| 1. |
- Stefanizzi, Maria Laura, et al.
(författare)
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COIN : Opening the internet of things to people's mobile devices
- 2017
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Ingår i: IEEE Communications Magazine. - : Institute of Electrical and Electronics Engineers Inc.. - 0163-6804 .- 1558-1896. ; 55:2, s. 20-26
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Tidskriftsartikel (refereegranskat)abstract
- People's interaction with IoT devices such as proximity beacons, body-worn sensors, and controllable light bulbs is often mediated through personal mobile devices. Current approaches usually make applications operate in separate silos, as the functionality of IoT devices is fixed by vendors and typically accessed only through low-level proprietary APIs. This limits the flexibility in designing applications and requires intense wireless interactions, which may impact energy consumption. COIN is a system architecture that breaks this separation by allowing developers to flexibly run a slice of a mobile app's logic onto IoT devices. Mobile apps can dynamically deploy arbitrary tasks implemented as loosely coupled components. The underlying runtime support takes care of the coordination across tasks and of their real-time scheduling. Our prototype indicates that COIN both enables increased flexibility and improves energy efficiency at the IoT device, compared to traditional architectures.
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| 2. |
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| 3. |
- Afanasov, Mikhail, et al.
(författare)
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Battery-less zero-maintenance embedded sensing at the mithræum of circus maximus
- 2020
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Ingår i: SenSys 2020 - Proceedings of the 2020 18th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450375900 ; , s. 368-381
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Konferensbidrag (refereegranskat)abstract
- We present the design and evaluation of a 3.5-year embedded sensing deployment at the Mithræum of Circus Maximus, a UNESCO-protected underground archaeological site in Rome (Italy). Unique to our work is the use of energy harvesting through thermal and kinetic energy sources. The extreme scarcity and erratic availability of energy, however, pose great challenges in system software, embedded hardware, and energy management. We tackle them by testing, for the first time in a multi-year deployment, existing solutions in intermittent computing, low-power hardware, and energy harvesting. Through three major design iterations, we find that these solutions operate as isolated silos and lack integration into a complete system, performing suboptimally. In contrast, we demonstrate the efficient performance of a hardware/software co-design featuring accurate energy management and capturing the coupling between energy sources and sensed quantities. Installing a battery-operated system alongside also allows us to perform a comparative study of energy harvesting in a demanding setting. Albeit the latter reduces energy availability and thus lowers the data yield to about 22% of that provided by batteries, our system provides a comparable level of insight into environmental conditions and structural health of the site. Further, unlike existing energy-harvesting deployments that are limited to a few months of operation in the best cases, our system runs with zero maintenance since almost 2 years, including 3 months of site inaccessibility due to a COVID19 lockdown
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| 4. |
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| 5. |
- Afanasov, M., et al.
(författare)
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Flyzone : A testbed for experimenting with aerial drone applications
- 2019
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Ingår i: MobiSys 2019 - Proceedings of the 17th Annual International Conference on Mobile Systems, Applications, and Services. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450366618 ; , s. 67-78
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Konferensbidrag (refereegranskat)abstract
- FlyZone is a testbed architecture to experiment with aerial drone applications. Unlike most existing drone testbeds that focus on low-level mechanical control, FlyZone offers a high-level API and features geared towards experimenting with application-level functionality. These include the emulation of environment influences, such as wind, and the automatic monitoring of developer-provided safety constraints, for example, to mimic obstacles. We conceive novel solutions to achieve this functionality, including a hardware/software architecture that maximizes decoupling from the main application and a custom visual localization technique expressly designed for testbed operation. We deploy two instances of FlyZone and study performance and effectiveness. We demonstrate that we realistically emulate the environment influence with a positioning error bound by the size of the smallest drone we test, that our localization technique provides a root mean square error of 9.2cm, and that detection of violations to safety constraints happens with a 50ms worst-case latency. We also report on how FlyZone supported developing three real-world drone applications, and discuss a user study demonstrating the benefits of FlyZone compared to drone simulators.
