Aerospace and Electronic Systems - March 2019 - 58

Energy-Efﬁcient Routing Algorithm Based on Localization and Clustering Techniques for Agricultural Applications

Figure 1.
General architecture of a monitoring system based on WSN for agricultural applications.

Figure 2.
Taxonomy of energy-efficient approaches for WSNs in
agricultural applications.

of dividing the network into subregions, where sensor
nodes are grouped and communicated together. In each
region, called cluster, one node is selected as a CH, which
is responsible for collecting data from cluster members
and transmitting them to the sink node or BS using singlehop or multihop communication schemes, where intermediate CHs are using as relay nodes.
Several energy-efficient cluster-based routing protocols are proposed in the literature. The low-energy adaptive
clustering hierarchy protocol [5] was the first hierarchicalbased protocol for WSNs, which makes local decisions to
select randomly the CH. The aggregated data have been
transmitted directly from CH to BS. The equalized CH
election routing protocol [6] models the network and the
energy consumed to send data from sensor nodes to the BS,
as a linear system. Using a Gaussian elimination algorithm,
the BS calculates the number of rounds at which every
node can be selected as a CH. However, most of these routing algorithms are not always suitable to cover large area
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network mainly in the case of agriculture applications.
In fact, these protocols follow a random deployment of all
nodes in the whole network causing a problem of coverage
and connectivity. If nodes are installed far away from the
BS, some regions may remain uncovered, which creates
black hole areas where the connectivity between nodes
becomes difficult. Since agricultural applications need
information from each part of the field, the cluster-based
routing protocol should realize a full coverage.
Moreover, most of the existing clustering algorithms use
single-hop routing where each node transmits data directly
to the CH, which collects and sends them to the BS. Therefore, it is not recommended for networks that are deployed
in large regions and especially for agricultural applications.
For a large network, where internode distance is important,
multihop communication is interesting to prolong the network lifetime by shortening the transmission distance
between nodes. Nevertheless, using multihop communication creates a hotspot problem since the closest CH to the BS
are burdened with heavy traffic and tend to die earlier.
For this reason, unequal sized clustering schemes are
developed. A distributed load balancing unequal clustering
based on fuzzy approach [7] is proposed, where the size of
a cluster is calculated based on different factors like distance to BS, node degree, and residual energy. The smallest
cluster size is assigned to CH nearer to BS since it acts as a
router for other distant CHs. Another fuzzy-based unequal
algorithm is the energy aware unequal clustering based on
fuzzy algorithm [8] in which clusters closer to the BS have
a smaller size compared to farther clusters. To calculate the
radius of each cluster, two fuzzy sets are defined, which are
the remaining energy and the distance to BS. The tentative
CHs are selected based on a probabilistic approach. Then,
the tentative CHs within same radius having higher residual

IEEE A&E SYSTEMS MAGAZINE

MARCH 2019

Aerospace and Electronic Systems - March 2019

Table of Contents for the Digital Edition of Aerospace and Electronic Systems - March 2019