Rays tend to be emitted upwards.

[CodingMasterZ]

Hi!

I have an O2I scenario where the transmitter is 1.8m tall outdoors and the receiver is 1.5m tall indoors. There are moving scattering objects (1.9m tall, 10m/s) around the outdoor transmitter. As this study focuses on the rapid variations of the precoding matrix over short time scales, it is necessary to simulate a channel with strong time-varying characteristics. To this end, the interaction between propagation rays and moving scatterers is enhanced in the channel simulation in order to capture the fast channel variations induced by a dynamic scattering environment. Accordingly, the transmitter is configured as illustrated below.

tx = Transmitter(name="tx", position=mi.Point3f(tx_position), orientation=[0, -20 * np.pi / 180, 0.0], power_dbm=0, color=[1, 0, 0])

However, as shown in the figure, the rays still tend to propagate upward above the vehicle rooftops, resulting in almost no interaction with the moving scatterers. How can the channel dynamics be enhanced and the interaction between propagation rays and vehicles be strengthened?

[jhoydis]

Did you enable diffuse reflections? If not, I am not surprised that you see no interactions with the cars.

[CodingMasterZ]

Yes, diffuse reflection has been enabled.

The path solver is configured as follows:
paths = p_solver(scene=scene, max_depth=5, max_num_paths_per_src=1000000, samples_per_src=1000000, los=False, specular_reflection=True, diffuse_reflection=True, refraction=True, diffraction=True, edge_diffraction=False, diffraction_lit_region=False, synthetic_array=True, # seed=42)

[jhoydis]

And did you configure the materials of the cars to be diffuse?

[CodingMasterZ]

Yes, the cars are assigned as 'itu_metal', and the scattering coefficient is set to 0.2.

for i in range(1, 17): car = scene.objects[f"car_west{i}"] car.radio_material = "itu_metal" car.radio_material.thickness = 0.2 car.radio_material.scattering_coefficient = 0.2 car.radio_material.xpd_coefficient = 0.3 car.radio_material.scattering_pattern = scattering_pattern

[jhoydis]

Have you tried moving the receiver outside of the building? One problem that you might have is that the scattered rays are so weak that they barely contributed to the field inside the building.

Another thing you could try is to disable specular reflections.

[CodingMasterZ]

I have not yet tried placing the receiver outside the building.
Okay, I will try disabling specular reflection. Thank you very much for your reply!