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Varshney, Ambuj
Publications (10 of 25) Show all publications
Carlos, P. P., Noda, C., Varshney, A. & Voigt, T. (2018). Battery-free 802.15. 4 Receiver. In: 7th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN): . Paper presented at 17th ACM/IEEE International Conference on Information Processing in Sensor Networks, Porto, Portugal, 11-13 April, 2018.. IEEE
Open this publication in new window or tab >>Battery-free 802.15. 4 Receiver
2018 (English)In: 7th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN), IEEE, 2018Conference paper, Published paper (Refereed)
Abstract [en]

We present the architecture of an 802.15.4 receiver that, for the first time, operates at a few hundred microwatts, enabling new battery-free applications. To reach the required micro-power consumption, the architecture diverges from that of commodity receivers in two important ways. First, it offloads the power-hungry local oscillator to an external device, much like backscatter transmitters do. Second, we avoid the energy cost of demodulating a phase-modulated signal by treating 802.15.4 as a frequency-modulated one, which allows us to receive with a simple passive detector and an energy-efficient thresholding circuit. We describe a prototype that can receive 802.15.4 frames with a power consumption of 361 μW. Our receiver prototype achieves sufficient communication range to integrate with deployed wireless sensor networks (WSNs). We illustrate this integration by pairing the prototype with an 802.15.4 backscatter transmitter and integrating it with unmodified 802.15.4 sensor nodes running the TSCH and Glossy protocols.

Place, publisher, year, edition, pages
IEEE, 2018
Keywords
Battery free, Backscatter, receiver, 802.15.4, Zigbee, sensor networks, passive radio, wireless
National Category
Computer Engineering
Identifiers
urn:nbn:se:uu:diva-366929 (URN)10.1109/IPSN.2018.00045 (DOI)000449016500037 ()978-1-5386-5298-5 (ISBN)
Conference
17th ACM/IEEE International Conference on Information Processing in Sensor Networks, Porto, Portugal, 11-13 April, 2018.
Funder
Swedish Research Council, 2017-045989Knowledge Foundation, 20140319
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-12-20Bibliographically approved
Giustiniano, D., Varshney, A. & Voigt, T. (2018). Connecting Battery-free IoT Tags Using LED Bulbs. In: : . Paper presented at 17th ACM Workshop on Hot Topics in Networks, Nov 8 - Nov 9, 2018,Redmond, Washington, USA.
Open this publication in new window or tab >>Connecting Battery-free IoT Tags Using LED Bulbs
2018 (English)Conference paper, Published paper (Refereed)
National Category
Computer Engineering
Identifiers
urn:nbn:se:uu:diva-366916 (URN)
Conference
17th ACM Workshop on Hot Topics in Networks, Nov 8 - Nov 9, 2018,Redmond, Washington, USA
Funder
Swedish Research Council
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-03-06Bibliographically approved
Carlos, P. P., Noda, C., Varshney, A. & Voigt, T. (2018). Demo Abstract: Battery-Free 802.15.4 Receiver. In: 17th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN): . Paper presented at 17th ACM/IEEE International Conference on Information Processing in Sensor Networks, Porto, Portugal, 11-13 April, 2018. (pp. 130-131). IEEE
Open this publication in new window or tab >>Demo Abstract: Battery-Free 802.15.4 Receiver
2018 (English)In: 17th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN), IEEE, 2018, p. 130-131Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

We present the architecture for an 802.15.4 receiver that enables battery-free operation. To reach micro-power consumption, the architecture diverges from that of commodity receivers in the following ways: First, similar to backscatter transmitters, it offloads the power-hungry local oscillator to an external device. Second, we avoid the energy cost of demodulating a phase-modulated signal by treating 802.15.4 as a frequency-modulated one, allowing us to receive with a simple passive detector and an energy-efficient thresholding circuit. We demonstrate an off-the-shelf prototype of our receiver receives 802.15.4 from a distance of 470 cm with the carrier generator 30 cm away. This range is sufficient to integrate with deployed wireless sensor networks (WSNs). We demonstrate this integration by pairing our receiver with a 802.15.4 backscatter transmitter and integrating it with unmodified commodity sensor nodes running the TSCH protocol.

