1. |
- Zhang, Kewei, et al.
(author)
-
Protecting GNSS Open Service-Navigation Message Authentication against Distance-Decreasing Attacks
-
Other publication (other academic/artistic)abstract
- As the security of global navigation satellite systems (GNSS) for civilian usage is increasingly important, navigation message authentication (NMA) significantly improves resilience to spoofing attacks. However, not all attacks can be effectively countered: a strong variant of replay/relay attacks, distance-decreasing (DD) attacks, can shorten pseudorange measurements, without manipulating the cryptographically protected navigation message, thus manipulating the position, velocity, and time solution undetected. First, we discuss how DD attacks can tamper with GNSS signals, demonstrating the attack effectiveness on a recorded Galileo signal. DD attacks might introduce bit errors to the forged signals, but the adversary can keep this error rate very low with proper attack parameter settings. Then, based on our mathematical model of the prompt correlator output of the tracking phase at the victim receiver, we find that the correlator output distribution changes in the presence of DD attacks. This leads us to apply hypothesis testing to detect DD attacks, notably a Goodness of Fit (GoF) test and a generalized likelihood ratio test (GLRT), depending on the victim’s knowledge on the DD attacks. Monte Carlo simulations are used to evaluate the detection probability and the receiver operating characteristic (ROC) curves for two tests, for different adversary configuration and noise settings. Then, we evaluate the effectiveness of the GoF and GLRT tests with a synthesized DD signal. Both tests can detect DD attacks with similar performance in high signal-to-noise ratio (SNR) environments. The GLRT detection probability is approximately 20% higher than that of the GoF test in low SNR environments.
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2. |
- Blanch, Krister, 1991
(author)
-
Beyond-application datasets and automated fair benchmarking
- 2023
-
Licentiate thesis (other academic/artistic)abstract
- Beyond-application perception datasets are generalised datasets that emphasise the fundamental components of good machine perception data. When analysing the history of perception datatsets, notable trends suggest that design of the dataset typically aligns with an application goal. Instead of focusing on a specific application, beyond-application datasets instead look at capturing high-quality, high-volume data from a highly kinematic environment, for the purpose of aiding algorithm development and testing in general. Algorithm benchmarking is a cornerstone of autonomous systems development, and allows developers to demonstrate their results in a comparative manner. However, most benchmarking systems allow developers to use their own hardware or select favourable data. There is also little focus on run time performance and consistency, with benchmarking systems instead showcasing algorithm accuracy. By combining both beyond-application dataset generation and methods for fair benchmarking, there is also the dilemma of how to provide the dataset to developers for this benchmarking, as the result of a high-volume, high-quality dataset generation is a significant increase in dataset size when compared to traditional perception datasets. This thesis presents the first results of attempting the creation of such a dataset. The dataset was built using a maritime platform, selected due to the highly dynamic environment presented on water. The design and initial testing of this platform is detailed, as well as as methods of sensor validation. Continuing, the thesis then presents a method of fair benchmarking, by utilising remote containerisation in a way that allows developers to present their software to the dataset, instead of having to first locally store a copy. To test this dataset and automatic online benchmarking, a number of reference algorithms were required for initial results. Three algorithms were built, using the data from three different sensors captured on the maritime platform. Each algorithm calculates vessel odometry, and the automatic benchmarking system was utilised to show the accuracy and run-time performance of these algorithms. It was found that the containerised approach alleviated data management concerns, prevented inflated accuracy results, and demonstrated precisely how computationally intensive each algorithm was.
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3. |
- Jang, Jeong Keun, et al.
(author)
-
Area-efficient scheduling scheme based FFT processor for various OFDM systems
- 2018
-
In: 2018 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS 2018). - : IEEE. - 9781538682401 ; , s. 338-341
-
Conference paper (other academic/artistic)abstract
- This paper presents an area-efficient fast Fouriertransform (FFT) processor for orthogonal frequency-division multiplexing systems based on multi-path delay commutator architecture. This paper proposes a data scheduling scheme to reduce the number of complex constant multipliers. The proposed mixed-radix multi-path delay commutator FFT processor can support 128-, 256-, and 512-point FFT sizes. The proposed processor was synthesized using the Samsung 65-nm CMOS standard cell library. The proposed processor with eight parallel data paths can achieve a high throughput rate of up to 2.64 GSample/s at 330 MHz.
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4. |
- Bengtsson, Lars, 1963
(author)
-
Mikrodatorteknik
- 1995
-
Book (other academic/artistic)abstract
- Första delen behandlar Microchips "Base-line"-kretsar och andra delen behandlar "Midrange"-kretsarna. De flesta funktioner belyses med konstruktionsexempel. Exempel och övningar är mycket hårdvarunära och boken behandlar konstruktion av mikrodatorer från grunden. Boken är avsedd för kurser i mikrodatorteknik på högskolan eller annan högre teknisk utbildning, men kan även användas som självstudiematerial eftersom de flesta exempel ges med detaljerade och verifierade lösningar av såväl hård- som mjukvaran. Tidigare erfarenhet av assemblerprogrammering är inte nödvändig men grundläggande kunskaper i digitalteknik förutsätts. Boken kan med fördel också läsas av rutinerade assemblerprogrammerare som vill veta hur prestanda hos de nya RISC-baserade PIC-controllerna står sig i konkurrensen med de mer etablerade enchipscontrollerna, t ex HC11 och 8751, som bygger på traditionell CISC-arkitektur.
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5. |
- Gülgün, Ziya, et al.
(author)
-
Multiple Spoofer Detection for Mobile GNSS Receivers Using Statistical Tests
- 2021
-
In: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 9, s. 166382-166394
-
Journal article (peer-reviewed)abstract
- We consider Global Navigation Satellite Systems (GNSS) spoofing attacks and devise a countermeasure appropriate for mobile GNSS receivers. Our approach is to design detectors that, operating after the signal acquisition, enable the victim receiver to determine with high probability whether it is under a spoofing attack or not. Namely, the binary hypothesis is that either the GNSS receiver tracks legitimate satellite signals, H-0, or spoofed signals, H-1. We assume that there exists an unknown number of multiple spoofers in the environment and the attack strategy (which legitimate signals are spoofed by which spoofers) is not known to the receiver. Based on these assumptions, we propose an algorithm that identifies the number of spoofers and clusters the spoofing data by using Bayesian information criterion (BIC) rule. Depending on the estimated and clustered data we propose a detector, called as generalized likelihood ratio (GLRT)-like detector. We compare the performance of the GLRT-like detector with a genie-aided detector in which the attack strategy and the number of spoofers is known by the receiver. In addition to this, we extend the GLRT-like detector for the case where the noise variance is also unknown and present the performance results.
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6. |
- Yanggratoke, Rerngvit, 1983-
(author)
-
Data-driven Performance Prediction and Resource Allocation for Cloud Services
- 2016
-
Doctoral thesis (other academic/artistic)abstract
- Cloud services, which provide online entertainment, enterprise resource management, tax filing, etc., are becoming essential for consumers, businesses, and governments. The key functionalities of such services are provided by backend systems in data centers. This thesis focuses on three fundamental problems related to management of backend systems. We address these problems using data-driven approaches: triggering dynamic allocation by changes in the environment, obtaining configuration parameters from measurements, and learning from observations. The first problem relates to resource allocation for large clouds with potentially hundreds of thousands of machines and services. We developed and evaluated a generic gossip protocol for distributed resource allocation. Extensive simulation studies suggest that the quality of the allocation is independent of the system size for the management objectives considered.The second problem focuses on performance modeling of a distributed key-value store, and we study specifically the Spotify backend for streaming music. We developed analytical models for system capacity under different data allocation policies and for response time distribution. We evaluated the models by comparing model predictions with measurements from our lab testbed and from the Spotify operational environment. We found the prediction error to be below 12% for all investigated scenarios.The third problem relates to real-time prediction of service metrics, which we address through statistical learning. Service metrics are learned from observing device and network statistics. We performed experiments on a server cluster running video streaming and key-value store services. We showed that feature set reduction significantly improves the prediction accuracy, while simultaneously reducing model computation time. Finally, we designed and implemented a real-time analytics engine, which produces model predictions through online learning.
