), where we can provide the sensor nodes with additional energy remotely. The WSNs with WET are called wirelessly powered sensor networks (WPSNs). In a WPSN, dedicated energy sources, e.g., static base stations or mobile chargers, transmit energy via radio frequency (RF) waves to the sensor nodes. The nodes can store the energy in their rechargeable batteries and use it later when it is needed. In so doing, they can use more energy to perform the sensing tasks. Thus, WET is a solution to improve the monitoring performance and lifetime at the same time.  As long as the nodes receive more energy than they consume, it is possible that the WSN be immortal, which is impossible in traditional WSNs. 

    Although WPSNs can potentially break the trade-off between monitoring performance and lifetime, they also bring many fundamental design and performance analysis challenges. Due to the safety issues, the power that the dedicated energy sources can use is limited. The propagation of the RF waves suffers high path losses. Therefore, the energy received by the sensor nodes is much less than the energy transmitted from the sources. As a result, to have a good WSN performance, we should optimize the energy transmission on the energy source side and the energy consumption on the nodes side. Compared to the traditional WSN scenarios where we can only optimize the sensing and data communication strategies, in WPSNs, we have an additional degree of freedom, i.e., the optimization of the energy transmission strategies. This aspect brings new technical challenges and problems that have not been studied in the traditional WSNs. Several novel research questions arise, such as when and how to transmit the energy, and which energy source should transmit. Such questions are not trivial especially when we jointly consider the energy consumption part.

    This thesis contributes to answer the questions above. It consists of three contributions as follows.

    In the first contribution, we consider a WPSN with single energy base stations (eBS) and multiple sensor nodes to monitor several separated areas of interest. The eBS has multiple antennas, and it uses energy beamforming to transmit energy to the nodes. Notice that, if we deploy multiple sensor nodes at the same area, these nodes may receive the energy from the eBS at the same time and they can reduce the energy consumption by applying sleep/awake mechanism. Therefore, we jointly study the deployment of the nodes, the energy transmission of the eBS, and the node activation. The problem is an integer optimization, and we decouple the problem into a node deployment problem and a scheduling problem. We provide a greedy-based algorithm to solve the problem, and show its performance in terms of optimality.

    The second contribution of the thesis starts by noticing that wireless channel state information (CSI) is important for energy beamforming. The more energy that an eBS spends in channel acquisition, the more accurate CSI it will have, thus improving the energy beamforming performance. However, if the eBS spends too much energy on channel acquisition, it will have less energy for WET, which might reduce the energy that is received by the sensor nodes. We thus investigate how much energy the eBS should spend in channel acquisition, i.e., we study the power allocation problem in channel acquisition and energy beamforming for WPSNs. We consider the general optimal channel acquisition and show that the problem is non-convex. Based on the idea of bisection search, we provide an algorithm to find the optimal solution for the single eBS cases, and a closed-form solution for the case where the eBS uses orthogonal pilot transmission, least-square channel estimation, and maximum ratio transmission for WET. The simulations show that the algorithm converges fast, and the performance is close to the theoretical upper bound.

    In the third contribution, we consider a joint energy beamforming and data routing problem for WPSNs. More specifically, we investigate the WPSNs consisting of multiple eBSs, multiple sensor nodes, and a sink node. Based on the received energy, the sensor nodes need to decide how to route their data. The problem aims at maximizing the minimum sensing rate of the sensor nodes while guaranteeing that the received energy of each node is no less than that is consumed. Such a problem is non-convex, and we provide a centralized solution algorithm based on a semi-definite programming transformation. We extend this approach with a distributed algorithm using alternating direction method of multipliers (ADMM). We prove that the centralized algorithm achieves the optimal energy beamforming and routing, and we show by simulation that the distributed one converges to the optimal solution. Additionally, for the cases where the energy beamforming options are pre-determined, we study the problem of finding the energy that should be spent on each vector. We observe that, if the pre-determined beamforming options are chosen wisely, their performance is close to the optimal.

    The results of the thesis show that WET can prolong the lifetime of WSNs, and even make them work sufficiently long for general monitoring applications. More importantly, we should optimize the WPSN by considering both the energy provision and the energy consumption part. The studies of the thesis have the potential to be used in many Internet of Things (IoT) systems in smart cities, such as water distribution lines and building monitoring.

