Information Technology Reference
In-Depth Information
Position Finding System
Mobilizer
Sensing Unit
Processing Unit
Transmission Unit
Processor
Transceiver
Sensor
ADC
Storage
Power Unit
Fig. 6.2
Components of a sensor node
Mobile entities (i.e. sensors, sinks, and/or relays) can follow diverse mobility patterns
which lead to different performances improvement. However, sensor mobility, despite
the numerous advantages it brings, imposes many challenges when designing
appropriate algorithms and protocols. Data dissemination in a mobile scenario is
another challenging issue that needs to be properly solved. It can be realized with
flooding and direct transmission, which are simple, but usually inefficient.
Furthermore, many protocols designed for static networks need to be radically
redesigned in order to meet mobility constraints.
The mobile entities of interest in WSN can be
sinks
,
relays,
or
sensors
. Sink
mobility may prevent the sink area to become a bottleneck [
5
]. Mobile relays can
inherit other sensors to improve network connectivity. Sensor mobility can be
further exploited to compensate for the lack of sensors and improve the network
coverage and detection time, which optimize energy utilization and prolong
network lifetime.
6.2.1
Mobile Sink Approach
The
mobile sink
approach is a common solution exploiting sink nodes' mobility in
order to get closer in the vicinity of the reporting sensors. It also achieves higher
degree of
load balancing
among sensor network nodes and can offer extensive
improvements of the
network lifetime
[
6
]. The mobile sink can follow random [
7-9
],
predictable [
10
], or controlled mobility [
11, 12
]. Random movement of the sink
node can be equivalent with the scenario where people wearing sinks randomly
move and collect information from sensors deployed in a certain area (market for
example). Predictable mobility can be the movement of a bus or train, while robots
can be enabled to achieve specific tasks with controllable movements.
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