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7. |
- Zhang, Kewei
(author)
-
Secure GNSS-based Positioning and Timing : Distance-Decreasing attacks, fault detection and exclusion, and attack detection with the help of opportunistic signals
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- With trillions of devices connected in large scale systems in a wired or wireless manner, positioning and synchronization become vital. Global Navigation Satellite System (GNSS) is the first choice to provide global coverage for positioning and synchronization services. From small mobile devices to aircraft, from intelligent transportation systems to cellular networks, and from cargo tracking to smart grids, GNSS plays an important role, thus, requiring high reliability and security protection. However, as GNSS signals propagate from satellites to receivers at distance of around 20 000 km, the signal power arriving at the receivers is very low, making the signals easily jammed or overpowered. Another vulnerability stems from that civilian GNSS signals and their specifications are publicly open, so that anyone can craft own signals to spoof GNSS receivers: an adversary forges own GNSS signals and broadcasts them to the victim receiver, to mislead the victim into believing that it is at an adversary desired location or follows a false trajectory, or adjusts its clock to a time dictated by the adversary. Another type of attack is replaying GNSS signals: an adversary transmits a pre-recorded GNSS signal stream to the victim receiver, so that the receiver calculates an erroneous position and time. Recent incidents reported in press show that the GNSS functionalities in a certain area, e.g., Black Sea, have been affected by cyberattacks composed of the above-mentioned attack types. This thesis, thus, studies GNSS vulnerabilities and proposes detection and mitigation methods for GNSS attacks, notably spoofing and replay attacks. We analyze the effectiveness of one important and powerful replay attack, the so-called Distance-decreasing (DD) attacks that were previously investigated for wireless communication systems, on GNSS signals. DD attacks are physical layer attacks, targeting time-of-flight ranging protocols, to shorten the perceived as measured distance between the transmitter and receiver. The attacker first transmits an adversary-chosen data bit to the victim receiver before the signal arrives at the attacker; upon receipt of the GNSS signal, the attacker estimates the data bit based on the early fraction of the bit period, and then switches to transmitting the estimate to the victim receiver. Consequently, the DD signal arrives at the victim receiver earlier than the genuine GNSS signals would have, which in effect shortens the pseudorange measurement between the sender (satellite) and the victim receiver, consequently, affecting the calculated position and time of the receiver. We study how the DD attacks affect the bit error rate (BER) of the received signals at the victim, and analyze its effectiveness, that is, the ability to shorten pseudorange measurements, on different GNSS signals. Several approaches are considered for the attacker to mount a DD attack with high probability of success (without being detected) against a victim receiver, for cryptographically unprotected and protected signals. We analyze the tracking output of the DD signals at the victim receiver and propose a Goodness of Fit (GoF) test and a Generalized Likelihood Ratio Test (GLRT) to detect the attacks. The evaluation of the two tests shows that they are effective, with the result being perhaps more interesting when considering DD attacks against Galileo signals that can be cryptographically protected. Moreover, this thesis investigates the feasibility of validating the authenticity of the GNSS signals with the help of opportunistic signals, which is information readily available in modern communication environments, e.g., 3G, 4G and WiFi. We analyze the time synchronization accuracy of different technologies, e.g., Network Time Protocol (NTP), WiFi and local oscillator, as the basis for detecting a discrepancy with the GNSS-obtained time. Two detection approaches are proposed and one testbench is designed for the evaluation. A synthesized spoofing attack is used to verify the effectiveness of the approaches. Beyond attack detection, we develop algorithms to detect and exclude faulty signals, namely the Clustering-based Solution Separation Algorithm (CSSA) and the Fast Multiple Fault Detection and Exclusion (FM-FDE). They both utilize the redundant available satellites, more than the minimum a GNSS receiver needs for position and time offset calculation. CSSA adopts data clustering to group subsets of positions calculated with different subsets of available satellites. Basically, these positions, calculated with subsets not containing any faulty satellites, should be close to each other, i.e., in a dense area; otherwise they should be scattered. FM-FDE is a more efficient algorithm that uses distances between positions, calculated with fixed-size subsets, as test statistics to detect and exclude faulty satellite signals. As the results show, FM-FDE runs faster than CSSA and other solution-separation fault detection and exclusion algorithms while remaining equally effective.
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8. |
- Chen, Jiajia
(author)
-
5G Transport networks : Capacity, latency and cost (invited)
- 2019
-
In: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209 ; Part F133-Networks 2019
-
Conference paper (peer-reviewed)abstract
- This paper summarizes recent research on 5G transport networks addressing challenges on capacity, service migration and techno-economics that are brought by 5G new attributes, e.g., cloud radio access networks, diverse usage scenarios and heterogeneous deployments.
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9. |
- Khan, Muhammad Sikandar Lal, 1988-
(author)
-
Presence through actions : theories, concepts, and implementations
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- During face-to-face meetings, humans use multimodal information, including verbal information, visual information, body language, facial expressions, and other non-verbal gestures. In contrast, during computer-mediated-communication (CMC), humans rely either on mono-modal information such as text-only, voice-only, or video-only or on bi-modal information by using audiovisual modalities such as video teleconferencing. Psychologically, the difference between the two lies in the level of the subjective experience of presence, where people perceive a reduced feeling of presence in the case of CMC. Despite the current advancements in CMC, it is still far from face-to-face communication, especially in terms of the experience of presence.This thesis aims to introduce new concepts, theories, and technologies for presence design where the core is actions for creating presence. Thus, the contribution of the thesis can be divided into a technical contribution and a knowledge contribution. Technically, this thesis details novel technologies for improving presence experience during mediated communication (video teleconferencing). The proposed technologies include action robots (including a telepresence mechatronic robot (TEBoT) and a face robot), embodied control techniques (head orientation modeling and virtual reality headset based collaboration), and face reconstruction/retrieval algorithms. The introduced technologies enable action possibilities and embodied interactions that improve the presence experience between the distantly located participants. The novel setups were put into real experimental scenarios, and the well-known social, spatial, and gaze related problems were analyzed.The developed technologies and the results of the experiments led to the knowledge contribution of this thesis. In terms of knowledge contribution, this thesis presents a more general theoretical conceptual framework for mediated communication technologies. This conceptual framework can guide telepresence researchers toward the development of appropriate technologies for mediated communication applications. Furthermore, this thesis also presents a novel strong concept – presence through actions - that brings in philosophical understandings for developing presence- related technologies. The strong concept - presence through actions is an intermediate-level knowledge that proposes a new way of creating and developing future 'presence artifacts'. Presence- through actions is an action-oriented phenomenological approach to presence that differs from traditional immersive presence approaches that are based (implicitly) on rationalist, internalist views.
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10. |
- Åkerberg, Johan, et al.
(author)
-
Design challenges and objectives in industrial wireless sensor networks
- 2017
-
In: Industrial Wireless Sensor Networks: Applications, Protocols, and Standards. - Boca Raton : CRC Press. - 9781466500525 - 9781466500518 ; , s. 79-100
-
Book chapter (other academic/artistic)abstract
- In recent years the advances in wireless sensor networks have grown exponentially and WSNs have been deployed in diverse application areas such as agriculture, disaster management, intelligent transport systems, and industrial automation. In industrial automation, wireless sensor networks have so far mostly been considered within building automation, factory automation, and process automation in order to save cost in cable reduction and maintenance but also improved flexibility [14]. Recently, wireless sensor networks for smart grid applications have been discussed. Several market forecasts have recently predicted exponential growths in the sensor market over the next few years, resulting in a multi-billion dollar market in the near future. For instance, ABI research [18] predicts that in 2015 around 645 million IEEE 802.15.4 chipsets will be shipped and that the worldwide market for automation systems in process industries will grow to roughly $150 billion.
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11. |
- Bengtsson, Lars, 1963
(author)
-
Embedded FPGA systems : VHDL programming and soft CPU systems
- 2018
-
Book (other academic/artistic)abstract
- This textbook introduces the reader to VHDL which is a Hardware Description Language, i.e. a means to describe digital electronic circuits in a text editor and how to compile this text into electronics. The first part is concluded by writing VHDL code for a simple CPU (a "soft CPU"). In the second part, a commercial soft CPU is downloaded to the FPGA target circuit and programmed in C.