Place, publisher, year, edition, pages
IEEE, 2018
Keywords
Sensor networks, battery free, backscatter, receiver, 802.15.4
National Category
Computer Engineering
Identifiers
urn:nbn:se:uu:diva-366926 (URN)10.1109/IPSN.2018.00028 (DOI)000449016500020 ()978-1-5386-5298-5 (ISBN)
Conference
17th ACM/IEEE International Conference on Information Processing in Sensor Networks, Porto, Portugal, 11-13 April, 2018.
Funder
Swedish Research Council, 2017-045989Knowledge Foundation, 20140319
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-12-20Bibliographically approved
Hylamia, A., Spanghero, M., Varshney, A., Voigt, T. & Papadimitratos, P. (2018). Demo: Security on Harvested Power. In: WISEC'18: PROCEEDINGS OF THE 11TH ACM CONFERENCE ON SECURITY & PRIVACY IN WIRELESS AND MOBILE NETWORKS. Paper presented at 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec), JUN 18-20, 2018, Stockholm, SWEDEN (pp. 296-298). ASSOC COMPUTING MACHINERY
Open this publication in new window or tab >>Demo: Security on Harvested Power
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2018 (English)In: WISEC'18: PROCEEDINGS OF THE 11TH ACM CONFERENCE ON SECURITY & PRIVACY IN WIRELESS AND MOBILE NETWORKS, ASSOC COMPUTING MACHINERY , 2018, p. 296-298Conference paper, Published paper (Refereed)
Abstract [en]

Security mechanisms for battery-free devices have to operate under severe energy constraints relying on harvested energy. This is challenging, as the energy harvested from the ambient environment is usually scarce, intermittent and unpredictable. One of the challenges for developing security mechanisms for such settings is the lack of hardware platforms that recreate energy harvesting conditions experienced on a battery-free sensor node. In this demonstration, we present an energy harvesting security (EHS) platform that enables the development of security algorithms for battery-free sensors. Our results demonstrate that our platform is able to harvest sufficient energy from indoor lighting to support several widely used cryptography algorithms.

Place, publisher, year, edition, pages
ASSOC COMPUTING MACHINERY, 2018
Keywords
Energy-harvesting, battery-free, embedded systems security, platforms
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-377116 (URN)10.1145/3212480.3226105 (DOI)000456097500038 ()978-1-4503-5731-9 (ISBN)
Conference
11th ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec), JUN 18-20, 2018, Stockholm, SWEDEN
Funder
Swedish Foundation for Strategic Research
Available from: 2019-02-13 Created: 2019-02-13 Last updated: 2019-02-13Bibliographically approved
Hylamia, A., Varshney, A., Soleiman, A., Papadimitratos, P., Rohner, C. & Voigt, T. (2018). Demo: Towards Battery-free Radio Tomographic Imaging. In: WISEC'18: PROCEEDINGS OF THE 11TH ACM CONFERENCE ON SECURITY & PRIVACY IN WIRELESS AND MOBILE NETWORKS. Paper presented at 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec), JUN 18-20, 2018, Stockholm, SWEDEN (pp. 293-295). ASSOC COMPUTING MACHINERY
Open this publication in new window or tab >>Demo: Towards Battery-free Radio Tomographic Imaging
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2018 (English)In: WISEC'18: PROCEEDINGS OF THE 11TH ACM CONFERENCE ON SECURITY & PRIVACY IN WIRELESS AND MOBILE NETWORKS, ASSOC COMPUTING MACHINERY , 2018, p. 293-295Conference paper, Published paper (Refereed)
Abstract [en]

Radio Tomographic Imaging (RTI) enables novel radio frequency (RF) sensing applications such as intrusion detection systems by observing variations in radio links caused by human actions. RTI applications are, however, severely limited by the requirement to retrofit existing infrastructure with energy-expensive sensors. In this demonstration, we present our ongoing efforts to develop the first battery-free RTI system that operates on minuscule amounts of energy harvested from the ambient environment. Our system eliminates the energy-expensive components employed on state-of-the-art RTI systems achieving two orders of magnitude lower power consumption. Battery-free operation enables a sustainable deployment, as RTI sensors could be deployed for long periods of time with little maintenance effort. Our demonstration showcases an intrusion detection scenario enabled by our system.

