Noise-Limited OTA Performance in Transmit Diversity Mode
R&S
®
AMS32-K31
8
User Manual 1175.6678.02 ─ 01
select "Sensitivity Horizontal" and "Sensitivity Vertical") as shown above. The test setup
remains fixed during the entire measurement; the two streams of the LTE downlink signal
from the R&S CMW500 are simultaneously fed to the two polarizations of the test
antenna.
To define the RF connector and external attenuation settings at the communication tester,
left-click the R&S CMW500 device symbol and open the "Settings" tab of the device driver
configuration dialog.
Fig. 2-2: RF input and output settings
Check "Set up RF Connectors during Test", select the RF input connector plus the two
RF output connectors at the R&S CMW500, and enter the external attenuations according
to your physical test setup. Notice that the "RF Output" is to be linked to the antenna
connector for the horizontal polarization (---> HOR), the "RF Output 2" to the vertical one
(--> VER).
The external attenuation of the "RF Output 2" does not appear as a configurable value;
it is automatically set with the aim of generating equal power densities of both downlink
streams at the EUT location. To achieve this, the external attenuation of "RF Output 2"
is set to the external attenuation value of "RF Output", corrected by the difference of the
attenuation values in the output attenuation tables associated with the two connectors.
This rule ensures equal power densities, provided that both downlink paths have been
correctly calibrated, so that the output attenuation tables reflect the true path attenuations.
Click "OK" to save your R&S CMW500 driver settings. Back in the "Hardware Setup"
dialog, the "RF In/Out" settings appear in the white information field below the R&S
CMW500 device symbol. Click "OK" to save your hardware setup, assigning an appro-
priate file name (e.g. "OTA Measurements_Single Antenna").
Configuration
