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Optimal Policy Derivation for Transmission Duty-Cycle Constrained LPWAN
Low-power wide-area network (LPWAN) technologies enable Internet of Things (IoT) devices to efficiently and robustly communicate over long distances, thus making them especially suited for industrial environments. However, the stringent regulations on the usage of certain industrial, scientific, and medical bands in many countries in which LPWAN operate limit the amount of time IoT motes can occupy the shared bands. This is particularly challenging in industrial scenarios, where not being able to report some detected events might result in the failure of critical assets. To alleviate this, and by mathematically modeling LPWAN-based IoT motes, we have derived optimal transmission policies that maximize the number of reported events (prioritized by their importance) while still complying with current regulations. The proposed solution has been customized for two widely known LPWAN technologies: 1) LoRa and 2) Sigfox. Analytical results reveal that our solution is feasible and performs remarkably close to the theoretical limit for a wide range of network activity patterns
Classical resolution of black hole singularities via wormholes
In certain extensions of General Relativity, wormholes generated by
spherically symmetric electric fields can resolve black hole singularities
without necessarily removing curvature divergences. This is shown by studying
geodesic completeness, the behavior of time-like congruences going through the
divergent region, and by means of scattering of waves off the wormhole. This
provides an example of the logical independence between curvature divergences
and space-time singularities, concepts very often identified with each other in
the literature.ns of curvature divergences in the context of space-time
singularities.Comment: 6 pages, 4 figures; several improvements in main body and abstract;
final version to appear in Eur. Phys. J.
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