5G NR and LTE Downlink Coexistence Measurements Using Software-Defined Radios

With the rapid deployment of 5G NR in the sub-6 GHz frequency bands, cellular operators need to accommodate this new technology within the limited spectrum licensed to them, occupied mainly by 4G LTE. This poses the challenge of migrating their 4G infrastructure to 5G, while supporting current 4G systems in the same band. This indicates a need for wireless coexistence between 4G and 5G systems. In this paper, we present measurements of mutual downlink interference between two adjacent 4G and 5G cells. The setup is based on software-defined radios operating with cellular open-source software. The measurements show the effect of different levels of frequency overlap, from adjacent channel to co-channel, and various levels of signal-to-interference ratio (SIR). The network performance is quantified using throughput and packet loss. The results show that higher frequency overlap and lower SIR cause lower throughput and increased packet loss and that the overlap region might affect the performance. This setup can be used to study further coexistence scenarios.