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| 6. |
- Afanasov, Mikhail, et al.
(författare)
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Programming Support for Time-sensitive Adaptation in Cyberphysical Systems
- 2018
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Ingår i: ACM SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; 14:4, s. 27-32
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Tidskriftsartikel (refereegranskat)abstract
- Cyberphysical systems (CPS) integrate embedded sensors,actuators, and computing elements for controlling physicalprocesses. Due to the intimate interactions with thesurrounding environment, CPS software must continuouslyadapt to changing conditions. Enacting adaptation decisionsis often subject to strict time requirements to ensure controlstability, while CPS software must operate within the tightresource constraints that characterize CPS platforms. Developersare typically left without dedicated programmingsupport to cope with these aspects. This results in either toneglect functional or timing issues that may potentially ariseor to invest significant efforts to implement hand-crafted solutions.We provide programming constructs that allow developersto simplify the specification of adaptive processingand to rely on well-defined time semantics. Our evaluationshows that using these constructs simplifies implementationswhile reducing developers’ effort, at the price of a modestmemory and processing overhead.
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| 7. |
- Afanasov, Mikhail, et al.
(författare)
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Software Adaptation in Wireless Sensor Networks
- 2018
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Ingår i: ACM Transactions on Autonomous and Adaptive Systems. - : Association for Computing Machinery (ACM). - 1556-4665 .- 1556-4703. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- We present design concepts, programming constructs, and automatic verification techniques to support the development of adaptive Wireless Sensor Network (WSN) software. WSNs operate at the interface between the physical world and the computing machine and are hence exposed to unpredictable environment dynamics. WSN software must adapt to these dynamics to maintain dependable and efficient operation. However, developers are left without proper support to develop adaptive functionality in WSN software. Our work fills this gap with three key contributions: (i) design concepts help developers organize the necessary adaptive functionality and understand their relations, (ii) dedicated programming constructs simplify the implementations, (iii) custom verification techniques allow developers to check the correctness of their design before deployment. We implement dedicated tool support to tie the three contributions, facilitating their practical application. Our evaluation considers representative WSN applications to analyze code metrics, synthetic simulations, and cycle-accurate emulation of popular WSN platforms. The results indicate that our work is effective in simplifying the development of adaptive WSN software; for example, implementations are provably easier to test and to maintain, the run-time overhead of our dedicated programming constructs is negligible, and our verification techniques return results in a matter of seconds.
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| 8. |
- Afanasov, Mikhail, et al.
(författare)
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The FlyZone Testbed Architecture for Aerial Drone Applications
- 2020
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Ingår i: GetMobile. - : Association for Computing Machinery (ACM). - 2375-0529 .- 2375-0537. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Aerial drones represent a new breed of mobile computing. Compared to mobile phones and connected cars that only opportunistically sense or communicate, aerial drones offer direct control over their movements. They can thus implement functionality that were previously beyond reach, such as collecting high-resolution imagery, exploring near-inaccessible areas, or inspecting remote areas to gather fine-grain environmental data.
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| 9. |
- Ahmed, Saad, et al.
(författare)
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Demystifying Energy Consumption Dynamics in Transiently Powered Computers
- 2020
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Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery. - 1539-9087 .- 1558-3465. ; 19:6
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Tidskriftsartikel (refereegranskat)abstract
- Transiently powered computers (TPCs) form the foundation of the battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This kind of power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption. Such a deceptively minor observation is overlooked in existing literature. Systems are thus designed and parameterized in overly conservative ways, missing on a number of optimizations.We rather demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and prove its use in two settings. First, we develop EPIC, a compile-time energy analysis tool. We use it to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, it avoids unnecessary program changes that hurt energy efficiency. Next, we extend the MSPsim emulator and explore its use in parameterizing a different TPC system support. The improvements in energy efficiency yield up to more than 1000% time speedup to complete a fixed workload.
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| 10. |
- Ahmed, Saad, et al.
