Question about RIS delay

[fanyimeng0]

Hello, I would like to know how you handle the delay in RIS. I noticed that scene.compute_paths doesn't seem to return the delay for the TX-RIS-RX path. Could you provide some insights on how to address this issue?

Thank you!

[jhoydis]

Hi @fanyimeng0,

Every path computed by scene.compute_paths has a delay and a complex amplitude, including paths involving RIS. I am hence not sure to understand your question. Could you provide a code snippet that explains the problem you encounter?

[fanyimeng0]

issue.zip
In this Jupyter notebook, I noticed that the dimensions of a and tau do not match correctly

[fanyimeng0]

Sionna version is 0.18.0, and TensorFlow version is 2.13.1.

[jhoydis]

I can reproduce the bug. There seems to be something wrong in the paths.cir() method when the flag cluster_ris_paths is enabled.
You should be able to get the delays for all individual paths by deactivating the flag :
a, tau = paths.cir(cluster_ris_paths=False)
This will be fixed in the next release.

[fanyimeng0]

Thank you for your quick response.