Overview of Passive Intermodulation in Modern Wireless Networks: Concepts and Cancellation Techniques

Passive Intermodulation (PIM) is a well-known phenomenon that poses a significant challenge to modern wireless communication systems. Although efforts have been made to reduce or mitigate the PIM through hardware design, frequency planning, and/or band separation techniques, the impact of PIM on radio performance remains significant. This is especially true for radio transceivers operating in the frequency division duplex mode, which are known to be susceptible to PIM interference. Moreover, with the adoption of carrier aggregation and advanced multi-antenna technology, PIM is increasingly becoming a major problem in multi-band multi-standard radio systems. Therefore, innovative approaches that exploit PIM detection, avoidance, and cancellation techniques are required to effectively mitigate or reduce its impact. In response to these challenges, this study highlights various PIM interference mechanisms and their interactions which cause potential receiver sensitivity degradation. The discussion further explores PIM mitigation strategies, and underscores the potential of digital PIM cancellation solutions to offer a hardware-independent resolution for reducing PIM impact in multi-band radios, in the 5G era and beyond in radio systems.