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  • Localization of Submerged Sensors Using a Single Mobile Beacon

    by

    Anisur Rahman

    School of Information and Communication Technology

    Griffith Sciences

    Griffith University

    August 2015

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    Anisur Rahman 2015

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    To my Mum & Dad

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    Statement of Originality

    This work has not previously been submitted for a degree or diploma in any university. To

    the best of my knowledge and belief, the thesis contains no material previously published

    or written by another person except where due reference is made in the thesis itself.

    _____________________________

    Anisur Rahman

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    Acknowledgements

    I would like to thank my supervisor Vallipuram Muthukkumarasamy and Xin-Wen Wu.

    Their encouragement and support throughout the PhD candidature have been vital and

    appreciated. I also thank my peer group for their valuable inputs in this endeavor.

    The sacrifices and encouragement of my wife would always be remembered and

    appreciated. I only wish my son Shomoy and daughter Nohor could have understood

    why I cant play with them like I used to.

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    List of Publications

    A. Rahman, V. Muthukkumarasamy, and X. Wu, Coordinates and Bearing of

    Submerged Sensors Using a Single Mobile Beacon (CSMB), Journal of Networks,

    2015 (accepted)

    A. Rahman, V. Muthukkumarasamy, and E. Sithirasenan, "The Effect of in-situ

    Underwater Acoustic Speed on Localization of Submerged Sensors" in PhD

    Forum of World of Wireless, Mobile and Multimedia Networks (WoWMoM), 2014.

    A. Rahman, V. Muthukkumarasamy, and E. Sithirasenan, "Localization of

    Submerged Sensors". Book Chapter: Nova Publishing Inc. 2014.

    A. Rahman, V. Muthukkumarasamy, and E. Sithirasenan, "Localization of

    Submerged Sensors Using Radio and Acoustic Signals with Single Beacon," in

    Ad-hoc, Mobile, and Wireless Network. LNCS. vol. 7960, J. Cicho, M. Gbala, and

    M. Klonowski, Eds., ed: Springer Berlin Heidelberg, pp. 293-304, 2013.

    A. Rahman, V. Muthukkumarasamy, and E. Sithirasenan, "The Analysis of

    Temperature, Depth, Salinity Effect on Acoustic Speed for a Vertical Water

    Column," in Distributed Computing in Sensor Systems (DCOSS), IEEE, pp. 310-312,

    2013.

    A. Rahman, V. Muthukkumarasamy, and E. Sithirasenan, "Coordinates

    Determination of Submerged Sensors Using Cayley-Menger Determinant," in

    Distributed Computing in Sensor Systems (DCOSS), IEEE, pp. 466-471, 2013.

    A. Rahman, V. Muthukkumarasamy, and X. Wu, Underwater Localization: a

    pragmatic Approach. IEEE Communication Magazine of Underwater Wireless

    Communications and Networks: Theory and Applications, 2015. (submitted)

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    Abstract

    nswerving navigation and positioning are becoming imperative in more and more

    underwater applications for the sustenance of flora and fauna of our marine biome.

    As marine life helps determine the very nature of our planet at a fundamental level, it

    becomes crucial to obtain accurate environmental data by using underwater sensors to

    enable the provision of underwater sanctuary areas. In addition, an underwater wireless

    sensor network (UWSN) is envisioned to enable application for offshore exploration for

    the profusion of the wealth underwater world has. It is not only monetary value, it is also

    deemed necessary to introduce controlled underwater vehicles for surveillance, to find lost

    objects and to track pollutants. Due to all these potential factors, researchers have shown

    fervent interest in exploring and exploiting underwater localization schemes to fulfill the

    multitude of needs as the time demands. To achieving such, a wide range of sensors are

    deployed underwater to gather data. Many a times, precise coordinates of the deployed

    sensors which actuate or collect data are vital, as data without the knowledge of its actual

    origin has limited value. So, a pragmatic dynamic approach is obligatory to localize

    submerged sensors precisely with minimal logistics, which will require no preinstalled

    infrastructure and reference points.

