| 1. |
- Al Nahas, Beshr, 1985, et al.
(författare)
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Low-power listening goes multi-channel
- 2014
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Ingår i: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2014. ; , s. 2-9
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Konferensbidrag (refereegranskat)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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| 2. |
- Rosenstatter, Thomas, et al.
(författare)
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Modelling the Level of Trust in a Cooperative Automated Vehicle Control System
- 2018
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - Piscataway, NJ : IEEE Press. - 1524-9050 .- 1558-0016. ; 19:4, s. 1267-1247
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Tiloca, Marco, et al.
(författare)
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SARDOS: Self-Adaptive Reaction against Denial of Service in the Internet of Things
- 2018
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Konferensbidrag (refereegranskat)abstract
- Denial of Service (DoS) is a common and severe security issue in computer networks. Typical DoS attacks overload servers with bogus requests, induce them to worthlessly commit resources, and even make them unable to serve legitimate clients. This is especially relevant in Internet of Things scenarios, where servers are particularly exposed and often equipped with limited resources. Although most countermeasures focus on detection and mitigation, they do not react to dynamically adapt victims' behavior, while at the same time preserving service availability. This paper presents SARDOS, a reactive security service that leverages detection mechanisms from different communication layers, and adaptively changes the operative behavior of victim servers while preserving service availability. We experimentally evaluated SARDOS with a prototype implementation running on an underclocked Raspberry Pi server. Our results show that, when running SARDOS, a server under attack displays considerably lower memory and CPU usage, while still ensuring (best-effort) fulfillment of legitimate requests.
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| 4. |
- Ahmed, J., et al.
(författare)
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Automated diagnostic of virtualized service performance degradation
- 2018
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Ingår i: Proceedings 2018 IEEE/IFIP Network Operations and Management Symposium, NOMS 2018. - New York : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Eriksson, Martin, et al.
(författare)
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Monitoring and modelling open compute servers
- 2017
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Ingår i: Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society. - Piscataway, NJ : Institute of Electrical and Electronics Engineers Inc.. - 9781538611272 ; , s. 7177-7184, s. 7177-7184
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Konferensbidrag (refereegranskat)abstract
- Energy efficient control of server rooms in modern data centers can help reducing the energy usage of this fast growing industry. Efficient control, however, cannot be achieved without: i) continuously monitoring in real-time the behavior of the basic thermal nodes within these infrastructures, i.e., the servers; ii) analyzing the acquired data to model the thermal dynamics within the data center. Accurate data and accurate models are indeed instrumental for implementing efficient data centers cooling strategies. In this paper we focus on a class of Open Compute Servers, designed in an open-source fashion and currently deployed by Facebook. We thus propose a set of methods for collecting real-time data from these platforms and a control-oriented model describing the thermal dynamics of the CPUs and RAMs of these servers as a function of both manipulable and exogenous inputs (e.g., the CPU utilization levels and the air mass flow produced by the server's fans). We identify the parameters of this model from real data and make the results available to other researchers.
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| 6. |
- Tiloca, Marco, et al.
(författare)
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Group rekeying based on member join history
- 2020
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Ingår i: International Journal of Information Security. - : Springer Berlin/Heidelberg. - 1615-5262 .- 1615-5270. ; 19, s. 343-381
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents GREP, a novel group rekeying scheme that leverages the history of join events in order to achieve efficiency and high scalability. GREP rekeys thegroup with only two broadcast messages, hence displaying an overhead which is small, constant and independent of the group size. Also, GREP efficiently recovers the group from collusion attack with no recourse to total member reinitialization. Even in the very unlikely worst case, collusion recovery displays a smooth impact on performance that gradually increases with the attack severity. We implemented GREP for the Contiki OS and tested it on different resource-constrained platforms. Our analytical and experimental evaluation confirm that GREP is efficient, highly scalable and deployable also on constrained nodes. The paper extends a previous version of this work, especially through additional security analysis, treatise of probabilities for worst case collusion, and experimental evaluation of performance.
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| 7. |
- Perez-Cerrolaza, Jon, et al.
(författare)
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Artificial Intelligence for Safety-Critical Systems in Industrial and Transportation Domains: A Survey
- 2024
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Ingår i: ACM Computing Surveys. - New York : Association for Computing Machinery. - 0360-0300 .- 1557-7341. ; 56:7
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Tidskriftsartikel (refereegranskat)abstract
- Artificial Intelligence (AI) can enable the development of next-generation autonomous safety-critical systems in which Machine Learning (ML) algorithms learn optimized and safe solutions. AI can also support and assist human safety engineers in developing safety-critical systems. However, reconciling both cutting-edge and state-of-the-art AI technology with safety engineering processes and safety standards is an open challenge that must be addressed before AI can be fully embraced in safety-critical systems. Many works already address this challenge, resulting in a vast and fragmented literature. Focusing on the industrial and transportation domains, this survey structures and analyzes challenges, techniques, and methods for developing AI-based safety-critical systems, from traditional functional safety systems to autonomous systems. AI trustworthiness spans several dimensions, such as engineering, ethics and legal, and this survey focuses on the safety engineering dimension.
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| 8. |
- Balador, Ali, et al.
(författare)
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A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET
- 2016
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Ingår i: 2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC). - Piscataway : IEEE. - 9781509032549 - 9781509032556 ; , s. 1586-1591
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Konferensbidrag (refereegranskat)abstract
- Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.
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| 9. |
- Bosse, Sebastian, et al.
(författare)
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A common framework for the evaluation of psychophysiological visual quality assessment
- 2019
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Ingår i: Quality and User Experience. - : Springer Science and Business Media LLC. - 2366-0139 .- 2366-0147. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- The assessment of perceived quality based on psychophysiological methods recently gained attraction as it potentially overcomes certain flaws of psychophysical approaches. Although studies report promising results, it is not possible to arrive at decisive and comparable conclusions that recommend the use of one or another method for a specific application or research question. The video quality expert group started a project on psychophysiological quality assessment to study these novel approaches and to develop a test plan that enables more systematic research. This test plan comprises of a specifically designed set of quality annotated video sequences, suggestions for psychophysiological methods to be studied in quality assessment, and recommendations for the documentation and publications of test results. The test plan is presented in this article.
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| 10. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Latency impact on Quality of Experience in a virtual reality simulator for remote control of machines
- 2020
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Ingår i: Signal processing. Image communication. - : Elsevier. - 0923-5965 .- 1879-2677. ; 89
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we have investigated a VR simulator of a forestry crane used for loading logs onto a truck. We have mainly studied the Quality of Experience (QoE) aspects that may be relevant for task completion, and whether there are any discomfort related symptoms experienced during the task execution. QoE experiments were designed to capture the general subjective experience of using the simulator, and to study task performance. The focus was to study the effects of latency on the subjective experience, with regards to delays in the crane control interface. Subjective studies were performed with controlled delays added to the display update and hand controller (joystick) signals. The added delays ranged from 0 to 30 ms for the display update, and from 0 to 800 ms for the hand controller. We found a strong effect on latency in the display update and a significant negative effect for 800 ms added delay on latency in the hand controller (in total approx. 880 ms latency including the system delay). The Simulator Sickness Questionnaire (SSQ) gave significantly higher scores after the experiment compared to before the experiment, but a majority of the participants reported experiencing only minor symptoms. Some test subjects ceased the test before finishing due to their symptoms, particularly due to the added latency in the display update.
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