(författare)
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Efficient intermittent computing with differential checkpointing
- 2019
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Ingår i: Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES). - New York, NY, USA : Association for Computing Machinery. - 9781450367240 ; , s. 70-81
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Konferensbidrag (refereegranskat)abstract
- Embedded devices running on ambient energy perform computations intermittently, depending upon energy availability. System support ensures forward progress of programs through state checkpointing in non-volatile memory. Checkpointing is, however, expensive in energy and adds to execution times. To reduce this overhead, we present DICE, a system design that efficiently achieves differential checkpointing in intermittent computing. Distinctive traits of DICE are its software-only nature and its ability to only operate in volatile main memory to determine differentials. DICE works with arbitrary programs using automatic code instrumentation, thus requiring no programmer intervention, and can be integrated with both reactive (Hibernus) or proactive (MementOS, HarvOS) checkpointing systems. By reducing the cost of checkpoints, performance markedly improves. For example, using DICE, Hibernus requires one order of magnitude shorter time to complete a fixed workload in real-world settings.
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| 11. |
- Ahmed, Saad, et al.
(författare)
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Fast and Energy-Efficient State Checkpointing for Intermittent Computing
- 2020
-
Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery. - 1539-9087 .- 1558-3465. ; 19:6
-
Tidskriftsartikel (refereegranskat)abstract
- Intermittently powered embedded devices ensure forward progress of programs through state checkpointing in non-volatile memory. Checkpointing is, however, expensive in energy and adds to the execution times. To minimize this overhead, we present DICE, a system that renders differential checkpointing profitable on these devices. DICE is unique because it is a software-only technique and efficient because it only operates in volatile main memory to evaluate the differential. DICE may be integrated with reactive (Hibernus) or proactive (MementOS, HarvOS) checkpointing systems, and arbitrary code can be enabled with DICE using automatic code-instrumentation requiring no additional programmer effort. By reducing the cost of checkpoints, DICE cuts the peak energy demand of these devices, allowing operation with energy buffers that are one-eighth of the size originally required, thus leading to benefits such as smaller device footprints and faster recharging to operational voltage level. The impact on final performance is striking: with DICE, Hibernus requires one order of magnitude fewer checkpoints and one order of magnitude shorter time to complete a workload in real-world settings.
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| 12. |
- Ahmed, Saad, et al.
(författare)
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Intermittent Computing with Dynamic Voltage and Frequency Scaling
- 2020
-
Ingår i: EWSN '20. ; , s. 97-107
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Konferensbidrag (refereegranskat)abstract
- We present D2VFS, a run-time technique to intelligently regulate supply voltage and accordingly reconfigure clock frequency of intermittently-computing devices. These devices rely on energy harvesting to power their operation and on small capacitors as energy buffer. Statically setting their clock frequency fails to achieve energy efficiency, as the setting remains oblivious of fluctuations in capacitor voltage and of their impact on a microcontroller operating range. In contrast, D2VFS captures these dynamics and places the microcontroller in the most efficient configuration by regulating the microcontroller supply voltage and changing its clock frequency. Our evaluation shows that D2VFS markedly increases energy efficiency; for example, ultimately enabling a 30-300% reduction of workload completion times.
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| 13. |
- Ahmed, Saad, et al.
(författare)
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The betrayal of constant power × time : Finding the missing joules of transiently-powered computers
- 2019
-
Ingår i: Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES). - New York, NY, USA : Association for Computing Machinery. - 9781450367240 ; , s. 97-109
-
Konferensbidrag (refereegranskat)abstract
- Transiently-powered computers (TPCs) lay the basis for a battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption, which determine energy efficiency. We demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and develop EPIC, a compile-time energy analysis tool. We use EPIC to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, programmers avoid unnecessary program changes that hurt energy efficiency.
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| 14. |
- Asad, H. A., et al.
