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Figure 13. Comparison of detection results when applying lease-based and ACK-based collaboration
in case of permanently failing sensing capabilities. The lease-based approach enhances the detection
accuracy by more than 30%. The ACK-based scheme indicated similar or slightly better performance
but has been aborted by the simulation environment due the huge number messages required. Moreover,
even if only 50% of all nodes are able to generate local detection result in the standard scheme, both
collaboration schemes still provide a detection accuracy that is higher than 80%.
scheme performed slightly better than the lease-
based scheme but required far more collaboration
messages to achieve such results. The number of
necessary messages differs by an average factor of
10 or higher. It is an unsolved question whether this
overhead will also cause real applications to fail
as it happened in the simulations. However, two
remarks need to be emphasized. First, this failure
scenario is (hopefully) rather unlikely to occur in
real deployments. Second, applications running
in such failure scenario possess a certain point
in time where the detection accuracy falls below
the required minimum in either way, regardless
of detection enhancement. A sensor network that
features too many failures should be renewed or
not be relied to.
the cost-efficiency of these means. Compared to
the improved detection accuracy, the overhead
associated with collaboration is worth to be spent
in such scenario. Nevertheless, these methods
need to be fine-tuned to achieve a sufficient cost-
efficiency. The ESL provides means to customize
parameters like the region and the leasing time
for collaboration. The event detection concept
based on ESL and EDT significantly improved
available ACK-based collaboration with regard
to cost-efficiency by introducing lease-based
publish/subscribe. Of course, there are dozens
of possible test deployments to further stress and
analyze the performance of lease-based publish/
subscribe under different conditions regarding
varying phenomena, node density, node deploy-
ments, unreliable links etc. These are considered
to be future work.
Presented simulation results only announce
the advantages of autonomous configuration and
phenomenon detection concept based on EDTs.
We have simulated further failure scenarios at the
Lessons Learnt from Simulations
Presented simulation results strongly indicate a
need for robust configuration means to enable
reliable application, especially with regard to
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