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Introduction to Simulating radio propagation models and COOJA ARM

Introduction to Simulating radio propagation models and COOJA ARM. One radio…. REFRACTION. REFLECTION. DIFFRACTION. … receiving a radio signal Typically 4 different categories Problem: What happens to the radio signal? (And how is sound quality affected?). SCATTERING.

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Introduction to Simulating radio propagation models and COOJA ARM

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  1. Introduction toSimulating radio propagation modelsand COOJA ARM

  2. One radio… REFRACTION REFLECTION DIFFRACTION • … receiving a radio signal • Typically 4 different categories • Problem: • What happens to the radio signal? • (And how is sound quality affected?) SCATTERING

  3. WSN radio model types • Unit Disk Graph • COOJA’s Standard Radio Medium • Bit Error Ratio (BER) • Collected statistical data (or empirical models) • Ray tracing

  4. COOJA ARM • Advanced Radio Medium • “Advanced” when compared to “Standard” :) • Radio propagation models introduction • How ARM works

  5. Wiki’s definitions • Radio Propagation “... is a term used to explain how radio waves behave when they are transmitted, or are propagated from one point on the Earth to another.” • Radio Propagation Model “... characterization of radio wave propagation as a function of frequency, distance and other conditions.”

  6. Empirical models • Lots of different models exist • Outdoor • City, Terrain, Rain, Earth curvature • Okumura model built using data collected in Tokyo • Indoor • ITU Model for indoor Attenuation • Log Distance Path Loss Model • Typical parameters: frequency, distance, number of floors, coefficients tuned to different environments etc. • Above models based on empirical data

  7. Analytical approach • Based on ray tracing • Calculates multi-path effects • Used in COOJA ARM

  8. Small-scale vs. Large-scale • Small-scale effects • Sum of many received signal from different directions • Often Gaussian random • Scattering • Large-scale effects • Shadowing • Reflections

  9. Free Space Propagation Model • (FSPL) • Predicts signal strength for LOS paths Antenna gains Wavelength Transmitted vs. received power Distance

  10. Ray tracing in ARM • 2D positions • Supports attenuating obstacles • Only rectangles • Refractions • Reflections • Diffractions • Potential support: • Scatterings

  11. Using ARM • Registers two plugins • Changing formula parameters • Visualizing radio coverage • Listens to all radios in the simulation • Transmitted power • Antenna gains • Packet lengths • SNR threshold • (Channel)

  12. Default valueMay be radio specific Frequency: ~900 MHz Formula Viewer

  13. From radio specification Default valuesMay be radio specific Formula Viewer

  14. From radio specification Default valuesMay be radio specific Formula Viewer

  15. FSPL mentioned earlier Fixed “penalty” constants FUTURE:Should be replaced by angle dependent formulas Maximum values used by ray tracer May become very time-consuming =) Formula Viewer

  16. Property of obstacle type(wood, glass, metal) Formula Viewer

  17. Area Viewer • Shows radios, obstacles and channel propagation

  18. Area Viewer • Obstacles are set by analyzing the background image

  19. Area Viewer • User may track ray paths from a transmitter to a point • Uses the current formula settings

  20. Area Viewer • Show surroundings of transmitter: • Signal strength • SNR ratio • Probability of reception • Delay spread

  21. Area Viewer Received signal strength vs. Probability of reception

  22. Future work • Validate models • Parameter estimation / Model calibration • From actual measurements

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