(författare)
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On Securing Persistent State in Intermittent Computing
- 2020
-
Ingår i: ENSsys 2020 - Proceedings of the 8th International Workshop on Energy Harvesting and Energy-Neutral Sensing Systems. - New York, NY, USA : Association for Computing Machinery, Inc. ; , s. 8-14, s. 8-14, s. 8-14
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Konferensbidrag (refereegranskat)abstract
- We present the experimental evaluation of different security mechanisms applied to persistent state in intermittent computing. Whenever executions become intermittent because of energy scarcity, systems employ persistent state on non-volatile memories (NVMs) to ensure forward progress of applications. Persistent state spans operating system and network stack, as well as applications. While a device is off recharging energy buffers, persistent state on NVMs may be subject to security threats such as stealing sensitive information or tampering with configuration data, which may ultimately corrupt the device state and render the system unusable. Based on modern platforms of the Cortex M*series, we experimentally investigate the impact on typical intermittent computing workloads of different means to protect persistent state, including software and hardware implementations of staple encryption algorithms and the use of ARM TrustZone protection mechanisms. Our results indicate that i) software implementations bear a significant overhead in energy and time, sometimes harming forward progress, but also retaining the advantage of modularity and easier updates; ii) hardware implementations offer much lower overhead compared to their software counterparts, but require a deeper understanding of their internals to gauge their applicability in given application scenarios; and iii) TrustZone shows almost negligible overhead, yet it requires a different memory management and is only effective as long as attackers cannot directly access the NVMs.
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| 15. |
- Azzarà, Andrea, et al.
(författare)
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Virtual Resources for the Internet of Things
- 2015. - 12
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Ingår i: 2015 IEEE 2nd World Forum on Internet of Things (WF-IoT). - 9781509003662 ; , s. 245-250
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Konferensbidrag (refereegranskat)abstract
- We present Virtual Resources: a software architecture to resolve the tension between effective development and efficient operation of Internet of Things (IoT) applications. Emerging IoT architectures exhibit recurring traits: resource-limited sensors and actuators with RESTful interfaces at one end; full-fledged Cloud-hosted applications at the opposite end. The application logic resides entirely at the latter, creating performance issues such as excessive energy consumption and high latencies. To ameliorate these, Virtual Resources allows developers to push a slice of the application logic to intermediate IoT devices, creating a continuum between physical resources and Cloud-hosted applications. With Virtual Resources, for example, developers can push processing of sensed data to IoT devices close to the physical sensors, reducing the data to transmit and thus saving energy. We describe the key concepts of Virtual Resources and their realization in a CoAP prototype atop resource-constrained devices. Experimental results from cycle-accurate emulation indicate that Virtual Resources enable better performance than Cloud-centric architectures, while retaining the RESTful interaction pattern. For example, energy consumption in representative scenarios improves up to 40% and control loop latencies reduce up to 60%.
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| 16. |
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| 17. |
- Baccour, Nouha, et al.
(författare)
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Radio Link Quality Estimation in Wireless Sensor Networks: a Survey
- 2012. - 13
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Ingår i: ACM Transactions on Sensor Networks. - : Association for Computing Machinery (ACM). - 1550-4859 .- 1550-4867. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- Radio link quality estimation inWireless SensorNetworks (WSNs) has a fundamental impact on the network performance and also affects the design of higher-layer protocols. Therefore, for about a decade, it has been attracting a vast array of research works. Reported works on link quality estimation are typically based on different assumptions, consider different scenarios, and provide radically different (and sometimes contradictory) results. This article provides a comprehensive survey on related literature, covering the characteristics of low-power links, the fundamental concepts of link quality estimation inWSNs, a taxonomy of existing link quality estimators, and their performance analysis. To the best of our knowledge, this is the first survey tackling in detail link quality estimation in WSNs. We believe our efforts will serve as a reference to orient researchers and system designers in this area.
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| 18. |
- Bambusi, Fulvio, et al.
