Performance Benchmarking of the 5G NR PHY on the OAI Codebase and USRP Hardware

The OPENAIRINTERFACE (OAI) system is a state-of-the-art open-source software stack for 5G new radio (NR). In this work, we benchmark the downlink throughput of the OAI 5G NR system at the physical layer. We describe the test setup and challenges involved in collecting measurements in a laboratory environment. The test setup comprises a base station (gNodeB or gNB) and a user equipment (UE) in three different connection modes: a simulator mode, where the baseband IQ samples are transmitted over a simulated channel and are made available to the UE for further processing; a cable-connected mode where the baseband IQ samples are carrier frequency shifted and transmitted over an RF cable to the UE; and finally with over-the-air transmission using antennas. The experiments are performed using the OAI 5G NR protocol stack in the PHY-TEST mode and USRP X310 hardware. The results reveal insights into the dependence of the throughput on radio configuration parameters such as the modulation and coding scheme, resource block size, number of scheduled slots, the transmit and receive gains, etc. A good match is observed between the theoretical transmission rate calculated using 3GPP standards and the measured throughput in all the connection modes that have been considered, provided the system parameters are chosen judiciously and the CPU is able to support real-time data processing.