4,997 research outputs found
Interference Minimization in Asymmetric Sensor Networks
A fundamental problem in wireless sensor networks is to connect a given set
of sensors while minimizing the \emph{receiver interference}. This is modeled
as follows: each sensor node corresponds to a point in and each
\emph{transmission range} corresponds to a ball. The receiver interference of a
sensor node is defined as the number of transmission ranges it lies in. Our
goal is to choose transmission radii that minimize the maximum interference
while maintaining a strongly connected asymmetric communication graph.
For the two-dimensional case, we show that it is NP-complete to decide
whether one can achieve a receiver interference of at most . In the
one-dimensional case, we prove that there are optimal solutions with nontrivial
structural properties. These properties can be exploited to obtain an exact
algorithm that runs in quasi-polynomial time. This generalizes a result by Tan
et al. to the asymmetric case.Comment: 15 pages, 5 figure
On interference among moving sensors and related problems
We show that for any set of points moving along "simple" trajectories
(i.e., each coordinate is described with a polynomial of bounded degree) in
and any parameter , one can select a fixed non-empty
subset of the points of size , such that the Voronoi diagram of
this subset is "balanced" at any given time (i.e., it contains points
per cell). We also show that the bound is near optimal even for
the one dimensional case in which points move linearly in time. As
applications, we show that one can assign communication radii to the sensors of
a network of moving sensors so that at any given time their interference is
. We also show some results in kinetic approximate range
counting and kinetic discrepancy. In order to obtain these results, we extend
well-known results from -net theory to kinetic environments
ptp++: A Precision Time Protocol Simulation Model for OMNeT++ / INET
Precise time synchronization is expected to play a key role in emerging
distributed and real-time applications such as the smart grid and Internet of
Things (IoT) based applications. The Precision Time Protocol (PTP) is currently
viewed as one of the main synchronization solutions over a packet-switched
network, which supports microsecond synchronization accuracy. In this paper, we
present a PTP simulation model for OMNeT++ INET, which allows to investigate
the synchronization accuracy under different network configurations and
conditions. To show some illustrative simulation results using the developed
module, we investigate on the network load fluctuations and their impacts on
the PTP performance by considering a network with class-based
quality-of-service (QoS) support. The simulation results show that the network
load significantly affects the network delay symmetry, and investigate a new
technique called class probing to improve the PTP accuracy and mitigate the
load fluctuation effects.Comment: Published in: A. F\"orster, C. Minkenberg, G. R. Herrera, M. Kirsche
(Eds.), Proc. of the 2nd OMNeT++ Community Summit, IBM Research - Zurich,
Switzerland, September 3-4, 201
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