4,913 research outputs found
On Capacity of Active Relaying in Magnetic Induction based Wireless Underground Sensor Networks
Wireless underground sensor networks (WUSNs) present a variety of new
research challenges. Magnetic induction (MI) based transmission has been
proposed to overcome the very harsh propagation conditions in underground
communications in recent years. In this approach, induction coils are utilized
as antennas in the sensor nodes. This solution achieves longer transmission
ranges compared to the traditional electromagnetic (EM) waves based approach.
Furthermore, a passive relaying technique has been proposed in the literature
where additional resonant circuits are deployed between the nodes. However,
this solution is shown to provide only a limited performance improvement under
practical system design contraints. In this work, the potential of an active
relay device is investigated which may improve the performance of the system by
combining the benefits of the traditional wireless relaying and the MI based
signal transmission.Comment: This paper has been accepted for presentation at IEEE ICC 2015. It
has 6 pages, 5 figures (4 colored), and 17 reference
Target Tracking in Confined Environments with Uncertain Sensor Positions
To ensure safety in confined environments such as mines or subway tunnels, a
(wireless) sensor network can be deployed to monitor various environmental
conditions. One of its most important applications is to track personnel,
mobile equipment and vehicles. However, the state-of-the-art algorithms assume
that the positions of the sensors are perfectly known, which is not necessarily
true due to imprecise placement and/or dropping of sensors. Therefore, we
propose an automatic approach for simultaneous refinement of sensors' positions
and target tracking. We divide the considered area in a finite number of cells,
define dynamic and measurement models, and apply a discrete variant of belief
propagation which can efficiently solve this high-dimensional problem, and
handle all non-Gaussian uncertainties expected in this kind of environments.
Finally, we use ray-tracing simulation to generate an artificial mine-like
environment and generate synthetic measurement data. According to our extensive
simulation study, the proposed approach performs significantly better than
standard Bayesian target tracking and localization algorithms, and provides
robustness against outliers.Comment: IEEE Transactions on Vehicular Technology, 201
ANTENNA FOR WIRELESS UNDERGROUND COMMUNICATION
Systems and methods are disclosed for an underground antenna structure for radiating through a dissipative medium, the antenna structure. The antenna structure includes a dielectric substrate, a feeding structure disposed on the substrate, and one or more electrical conductors. The one or more electrical conductors are disposed on the substrate, oriented, and buried within the dissipative medium. The electrical conductors are also adapted to radiate signals at a frequency in half-space adjacent to the dissipative medium. The adaptation includes a beamwidth state for one or more of the electrical conductors based at least in part on the relative permittivity of the dissipative medium
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