MmWave Fronthaul-to-Backhaul Interference in 5G NR Networks

Abstract

Fixed point-to-point microwave links (P-P links) are widely used for vital backhaul connections in cellular networks. One frequency range allocated to P-P links by the International Telecommunications Union ranges from 24.25GHz to 29.5GHz. The same frequency range was also allocated to mobile services, with bands dedicated to 5G new radio (NR). Potential outages or performance drops in P-P links due to interference from 5G NR are therefore a concern to mobile network operators. We characterize the link-level performance of a commercial off-the-shelf (COTS) P-P link experimentally through measurements. We install a COTS P-P link on our campus. Through an additional experimental transmitter, we generate a 5G NR interference signal, allowing us to measure the link performance depending on signal-to-interference ratio (SIR) in the field. We measure the data rate that the P-P link achieves with respect to the interferer’s location and transmit power. We establish a relation between the P-P link’s SIR and data rate based on our measurements. We further measure the P-P link’s antenna pattern in an anechoic chamber. To investigate the impact of interfering 5G NR user equipments (UEs) in typical cellular network deployment, we perform system-level simulations based on our link-level measurements. We simulate the impact of 5G NR users on a P-P links backhaul connection in typical cell geometries. We identify the cell’s key parameter that determines the P-P link’s achievable data rate.