(författare)
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The Case for Approximate Intermittent Computing
- 2022
-
Ingår i: 2022 21st ACM/IEEE International Conference on Information Processing in Sensor Networks (ISPN 2022). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665496247 - 9781665496254 ; , s. 463-476
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Konferensbidrag (refereegranskat)abstract
- We present the concept of approximate intermittent computing and concretely demonstrate its application. Intermittent computations stem from the erratic energy patterns caused by energy harvesting: computations unpredictably terminate whenever energy is insufficient and the application state is lost. Existing solutions maintain equivalence to continuous executions by creating persistent state on non-volatile memory, enabling stateful computations to cross power failures. The performance penalty is massive: system throughput reduces while energy consumption increases. In contrast, approximate intermittent computations trade the accuracy of the results for sparing the entire overhead to maintain equivalence to a continuous execution. This is possible as we use approximation to limit the extent of stateful computations to the single power cycle, enabling the system to completely shift the energy budget for managing persistent state to useful computations towards an immediate approximate result. To this end, we effectively reverse the regular formulation of approximate computing problems. First, we apply approximate intermittent computing to human activity recognition. We design an anytime variation of support vector machines able to improve the accuracy of the classification as energy is available. We build a hw/sw prototype using kinetic energy and show a 7x improvement in system throughput compared to state-of-the-art system support for intermittent computing, while retaining 83% accuracy in a setting where the best attainable accuracy is 88%. Next, we apply approximate intermittent computing in a sharply different scenario, that is, embedded image processing, using loop perforation. Using a different hw/sw prototype we build and diverse energy traces, we show a 5x improvement in system throughput compared to state-of-the-art system support for intermittent computing, while providing an equivalent output in 84% of the cases.
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| 19. |
- Baresi, Luciano, et al.
(författare)
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Building Software for the Internet of Things
- 2015. - 9
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Ingår i: IEEE Internet Computing. - 1089-7801 .- 1941-0131. ; 19:2, s. 6-8
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Tidskriftsartikel (refereegranskat)abstract
- The guest editors present a special issue on building software for the Internet of Things (IoT).
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Boano, Carlo Alberto, et al.
(författare)
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IoTBench: Towards a Benchmark for Low-power Wireless Networking
- 2018
-
Ingår i: 2018 1ST IEEE WORKSHOP ON BENCHMARKING CYBER-PHYSICAL NETWORKS AND SYSTEMS (CPSBENCH 2018). - 9781538667422 ; , s. 36-41
-
Konferensbidrag (refereegranskat)abstract
- Unlike other fields of computing and communications, low-power wireless networking is plagued by one major issue: the absence of a well-defined, agreed-upon yardstick to compare the performance of systems, namely, a benchmark. We argue that this situation may eventually represent a hampering factor for a technology expected to be key in the Internet of Things (IoT) and Cyber-physical Systems (CPS). This paper describes a recent initiative to remedy this situation, seeking to enlarge the participation from the community.
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| 24. |
- Boano, Carlo Alberto, et al.
(författare)
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Making Sensornet MAC Protocols Robust Against Interference
- 2010. - 10
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Konferensbidrag (refereegranskat)abstract
- Radio interference may lead to packet losses, thus negatively affecting the performance of sensornet applications. In this paper, we experimentally assess the impact of external interference on state-of-the-art sensornet MAC protocols. Our experiments illustrate that specific features of existing protocols, e.g., hand-shaking schemes preceding the actual data transmission, play a critical role in this setting. We leverage these results by identifying mechanisms to improve the robustness of existing MAC protocols under interference. These mechanisms include the use of multiple hand-shaking attempts coupled with packet trains and suitable congestion backoff schemes to better tolerate interference. We embed these mechanisms within an existing X-MAC implementation and show that they considerably improve the packet delivery rate while keeping the power consumption at a moderate level.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Costa, Paolo, et al.
(författare)
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Tuple space middleware for wireless networks
- 2009. - 1
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Ingår i: Middleware for Network Eccentric and Mobile Applications. - Berlin, Heidelberg : Springer Press. - 9783540897064
-
Bokkapitel (refereegranskat)abstract
- This chapter addresses tuple spaces, a programming abstraction for data sharing and coordination among distributed processes. The shared memory is called a tuple space, a multiset of elementary data structures. Each tuple is a sequence of typed fields and coordination among processes occurs through the writing and reading of tuples. Originally introduced in the context of parallel computing, it has recently enjoyed wide popularity to develop wireless applications. This chapter concisely describes some of the most representative systems implementing this abstraction and analyzes them along some fundamental dimensions of comparison.
