GNU Radio is a free software development toolkit that provides signal processing blocks to implement software-defined radios and signal-processing systems. It can be used with external RF hardware to create software-defined radios, or without hardware in a simulation-like environment. https://www.gnuradio.org
The testbed contains software-defined nano-satellites from GomSpace which are acting as 4G/5G relays (transparent payload) that are monitored and controlled by GNURadio through the IIO driver.
GNURadio is running on an Intelx86 workstation that is interconnected with GomSpace SDR for monitoring and control. Accordingly, the GNURadio takes as an Input the 5G waveform signal that is recieved by GomSpace SDR from the 5G-BaseStation and generate the 5G-waveform on the forward link to the User-Terminal. This is visualized in real-time as illustrated below.
Using GNURadio wer are able to send telemetry commands to GomSpace SDR by invoking the IIO APIs to change transceivers operating parameters.