ICDT 2007

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Oral presentation in Internation Conference Digital Telecommunication, USA, 2007

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  • Title: Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Authors: NGUYEN DINH QUY, Student IEEE member, email: n060075@ntu.edu.sg Prof. GAN WOON SENG, Senior Member, IEEE, email: ewsgan@ntu.edu.sg
  • Before we go into the details, let us look at the scope of the paper. To major objective of the project is to improve Green’s function estimation in Time Reversal Signal Processing In this paper, two approaches to improve Green’s function have been investigated. (1) The first approach is to change the coordinate system to estimate Green’s function in theoretical condition (2) The second approach is to propose new Green’s function estimation in practical condition
  • TRSP can use higher power in multipath environment
  • From complexity comparison table, + Reduce nearly half of computation complexity + Number of scatterers is large, the proposed Green’s function estimation in theory and practice have more significant computational complexity saving compared to existing Green’s function estimation. (2) In DSP implementation, the smaller computation resource in structure, the fewer quantization and truncation errors in DSP Operation (3) Proposed Green’s function estimation contributes to a feasibility study of time reversal signal processing in communication with faster simulation and provides more accuracy experiment in homogeneous and multiple scattering medium (J.V. Candy, Lawrence Livermore National Laboratory)
  • ICDT 2007

    1. 1. Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication NGUYEN DINH QUY, Prof. GAN WOON SENG The Second International Conference on Digital Communication (ICDT’07) July 1-6, 2007 - Sillicon Valley, USA
    2. 2. Scope <ul><li>Basic communication problem </li></ul><ul><li>Time Reversal Signal Processing (TRSP) </li></ul><ul><li>Time Reversal (TR) communication </li></ul><ul><li>Green’s function estimation </li></ul><ul><li>Discussions </li></ul><ul><li>Applications </li></ul><ul><li>Conclusions </li></ul><ul><li>Future works </li></ul>
    3. 3. Basic Communication Problem <ul><li>Multipath corrupts information (fading) </li></ul><ul><li>Multipath reduces the effectiveness of channel capacity by increasing inter-symbol interference (ISI) </li></ul><ul><li>Channel equalization requires very high complexity </li></ul>Multipath environment Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    4. 4. Time Reversal Signal Processing (TRSP) <ul><li>TRSP is lower complexity than channel equalization </li></ul><ul><li>TRSP mitigates the effects of multipaths </li></ul><ul><li>TRSP increases channel bandwidth </li></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    5. 5. TR communication (1) Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Green’s function estimation on transmission
    6. 6. TR communication (2) Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Green’s function estimation on reception
    7. 7. Green’s function estimation <ul><li>Medium: </li></ul><ul><ul><li>Homogeneous </li></ul></ul><ul><ul><li>Multiple scattering (multipath environment) </li></ul></ul><ul><li>Green’s function estimation: </li></ul><ul><li>Depend on total length between transmitter and receiver through multiple scatterers because of </li></ul><ul><ul><li>Time shift </li></ul></ul><ul><ul><li>Amplitude reduction </li></ul></ul><ul><ul><li>-> Objective: How to estimate total length propagation L i </li></ul></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    8. 8. Total length estimation in arbitrary Cartesian 2D,3D Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication (1) (2)
    9. 9. Total length estimation in 2D,3D in theory Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    10. 10. Total length estimation in 2D,3D in theory Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Total length estimation in 2D in practice: Green’s function estimation in 2D in practice: v: propagation speed Total length estimation in 3D in practice: Green’s function estimation in 3D in practice: (3) (4)
    11. 11. Total length estimation in 2D in practical condition <ul><li>In practical condition: </li></ul><ul><ul><li>Total length propagation is longer because of reflection and scattering </li></ul></ul><ul><ul><li> L i is Big Oh function of previous function </li></ul></ul><ul><ul><li>Apply Cauchy–Bunyakovski–Schwarz inequality </li></ul></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    12. 12. Total length estimation in 2D,3D in practice Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Total length estimation in 2D in practice: Green’s function estimation in 2D in practice: C i : Reflectivity coefficient. Total length estimation in 3D in practice: Green’s function estimation in 3D in practice: (5) (6)
    13. 13. Complexity comparison Total length propagation estimation 3D Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication Total length propagation estimation 2D 1 2 2 Square root 3 4 4 Multiplication 3 4 7 Additions Proposed reality Proposed theory Previous theory 1 2 2 Square root 5 6 6 Multiplication 3 6 11 Additions Proposed reality Proposed theory Previous theory
    14. 14. Discussion (1) <ul><li>Advantage: </li></ul><ul><ul><li>Reduces from 27.27% to 52.94% of computational complexity (addition and multiplication) compared to previous </li></ul></ul><ul><ul><li>The proposed Green’s function in practical condition 3D is minimal computational complexity and more accurate </li></ul></ul><ul><ul><li>The proposed Green’s function estimation is more robust and accurate in DSP implementation </li></ul></ul><ul><ul><li>The proposed Green’s function estimation contributes to a feasibility study of time reversal signal processing in communication </li></ul></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    15. 15. Discussion (2) <ul><li>Disadvantage: </li></ul><ul><ul><li>Applicable in specific environment (homogeneous and scattering phenomenon) </li></ul></ul><ul><ul><li>In complicated environment, proposed Green’s functions are more errors than that in Wienner method (but drawbacks are intensive computation and large memory requirement) </li></ul></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    16. 16. Applications <ul><li>Communication in highly reverberation </li></ul><ul><li>Enhance higher data rates </li></ul><ul><li>Medical ultrasound treatment </li></ul><ul><li>Intruder detection </li></ul><ul><li>Focus measurement </li></ul><ul><li>Location of scatterers estimation </li></ul><ul><li>Maximum Likelihood Estimation (MLE) </li></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    17. 17. Conclusions <ul><li>Proposed Green’s function estimations have less computational complexity and more accuracy in homogeneous and scattering environment </li></ul><ul><li>Green’s function estimation can be applied in TRSP communication that is efficient method in highly reverberation </li></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    18. 18. Future works <ul><li>Develop Green’s function estimation in heterogeneous medium </li></ul><ul><li>Apply Green’s function estimation in Time Reversal Signal Processing for focusing sound </li></ul><ul><li>Improve TRSP in communication </li></ul>Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication
    19. 19. Green’s function estimation in homogeneous and scattering medium for Time Reversal Signal Processing (TRSP) communication THANK YOU! Any information, feel free contact: Nguyen Dinh Quy [email_address]

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