Tools

Wireless Fading channel : Clarke's Model

A. One-Ring Diagram Exploration

  1. Static View:

    • Identify Tx (center red), Scatterers (red on ring), Rx (blue).

  2. Change Number of Paths (K):

    • Use the slider to vary K (e.g., min, mid, max).
    • Observe scatterer count updates immediately without needing to click "Update Simulation".

  3. Animate Rx Movement:

    • Set Mobile Velocity (e.g., 10–20 m/s), click Start Animation.
    • Watch the Rx (blue circle) move along the ring with an orange velocity vector.
    • Change velocity during animation to see the speed effect.
    • Click Stop Animation to end.
    • Note: Animation is visual only; it doesn't affect charts unless "Update Simulation" is clicked.

B. Autocorrelation Function (R₀[n])

After each change, click Update Simulation to refresh the plot.

  1. Amplitude (a):

    • Higher a increases the peak at n=0.
    • The overall shape and width of the main lobe remain mostly the same.

  2. Doppler Spread (Dᵥ):

    • Increasing Dᵥ narrows the main lobe → faster decorrelation (shorter coherence time).

  3. Bandwidth (W):

    • Increasing W → slower decay of R₀[n] (wider main lobe).
    • Related to J₀ argument: nπDᵥ/W.

  4. Number of Samples:

    • Affects x-axis range (length of the plot), not the core shape of R₀[n].

C. Doppler Power Spectrum (S(f))

After each change, click Update Simulation to refresh the plot.

  1. Default Shape:

    • Observe the characteristic “U-shape” or “bathtub” spectrum with edge peaks.

  2. Amplitude (a):

    • Changes the y-axis scale (overall power).
    • Spectrum shape and frequency extent remain unchanged.

  3. Doppler Spread (Dᵥ):

    • Wider Dᵥ → broader frequency range.
    • Non-zero values for |f| ≤ Dᵥ/(2W).

  4. Bandwidth (W):

    • Increasing W → narrower spectrum range.
    • Inversely proportional to frequency spread (Dᵥ/2W).

  5. Number of Samples:

    • Higher sample count → smoother, more detailed plot.

D. Additional Parameters

  1. Coherence Time Factor:

    • Vary it and observe if there's any effect.
    • It may not directly affect R₀[n] or S(f) in this version.

  2. Number of Paths (K):

    • Affects only the One-Ring Diagram.
    • Higher K better approximates the ideal infinite-scatterer assumption in Clarke’s model.