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  • 45.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Power Allocation for Channel Estimation and EnergyBeamforming in Wirelessly Powered Sensor Networks2018In: Proceedings of IEEE International Conference on Communications Workshops, 2018Conference paper (Refereed)
    Abstract [en]

    Wirelessly powered sensor networks (WPSNs) are becoming increasingly important to monitor many internet-of-things systems. In these WPSNs, dedicated base stations (BSs) with multiple antennas charge the sensor nodes without the need of replacing their batteries thanks to two essential procedures: i)  getting of the channel state information of the nodes by sending pilots, and based on this, ii) performing energy beamforming to transmit energy to the nodes. However, the BSs have limited power budget and thus these two procedures are not independent, contrarily to what  is assumed in some previous studies. In this paper, we investigate the novel problem of how to optimally allocate the power for channel estimation and energy transmission. Although the problem is non-convex, we provide a new solution approach and a performance analysis in terms of optimality and complexity. We also provide a closed form solution for the case where the channels are estimated based on a least square estimation. The simulations show a gain of approximately 10% in allocating the power optimally, and the importance of improving the channel estimation efficiency.

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  • 46.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Poster: On the immortality of wireless sensor networks by wireless energy transfer — a node deployment perspective2017In: International Conference on Embedded Wireless Systems and Networks, Junction Publishing , 2017, p. 206-207Conference paper (Refereed)
    Abstract [en]

    The lifetime of wireless sensor networks (WSNs) can be substantially extended by transferring energy wirelessly to the sensor nodes. In this poster, a wireless energy transfer (WET) enabled WSN is presented, where a base station transfers energy wirelessly to the sensor nodes that are deployed in several regions of interest, to supply them with energy to sense and to upload data. The WSN lifetime can be extended by deploying redundant sensor nodes, which allows the implementation of duty-cycling mechanisms to reduce nodes’ energy consumption. In this context, a problem on sensor node deployment naturally arises, where one needs to determine how many sensor nodes to deploy in each region such that the total number of nodes is minimized, and the WSN is immortal. The problem is formulated as an integer optimization, whose solution is challenging due to the binary decision variables and a non-linear constraint. A greedybased algorithm is proposed to achieve the optimal solution of such deployment problem. It is argued that such scheme can be used in monitoring systems in smart cities, such as smart buildings and water lines. 

  • 47.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Gkatzikis, Lazaros
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    On Maximizing Sensor Network Lifetime by Energy Balancing2018In: IEEE Transactions on Control of Network Systems, E-ISSN 2325-5870, Vol. 5, no 3Article in journal (Refereed)
    Abstract [en]

    Many physical systems, such as water/electricity distribution networks, are monitored by battery-powered wireless-sensor networks (WSNs). Since battery replacement of sensor nodes is generally difficult, long-term monitoring can be only achieved if the operation of the WSN nodes contributes to long WSN lifetime. Two prominent techniques to long WSN lifetime are 1) optimal sensor activation and 2) efficient data gathering and forwarding based on compressive sensing. These techniques are feasible only if the activated sensor nodes establish a connected communication network (connectivity constraint), and satisfy a compressive sensing decoding constraint (cardinality constraint). These two constraints make the problem of maximizing network lifetime via sensor node activation and compressive sensing NP-hard. To overcome this difficulty, an alternative approach that iteratively solves energy balancing problems is proposed. However, understanding whether maximizing network lifetime and energy balancing problems are aligned objectives is a fundamental open issue. The analysis reveals that the two optimization problems give different solutions, but the difference between the lifetime achieved by the energy balancing approach and the maximum lifetime is small when the initial energy at sensor nodes is significantly larger than the energy consumed for a single transmission. The lifetime achieved by energy balancing is asymptotically optimal, and that the achievable network lifetime is at least 50% of the optimum. Analysis and numerical simulations quantify the efficiency of the proposed energy balancing approach.

