Long-term tracking and monitoring of mobile entities in the outdoors using wireless sensors
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Date
07/07/2017Author
Radoi, Ion Emilian
Metadata
Abstract
There is an emerging class of applications that require long-term tracking and monitoring
of mobile entities for characterising their contexts and behaviours using data
from wireless sensors. Examples include monitoring animals in their natural habitat
over the annual cycle; tracking shipping containers and their handling during transit;
and monitoring air quality using sensors attached to bicycles used in public sharing
schemes. All applications within this class require the acquisition of sensor data
tagged with spatio-temporal information and uploaded wirelessly. Currently there is
no solution targeting the entire class of applications, only point solutions focused on
specific scenarios. This thesis presents a complete solution (firmware and hardware)
for applications within this class that consists of attaching mobile sensor nodes to the
entities for tracking and monitoring their behaviour, and deploying an infrastructure
of base-stations for collecting the data wirelessly. The proposed solution is more energy
efficient compared to the existing solutions that target specific scenarios, offering
a longer deployment lifetime with a reduced size and weight of the devices. This is
achieved mainly by using the VB-TDMA low-power data upload protocol proposed in
this thesis. The mobile sensor nodes, consisting of the GPS and radio modules among
others, and the base-stations are powered by batteries, and the optimisation of their
energy usage is of primary concern. The presence of the GPS module, in particular
its acquisition of accurate time, is used by the VB-TDMA protocol to synchronise the
communication between nodes at no additional energy costs, resulting in an energy-efficient
data upload protocol for sparse networks of mobile nodes, that can potentially
be out of range of base-stations for extended periods of time. The VB-TDMA
and an asynchronous data upload protocol were implemented on the custom-designed
Prospeckz-5-based wireless sensor nodes. The protocols’ performances were simulated
in the SpeckSim simulator and validated in real-world deployments of tracking
and monitoring thirty-two Retuerta wild horses in the Doñana National Park in Spain,
and a herd of domesticated horses in Edinburgh. The chosen test scenario of long-term
wildlife tracking and monitoring is representative for the targeted class of applications.
The VB-TDMA protocol showed a significantly lower power consumption than other
comparable MAC protocols, effectively doubling the battery lifetime. The main contributions
of the thesis are the development of the VB-TDMA data upload protocol
and its performance evaluation, along with the development of simulation models for
performance analysis of wireless sensor networks, validated using data from the two
real-world deployments.