Why i can not configure the locations of the antennas when generating the channel coefficients for CDL?

For nrCDLChannel, it is stated that the implementation is following aspects of TR 38.90. Section 7.7.1 step 4 in coefficients generation we have to follow the below equation of generating channel coefficients

where d_rx and d_tx are the antenna locations (BS location and UT location or vise versa). I can not find on nrCDLChannel object a configuration parameters for antenna location? are you neglecting these two terms?

Thank you

Answer 1

[Carlos Lopez]

Hi Mohamed,

The spherical unit vector is defined in the transmitter's (Tx) local coordinate system. Therefore, the location vector of the transmit antenna element must be defined in the same local coordinate system for the dot product to be meaningful in this context. The same applies to the receive side. It's unnecessary to define the position of both the Tx and Rx in a common coordinate system for the purpose of calculating H(t) in equation 7.5-22.

Carlos

[Mohamed Essam]

Hi Carlos and Greetings to you,

Thank you for your answer but i have a point i want to share with you. According to my understanding on your answer you mean that the exponential term will be equal 1 as the antenna location vector in local coordinate system will be [0;0;0]. But this assumption due to the first assumption that is defined in local coordinate system. I got back to aspects of TR 38.90. Section 7.1.3 and it is stated that GCS with coordinates and unit vectors and an LCS with "primed" coordinates and "primed" unit vectors . so i think is defined for global coordinate system as it is a function of theta and phi not (theta prime and phi prime). So the exponential term is existing. So my question " is the definition of sperical unit vector to be in LCS is an assumption assumed by matlab?"

Another questions, for the CDL predefined profiles in sections 7.1.1 are the azimuth angles and zenith angles defined in LCS or GCS?

Mohamed

[Carlos Lopez]

Mohamed,

Sorry for the confusion. I don't mean the antenna LCS defined in Section 7.1.3, which is defined mostly to help defining and transforming antenna radiation fields. Note that in 7.1.3, there is no position information nor translation of coordinate systems in the transmformation from LCS to GCS (only rotations).

I mean a transmitter's LCS placed at the center of the antenna array with the same orientation as the GCS. Note that is the antenna element s location vector. The exponential term is not equal to 1 because is not null in general, unless the LCS is centred in the position of the antenna element s.

The angles in 7.7.1 are defined in a GCS (rotation wise) but are relative to the center of the corresponding array.

[Mohamed Essam]

Carlos,

Many thanks