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  • 48.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. KTH Royal Inst Technol, Div Network & Syst Engn, Stockholm, Sweden..
    Magnusson, Sindri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    The Internet of Things as a Deep Neural Network2020In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 58, no 9, p. 20-25Article in journal (Refereed)
    Abstract [en]

    An important task in the Internet of Things (IoT) is field monitoring, where multiple IoT nodes take measurements and communicate them to the base station or the cloud for processing, inference, and analysis. When the measurements are high-dimensional (e.g., videos or time-series data), IoT networks with limited bandwidth and low-power devices may not be able to support such frequent transmissions with high data rates. To ensure communication efficiency, this article proposes to model the measurement compression at IoT nodes and the inference at the base station or cloud as a deep neural network (DNN). We propose a new framework where the data to be transmitted from nodes are the intermediate outputs of a layer of the DNN. We show how to learn the model parameters of the DNN and study the trade-off between the communication rate and the inference accuracy. The experimental results show that we can save approximately 96 percent transmissions with only a degradation of 2.5 percent in inference accuracy, which shows the potentiality to enable many new IoT data analysis applications that generate a large amount of measurements.

  • 49.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Ozcelikkale, Ayca
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Xiao, Ming
    Towards Immortal Wireless Sensor Networks by Optimal Energy Beamforming and Data Routing2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 8, p. 5338-5352Article in journal (Refereed)
    Abstract [en]

    The lifetime of a wireless sensor network (WSN) determines how long the network can be used to monitor the area of interest. Hence, it is one of the most important performance metrics for WSN. The approaches used to prolong the lifetime can be briefly divided into two categories: reducing the energy consumption, such as designing an efficient routing, and providing extra energy, such as using wireless energy transfer (WET) to charge the nodes. Contrary to the previous line of work where only one of those two aspects is considered, we investigate these two together. In particular, we consider a scenario where dedicated wireless chargers transfer energy wirelessly to sensors. The overall goal is to maximize the minimum sampling rate of the nodes while keeping the energy consumption of each node smaller than the energy it receives. This is done by properly designing the routing of the sensors and the WET strategy of the chargers. Although such a joint routing and energy beamforming problem is non-convex, we show that it can be transformed into a semi-definite optimization problem (SDP). We then prove that the strong duality of the SDP problem holds, and hence the optimal solution of the SDP problem is attained. Accordingly, the optimal solution for the original problem is achieved by a simple transformation. We also propose a low-complexity approach based on pre-determined beamforming directions. Moreover, based on the alternating direction method of multipliers (ADMM), the distributed implementations of the proposed approaches are studied. The simulation results illustrate the significant performance improvement achieved by the proposed methods. In particular, the proposed energy beamforming scheme significantly out-performs the schemes where one does not use energy beamforming, or one does not use optimized routing. A thorough investigation of the effect of system parameters, including the number of antennas, the number of nodes, and the number of chargers, on the system performance is provided. The promising convergence behaviour of the proposed distributed approaches is illustrated.

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  • 50.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Santi, Paolo
    Department of Urban Studies and Planning, MIT Senseable City Laboratory, Cambridge, MA, USA.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Vasilakos, Athanasios
    Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    The sensable city: A survey on the deployment and management for smart city monitoring2019In: IEEE Communications Surveys and Tutorials, E-ISSN 1553-877X, Vol. 21, no 2, p. 1533-1560Article in journal (Refereed)
    Abstract [en]

    In last two decades, various monitoring systems have been designed and deployed in urban environments, toward the realization of the so called smart cities. Such systems are based on both dedicated sensor nodes, and ubiquitous but not dedicated devices such as smart phones and vehicles' sensors. When we design sensor network monitoring systems for smart cities, we have two essential problems: node deployment and sensing management. These design problems are challenging, due to large urban areas to monitor, constrained locations for deployments, and heterogeneous type of sensing devices. There is a vast body of literature from different disciplines that have addressed these challenges. However, we do not have yet a comprehensive understanding and sound design guidelines. This paper addresses such a research gap and provides an overview of the theoretical problems we face, and what possible approaches we may use to solve these problems. Specifically, this paper focuses on the problems on both the deployment of the devices (which is the system design/configuration part) and the sensing management of the devices (which is the system running part). We also discuss how to choose the existing algorithms in different type of monitoring applications in smart cities, such as structural health monitoring, water pipeline networks, traffic monitoring. We finally discuss future research opportunities and open challenges for smart city monitoring.

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