Effective Digital PIM Cancellation in Multi-Band MIMO FDD Radios in 5G and Beyond

This paper investigates advanced digital cancellation techniques for passive intermodulation (PIM) in multi-band, multiple-input multiple-output (MIMO), frequency-division duplexing transceivers targeting 5 G and future wireless systems. A novel, unifying PIM signal model is proposed, applicable to multi-band radios with arbitrary number of transmit and receive antennas, enabling systematic generation of basis functions across all relevant intermodulation frequencies. Building on this framework, a comparative evaluation is conducted on three state-of-the-art nonlinear models—the memory polynomial, generalized memory polynomial, and Volterra—using real-world radio frequency measurements from commercial 5 G New Radio single- and dual-band units. The analysis highlights trade-offs between modeling accuracy and computational complexity, revealing limitations of existing PIM cancellation (PIMC) techniques. Results show that digital PIMC achieves up to 12–14 dB of suppression, underscoring its potential as a hardware-agnostic solution for effective PIM mitigation in next-generation MIMO radios.