Abstract:
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Wireless sensor networks are an emerging technology that has recently
gained attention for their potential use in many applications such disaster
management, combat field reconnaissance, border protection, object localization,
harbors, coal mines, and so on.
Sensors in these kind of applications are expected to be remotely deployed
and to operate autonomously in unattended environments.
Since sensors typically operate on batteries and are often deployed in
harsh environment where human operators cannot access them easily, much
of the research on wireless sensor networks has focused on the energy depletion
in order to achieve energy efficiency to extend the network lifetime.
In multihop wireless networks that are often characterized by many to
one traffic patterns, it is very common to find problems related to energy
depletion. Along the network, sensors experiment different traffic intensities
and energy depletion rates. Usually, the sensors near the sink tend to
deplete their energy sooner because they act as data originators and data
relayers and are required to forward a large amount of traffic of the most
remote sensors to the sink while the sensors located in the periphery of the
network remain much of the time inactive.
Therefore, these sensors located close to the sink tend to die early, leaving
areas of the network completely disconnected from the sink reducing
the functional network lifetime.
In order to achieve equal power consumption at different levels of our
network, we have decided to add extra relay nodes to reduce and balance
the traffic load that normal nodes have to carry. As mentioned above, each
level within the network faces a different amount of traffic, which becomes
more intense as we approach the interior levels. This behavior causes that
the external nodes, with less traffic to handle, stay more time at rest while
the nodes in the inner rings face a great amount of traffic which forces them
to be more active, generating a more accelerated exhaustion, reason why
nodes located in the inner rings exhaust its battery faster causing the lifetime
of the network to come to an end.
This work presents a comprehensive analysis on the maximum achievable
sensor network lifetime for different deployment strategies (linear, quadratic,
and exponential ) in order to equalize the energy consumption rates of all
nodes. More specifically the deployment of extra relay nodes around the
sink in order to solve the energy imbalanced problem and guarantee that
all nodes have balanced energy consumption and die almost at the same
time. |