Problem in Reproducing the Code of the Paper.

I would like to inquire about the Shape of some variables like the ideal_H, which is 5D, however, in the paper, only 3D variables are considered. Any hints, please? Moreover, the generated dataset with R0 refers to what exactly? Knowing that "R_{number_RX_antennas}" in the save function in Matlab.

Thank you in advance for your feedback.