Image Processing Reference
In-Depth Information
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Application layer
: It usually links the user's applications with the underlying layers in the
protocol stack. Sensor networks are designed to fulfill one single application scenario for
each particular case. he whole protocol stack is designed for a special application and the
whole network is seen as an instrument. hese make the application layer to be distributed
along the whole protocol stack, and not appear explicitly. Still, for the sake of classifica-
tion we can consider an explicit application layer that could have one of the following
functionality []: sensor management protocol, task management and data advertisement
protocol, and sensor query and data extraction protocol.
Sensor networks reached the phase in which their integration with existing infras-
tructure is a topic of interest. From this perspective, the application layer can also be
interpreted as a part of the middleware layer between existing infrastructure and the
stream of live data provided by sensors. his interfacing is an interesting and diicult topic
due to the mesh network characteristics. The design mentality under which it is devel-
oped is that the existing systems should not change at all—the sensor networks should
adapt to what is already in place (which was designed usually at a time sensor networks
were not present even as a concept).
4.2.2 EYES Project Approach
We bring now into discussion the architecture view proposed by the EYES European project []. [].This
was the first European project dedicated to sensor networks and the architecture design was one of
the major questions addressed. The approach taken in this project consists of only two key system
abstraction layers: the sensor and networking layer and the distributed services layer (see Figure .).
Each layer provides services that may be spontaneously specified and reconfigured.
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Sensor and networking layer
: It contains the sensor nodes (the physical sensor and wire-
less transmission modules) and the network protocols. Ad-hoc routing protocols allow
messages to be forwarded through multiple sensor nodes taking into account the mobil-
ity of nodes and the dynamic change of topology. Communication protocols must be
Applications
Distributed
services
Lookup
service
Information
service
Sensors and
networking
FIGURE .
EYES project architecture description.