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12. |
- Bengtsson, Lars, 1963
(author)
-
Embedded Measurement Systems
- 2013
-
Doctoral thesis (other academic/artistic)abstract
- The subject of Embedded Measurement Systems (EMS) is the merging of embedded systems and electrical measurement systems. This indicates that EMSs are hardware-software systems dedicated to measuring one or a few physical quantities. Applications are numerous; EMSs measure the temperature in refrigerators, freezers, irons, ovens and automobile combustion engines, they sense vibrations in tilt alarms and game consoles, they measure airflow in engines and ventilation systems, they measure shock impact in crash detectors and are used as shock and temperature loggers for transport goods, they measure air pressure in airplane cabins, humidity in air-conditioned environments, they measure liquid levels in fuel tanks, they detect smoke in fire alarms, they measure the viscosity of lubricant oil in engines, they measure the rotation speed of spinning wheels (in any engine), they measure torque in engines and are used as heart rate and ECG detectors in medicine etc. The commercial demand for ever cheaper products and worldwide environmental legislations force vendors to continuously look for more cost-efficient and less power-consuming solutions for their embedded measurement systems. This thesis is concerned most of all with the implementation of cost-efficient/low-power measurement systems in embedded controllers. This includes some novel ideas in voltage, time and resistance measurements with embedded controllers and it will demonstrate how these quantities, analog in nature, can be measured accurately and precisely by inherently digital embedded controllers.
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13. |
- Bengtsson, Lars, 1963
(author)
-
RISC-baserad 50 MHz räknare med alfanumerisk display
- 1995
-
In: Allt om elektronik. ; 6, s. 35-37
-
Journal article (other academic/artistic)abstract
- Denna artikel presenterar en konstruktion som använder en RISC-kontroller (PIC16C54) som frekvensräknare. Frekvensen räknas på controllerns RTCC-ingång och signalfrekvensen, uttryckt i kHz visas på en alfanumerisk display.
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14. |
- Bengtsson, Lars, 1963
(author)
-
Single-Chip Implementation of Level-Crossing ADC for ECG sampling
- 2017
-
In: Journal of Electrical & Electronic Systems. - : OMICS Publishing Group. - 2332-0796. ; 6:1
-
Journal article (peer-reviewed)abstract
- This work demonstrates for the first time the implementation of a level-crossing analog-to-digital converter (LC-ADC) in a single, commercially available IC (that costs less than $2). The implementation utilizes adaptive threshold levels in order to prevent overload distortions for fast-changing signals. The entire design is based on a 20-pin PIC16F1769 microcontroller from Microchip and no external components are required. In fact, the only external circuitry required is a single jumper wire. This is due to the fact that the new generation of microcontrollers have integrated core-independent hardware, analog as well as digital. This design takes full advantage of the core-independent logic and analog blocks in a PIC16F17xx circuit to implement the LC-ADC technique that so far has required multiple-circuit designs or ASIC implementation. The design is demonstrated on a standard electrocardiogram (ECG) signal.
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15. |
- Di Orio, Giovanni, et al.
(author)
-
The PRIME Semantic Language: Plug and Produce in Standard- based Manufacturing Production Systems
- 2015
-
In: Proceedings of the Flexible Automation and Intelligent Manufacturing Conference.
-
Conference paper (other academic/artistic)abstract
- Nowadays manufacturing production systems are becoming more and more responsive in order to succeed in ahighly unstable environment. The capability of a production system to effectively and efficiently adapt and evolveto face the changing requirements – imposed by volatile and dynamic global markets – is a necessary conditionto enable manufacturing enterprises to be agile. Since the agility of a manufacturing enterprise is always limitedby the agility of its own building blocks than it needs to be spread over the whole enterprise including the operationand information technologies (OT/IT). Turning to production systems, one of the significant challenges isrepresented by the possibility to provide easy and rapid (re-)configuration of their internal components and/orprocesses. Innovative technologies and paradigms have been explored during the years that combined with theincreasing advancement in manufacturing technologies enable the implementation of the “plug and produce”paradigm. The “plug and produce” paradigm is the foundation of any agile production system, since to be agile itis inevitably required to reduce the installation and (re-)engineering activities time – changing/adapting the systemto new requirements – while promoting configuration rather than programming. Therefore, the “plug andproduce” paradigm is a necessary but not sufficient condition for implementing agile production systems. Modernproduction systems are typically known for their plethora of heterogeneous component/equipment. In this complexscenario, the implementation of the “plug and produce” paradigm implies the existence of a well-definedontological model to support components/equipment abstraction with the objective to allow interactions,collaboration and knowledge sharing between them. The PRIME semantic language specifies the semanticstructure for the knowledge models and overall system communication language.
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16. |
- Jiang, Yuning, 1993-
(author)
-
Vulnerability Analysis for Critical Infrastructures
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- The rapid advances in information and communication technology enable a shift from diverse systems empowered mainly by either hardware or software to cyber-physical systems (CPSs) that are driving Critical infrastructures (CIs), such as energy and manufacturing systems. However, alongside the expected enhancements in efficiency and reliability, the induced connectivity exposes these CIs to cyberattacks exemplified by Stuxnet and WannaCry ransomware cyber incidents. Therefore, the need to improve cybersecurity expectations of CIs through vulnerability assessments cannot be overstated. Yet, CI cybersecurity has intrinsic challenges due to the convergence of information technology (IT) and operational technology (OT) as well as the crosslayer dependencies that are inherent to CPS based CIs. Different IT and OT security terminologies also lead to ambiguities induced by knowledge gaps in CI cybersecurity. Moreover, current vulnerability-assessment processes in CIs are mostly subjective and human-centered. The imprecise nature of manual vulnerability assessment operations and the massive volume of data cause an unbearable burden for security analysts. Latest advances in machine-learning (ML) based cybersecurity solutions promise to shift such burden onto digital alternatives. Nevertheless, the heterogeneity, diversity and information gaps in existing vulnerability data repositories hamper accurate assessments anticipated by these ML-based approaches. Therefore, a comprehensive approach is envisioned in this thesis to unleash the power of ML advances while still involving human operators in assessing cybersecurity vulnerabilities within deployed CI networks.Specifically, this thesis proposes data-driven cybersecurity indicators to bridge vulnerability management gaps induced by ad-hoc and subjective auditing processes as well as to increase the level of automation in vulnerability analysis. The proposed methodology follows design science research principles to support the development and validation of scientifically-sound artifacts. More specifically, the proposed data-driven cybersecurity architecture orchestrates a range of modules that include: (i) a vulnerability data model that captures a variety of publicly accessible cybersecurity-related data sources; (ii) an ensemble-based ML pipeline method that self-adjusts to the best learning models for given cybersecurity tasks; and (iii) a knowledge taxonomy and its instantiated power grid and manufacturing models that capture CI common semantics of cyberphysical functional dependencies across CI networks in critical societal domains. This research contributes data-driven vulnerability analysis approaches that bridge the knowledge gaps among different security functions, such as vulnerability management through related reports analysis. This thesis also correlates vulnerability analysis findings to coordinate mitigation responses in complex CIs. More specifically, the vulnerability data model expands the vulnerability knowledge scope and curates meaningful contexts for vulnerability analysis processes. The proposed ML methods fill information gaps in vulnerability repositories using curated data while further streamlining vulnerability assessment processes. Moreover, the CI security taxonomy provides disciplined and coherent support to specify and group semanticallyrelated components and coordination mechanisms in order to harness the notorious complexity of CI networks such as those prevalent in power grids and manufacturing infrastructures. These approaches learn through interactive processes to proactively detect and analyze vulnerabilities while facilitating actionable insights for security actors to make informed decisions.
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17. |
- Al Nahas, Beshr, 1985, et al.