Place, publisher, year, edition, pages
ASSOC COMPUTING MACHINERY, 2018
Keywords
radio-tomographic-imaging, battery-free, backscatter
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-377115 (URN)10.1145/3212480.3226107 (DOI)000456097500037 ()978-1-4503-5731-9 (ISBN)
Conference
11th ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec), JUN 18-20, 2018, Stockholm, SWEDEN
Funder
Swedish Foundation for Strategic Research
Available from: 2019-02-13 Created: 2019-02-13 Last updated: 2019-02-13Bibliographically approved
Varshney, A. (2018). Enabling Sustainable Networked Embedded Systems. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Enabling Sustainable Networked Embedded Systems
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Networked Embedded Systems (NES) are small energy-constrained devices typically with sensors, radio and some form of energy storage. The past several years have seen a rapid growth of applications of NES, with several predictions stating billions of devices deployed in the near future. As NES are deployed at large scale, a growing challenge is to support NES for long periods of time without negatively impacting their physical or the radio environment, i.e., in a sustainable manner. In this dissertation, we identify intertwined challenges that affect the sustainability of NES systems: co-existence on the shared wireless spectrum; energy consumption; and the cost of the deployment and maintenance. We identify research directions to overcome these challenges and address them through the six research papers.

Firstly, NES have to co-exist with other wireless devices that operate on the shared wireless spectrum. A growing number of devices contending for the spectrum is challenging and leads to increased interference among them. To enable NES to co-exist with other wireless devices, we investigate the use of electronically steerable directional antennas (ESD). ESD antennas allow software-based control of the direction of maximum antenna gain on a per-packet basis and can operate within the severe energy constraints of NES. In the dissertation, we demonstrate that ESD antennas allow solutions that outperform the state-of-the-art in sensing and communication in wireless sensor networks while supporting operations on a single wireless channel reducing the contention on the shared wireless spectrum.

Secondly, we explore the emerging area of visible light sensing and communication to avoid the crowded radio frequency spectrum. Visible light can be an alternative or a complement to radio frequency for sensing and communication. We make two contributions in the dissertation to make the visible light communication a viable option for NES. We design a novel visible light sensing architecture that supports sensing and communication at tens of microwatts of power. An ultra-low power consumption can make visible light sensing systems pervasive. Our second contribution brings high-speed visible light communication to energy-constrained NES. We design a novel visible light receiver that adapts to the dynamics of changing light conditions, and the energy constraints of the host device while supporting a throughput comparable to radio frequency standards for NES. Through our contribution, we take a significant step to enable visible light-based sustainable NES.

Finally, replacing batteries on sensor nodes significantly affects the sustainability of NES. Battery-free sensors that harvest small amounts of energy from the ambient environment have a great potential to enable pervasive deployment of NES. To support wide-area deployments of battery-free sensors, we develop an ultra-low power and long-range communication mechanism. We demonstrate the ability to communicate to distances as long as a few kilometres while consuming tens of microwatts at the sensor device. Our contributions pave the way for a wide-area deployment of battery-free sustainable NES.

