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Estimating the State of Radio Waves Using the Compressed Sensing Method

Toshihiko Nishimura Professor
Faculty of Information Science and Technology
Hokkaido University Researcher Directory

Co-researchers

Toward highly accurate location estimation and channel prediction

The compressed sensing method is a method to find a solution under certain conditions from a smaller number of observation data than the number of unknowns required. In this study, we use compressed sensing for estimating the direction of arrival of radio waves, to predict the channel, and detect scatterers.

Content of research

It is usually impossible to specify unknowns if their number among observation data is smaller than the number of unknowns that need to be found. However, in case the majority of unknowns are zero, it is sometimes possible to obtain the exact solution. Compressed sensing is a method for obtaining an accurate solution while minimizing the number of observations by using this property. In our laboratory, we are investigating the application of this method to high-precision estimation of the direction of arrival of radio waves as shown in Fig. 1, a method of channel prediction by dividing the incoming wave into elementary waves using this method (Fig. 2), and scatterer detection using the compressed sensing used in radar systems (Fig. 3).

  • Fig. 1: Image of the estimation of the direction of arrival of radio waves.
    The compressed sensing algorithm is applied by dividing the area around the receiver into fine angles and using the complex amplitude as an element of the vector if there is an incoming wave (or 0 if there is not an incoming wave) at each angle.

  • Fig. 2: Channel prediction by combining incoming elementary waves.
    By finely separating the radio waves arriving at the terminal and resynthesizing them, the future communication status (channel) can be predicted.

  • Fig. 3: Schematic diagram of scatterer detection
    A radio wave is sent out from a transmitting antenna, and the reflected wave from the scatterer is received by multiple receiving antennas. The position of the scatterer can be detected by analyzing changes from the transmitted to the received signals, or differences between received signals.

Potential for social implementation

  • ・Radar
  • ・Pedestrian detection
  • ・Radio wave monitoring
  • ・Terminal location estimation
  • Communication channel prediction
  • Scatterer detection
  • ・通信チャネル予測
  • ・散乱体検出

Appealing points to industry and local governments

With the explosive growth in smart phones, wireless communication traffic continues to rise. To make effective use of limited frequency resources, it is very important to accurately know the direction of arrival of radio waves, the location of terminals, and the communication channels. We believe that the high-precision estimation of these factors made possible by this research will be of great help in the development of future wireless communication systems.

Keywords

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2022/5/27Released

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