(author)
-
Low-power listening goes multi-channel
- 2014
-
In: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2014. ; , s. 2-9
-
Conference paper (peer-reviewed)abstract
- Exploiting multiple radio channels for communication has been long known as a practical way to mitigate interference in wireless settings. In Wireless Sensor Networks, however, multi-channel solutions have not reached their full potential: the MAC layers included in TinyOS or the Contiki OS for example are mostly single-channel. The literature offers a number of interesting solutions, but experimental results were often too few to build confidence. We propose a practical extension of low-power listening, MiCMAC, that performs channel hopping, operates in a distributed way, and is independent of upper layers of the protocol stack. The above properties make it easy to deploy in a variety of scenarios, without any extra configuration/scheduling/channel selection hassle. We implement our solution in Contiki and evaluate it in a 97-node~testbed while running a complete, out-of-the-box low-power IPv6 communication stack (UDP/RPL/6LoWPAN). Our experimental results demonstrate increased resilience to emulated WiFi interference (e.g., data yield kept above 90% when Contiki MAC drops in the 40% range). In noiseless environments, MiCMAC keeps the overhead low in comparison to Contiki MAC, achieving performance as high as 99% data yield along with sub-percent duty cycle and sub-second latency for a 1-minute inter-packet interval data collection. © 2014 IEEE.
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18. |
- Ribeiro, Luis, et al.
(author)
-
Industrial Agents for the Fast Deployment of Evolvable Assembly Systems
- 2015. - 1st ed.
-
In: Industrial Agents. - Amsterdam, Netherlands : Elsevier. - 9780128003411 ; , s. 301-321, s. 301-322
-
Book chapter (peer-reviewed)abstract
- The current manufacturing scenario is characterized by high market unpredictability. Agility is therefore a central challenge for modern companies that need to understand and be proactive towards their product offer in respect to “what is offered, when it is offered, where, how and by whom” (Brown & Bessant 2003).The “what” and the “when” are particularly relevant to the research in emerging paradigms as they account for variety, customization and volume; and timing, speed and seasonality (Brown & Bessant 2003).In this scenario, several design approaches and models have been proposed in the last decade to enable re-configurability and subsequently enhance the companies’ ability to adjust their offer in nature and time.From a paradigmatic point of view research has concentrated on the organizational structure of the shop-floor and the associated controls aspects. Concepts like Reconfigurable Manufacturing Systems (RMS) (Koren & Shpitalni 2010) and Fractal Factories (FF) (Montreuil 1999) support the physical construction of production systems by regulating their layout and making a few assumptions on their logical organization. On the other hand, concepts like Bionic Manufacturing Systems (BMS)(Ueda 1992), Holonic Manufacturing Systems (HMS)(Van Brussel et al. 1998), Evolvable Assembly Systems (Ribeiro et al. 2010) essentially provide the theoretical guidelines for the logical/computational organization of the system (see (Tharumarajah 1996) for a comparison between BMS, HMS and FF and (Setchi & Lagos 2004) for the rationale supporting the shift from Dedicated Lines to Flexible Manufacturing System and finally RMS).While these paradigms provide the conceptual framework and the main design guidelines their actual interpretation and implementation has led to a wider set of architectures (Monostori, Váncza & Kumara 2006; Leitão 2009; Parunak 2000; Pěchouček & Mařík 2008).These architectures align the high-level principles with the technological offer and limitations while seeking to address the re-configurability requirements of (Mehrabi, Ulsoy & Koren 2000; Rösiö & Säfsten 2013):module mobility – modules are easy and quick to move and install;“diagnosability” – it is quick to identify the sources of quality and reliability problems;“integrability” – modules are easy to integrate into the rest of the system.“convertibility” – it is easy and quick to switch between existing products and it is easy to adapt the system to future products;scalability – it is easy to enlarge and downsize the production system;“automatibility” – a dynamic level of automation is enabled;modularity – all system elements are designed to be modular;customization – the capability and flexibility of the production system is designed according to the products to be produced in the system.Instant deployment, as addressed in the present chapter directly addresses mobility, “integrability”, “convertibility”, scalability and customization. Mechatronic modularity is a prerequisite and is enforced by the proposed architecture and the considered modular design. “Diagnosability” was not specifically tackled.In this context, the chapter analyses the agent-based architecture related with the Instantly Deployable Evolvable Assembly System (IDEAS) project that is inspired by the Evolvable Assembly System (EAS) paradigm (Ribeiro et al. 2010) as a mechanism to enable fast deployment of mechatronic modules. EAS advocates the use of process-oriented modules and envisions the production system as a collection of processes and the associated interacting agents.The architecture and the related test cases are used to draw the main lessons learned in respect to technological and conceptual implications.In this context, the remainder of this text is organized as follows: section 1.1 discusses the main deployment challenges, section 1.2 details the reference architecture and associated concepts, section 1.3 presents the principal implementation decisions, section 1.4 features the main lessons learned, sections 1.5 discusses the benefits of the proposed approach and finally section 1.6 reflects on the main conclusions.
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19. |
- Rosenstatter, Thomas, 1992, et al.
(author)
-
Extending AUTOSAR's Counter-based Solution for Freshness of Authenticated Messages in Vehicles
- 2019
-
In: Proceedings of IEEE Pacific Rim International Symposium on Dependable Computing, PRDC. - 1541-0110. ; 2019-December, s. 1-109
-
Conference paper (peer-reviewed)abstract
- Nowadays vehicles have an internal network consisting of more than 100 microcontrollers, so-called Electronic Control Units (ECUs), which control core functionalities, active safety, diagnostics, comfort and infotainment. The Controller Area Network (CAN) bus is one of the most widespread bus technologies in use, and thus is a primary target for attackers. AUTOSAR, an open system platform for vehicles, introduced in version 4.3 SecOC Profile 3, a counter-based solution to provide freshness in authenticated messages to protect the system against replay attacks. In this paper, we analyse and assess this method regarding safety constraints and usability, and discuss design considerations when implementing such a system. Furthermore, we propose a novel security profile addressing the identified deficiencies which allows faster resynchronisation when only truncated counter values are transmitted. Finally, we evaluate our solution in an experimental setup in regard to communication overhead and time to synchronise the freshness counter.
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20. |
- Shafiq, ur Réhman, 1978-, et al.
(author)
-
Using Vibrotactile Language for Multimodal Human Animals Communication and Interaction
- 2014
-
In: Proceedings of the 2014 Workshops on Advances in Computer Entertainment Conference, ACE '14. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450333146 ; , s. 1:1-1:5
-
Conference paper (peer-reviewed)abstract
- In this work we aim to facilitate computer mediated multimodal communication and interaction between human and animal based on vibrotactile stimuli. To study and influence the behavior of animals, usually researchers use 2D/3D visual stimuli. However we use vibrotactile pattern based language which provides the opportunity to communicate and interact with animals. We have performed experiment with a vibrotactile based human-animal multimodal communication system to study the effectiveness of vibratory stimuli applied to the animal skin along with audio and visual stimuli. The preliminary results are encouraging and indicate that low-resolution tactual displays are effective in transmitting information.
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21. |
- Fallgren, Mikael, et al.
(author)
-
Multicast and Broadcast Enablers for High-Performing Cellular V2X Systems
- 2019
-
In: IEEE Transactions on Broadcasting. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9316 .- 1557-9611. ; 65:2, s. 454-463
-
Journal article (peer-reviewed)abstract
- This paper focuses on capabilities enabled by 5G connectivity in the cooperative, connected and autonomous cars, and elaborates on two technical enablers. One of the technical enablers consists of a beamformed broadcast/multicast technology that builds on adaptive and robust beam management techniques at the air interface. The other proposed technical component aims to improve the end-to-end architectural design of 5G networks to enable efficient broadcast and multicast transmissions for vehicle-to-anything services. Finally, the key results of multicast and broadcast technical components are described and ongoing and future areas of work and research are detailed.
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22. |
- Karlsson, Marcus, 1988-
(author)
-
Aspects of Massive MIMO
- 2016
-
Licentiate thesis (other academic/artistic)abstract
- Next generation cellular wireless technology faces tough demands: increasing the throughput and reliability without consuming more resources, be it spectrum or energy. Massive mimo (Multiple-Input Multiple-Output) has proven, both in theory and practice, that it is up for the challenge. Massive mimo can offer uniformly good service to many users using low-end hardware, simultaneously, without increasing the radiated power compared to contemporary system. In Massive mimo, the base stations are equipped with hundreds of antennas. This abundance of antennas brings many new, interesting aspects compared to single-user mimo and multi-user mimo. Some issues of older technologies are nonexistent in massive mimo, while new issues in need of solutions arise. This thesis considers two aspects, and how these aspects differ in a massive mimo context: physical layer security and transmission of system information. First, it is shown that a jammer with a large number of antennas can outperform a traditional, single-antenna jammer in degrading the legitimate link. The excess of antennas gives the jammer opportunity to find and exploit structure in signals to improve its jamming capability. Second, for transmission of system information, the vast number of antennas prove useful even when the base station does not have any channel state information, because of the increased availability of space-time coding. We show how transmission without channel state information can be done in massive mimo by using a fixed precoding matrix to reduce the pilot overhead and simultaneously apply space-time block coding to use the excess of antennas for spatial diversity.