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| 33. |
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| 34. |
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| 35. |
- El Yaacoub, Ahmed, 1996-, et al.
(författare)
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NeRTA : Enabling Dynamic Software Updates in Mobile Robotics
- 2022
-
Konferensbidrag (refereegranskat)abstract
- We present NeRTA (Next Release Time Analysis), a technique to schedule dynamic software updates of the low-level control loops of mobile robots. Dynamic software updates enable software correction and evolution during system operation. In mobile robotics, they are crucial to resolve software defects without interrupting system operation or to enable on-the-fly extensions. Low-level control loops of mobile robots, however, are time sensitive and run on resource-constrained hardware with no operating system support. To minimize the impact of the update process, NeRTA safely schedules updates during times when the computing unit would otherwise be idle. It does so by utilizing information from the existing scheduling algorithm without impacting its operation. As such, NeRTA works orthogonal to the existing scheduler, retaining the existing platform-specific optimizations and fine-tuning, and may simply operate as a plug-in component. Our experimental evaluation shows that NeRTA estimates are within 15% of the actual idle times in more than three-quarters of the cases. We also show that the processing overhead of NeRTA is essentially negligible.
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| 36. |
- El Yaacoub, Ahmed, et al.
(författare)
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Poster Abstract: Scheduling Dynamic Software Updates in Safety-critical Embedded Systems : the Case of Aerial Drones
- 2022
-
Ingår i: 2022 ACM/IEEE 13th International Conference on Cyber-Physical Systems (ICCPS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665409674 - 9781665409681 ; , s. 284-285
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Konferensbidrag (refereegranskat)abstract
- Dynamic software updates enable software evolution and bug fixes to embedded systems without disrupting their run-time operation. Scheduling dynamic updates for safety-critical embedded systems, such as aerial drones, must be done with great care. Otherwise, the system's control loop will be delayed leading to a partial or even complete loss of control, ultimately impacting the dependable operation. We propose an update scheduling algorithm called NeRTA, which schedules updates during the short times when the processor would have been idle. NeRTA consequently avoids the loss of control that would occur if an update delayed the execution of the control loop. The algorithm computes conservative estimations of idle times to determine if an update is possible, but is also sufficiently accurate that the estimated idle time is typically within 15% of the actual idle time.
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| 37. |
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| 38. |
- El Yaacoub, Ahmed, 1996-, et al.
(författare)
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Scheduling Dynamic Software Updates in Mobile Robots
- 2023
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Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery (ACM). - 1539-9087 .- 1558-3465. ; 22:6, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- We present NeRTA (Next Release Time Analysis), a technique to enable dynamic software updates for low-level control software of mobile robots. Dynamic software updates enable software correction and evolution during system operation. In mobile robotics, they are crucial to resolve software defects without interrupting system operation or to enable on-the-fly extensions. Low-level control software for mobile robots, however, is time sensitive and runs on resource-constrained hardware with no operating system support. To minimize the impact of the update process, NeRTA safely schedules updates during times when the computing unit would otherwise be idle. It does so by utilizing information from the existing scheduling algorithm without impacting its operation. As such, NeRTA works orthogonal to the existing scheduler, retaining the existing platform-specific optimizations and fine-tuning, and may simply operate as a plug-in component. To enable larger dynamic updates, we further conceive an additional mechanism called bounded reactive control and apply mixed-criticality concepts. The former cautiously reduces the overall control frequency, whereas the latter excludes less critical tasks from NeRTA processing. Their use increases the available idle times. We combine real-world experiments on embedded hardware with simulations to evaluate NeRTA. Our experimental evaluation shows that the difference between NeRTA’s estimated idle times and the measured idle times is less than 15% in more than three-quarters of the samples. The combined effect of bounded reactive control and mixed-criticality concepts results in a 150+% increase in available idle times. We also show that the processing overhead of NeRTA and of the additional mechanisms is essentially negligible.
