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very heavy for a processor with limited processing capacity. Hence, connectivity
to the IP network is made only through the sink node.
• Designing position-aware sensor networks is another challenge. For example,
consider a mobile node in an enemy territory that is able to sense some movement
and relay this suspicious activity to the sink node. Soon after the relay, if the node
is compromised or destroyed, it could be difficult for the sink node to find the
exact location, as it is unable to reach the compromised node. Hence, addressing
schemes in WSN should take location into consideration.
1.9 Broadcasting and Multicasting
One of the fundamental operations in WSN is data dissemination from sensor nodes
to their sink nodes and vice versa. This is usually achieved by performing a broadcast,
multicast, or geocast operation.
1.9.1 Broadcasting
Broadcast operation is a “one-to-all” operation, in which packets are disseminated
from a source to all the nodes in the network. Broadcasting can be broadly divided
into simple broadcast schemes, probability-based broadcasting, neighborhood-aware
broadcast mechanism, location-aided broadcasting, energy-efficient broadcasting, and
reliable broadcasting (Ni et al. 1999).
1.9.1.1 Simple Broadcasting
Simple broadcasting does not require any prior knowledge of the network or the states in
which the nodes of the network exist. A few examples of this mechanism include blind
broadcast, probability-based broadcast, distance-based broadcast, area-based broadcast,
and counter-based broadcast. However, in most of the broadcast schemes, there is a
possibility of duplicating packets, which could be devastating in a WSN environment.
1.9.1.2 Multicasting
The multicasting mechanism is “one-to-many.” In this operation, packets are dissemi-
nated from one source to multiple destinations. For example, in WSN, a sink node can
send multicast messages to a selected set of sensor nodes. One of the main objectives of
introducing this scheme is to improve the overall efficiency of the system by decreas-
ing the number of relaying nodes. Multicasting in WSN can be broadly divided into
tree-based and location-based schemes. Examples of tree-based multicasting mecha-
nisms in WSN include multicast-enabled, ad-hoc, on-demand distance vector routing,
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