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23. |
- Lin, Hsuan-Yin, et al.
(author)
-
An MDS-PIR Capacity-Achieving Protocol for Distributed Storage Using Non-MDS Linear Codes
- 2018
-
In: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. ; 2018-June, s. 966-970
-
Conference paper (peer-reviewed)abstract
- We propose a private information retrieval (PIR) protocol for distributed storage systems (DSSs) with noncolluding nodes where data is stored using an arbitrary linear code. An expression for the PIR rate, i.e., the ratio of the amount of retrieved stored data per unit of downloaded data, is derived, and a necessary and a sufficient condition for codes to achieve the PIR capacity are given. The necessary condition is based on the generalized Hamming weights of the storage code, while the sufficient condition is based on code automorphisms. We show that cyclic codes and Reed-Muller codes satisfy the sufficient condition and are thus PIR capacity-achieving.
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24. |
- Sundman, Dennis, et al.
(author)
-
Parallel pursuit for distributed compressed sensing
- 2013
-
In: 2013 IEEE Global Conference on Signal and Information Processing, GlobalSIP 2013 - Proceedings. - : IEEE conference proceedings. - 9781479902484 ; , s. 783-786
-
Conference paper (peer-reviewed)abstract
- We develop a greedy (pursuit) algorithm for a distributed compressed sensing problem where multiple sensors are connected over a de-centralized network. The algorithm is referred to as distributed parallel pursuit and it solves the distributed compressed sensing problem in two stages; first by a distributed estimation stage and then an information fusion stage. Along with worst case theoretical analysis for the distributed algorithm, we also perform simulation experiments in a controlled manner. We show that the distributed algorithm performs significantly better than the stand-alone (disconnected) solution and close to a centralized (fully connected to a central point) solution.
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25. |
- Theorin, Alfred, et al.
(author)
-
An event-driven manufacturing information system architecture for Industry 4.0
- 2017
-
In: International Journal of Production Research. - : Taylor & Francis. - 0020-7543 .- 1366-588X. ; 55:5, s. 1297-1311
-
Research review (peer-reviewed)abstract
- Future manufacturing systems need to be more flexible, to embrace tougher and constantly changing market demands. They need to make better use of plant data, ideally utilising all data from the entire plant. Low-level data should be refined to real-time information for decision-making, to facilitate competitiveness through informed and timely decisions. The Line Information System Architecture (LISA), is presented in this paper. It is an event-driven architecture featuring loose coupling, a prototype-oriented information model and formalised transformation services. LISA is designed to enable flexible factory integration and data utilisation. The focus of LISA is on integration of devices and services on all levels, simplifying hardware changes and integration of new smart services as well as supporting continuous improvements on information visualisation and control. The architecture has been evaluated on both real industrial data and industrial demonstrators and it is also being installed at a large automotive company. This article is an extended and revised version of the paper presented at the 2015 IFAC Symposium on Information Control in Manufacturing (INCOM 2015). The paper has been restructured in regards to the order and title of the chapters, and additional information about the integration between devices and services aspects have been added. The introduction and the general structure of the paper now better highlight the contributions of the paper and the uniqueness of the framework.
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26. |
- Yin, Hang, et al.
(author)
-
Policy Learning with Embedded Koopman Optimal Control
-
Other publication (other academic/artistic)abstract
- Embedding an optimization process has been explored for imposing efficient and flexible policy structures. Existing work often build upon nonlinear optimization with explicitly unrolling of iteration steps, making policy inference prohibitively expensive for online learning and real-time control. Our approach embeds a linear-quadratic-regulator (LQR) formulation with a Koopman representation, thus exhibiting the tractability from a closed-form solution and richness from a non-convex neural network. We use a few auxiliary objectives and reparameterization to enforce optimality conditions of the policy that can be easily integrated to standard gradient-based learning. Our approach is shown to be effective for learning policies rendering an optimality structure and efficient reinforcement learning, including simulated pendulum control, 2D and 3D walking, and manipulation for both rigid and deformable objects. We also demonstrate real world application in a robot pivoting task.
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27. |
- Haubro, Martin, et al.
(author)
-
TSCH-over-LoRA: Long Range and Reliable IPv6 Multi-hopNetworks for the Internet of Things
- 2020
-
In: Internet Technology Letters. - : Wiley. - 2476-1508.
-
Journal article (peer-reviewed)abstract
- TSCH-over-LoRa is a long range and reliable IPv6 multi-hop solution that aims atcombining the reliability of TSCH (Time-Slotted, Channel Hopping) together withthe long range capabilities of LoRa. TSCH-over-LoRa brings mesh IPv6 network-ing to LoRa devices, enabling the use of standard protocols (such as RPL, UDP, andCoAP) and long range operation to TSCH/6TiSCH industrial wireless IoT networks.We design, implement, and integrate TSCH-over-LoRa into the TSCH/6TiSCH net-working stack of the Contiki-NG operating system and experimentally demonstrateits compatibility with higher-level protocols and its resilience to interference.
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28. |
- Ortiz Morales, Daniel, 1984-, et al.
(author)
-
Path-constrained motion analysis : an algorithm to understand human performance on hydraulic manipulators
- 2015
-
In: IEEE Transactions on Human-Machine Systems. - 2168-2291. ; 45:2, s. 187-199
-
Journal article (peer-reviewed)abstract
- We propose a novel method to analyze how human operators use hydraulic manipulators of heavy-duty equipment. The approach is novel in the sense that it applies knowledge of motion planning and optimization techniques used in robotics. As an example, we consider the case of operating a forestry crane. To that end, we use motion data that has been recorded during standard operation with the help of sensors and a data acquisition unit. The data backs up the notion that operators work by performing repeatable patterns observed in the trajectories of the manipulator's joints. We show how this nominal behavior is computed, and consequently this allow us to present the following: 1) an analytical procedure to analyze motions, 2) how to represent the "performance" of the operator in a 2D plot, 3) an example of how to use this information to suggest customized control settings, and 4) some complementary ideas needed for improving efficiency through automation.
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29. |
- Behdadi, Dorna, 1988, et al.
(author)
-
A Normative Approach to Artificial Moral Agency
- 2020
-
In: Minds and Machines. - : Springer Science and Business Media LLC. - 0924-6495 .- 1572-8641. ; 30:2, s. 195-218
-
Journal article (peer-reviewed)abstract
- This paper proposes a methodological redirection of the philosophical debate on artificial moral agency (AMA) in view of increasingly pressing practical needs due to technological development. This “normative approach” suggests abandoning theoretical discussions about what conditions may hold for moral agency and to what extent these may be met by artificial entities such as AI systems and robots. Instead, the debate should focus on how and to what extent such entities should be included in human practices normally assuming moral agency and responsibility of participants. The proposal is backed up by an analysis of the AMA debate, which is found to be overly caught in the opposition between so-called standard and functionalist conceptions of moral agency, conceptually confused and practically inert. Additionally, we outline some main themes of research in need of attention in light of the suggested normative approach to AMA.
