Over-the-air 5G testbeds were built using USRP software-defined radio (SDR) hardware, e.g., X410, N310, and B210, running full gNB functionality via the open-source OpenAirInterface (OAI) protocol stack, in SISO configuration. Rather than relying on a commercial device, the testbed used OAI’s own software-based nrUE as the user equipment, enabling a fully open-source, end-to-end 5G link from base station to user terminal over a live radio-frequency connection. Testing was carried out at two levels: physical-layer test mode, to validate the radio link in isolation, and full end-to-end operation througt the core network (i.re., Open5GS or OAI built-in core network), to confirm complete network behavior from attachment through data connectivity. This connectivity of USRP hardware with the host PC are examin using differnt interface depending on the type of the tested USRP including X410 (QSFP+ up to 100 GbE), B210 (USB 3.0), N310 (SFP+ up to 10 GbE). The testbeds were first validated using a cable-based RF connection to confirm correct system operation before transitioning to full over-the-air testing.
