Pathloss and distance for each ray

[fightingsoul042]

Hi,

I wanted to ask is it possible to get the pathloss and propagation distance for each ray. Like in the following example from matlab
https://se.mathworks.com/help/comm/ug/indoor-mimo-ofdm-communication-link-using-ray-tracing.html

Thank you.

[merlinND]

Hello @fightingsoul042,

Does the following discussion help compute the quantities you need? ➡️ #360

[fightingsoul042]

@merlinND I believe it might help with calculating distance for each ray. But now sure if it could help in calculating the pathloss for each ray, i.e. the power lost due to propagation and reflection.

[jhoydis]

Hi @fightingsoul042,

Actually, paths.a gives you the complex gain for each ray and paths.tau the corresponding delay.
The pathloss in dB would then simply be -20*np.log10(np.abs(paths.a) and the distance paths.tau*sionna.constants.SPEED_OF_LIGHT.

[fightingsoul042]

Hi @jhoydis,
Thank you for the input. If I am not mistaking the paths.a, also includes gain from the antenna array. Is it possible to separate the gains contributed by the antenna array.

[jhoydis]

No, it does not contain any array gain. Paths are computed between antenna elements, not arrays. That means, however, that the antenna pattern is included in paths.a. If you choose an isotropic antenna pattern, the antenna has no effect.

[fightingsoul042]

@jhoydis Thank you, this helps.

[sathibabu9]

May i use the following expression PL_RAYTRACE = -10*np.log10(np.sum(np.abs(a)**2)) for a MISO narrowband channel

[sathibabu9]

I’m using Sionna RT with scenes loaded from XML (large outdoor / UTM-scale scenes). Calling

scene.preview()      

does not show any visualization.

I found that manually placing a camera using the scene bounding box works:

bbox = scene.mi_scene.bbox()
center = 0.5 * (bbox.min + bbox.max)
from sionna.rt import Camera
cam = Camera(
    position=[center[0], center[1] - 500, center[2] + 300],
    look_at=center
)

scene.render(camera=cam)

This renders the scene correctly.

My questions are:

Is this the recommended / intended way to preview RT scenes when scene.preview() fails?

Is there a scene-independent utility (or best practice) for automatically positioning a camera based on the scene extent?

After computing paths with PathSolver, is it safe to reuse the same camera to preview the scene again (optionally with rays using scene.render(camera=cam, paths=paths))?

Are there known limitations of scene.preview() for large scenes, merged shapes, or XML-loaded environments?

Any guidance or official recommendations would be appreciated.

[merlinND]

Hello @sathibabu9,

Your questions do not seem related to this current discussion; please open a new one.