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30. |
- Krook, Jonas, 1986
(author)
-
Formal Methods and Safety for Automated Vehicles: Modeling, Abstractions, and Synthesis of Tactical Planners
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- One goal of developing automated road vehicles is to completely free people from driving tasks. Automated vehicles with no human driver must handle all traffic situations that human drivers are expected to handle, possibly more. Though human drivers cause a lot of traffic accidents, they still have a very low accident and failure rate that automated vehicles must match. Tactical planners are responsible for making discrete decisions for the coming seconds or minutes. As with all subsystems in an automated vehicle, these planners need to be supported with a credible and convincing argument of their correctness. The planners interact with other road users in a feedback loop, so their correctness depends on their behavior in relation to other drivers and road users over time. One way to ascertain their correctness is to test the vehicles in real traffic. But to be sufficiently certain that a tactical planner is safe, it has to be tested on 255 million miles with no accidents. Formal methods can, in contrast to testing, mathematically prove that given requirements are fulfilled. Hence, these methods are a promising alternative for making credible arguments for tactical planners’ correctness. The topic of this thesis is the use of formal methods in the automotive industry to design safe tactical planners. What is interesting is both how automotive systems can be modeled in formal frameworks, and how formal methods can be used practically within the automotive development process. The main findings of this thesis are that it is viable to formally express desired properties of tactical planners, and to use formal methods to prove their correctness. However, the difficulty to anticipate and inspect the interaction of several desired properties is found to be an obstacle. Model Checking, Reactive Synthesis, and Supervisory Control Theory have been used in the design and development process of tactical planners, and these methods have their benefits, depending on the application. To be feasible and useful, these methods need to operate on both a high and a low level of abstraction, and this thesis contributes an automatic abstraction method that bridges this divide. It is also found that artifacts from formal methods tools may be used to convincingly argue that a realization of a tactical planner is safe, and that such an argument puts formal requirements on the vehicle’s other subsystems and its surroundings.
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31. |
- Nielsen, Stig Anton, 1981, et al.
(author)
-
Propositional Architecture using Induced Representation
- 2014
-
In: What’s the Matter? Materiality and Materialism at the Age of Computation. - 9789608932067 ; , s. 297-312
-
Conference paper (peer-reviewed)abstract
- The paper describes a method and an approach to using sensor data, machine-learning and pattern recognition for proposing and guiding immediate modifications to the existing built environment. The proposed method; Induced Representation, consists of a few steps which we have identified as crucial for such an approach. The steps are A: data collection from the environment, B: machine cognition, learning, prediction, and, c: proposition, visualization, and embodied representations for quick implementation. In the paper we outline the factual and theoretical basis for this approach, and we present and discuss three experiments that each deal with the steps A, B and C.
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32. |
- Rosenstatter, Thomas, et al.
(author)
-
Modelling the Level of Trust in a Cooperative Automated Vehicle Control System
- 2018
-
In: IEEE transactions on intelligent transportation systems (Print). - Piscataway, NJ : IEEE Press. - 1524-9050 .- 1558-0016. ; 19:4, s. 1267-1247
-
Journal article (peer-reviewed)abstract
- Vehicle-to-vehicle communication is a key technology for achieving increased perception for automated vehicles, where the communication enables virtual sensing by means of sensors in other vehicles. In addition, this technology also allows detection and recognition of objects that are out-of-sight. This paper presents a trust system that allows a cooperative and automated vehicle to make more reliable and safe decisions. The system evaluates the current situation and generates a trust index indicating the level of trust in the environment, the ego vehicle, and the surrounding vehicles. This research goes beyond secure communication and concerns the verification of the received data on a system level. The results show that the proposed method is capable of correctly identifying various traffic situations and how the trust index is used while manoeuvring in a platoon merge scenario.
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33. |
- Selvaraj, Yuvaraj, 1990
(author)
-
On Provably Correct Decision-Making for Automated Driving
- 2020
-
Licentiate thesis (other academic/artistic)abstract
- The introduction of driving automation in road vehicles can potentially reduce road traffic crashes and significantly improve road safety. Automation in road vehicles also brings several other benefits such as the possibility to provide independent mobility for people who cannot and/or should not drive. Many different hardware and software components (e.g. sensing, decision-making, actuation, and control) interact to solve the autonomous driving task. Correctness of such automated driving systems is crucial as incorrect behaviour may have catastrophic consequences. Autonomous vehicles operate in complex and dynamic environments, which requires decision-making and planning at different levels. The aim of such decision-making components in these systems is to make safe decisions at all times. The challenge of safety verification of these systems is crucial for the commercial deployment of full autonomy in vehicles. Testing for safety is expensive, impractical, and can never guarantee the absence of errors. In contrast, formal methods , which are techniques that use rigorous mathematical models to build hardware and software systems can provide a mathematical proof of the correctness of the system. The focus of this thesis is to address some of the challenges in the safety verification of decision-making in automated driving systems. A central question here is how to establish formal verification as an efficient tool for automated driving software development. A key finding is the need for an integrated formal approach to prove correctness and to provide a complete safety argument. This thesis provides insights into how three different formal verification approaches, namely supervisory control theory, model checking, and deductive verification differ in their application to automated driving and identifies the challenges associated with each method. It identifies the need for the introduction of more rigour in the requirement refinement process and presents one possible solution by using a formal model-based safety analysis approach. To address challenges in the manual modelling process, a possible solution by automatically learning formal models directly from code is proposed.
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34. |
- Aramrattana, Maytheewat
(author)
-
Modelling and Simulation for Evaluation of Cooperative Intelligent Transport System Functions
- 2016
-
Licentiate thesis (other academic/artistic)abstract
- Future vehicles are expected to be equipped with wireless communication technology, that enables them to be “connected” to each others and road infrastructures. Complementing current autonomous vehicles and automated driving systems, the wireless communication allows the vehicles to interact, cooperate, and be aware of its surroundings beyond their own sensors’ range. Such sys- tems are often referred to as Cooperative Intelligent Transport Systems (C-ITS), which aims to provide extra safety, efficiency, and sustainability to transporta- tion systems. Several C-ITS applications are under development and will require thorough testing and evaluation before their deployment in the real-world. C- ITS depend on several sub-systems, which increase their complexity, and makes them difficult to evaluate.Simulations are often used to evaluate many different automotive applications, including C-ITS. Although they have been used extensively, simulation tools dedicated to determine all aspects of C-ITS are rare, especially human factors aspects, which are often ignored. The majority of the simulation tools for C-ITS rely heavily on different combinations of network and traffic simulators. The human factors issues have been covered in only a few C-ITS simulation tools, that involve a driving simulator. Therefore, in this thesis, a C-ITS simulation framework that combines driving, network, and traffic simulators is presented. The simulation framework is able to evaluate C-ITS applications from three perspectives; a) human driver; b) wireless communication; and c) traffic systems.Cooperative Adaptive Cruise Control (CACC) and its applications are chosen as the first set of C-ITS functions to be evaluated. Example scenarios from CACC and platoon merging applications are presented, and used as test cases for the simulation framework, as well as to elaborate potential usages of it. Moreover, approaches, results, and challenges from composing the simulation framework are presented and discussed. The results shows the usefulness of the proposed simulation framework.
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35. |
- Peterson, Lena, 1961, et al.
(author)
-
High-performance clock-powered logic
- 2006
-
Patent (other academic/artistic)abstract
- High performance clock-powered logic runs at below supply levels and reduces the need for faster digital logic circuitry. In a preferred embodiment, a clocked buffer (101) is used to drive the signal line. The receiving end of the line is connected to a jam latch (123), preferably followed by an n-latch (125), followed by the digital logic (109), and followed by a second n-latch (127). The first n-latch is eliminated in an alternative embodiment, preferably one that uses complementary data signals.
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36. |
- Rico, Sergio
(author)
-
Building Stronger Bridges: Strategies for Improving Communication and Collaboration Between Industry and Academia in Software Engineering
- 2023
-
Doctoral thesis (other academic/artistic)abstract
- Background: The software engineering community has expressed growing concern regarding the need for more connections between research and practice. Despite the large amount of knowledge researchers generate, its impact on real-world practice is uncertain. Meanwhile, practitioners in industry often struggle to access and utilize relevant research outcomes that could inform and enhance their work. Collaboration between industry and academia is seen as a potential solution to bridge this gap, ensuring that research remains relevant and applicable in real-world contexts.Objective: This research aims to explore challenges in communication and collaboration between industry and to design, evaluate, and implement strategies that foster this collaboration. Methodology: The design science paradigm inspires this research, as we aim to obtain knowledge about industry-academia communication and collaboration by studying challenges and solutions in context. The thesis includes case studies; some are exploratory, while others focus on evaluating specific strategies.Results: In terms of problem understanding, we identified challenges that impact communication and collaboration, such as different expectations, perspectives, and ways of working. Furthermore, we pinpointed factors facilitating communication, including long-term projects, research relevance, and practitioners' involvement.Regarding how to improve communication and collaboration, we investigated two strategies. The first strategy involves using the SERP-taxonomy approach in a project on software vulnerability management in IoT systems. The second strategy involves the proposal of interactive rapid reviews, conducted in close collaboration with practitioners. We share the lessons from conducting two reviews (one in testing machine learning systems and the other in software component selection). The benefits of conducting interactive rapid reviews include mutual understanding, the development of networks, and increased motivation for further studies.Conclusion: The thesis emphasizes the importance of industry-academia collaboration as a key aspect in closing gaps between research and practice. The strategies discussed provide tools to understand industry-academia partnerships better and support future collaborations.
