394 research outputs found
Living IoT: A Flying Wireless Platform on Live Insects
Sensor networks with devices capable of moving could enable applications
ranging from precision irrigation to environmental sensing. Using mechanical
drones to move sensors, however, severely limits operation time since flight
time is limited by the energy density of current battery technology. We explore
an alternative, biology-based solution: integrate sensing, computing and
communication functionalities onto live flying insects to create a mobile IoT
platform.
Such an approach takes advantage of these tiny, highly efficient biological
insects which are ubiquitous in many outdoor ecosystems, to essentially provide
mobility for free. Doing so however requires addressing key technical
challenges of power, size, weight and self-localization in order for the
insects to perform location-dependent sensing operations as they carry our IoT
payload through the environment. We develop and deploy our platform on
bumblebees which includes backscatter communication, low-power
self-localization hardware, sensors, and a power source. We show that our
platform is capable of sensing, backscattering data at 1 kbps when the insects
are back at the hive, and localizing itself up to distances of 80 m from the
access points, all within a total weight budget of 102 mg.Comment: Co-primary authors: Vikram Iyer, Rajalakshmi Nandakumar, Anran Wang,
In Proceedings of Mobicom. ACM, New York, NY, USA, 15 pages, 201
Concurrent Backscatter Streaming from Batteryless and Wireless Sensor Tags with Multiple Subcarrier Multiple Access
This paper proposes a novel multiple access method that enables concurrent sensor data streaming from multiple batteryless, wireless sensor tags. The access method is a pseudo-FDMA scheme based on the subcarrier backscatter communication principle, which is widely employed in passive RFID and radar systems. Concurrency is realized by assigning a dedicated subcarrier to each sensor tag and letting all sensor tags backscatter simultaneously. Because of the nature of the subcarrier, which is produced by constant rate switching of antenna impedance without any channel filter in the sensor tag, the tag-to-reader link always exhibits harmonics. Thus, it is important to reject harmonics when concurrent data streaming is required. This paper proposes a harmonics rejecting receiver to allow simultaneous multiple subcarrier usage. This paper particularly focuses on analog sensor data streaming which minimizes the functional requirements on the sensor tag and frequency bandwidth. The harmonics rejection receiver is realized by carefully handling group delay and phase delay of the subcarrier envelope and the carrier signal to accurately produce replica of the harmonics by introducing Hilbert and inverse Hilbert transformations. A numerical simulator with Simulink and a hardware implementation with USRP and LabVIEW have been developed. Simulations and experiments reveal that even if the CIR before harmonics rejection is 0dB, the proposed receiver recovers the original sensor data with over 0.98 cross-correlation
Slocalization: Sub-{\mu}W Ultra Wideband Backscatter Localization
Ultra wideband technology has shown great promise for providing high-quality
location estimation, even in complex indoor multipath environments, but
existing ultra wideband systems require tens to hundreds of milliwatts during
operation. Backscatter communication has demonstrated the viability of
astonishingly low-power tags, but has thus far been restricted to narrowband
systems with low localization resolution. The challenge to combining these
complimentary technologies is that they share a compounding limitation,
constrained transmit power. Regulations limit ultra wideband transmissions to
just -41.3 dBm/MHz, and a backscatter device can only reflect the power it
receives. The solution is long-term integration of this limited power, lifting
the initially imperceptible signal out of the noise. This integration only
works while the target is stationary. However, stationary describes the vast
majority of objects, especially lost ones. With this insight, we design
Slocalization, a sub-microwatt, decimeter-accurate localization system that
opens a new tradeoff space in localization systems and realizes an energy,
size, and cost point that invites the localization of every thing. To evaluate
this concept, we implement an energy-harvesting Slocalization tag and find that
Slocalization can recover ultra wideband backscatter in under fifteen minutes
across thirty meters of space and localize tags with a mean 3D Euclidean error
of only 30 cm.Comment: Published at the 17th ACM/IEEE Conference on Information Processing
in Sensor Networks (IPSN'18
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