    A plethora of techniques has been proposed to determine the coordinates of

    submerged sensors, each with its own limitations. Preinstalled infrastructure, multiple

    references and auxiliary nodes are commonly used; whereas a single reference point, like a

    boat, should suffice to localize the sensors for any problem domain without the complexity

    and tedium of installing reference points. Moreover, the multilateration technique is used

    to determine the location of the sensors with respect to three or more known beacon

    nodes. Furthermore, incorporated nonlinear distance equations are solved by conventional

    methods whereby degree-of-freedom does not guarantee a unique solution. This thesis

    investigates the problem of localizing submerged sensors and advocates a closed-form

    solution to determine the coordinates and bearings of those using only a single beacon

    node at the surface. The propounded method is capable of continuous localization of

    submerged sensors with precision, in a dynamic fashion, without a preinstalled

    U

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    infrastructure or reference points. Moreover, the Cayley-Menger determinant and linearized

    trilateration are used to determine the coordinates of the nodes where none of the nodes

    have a priori knowledge about its location. Simulation results validate the mathematical

    model proposed herein, by computing the coordinates of sensor nodes with bearing

    information; thereby generating 10-12 to 10-14m positional error with 0.972% variation in

    bearing with Euclidean distance.

    Underwater distance determination between the beacon and sensor nodes is an

    important factor in localization; and the use of acoustic signals has been the proven

    technology so far. Usually, the bouncing technique or two-way message transfer is used to

    measure the distances from beacon to sensors. In fact, the bouncing technique requires

    lowering a reflector to a specific height, and the two-way message transfer method lacks

    time synchronization. In both cases, measured distances and the unreliable time

    synchronization are subject to a huge degree of error. Moreover, a default acoustic speed is

    considered, regardless of problem domain, which also upsurge the errors in coordinate

    determination. To minimize such distance determination error, a new method has been

    devised here, in which in-situ acoustic speed is determined from the gathered environmental

    variables (i.e. temperature, depth and salinity) from the vicinity of beacon and sensor

    nodes. Therefore, due to the different nature of problem domain, the acoustic speed varies

    and provides more accurate localization. It is logical to consider that with the advent of

    incorporating 4th generation computing into the sensors; it is now indispensable to

    reconsider the use of underwater radio to some extent. As such, the method uses radio

    signals for time synchronization between the beacon and underwater sensors; and it

    measures the flight time of generated acoustic signals from the beacon to the sensors.

    Simulation results show in-situ determination of acoustic speed for various problem

    domains with different combinations of environmental variable varies from 1499.8-

    1507.6m/s and the experimental results also confirm the potential of determining flight

    time of acoustic signals between two nodes.

    This research could be extended to address and consider the mobility of the

    submerged sensors while localizing. Voluntary or involuntary mobility can be analyzed to

    find the Doppler effect, as UWSN is more susceptible than WSN. Therefore, mobility

    introduces another challenge from the view point of communications overheads and

    energy-efficiency, since underwater equipment is expected to be left in the ocean for

    several weeks or months before it is collected and recharged for the next mission. Another

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    interesting research direction could be inventing sensors and methods which can detect

    lower radio signals and can be capable of better communication, so that all

    communications can be replaced by radio instead of acoustic signals as done

    conventionally.

    To conclude, the model delineates the determination of in-situ underwater acoustic

    speed; as well as the coordinates and bearings determination in a pragmatic fashion with a

    single beacon. Scrupulous accuracy in simulation and experimental result shows the

    potential of proposed model in coordinate determination of submerged sensors with a

    single beacon.

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    Contents

    CHAPTER 1 INTRODUCTION ............................................................................ 1

    CHAPTER 2 BACKGROUND .............................................................................. 7

    2.5.1.1 Time of Arrival (ToA) Measurements ...................................... 25

    2.5.1.2 Time Difference of Arrival (TDoA) Measurements ............... 26

    2.5.1.3 Received Signals Strength Measurements ................................ 28

    2.6.1.1 Infrastructure-based Positioning Schemes ............................... 34

    2.6.1.2 Distributed Positioning Schemes .............................