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Guna, Stefan T., et al.
(författare)
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DICE : Monitoring global invariants with wireless sensor networks
- 2014
-
Ingår i: ACM transactions on sensor networks. - : Association for Computing Machinery. - 1550-4867 .- 1550-4859. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Wireless sensor networks (WSNs) enable decentralized architectures to monitor the behavior of physical processes and to detect deviations from a specified "safe" behavior, for example, to check the operation of control loops. Such correct behavior is typically expressed by global invariants over the state of different sensors or actuators. Nevertheless, to leverage the computing capabilities of WSN nodes, the application intelligence needs to reside inside the network. The task of ensuring that the monitored processes behave safely thus becomes inherently distributed, and hence more complex. In this article we present DICE, a system enabling WSN-based distributed monitoring of global invariants. A DICE invariant is expressed by predicates defined over the state of multiple WSN nodes, such as the expected state of actuators based on given sensed environmental conditions. Our modular design allows two alternative protocols for detecting invariant violations: both perform in-network aggregation but with different degrees of decentralization, therefore supporting scenarios with different network and data dynamics. We characterize and compare the two protocols using large-scale simulations and a real-world testbed. Our results indicate that invariant violations are detected in a timely and energy-efficient manner. For instance, in a 225-node 15-hop network, invariant violations are detected in less than a second and with only a few packets sent by each node.
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| 43. |
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| 44. |
- He, Yuan, et al.
(författare)
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Acoustic Localization System for Precise Drone Landing
- 2024
-
Ingår i: IEEE Transactions on Mobile Computing. ; 23:5, s. 4126-4144
-
Tidskriftsartikel (refereegranskat)abstract
- We present MicNest: an acoustic localization system enabling precise drone landing. In MicNest, multiple microphones are deployed on a landing platform in carefully devised configurations. The drone carries a speaker transmitting purposefully-designed acoustic pulses. The drone may be localized as long as the pulses are correctly detected. Doing so is challenging: i) because of limited transmission power, propagation attenuation, background noise, and propeller interference, the Signal-to-Noise Ratio (SNR) of received pulses is intrinsically low; ii) the pulses experience non-linear Doppler distortion due to the physical drone dynamics; iii) as location information is used during landing, the processing latency must be reduced to effectively feed the flight control loop. To tackle these issues, we design a novel pulse detector, Matched Filter Tree (MFT), whose idea is to convert pulse detection to a tree search problem. We further present three practical methods to accelerate tree search jointly. Our experiments show that MicNest can localize a drone 120 m away with 0.53% relative localization error at 20 Hz location update frequency. For navigating drone landing, MicNest can achieve a success rate of 94 %. The average landing error (distance between landing point and target point) is only 4.3 cm.
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| 45. |
- Hokke, N H, et al.
(författare)
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RF Information Harvesting for Medium Access in Event-driven Batteryless Sensing
- 2022
-
Ingår i: 2022 21st ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN). - : IEEE. - 9781665496247 - 9781665496254 ; , s. 377-389
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Konferensbidrag (refereegranskat)abstract
- We present radio-frequency (RF) information harvesting, a channel sensing technique that takes advantage of the energy in the wireless medium to detect channel activity at essentially no energy cost. RF information harvesting is essential for event-driven wireless sensing applications using battery-less devices that harvest tiny amounts of energy from impromptu events, such as operating a switch, and then transmit the event notification to a one-hop gateway. As multiple such devices may concurrently detect events, coordinating access to the channel is key. RF information harvesting allows devices to break the symmetry between concurrently-transmitting devices based on the harvested energy from the ongoing transmissions. To demonstrate the benefits of RF information harvesting, we integrate it in a tailor-made ultra lowpower hardware MAC protocol we call Radio Frequency-Distance Packet Queuing (RF-DiPaQ). We build a hardware/software prototype of RF-DiPaQ and use an established Markov framework to study its performance at scale. Comparing RF-DiPaQ against staple contention-based MAC protocols, we show that it outperforms pure Aloha and 1-CSMA by factors of 3.55 and 1.21 respectively in throughput, while it saturates at more than double the offered load compared to 1-CSMA. As traffic increases, the energy saving of RF-DiPaQ against CSMA protocols increases, consuming 36% less energy than np-CSMA at typical offered loads.
