Yazar "Pawelczak, Przemyslaw" seçeneğine göre listele

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    Dynamic Task-based Intermittent Execution for Energy-harvesting Devices
    (Assoc Computing Machinery, 2020) Majid, Amjad Yousef; Delle Donne, Carlo; Maeng, Kiwan; Colin, Alexei; Yildirim, Kasim Sinan; Lucia, Brandon; Pawelczak, Przemyslaw
    Energy-neutral Internet of Things requires freeing embedded devices from batteries and powering them from ambient energy. Ambient energy is, however, unpredictable and can only power a device intermittently. Therefore, the paradigm of intermittent execution is to save the program state into non-volatile memory frequently to preserve the execution progress. in task-based intermittent programming, the state is saved at task transition. Tasks are fixed at compile time and agnostic to energy conditions. Thus, the state may be saved either more often than necessary or not often enough for the program to progress and terminate. To address these challenges, we propose Coala, an adaptive and efficient task-based execution model. Coala progresses on a multi-task scale when energy permits and preserves the computation progress on a sub-task scale if necessary. Coala's specialized memory virtualization mechanism ensures that power failures do not leave the program state in non-volatile memory inconsistent. Our evaluation on a real energy-harvesting platform not only shows that Coala reduces runtime by up to 54% as compared to a state-of-the-art system, but also it is able to progress where static systems fail.
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    InK: Reactive Kernel for Tiny Batteryless Sensors
    (Assoc Computing Machinery, 2018) Yildirim, Kasim Sinan; Majid, Amjad Yousef; Patoukas, Dimitris; Schaper, Koen; Pawelczak, Przemyslaw; Hester, Josiah
    Tiny energy harvesting battery-free devices promise maintenance free operation for decades, providing swarm scale intelligence in applications from healthcare to building monitoring. These devices operate intermittently because of unpredictable, dynamic energy harvesting environments, failing when energy is scarce. Despite this dynamic operation, current programming models are static; they ignore the event-driven and time-sensitive nature of sensing applications, focusing only on preserving forward progress while maintaining performance. This paper proposes InK; the first reactive kernel that provides a novel way to program these tiny energy harvesting devices that focuses on their main application of event-driven sensing. InK brings an event-driven paradigm shift for batteryless applications, introducing building blocks and abstractions that enable reacting to changes in available energy and variations in sensing data, alongside task scheduling, while maintaining a consistent memory and sense of time. We implemented several event-driven applications for InK, conducted a user study, and benchmarked InK against the state-of-the-art; InK provides up to 14 times more responsiveness and was easier to use. We show that InK enables never before seen batteryless applications, and facilitates more sophisticated batteryless programs.
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    On Distributed Sensor Fusion in Batteryless Intermittent Networks
    (Ieee, 2019) Yildirim, Kasim Sinan; Pawelczak, Przemyslaw
    Distributed and collaborative computation has never been considered before in networks of batteryless sensors. This can bring many advantages for applications (e.g. longer transmission ranges, lower network costs), however introducing new research challenges. in this paper, we focus on the well-known distributed sensor fusion but in an intermittently-powered batteryless sensor network. the goal is to estimate a parameter collaboratively by considering individual sensor measurements. We show that, even though the nodes stop operation with high probability due to random power failures and they neither communicate with their neighbors nor perform computation most of the time, the simplest implementation of the fully-distributed sensor fusion based on average consensus improves the overall estimation quality of the network considerably. in the light of this, we anticipate that if harvested energy is used efficiently so that nodes have more opportunity to receive and send packets, existing fully-distributed protocols can be implemented with tiny modifications in networks of batteryless sensors.
