CIR for multiple UEs

[Advaith2212]

I have some doubt in generating CIR for multiple (e.g. 1000)UEs. I followed the following procedure:

1. Generated a coverage map and using it to sampled positions using cm.sample_positions()
2. Since no of UE is not so huge, I used the positions to deploy rx antennas
3. Used the scene.compute_paths() to generate a and tau
4. Shape of a : 1,num_rx,num_rx_ant,num_tx,num_tx_ant,num_paths
5. When I visualize the CIR between a particular UE and BS, I am seeing negative delay in some paths.

Can you let me know if my procedure to generate CIR correct ?

[jhoydis]

That's all correct. The paths with negative delay have also zero amplitude and will be ignored.

[Advaith2212]

In the t uploaded above, the third path has a negative delay. What does it imply ?

[jhoydis]

It means that this is a non-existent path. If you check the corresponding amplitude, it will be equal to zero.
The number of paths per transmit-receive antenna pair is not necessarily equal, but we need to return a tensor where each CIR has the same number of paths. In order to indicate invalid (= non existent) paths, we have chosen to represent them with a negative delay and zero amplitude.