Through the contributions made in the dissertation, we take a significant step towards the broader goal of sustainable NES. The work included in the dissertation significantly improves the state-of-the-art in NES, in some case by orders of magnitude.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 52
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1648
Keywords
Wireless Sensor Network; Energy harvesting; backscatter; RFID; Sensors
National Category
Computer Systems
Research subject
Computer Science with specialization in Computer Communication
Identifiers
urn:nbn:se:uu:diva-346267 (URN)978-91-513-0279-9 (ISBN)
Public defence
2018-05-07, 2446, ITC, Lägerhyddsvägen 2, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2018-04-18 Created: 2018-03-16 Last updated: 2018-10-08
Catalán Rivas, V., Fröjd, E., Holmberg, T., Ragnarsson, F., Rick, E., Corneo, L., . . . Gunningberg, P. (2018). Environmental Control at the Edge. In: : . Paper presented at 14th Swedish National Computer Networking Workshop (SNCNW), Karlskrona, May 31 – June 1, 2018.
Open this publication in new window or tab >>Environmental Control at the Edge
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Computer Engineering
Identifiers
urn:nbn:se:uu:diva-366910 (URN)
Conference
14th Swedish National Computer Networking Workshop (SNCNW), Karlskrona, May 31 – June 1, 2018
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-10-14Bibliographically approved
Eriksson, G., Varshney, A., Rohner, C., Voigt, T. & Dancila, D. (2018). Towards Long-range Backscatter Communication with Tunnel Diode Reflection Amplifier. In: : . Paper presented at GigaHertz Symposium, Lund, May 24-25, 2018.
Open this publication in new window or tab >>Towards Long-range Backscatter Communication with Tunnel Diode Reflection Amplifier
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2018 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-369185 (URN)
Conference
GigaHertz Symposium, Lund, May 24-25, 2018
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-14Bibliographically approved
Perez Penichet, C., Noda, C., Varshney, A. & Voigt, T. (2017). Augmenting WSNs with Interoperable 802.15.4 Sensor Tags. In: Proceedings of the 15th ACM Conference on Embedded Networked Sensor Systems: . Paper presented at 15th ACM Conference on Embedded Networked Sensor Systems (Sensys), Delft, Netherlands, nov 06-08, 2017.
Open this publication in new window or tab >>Augmenting WSNs with Interoperable 802.15.4 Sensor Tags
2017 (English)In: Proceedings of the 15th ACM Conference on Embedded Networked Sensor Systems, 2017Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The sensing capabilities of most sensor networks are fixed at the time of deployment. Adding new sensing capabilities to such networks is a costly and cumbersome process. We present Passive Sensor Tags, battery-free sensing devices that could be used to extend the sensing capabilities of an existing network. Sensor tags feature our new 802.15.4 receiver design which is suitable for micro-power operation, making battery-free tags possible. Because our tags can both transmit and receive 802.15.4 frames there is no need for any modification to the deployed hardware. We present preliminary measurements of transmission and reception range.

National Category
Communication Systems Embedded Systems Telecommunications Signal Processing
Identifiers
urn:nbn:se:uu:diva-335570 (URN)10.1145/3131672.3136999 (DOI)000462783500075 ()
Conference
15th ACM Conference on Embedded Networked Sensor Systems (Sensys), Delft, Netherlands, nov 06-08, 2017
Funder
Swedish Energy Agency
Available from: 2017-12-06 Created: 2017-12-06 Last updated: 2019-08-22Bibliographically approved
Varshney, A., Soleiman, A., Mottola, L. & Voigt, T. (2017). Battery-free Visible Light Sensing. In: Proc. 4th ACM Workshop on Visible Light Communication Systems: . Paper presented at VLCS 2017, October 16, Snowbird, UT (pp. 3-8). New York: ACM Press
Open this publication in new window or tab >>Battery-free Visible Light Sensing
2017 (English)In: Proc. 4th ACM Workshop on Visible Light Communication Systems, New York: ACM Press, 2017, p. 3-8Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
New York: ACM Press, 2017
National Category
Computer Engineering
Identifiers
urn:nbn:se:uu:diva-335564 (URN)10.1145/3129881.3129890 (DOI)978-1-4503-5142-3 (ISBN)
Conference
VLCS 2017, October 16, Snowbird, UT
Available from: 2017-10-16 Created: 2017-12-06 Last updated: 2018-03-16Bibliographically approved
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