Image Processing Reference
In-Depth Information
Cross-layer optimization
Query processor schedules
queries to allow more efficient
communication
In-network processing
Sensor nodes process data
internally before transmitting
Results in a reduction of the
number of messages
transmitted
Reduces chances of message
collisions
Query management
system for WSNs
Reduces burden of the MAC
Acquisitional query
processing
Data-centric data/query
dissemination
Decides how to route data/query
to only the relevant parts of
the network
Prevents the need to flood
the entire network
Query processor indicates
how sampling of sensors
should be performed in an
energy-efficient manner
Saves energy by eliminating
unnecessary sampling of
sensors
FIGURE .
Essential building blocks of a distributed query extraction system for WSNs.
In-network processing
Cross-layer
optimization
Acquisitional
query
processing
Data-centric
data/query
dissemination
FIGURE .
Relationship between the building blocks.
In order to distinguish between sensors attached with wireless transmitters and wireless sensor
nodes, which are actually capable of performing simple computations within them, and also because
in-network processing is a very generic term (i.e., it could essentially refer to any sort of processing
that takes place within a node) we have placed acquisitional query processing, cross-layer opti-
mization, and data-centric data/query dissemination all within the class of in-network processing.
Allthesethreesubclassesrequireasensornodetoanalyzethedataithasathandandmakecertain
decisions based on the outcome of the analysis instead of transmitting all the data to a central server
for off-line processing or centralized decision-making. Such processing is not possible in normal sen-
sors that only have attached wireless transmitters. he kind of processing that can take place within
a wireless sensor node varies greatly, which is why we have these three other subcategories.
Cross-layer optimization generally refers to schemes where the application influences the opera-
tion of the routing or MAC layers. In the cross-layer optimization category, we cover literature which
studies the relationship between the MAC and the application layers. Data-centric data/query dis-
semination is classified as a subclass of cross-layer optimization as it involves creating links between
the application and routing layers. Acquisitional query processing falls under cross-layer optimiza-
tion as it deals with schemes where sensor sampling can be dependent on information gathered
from the injected query (i.e., application layer) or even the underlying MAC.
