Thus, instead of deploying sensors over a large area,
the nodes are directly attached to the objects of interest, i.e., the whales. The
nodes then use their sensors to measure the quantities of interest, and report
these measurements to one or more sinks that are located in the sea.
Design Problems
The above network architecture presents several unique design problems due
to high node mobility, some of which are as follows.
1. Sink Deployment: Since the whales have very high mobility, it is not
possible to ensure that the whales are always in the communication range
of a sink. However, it is important to note that there is no stringent delay
requirement in this application. Hence the sensor nodes may store the
measured data for a long duration before they are able to communicate
with a sink. Thus, if the sinks are placed at a few locations that the whales
are expected to visit often, then only a small number of sinks are required.
Hence, in SWIM, sinks are placed on floating devices (buoys) at common
food habitat of the whales, and along the paths frequently traveled by
the whales. Since the sensor nodes have to store the data until they come
within the communication range of a sink, the number of sinks required
depends on factors such as the data storage capacity of a node, and the
frequency with which the whales come within the communication range
of a sink. The sinks can also be mobile for systematic and periodic survey
(e.
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