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37. |
- Alibakhshikenari, Mohammad, et al.
(author)
-
An innovative antenna array with high inter element isolation for sub-6 GHz 5G MIMO communication systems
- 2022
-
In: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
-
Journal article (peer-reviewed)abstract
- A novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna's footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted from a 3 x 3 matrix of interconnected resonant elements. The technique involves (1) incorporating matching stubs within the resonant elements, (2) framing each of the four-radiating elements inside a dot-wall, and (3) defecting the ground plane with dielectric slots that are aligned under the dot-walls. Results show that with the proposed approach the impedance bandwidth of the array is increased by 58.82% and the improvement in the average isolation between antennas #1&2, #1&3, #1&4 are 8 dB, 14 dB, 16 dB, and 13 dB, respectively. Moreover, improvement in the antenna gain is 4.2% and the total radiation efficiency is 23.53%. These results confirm the efficacy of the technique. The agreement between the simulated and measured results is excellent. Furthermore, the manufacture of the antenna array using the proposed approach is relatively straightforward and cost effective.
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38. |
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39. |
- Ashouri, Majid
(author)
-
Towards Supporting IoT System Designers in Edge Computing Deployment Decisions
- 2021
-
Licentiate thesis (other academic/artistic)abstract
- The rapidly evolving Internet of Things (IoT) systems demands addressing new requirements. This particularly needs efficient deployment of IoT systems to meet the quality requirements such as latency, energy consumption, privacy, and bandwidth utilization. The increasing availability of computational resources close to the edge has prompted the idea of using these for distributed computing and storage, known as edge computing. Edge computing may help and complement cloud computing to facilitate deployment of IoT systems and improve their quality. However, deciding where to deploy the various application components is not a straightforward task, and IoT system designer should be supported for the decision.To support the designers, in this thesis we focused on the system qualities, and aimed for three main contributions. First, by reviewing the literature, we identified the relevant and most used qualities and metrics. Moreover, to analyse how computer simulation can be used as a supporting tool, we investigated the edge computing simulators, and in particular the metrics they provide for modeling and analyzing IoT systems in edge computing. Finally, we introduced a method to represent how multiple qualities can be considered in the decision. In particular, we considered distributing Deep Neural Network layers as a use case and raked the deployment options by measuring the relevant metrics via simulation.
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40. |
- Babu, Challa, et al.
(author)
-
Power Monitoring and Control System for Medium Voltage Smart Grid Using IoT
- 2020
-
In: IOP Conference Series. - : IOP Publishing.
-
Conference paper (peer-reviewed)abstract
- This paper presents a power monitoring and control system for a medium voltage smart grid system. The smart grid interconnects the power sources between solar PV panel and 220V distribution network. This system consisting major components of inverters, measuring meters, solar charge controllers, relays, Arduino NANO and Raspberry Pi. The Current, power and energy readings are duly recorded. The Internet of Things (IoT) plays the vital role in the data communication between the sensors and electric power system. The voltage and current sensor data is used for the protection of power system network. In the traditional systems only the communication is uni-directional. The reliability of power supply is increased by used the bi directional network communication medium such as IoT. The tabulated results of voltage levels between 203.5V up to 212.8V shows the feasibility and effectiveness of proposed design. The proposed IoT model demonstrated the bidirectional communication from the sensors to the control unit and vice versa.
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41. |
- Butun, Ismail, et al.
(author)
-
Detecting Intrusions in Cyber-Physical Systems of Smart Cities : Challenges and Directions
- 2019
-
In: Secure Cyber-Physical Systems for Smart Cities. - Hershey, USA : IGI Global. - 9781522571896 ; , s. 74-102
-
Book chapter (peer-reviewed)abstract
- Interfacing the smart cities with cyber-physical systems (CPSs) improves cyber infrastructures while introducing security vulnerabilities that may lead to severe problems such as system failure, privacy violation, and/or issues related to data integrity if security and privacy are not addressed properly. In order for the CPSs of smart cities to be designed with proactive intelligence against such vulnerabilities, anomaly detection approaches need to be employed. This chapter will provide a brief overview of the security vulnerabilities in CPSs of smart cities. Following a thorough discussion on the applicability of conventional anomaly detection schemes in CPSs of smart cities, possible adoption of distributed anomaly detection systems by CPSs of smart cities will be discussed along with a comprehensive survey of the state of the art. The chapter will discuss challenges in tailoring appropriate anomaly detection schemes for CPSs of smart cities and provide insights into future directions for the researchers working in this field.
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42. |
- Degen, René, 1994-
(author)
-
Urban Virtual Test Field for HighlyAutomated Vehicle Systems
- 2021
-
Licentiate thesis (other academic/artistic)abstract
- Autonomous driving is one of the key technologies for increasing road safetyand reducing traffic volumes. Therefore, science and industry are workingtogether on new innovative solutions in this field of technology. One importantcomponent in this context is the approval and testing of new solution concepts,with special focus on the ones for urban environments. Not only because ofthe high diversity of traffic situations, but also because of the close contactbetween vulnerable road users (VRU) and automated vehicles.In the course of this work, a novel approach for testing automated drivingfunctions and vehicle systems in urban environments is presented. The goal isto create a safe and valid environment in which the automated vehicle and theVRU can meet and interact. The basis is a highly realistic virtual model of acity center. The physical behavior of the vehicle and VRU is recorded usingmeasurement technology and transferred to the virtual city model.Based on representative urban traffic scenarios, the functionality of the urbantest field is investigated from various points of view. Thereby, the focus is onreal-time capability and the quality of interaction between the vehicle and theVRU.The investigations show that both the real-time capability and the interactionpossibilities could be demonstrated. Further, the developed methodologies aresuitable for real time applications.
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43. |
- Eklund, Johan, 1966-, et al.
(author)
-
Tuning SCTP failover for carrier grade telephony signaling
- 2010
-
In: Computer Networks. - : Elsevier BV. - 1389-1286 .- 1872-7069. ; 54:1, s. 133-149
-
Journal article (peer-reviewed)abstract
- The Stream Control Transmission Protocol (SCTP) has not only been selected as the signaling transport protocol of choice in IETF SIGTRAN, the architecture that bridges circuit-switched and IP-based mobile core networks, but also plays a pivotal role in SAE/LTE, the next-generation UMTS/HSPA networks. To meet the redundancy requirements of telecom signaling traffic, SCTP includes a failover mechanism that enables rerouting of traffic from an unreachable network path to a backup path. However, the recommendations provided by IETF on how to configure the SCTP failover mechanism to meet telecom signaling requirements are kept quite general and leave much of the tuning to the telecom equipment vendor and/or operator. Several works by us and others have been carried out to study the effect of different SCTP parameters on the failover performance. The main contribution of this paper is that it gives a coherent treatment of how to configure the SCTP failover mechanism for carrier-grade telephony signaling, and provides practically usable configuration recommendations. The paper also discusses an alternate or complementary way of optimizing the SCTP failover mechanism by relaxing the exponential backoff that foregoes a retransmission timeout in SCTP. Some results showing significantly reduced failover times by use of this mechanism, with only marginal deteriorating effects on a signaling network, are discussed and analyzed in the paper. (C) 2009 Elsevier B.V. All rights reserved.
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44. |
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45. |
- Ippolito, M. G., et al.
(author)
-
Damping Provision by Different Virtual Synchronous Machine Schemes
- 2020
-
In: Proceedings - 2020 IEEE International Conference on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2020.
