Other ways to reduce idle mode energy
15 Chapter 1 Design of Large-scale Sensor Networks
Aravind Iyer et al.
consumption include, for instance, using an additional low power radio just
for channel sensing [20].
5.2 Data Gathering and Periodic Reporting
Data gathering and periodic reporting sensor networks form the class of sensor
networks in which the objective of the network is to send periodic updates to
the sink. Thus there is regularity in terms of data gathering phases, and there
is a steady flow of data from the sensor nodes to the sink. In-network data
aggregation is useful in such applications because measurements of neighboring
nodes are likely to be correlated, and could be used to reduce the amount
of data that needs to be communicated to the sink. This in turn reduces
communication energy expenditure of the nodes, and prolongs the lifetime of
the network. Depending on the nature of application, lifetime could mean the
time duration after which: the first node in the network exhausts its battery;
a certain fraction of the nodes in the network exhaust their batteries; or network
connectivity or coverage falls below a certain percentage; or some other
appropriate event.
Since the correlation in measurements is primarily due to the proximity
of the neighboring nodes, clustering could be used as a means of aggregation.
In clustered sensor networks, nodes are organized into smaller groups called
clusters.
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