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Figure 7.2. Data-Centric Communication in WSN
model is more focused on the aggregated data, rather than identifying the exact node's
identifiers. Although the request/response scheme is similar in both the models, the
sink node or cluster head initiates a request for interested data and the responsible nodes
respond with the requested data; they vary in the manner in which the nodes send data
back to the sink node or cluster heads. The intermediate routing nodes inspect the data
that is being sent to the sink node and perform some form of consolidation operation,
such that the sink node receives aggregated data from different sources. Figures 7.1 and
7.2 illustrate the distinction between address-centric and data-centric models in WSN.
Figure 7.1 shows the address-centric model in which two sources (nodes C and E) send
information to the sink node via the shortest path. Node C sends via node A and node
E sends via nodes D and B.
In contrast, Figure 7.2 shows the data-centric model in which data from node C
is directly sent to node B for consolidation, and, subsequently, the aggregated data is
then sent to the sink node. In cases where node C cannot directly contact node B, an
intermediate node closer to node B is responsible for forwarding the data to node B.
On comparing both models, the data-centric model is more energy efficient because
only four messages are utilized in sending information from two different sources to
the sink node, as opposed to five messages in the address-centric model (Figure 7.1).
7. 2 . 2 Location Information
The physical location of a node in a network is an essential metric for designing rout-
ing protocols in a WSN. For example, the protocols could be designed for short- or
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