Question: In a MIMO channel model using cross-polarized antennas, how are the antennas labeled when there are N antennas, considering two polarizations?
Option 1: Antennas for both polarizations are interspersed (e.g., 1, 2 for polarization A and B respectively, then 3, 4 for A and B, and so on up to N)
Option 2: Antennas for one polarization are listed from 1 to N/2 and antennas for the other polarization are listed from N/2+1 to N
Option 3: All antennas for both polarizations are grouped by their slant angles (+45, -45, +90, 0 degrees) regardless of the polarization type
Option 4: The labeling starts with the receive antennas (listed 1 to N/2 for one polarization and N/2+1 to N for the other) followed by the transmit antennas
Explanation: According to standard practices, when using cross-polarized antennas in MIMO channel models, antennas for one polarization are sequentially listed first (from 1 to N/2), followed by those of the other polarization (from N/2+1 to N), ensuring clarity and consistency in antenna setup configurations.