-
Conference paper (peer-reviewed)abstract
- The adoption of virtual synchronous machine (VSM) schemes for the control of power converters is gaining more and more attention both in academia and industry. The VSM control strategies fall into the category of grid-forming converter controls, and they are intended for a range of different applications, providing specific services and different kinds of support to the grid. The paper investigates the possibility of damping provision to the system by VSM power converters. Different schemes are considered and compared, showing the opportunity of the investigated solutions through combined modal and time domain analyses. A specific modification of the power synchronization loop is recognized as the most suitable method to contain the power oscillations and increase the damping level in the system.
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46. |
- Ippolito, M. G., et al.
(author)
-
Extension and Tuning of Virtual Synchronous Machine to Avoid Oscillatory Instability in Isolated Power Networks
- 2020
-
In: 12th AEIT International Annual Conference, AEIT 2020.
-
Conference paper (peer-reviewed)abstract
- The risk of oscillatory instability introduced by virtual synchronous machines (VSM) control in isolated power networks is investigated. The considered control is a common scheme widely studied in literature, in several configurations and for different case studies. The impact of the VSM control on the system stability is examined for the existing power network of a Mediterranean island. The VSM control is implemented within the power converters interfacing the energy storage systems (ESS) installed in the network. Simulations and analysis show the occurrence of oscillatory instability in the system, with the ESS-VSM and the synchronous machines of the network progressively swinging against each other. The reasons of the instability are identified as the lack of damping in the system and the adverse interaction between the VSM converter control and the synchronous machine dynamics. The possibility of extending the VSM control with a corrective action for the stabilization of the system is analyzed and discussed. A proper tuning procedure of the extended control is also provided.
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47. |
- Kalsson, Stefan, et al.
(author)
-
Eavesdropping G.652 vs. G.657 fibres: a performance comparison
- 2022
-
In: 2022 International Conference on Optical Network Design and Modeling, ONDM 2022.
-
Conference paper (peer-reviewed)abstract
- With increasing dependence on secure access to digital services and the ultra-high traffic volumes running on the optical fibre communication infrastructure, the protection of this infrastructure from eavesdropping is extremely important, especially in defense and military applications. The G.657 fibre is recommended to be deployed in in-building installations for its improved bending performance compared to the G.652 fibre. However, the easiness to be eavesdropped, which reflects the security level of those two types of fibres has not yet been investigated. In this paper, we study the eavesdropping of fibre from a system perspective and compare the bending property of G.652 and G.657 fibres. The measurement results show that G.657 can be bent sharper than G.652 without causing any additional power attenuation at the receiver. This indicates that the so-called bending-insensitive G.657 fibre can potentially be eavesdropped more easily than their G.652 counterparts. The paper also shows that the power level measurement at the receiver may not be sufficient for unambiguous eavesdrop detection.
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48. |
- Khan, Suleman, et al.
(author)
-
AKAASH: A realizable authentication, key agreement, and secure handover approach for controller-pilot data link communications
- 2023
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In: International Journal of Critical Infrastructure Protection. - : ELSEVIER. - 1874-5482 .- 2212-2087. ; 42
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Journal article (peer-reviewed)abstract
- Controller-Pilot Data Link Communications (CPDLC) are rapidly replacing voice-based Air Traffic Control (ATC) communications worldwide. Being digital, CPDLC is highly resilient and bandwidth efficient, which makes it the best choice for traffic-congested airports. Although CPDLC initially seems to be a perfect solution for modern-day ATC operations, it suffers from serious security issues. For instance, eavesdropping, spoofing, man-in-the-middle, message replay, impersonation attacks, etc. Cyber attacks on the aviation communication network could be hazardous, leading to fatal aircraft incidents and causing damage to individuals, service providers, and the aviation industry. Therefore, we propose a new security model called AKAASH, enabling several paramount security services, such as efficient and robust mutual authentication, key establishment, and a secure handover approach for the CPDLC-enabled aviation communication network. We implement the approach on hardware to examine the practicality of the proposed approach and verify its computational and communication efficiency and efficacy. We investigate the robustness of AKAASH through formal (proverif) and informal security analysis. The analysis reveals that the AKAASH adheres to the CPDLC standards and can easily integrate into the CPDLC framework.
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49. |
- Lavassani, Mehrzad
(author)
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Evolving Industrial Networks : Data-Driven Network Traffic Modelling and Monitoring
- 2023
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Doctoral thesis (other academic/artistic)abstract
- The concept of Industrial IoT encompasses the joint applicability of operation and information technologies to expand the efficiency expectation of automation to green and flexible processes with innovative products and services. Future industrial networks need to accommodate, manage and guarantee the performance of converged traffic from different technologies. The network infrastructures are transforming to enable data availability for advanced applications and enhance flexibility. Nonetheless, the pace of IT–OT networks development has been slow despite their considered benefits in optimising performance and enhancing information flows. The hindering factors vary from general challenges in performance management of the diverse traffic for greenfield configuration to the lack of outlines for evolving from brownfield installations without interrupting the operation of ongoing processes. One tangible gap is the lack of insight into the brownfield installation in operation. This dissertation explores the possible evolutionary steps from brownfield installations to future industrial networks.The goal is to ensure the uninterrupted performance of brownfield installations on the path of evolving to the envisioned smart factories. It addresses the gap between the state of the art and state of practice, and the technical prerequisites of the integrated traffic classes for the development of an IIoT monitoring mechanism. A novel lightweight learning algorithm at the sensor level for an IIoT compliance monitoring system, together with a case study of traffic collected from a brownfield installation, provides the baseline of comparative analysis between the common assumptions and the state of practice. The identified gaps and challenges to address them directs the research for proposing a two-step aggregated traffic modelling by introducing new measurement method and performance indicator parameters for capturing the communication dynamics. Lastly, the sensor-level learning algorithm is refined with the knowledge gained from practice and research contributions to propose an in-band telemetry mechanism for monitoring aggregated network traffic.
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50. |
- Muddala, Suryanarayana Murthy, 1984-
(author)
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Free View Rendering for 3D Video : Edge-Aided Rendering and Depth-Based Image Inpainting
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Three Dimensional Video (3DV) has become increasingly popular with the success of 3D cinema. Moreover, emerging display technology offers an immersive experience to the viewer without the necessity of any visual aids such as 3D glasses. 3DV applications, Three Dimensional Television (3DTV) and Free Viewpoint Television (FTV) are auspicious technologies for living room environments by providing immersive experience and look around facilities. In order to provide such an experience, these technologies require a number of camera views captured from different viewpoints. However, the capture and transmission of the required number of views is not a feasible solution, and thus view rendering is employed as an efficient solution to produce the necessary number of views. Depth-image-based rendering (DIBR) is a commonly used rendering method. Although DIBR is a simple approach that can produce the desired number of views, inherent artifacts are major issues in the view rendering. Despite much effort to tackle the rendering artifacts over the years, rendered views still contain visible artifacts.This dissertation addresses three problems in order to improve 3DV quality: 1) How to improve the rendered view quality using a direct approach without dealing each artifact specifically. 2) How to handle disocclusions (a.k.a. holes) in the rendered views in a visually plausible manner using inpainting. 3) How to reduce spatial inconsistencies in the rendered view. The first problem is tackled by an edge-aided rendering method that uses a direct approach with one-dimensional interpolation, which is applicable when the virtual camera distance is small. The second problem is addressed by using a depth-based inpainting method in the virtual view, which reconstructs the missing texture with background data at the disocclusions. The third problem is undertaken by a rendering method that firstly inpaint occlusions as a layered depth image (LDI) in the original view, and then renders a spatially consistent virtual view.Objective assessments of proposed methods show improvements over the state-of-the-art rendering methods. Visual inspection shows slight improvements for intermediate views rendered from multiview videos-plus-depth, and the proposed methods outperforms other view rendering methods in the case of rendering from single view video-plus-depth. Results confirm that the proposed methods are capable of reducing rendering artifacts and producing spatially consistent virtual views.In conclusion, the view rendering methods proposed in this dissertation can support the production of high quality virtual views based on a limited number of input views. When used to create a multi-scopic presentation, the outcome of this dissertation can benefit 3DV technologies to improve the immersive experience.
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