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Title
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A pragmatic approach to area coverage in hybrid wireless sensor networks
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| Author(s) |
Ahmed, Nadeem , Computer Science & Engineering, Faculty of Engineering, UNSW
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| Resource Type |
Thesis
PhD Doctorate
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| Supervisor(s) |
Jha, Sanjay, Computer Science & Engineering, Faculty of Engineering, UNSW
Kanhere, Salil, Computer Science & Engineering, Faculty of Engineering, UNSW
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| Keyword(s) |
Coverage Issues
Wireless Sensor Networks
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| Date |
2007 |
| School/Centre |
University of New South Wales. |
| Description/Abstract |
Success of Wireless Sensor Networks (WSN) largely depends on whether
the deployed network can provide desired area coverage with acceptable network
lifetime. In hostile or harsh environments such as enemy territories in battlefields,
fire or chemical spills, it is impossible to deploy the sensor nodes in a predeter-
mined regular topology to guarantee adequate coverage. Random deployment is
thus more practical and feasible for large target areas. On the other hand, random
deployment of sensors is highly susceptible to the occurrence of coverage holes in
the target area. A potential solution for enhancing the existing coverage achieved
by random deployments involves the use of mobility capable sensors that would
help fill the coverage holes. This thesis seeks to address the problem of determin-
ing the current coverage achieved by the non-deterministic deployment of static
sensor nodes and subsequently enhancing the coverage using mobile sensors.
The main contributions of this dissertation are the design and evaluation
of MAPC (Mobility Assisted Probabilistic Coverage), a distributed protocol for
ensuring area coverage in hybrid wireless sensor networks. The primary contribu-
tion is a pragmatic approach to sensor coverage and maintenance that we hope
would lower the technical barriers to its field deployment. Most of the assump-
tions made in the MAPC protocol are realistic and implementable in real-life
applications e.g., practical boundary estimation, coverage calculations based on
a realistic sensing model, and use of movement triggering thresholds based on
real radio characteristics etc. The MAPC is a comprehensive three phase proto-
vi
col. In the first phase, the static sensors calculate the area coverage using the
Probabilistic Coverage Algorithm (PCA). This is a deviation from the idealistic
assumption used in the binary detection model, wherein a sensor can sense accu-
rately within a well defined (usually circular) region. Static sensors execute the
PCA algorithm, in a distributed way, to identify any holes in the coverage. In
the second phase, MAPC scheme moves the mobile nodes in an optimal manner
to fill these uncovered locations. For different types of initial deployments, the
proposed movement algorithms consume only 30-40% of the energy consumed by
the basic virtual force algorithm. In addition, this thesis addresses the problem of
coverage loss due to damaged and energy depleted nodes. The problem has been
formulated as an Integer Linear Program and implementable heuristics are devel-
oped that perform close to optimal solutions. By replacing in-operational nodes
in phase three, MAPC scheme ensures the continuous operation of the WSN.
Experiments with real mote hardware were conducted to validate the bound-
ary and coverage estimation part of the MAPC protocol. Extensive discrete event
simulations (using NS2) were also performed for the complete MAPC protocol and
the results demonstrate that MAPC can enhance and maintain the area coverage
by efficiently moving mobile sensor nodes to strategic positions in the uncovered
area. |
| Language |
EN |
| Rights |
Please click here to view the rights |
| Citation Link |
Please use this identifier to cite or link to this item: http://handle.unsw.edu.au/1959.4/39680 |
| Full Text | 
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| Total Attachment(s) | 2 |
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