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    On the Accuracy of Network Synchronization Using Persistent Hourglass Clocks
    (Assoc Computing Machinery, 2019) Curuk, Eren; Yildirim, Kasim Sinan; Pawelczak, Przemyslaw; Hester, Josiah
    Batteryless sensor nodes compute, sense, and communicate using only energy harvested from the ambient. These devices promise long maintenance free operation in hard to deploy scenarios, making them an attractive alternative to battery-powered wireless sensor networks. However, complications from frequent power failures due to unpredictable ambient energy stand in the way of robust network operation. Unlike continuously-powered systems, intermittently-powered batteryless nodes lose their time upon each reboot, along with all volatile memory, making synchronization and coordination difficult. in this paper, we consider the case where each batteryless sensor is equipped with a hourglass capacitor to estimate the elapsed time between power failures. Contrary to prior work that focused on providing a continuous notion of time for a single batteryless sensor, we consider a network of batteryless sensors and explore how to provide a network-wide, continuous, and synchronous notion of time. First, we build a mathematical model that represents the estimated time between power failures by using hourglass capacitors. This allowed us to simulate the local (and continuous) time of a single batteryless node. Second, we show-through simulations-the effect of hourglass capacitors and in turn the performance degradation of the state of the art synchronization protocol in wireless sensor networks in a network of batteryless devices.
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    On the Synchronization of Computational RFIDs
    (Ieee Computer Soc, 2019) Yildirim, Kasim Sinan; Aantjes, Henko; Pawelczak, Przemyslaw; Majid, Amjad Yousef
    Battery-free computational RFID platforms, such as WISP (Wireless Identification and Sensing Platform), are intermittently-powered devices designed for replacing existing sensor networks. Accordingly, synchronization appears as one of the crucial building blocks for collaborative and coordinated actions in these platforms. However, intermittent power leads to frequent loss of computational state and short-term clock frequency instability that makes synchronization challenging. In this article, we introduce the WISP-Sync protocol that provides synchronization among WISP tags in the communication range of an RFID reader. WISP-Sync overcomes the aforementioned challenges by employing a Proportional-Integral (PI) controller-inspired algorithm which (i) is adaptive-reactive to short-term clock instabilities; (ii) requires only a few computation steps-suitable for limited harvested energy; and (iii) keeps a few variables to hold the synchronization state-minimum overhead to recover from power interrupts. Evaluations in our testbed showed that WISP-Sync ensured an average synchronization error of approximately 1 ms among the tags with an average energy overhead of 1.85 mu J per synchronization round.
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    Perpetual Bluetooth Communications for the IoT
    (Ieee-Inst Electrical Electronics Engineers Inc, 2021) Liu, Qingzhi; IJntema, Wieger; Drif, Anass; Pawelczak, Przemyslaw; Zuniga, Marco; Yildirim, Kasim Sinan
    Battery-powered beacon devices introduce high maintenance costs due to the finite operation time dictated by the fixed capacity of their batteries. To tackle this problem we propose FreeBLE: an indoor beacon system aimed at operating perpetually without batteries. We propose three methods to increase the utilization efficiency of harvested Radio Frequency (RF) energy in the beacon system, by which the energy consumption level becomes low enough to fit within the energy harvesting budget. We implement FreeBLE using off-the-shelf Bluetooth Low Energy (BLE) and RF energy harvesting devices, and test FreeBLE in a laboratory environment. Our results show that FreeBLE enables perpetual operation in an indoor deployment of RF-powered BLE beacon devices.
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    Safe and Secure Wireless Power Transfer Networks: Challenges and Opportunities in RF-Based Systems
    (Ieee-Inst Electrical Electronics Engineers Inc, 2016) Liu, Qingzhi; Yildirim, Kasim Sinan; Pawelczak, Przemyslaw; Warnier, Martijn
    RF-based WPTNs are deployed to transfer power to embedded devices over the air via radio frequency waves. Up until now, a considerable amount of effort has been devoted by researchers to design WPTNs that maximize several objectives such as harvested power, energy outage, and charging delay. However, inherent security and safety issues are generally overlooked, and these need to be solved if WPTNs are to become widespread. This article focuses on the safety and security problems related to WPTNs and highlights their cruciality in terms of efficient and dependable operation of RF-based WPTNs. We provide an overview of new research opportunities in this emerging domain.