Digital cancellation scheme and hardware implementation for high-order passive intermodulation interference based on Hammerstein model

Abstract

Passive intermodulation (PIM) interference urgently needs to be solved in the satellite communication system, owing to degrading the whole performance. Mainstream research contributions to the cancellation method for PIM were focused on the analog domain, however, the PIM distortion cannot be eliminated completely with the approaches. Meanwhile, some researchers attempt to tackle the problem through digital signal processing, nevertheless, the proposed methods were not suitable for the practical satellite communication scenario. In this paper, we present a general scheme for the adaptive feedforward PIM cancellation. High-order PIM signals at base-band are estimated by modeling the PIM distortion with Hammerstein model in the digital domain. Based on the reconstructed PIM signal, we adopt the least mean square algorithm to adaptively mitigate the PIM interference for tracking the variation of PIM. The time and frequency synchronization of PIM are based on the correlation of the peak of received signals with the corresponding reconstructed PIM signal. Practical experimental results show that the scheme can effectively cancel the PIM interference, and achieve an interference suppression gain more than 20dB.