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Optimum Wireless Communication Through Unknown Obscuring Environments Using The Time-Reversal Principle:Theory And Experiments

  • Sermsak Jaruwatanadilok
  • Akira Ishimaru
  • Yasuo Kuga

Wireless communication in unknown and cluttered environments is an important problem which has several practical applications, such as communication in urban areas and disaster areas. This paper presents a method to maximize power transfer efficiency for communication in such environments. The method applies to communication between a transmitting array and a receiving array where the transmitting array sends out a probe signal, and at the receiving array, the transfer matrix can be constructed. From this measurement, we perform the time-reversal and eigen analysis. The highest eigenvalue is the best possible transmission efficiency and its corresponding eigenvector represents the transmitting excitation at the transmitting elements to achieve maximum efficiency. The nature of this method makes it possible to operate in unknown, random, and cluttered environments because the maximization is based on the measured signals. Also, this method allows for the adjustment of the system due to the change of the channel, which makes this method adaptive and robust. The time-reversal technique was introduced by Fink. Then, Prada and Fink illustrated the idea of time-reversal imaging to obtain selective focusing. Here, we present the theory of time-reversal communication. We show relevant numerical examples and illustrate experimental verifications in a simple geometry. We further illustrate the effectiveness of this method in laboratory/office environments and in through-the-wall situations. We also investigate the effectiveness of this method in wide-band communication.

Keywords

Transmission Efficiency Versus Versus Versus Versus Versus Versus Versus Versus Versus Communication Efficiency Disaster Area 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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6. References

  1. 1.
    M. Fink, “Time reversed acoustics,” Physics Today, 50(3), 34-40 (1997).CrossRefMathSciNetGoogle Scholar
  2. 2.
    C. Prada and M. Fink, “Eigenmodes of the time reversal operator: A solution to selective focusing in multiple-target media,” Wave Motion, 20(2), 151-163, (1994).MATHCrossRefMathSciNetGoogle Scholar
  3. 3.
    A. Ishimaru, S. Jaruwatanadilok, and Y. Kuga, “Time-reversal techniques applied to communication through unknown obscuring media,” AMS Meeting, San Antonio, TX, USA, January 10-15 (2006).Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Sermsak Jaruwatanadilok
    • 1
  • Akira Ishimaru
    • 1
  • Yasuo Kuga
    • 1
  1. 1.Department of Electrical EngineeringUniversity of WashingtonSeattleUSA

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