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| 46. |
- Izzo, Federico Amedeo, et al.
(författare)
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Demo abstract : 64Key - A mesh-based collaborative plaform
- 2018
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Ingår i: SenSys 2018 - Proceedings of the 16th Conference on Embedded Networked Sensor Systems. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450359528 ; , s. 422-423
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Konferensbidrag (refereegranskat)abstract
- We present 64Key, a hardware/software platform that enables impromptu sensing, data sharing, collaborative working, and social networking among physically co-located users independently of their own hardware platform, operating system, network stack, and of the availability of Internet access. 64Key caters to those scenarios such as computer labs, large conferences, and emergency situations where the network infrastructure is limited in operation or simply not available, and peer-to-peer interactions are prevented or not possible. By plugging a 64Key device in one’s mobile device USB port, an independent network is created on the fly, which users access from their own device though a web-based interface. In addition to default apps such as chat, file sharing, and collaborative text editing, 64Key’s functionality may be extended through the run-time installation of third-party apps, available at a public app store. We demonstrate our proof-of-concept implementation of 64Key with multiple apps in a set of key scenarios.
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| 47. |
- Jhumka, A., et al.
(författare)
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Neighborhood view consistency in wireless sensor networks
- 2016
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Ingår i: ACM transactions on sensor networks. - : Association for Computing Machinery. - 1550-4867 .- 1550-4859. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Wireless sensor networks (WSNs) are characterized by localized interactions, that is, protocols are often based on message exchanges within a node's direct radio range. We recognize that for these protocols to work effectively, nodes must have consistent information about their shared neighborhoods. Different types of faults, however, can affect this information, severely impacting a protocol's performance. We factor this problem out of existing WSN protocols and argue that a notion of neighborhood view consistency (NVC) can be embedded within existing designs to improve their performance. To this end, we study the problem from both a theoretical and a system perspective. We prove that the problem cannot be solved in an asynchronous system using any of Chandra and Toueg's failure detectors. Because of this, we introduce a new software device called pseudocrash failure detector (PCD), study its properties, and identify necessary and sufficient conditions for solving NVC with PCDs. We prove that, in the presence of transient faults, NVC is impossible to solve with any PCDs, thus define two weaker specifications of the problem. We develop a global algorithm that satisfies both specifications in the presence of unidirectional links, and a localized algorithm that solves the weakest specification in networks of bidirectional links. We implement the latter atop two different WSN operating systems, integrate our implementations with four different WSN protocols, and run extensive micro-benchmarks and full-stack experiments on a real 90-node WSN testbed. Our results show that the performance significantly improves for NVC-equipped protocols; for example, the Collection Tree Protocol (CTP) halves energy consumption with higher data delivery.
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| 48. |
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| 49. |
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| 50. |
- Mahima, K.T.Y, et al.
(författare)
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Fighting Dengue Fever with Aerial Drones
- 2022
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Ingår i: EWSN '22. - : Association for Computing Machinery (ACM). ; , s. 206-207
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Konferensbidrag (refereegranskat)abstract
- Dengue and Zika are two arboviral viruses that affect a significant portion of the world population. Each year, almost 400 million dengue infections happen. Due to severe dengue fever, around half a million people each year are in need of hospitalization and about 36.000 people die.Dengue spreads rapidly in densely populated urban areas. The principle vector species of both dengue and zika viruses are the Aedes aegypti and Aedes albopictus mosquitoes. They breed in very slow-flowing or standing water pools. It is important to reduce and control such potential breeding grounds to contain the spread of these diseases.We describe our system design and presents initial results. We employ mmWave radios to detect water retention areas as potential mosquito habitats. Next, we use multi-spectral images to analyze the water area, measure the depth of the water, and understand the larvae density. After that, we fuse the results for the final classification of the water area.
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