Addressing PIM Challenges in Radio Base Stations: Field Issues and Testing Methods for Large-Scale Deployments

Mobile wireless broadband systems using 4G and 5G are being widely deployed. At the same time, traffic demand is still growing with operators challenged for capacity from their spectrum. The need is addressed through more compact site installations and further integrating multi-band radios and MIMO antenna systems together on the same site. However, high transmitted power levels of multiple 3GPP broadband carriers tend to generate Passive Intermodulation (PIM) sources in such high electric-field situations. With the surge of these compact integrated radio antenna systems came an increase in PIM requirements for site deployments as well as the need for suitable testing methods. This paper addresses the complexity of real-world scenarios by conducting a comprehensive investigation into Radio Base Station (RBS) equipment with PIM issues observed over the past few years. Using realistic measurements and empirical data, the findings provide valuable insights into PIM test methodologies using both Continuous-Wave (CW) and modulated signals. Furthermore, this work contributes to the development of large-scale deployment testing methodologies, fostering a deeper understanding of PIM-related challenges in 5G wireless systems. This work can help mitigate and manage PIM issues in the evolving landscape of 5G wireless communication systems.